Chapter 5 - Sampling and Testing
5.2 Chemical residues

This page is part of the Guidance Document Repository (GDR).

Looking for related documents?
Search for related documents in the Guidance Document Repository

5.2.1 Introduction

5.2.1.1 Definition

A chemical residue is the presence of a chemical in one or more tissues of the body at some time after administration or exposure, particularly at the time of slaughter. The tissues of importance for the purposes of the chemical residues program are skeletal muscle, liver, kidney, and fat. Techniques and instrumentation used today are sufficiently sophisticated to detect a variety of drugs in small amounts.

5.2.1.2 Concerns

Although microbial contamination of food continues to account for the majority of instances of illness, consumers still have a high level of concern about chemical residues in food. Drugs developed for use by the animal industry in Canada must be thoroughly tested and approved by Health Canada's Health Products and Food Branch, Veterinary Drugs Directorate, prior to being offered for sale in Canada. Veterinary biologics are regulated by the CFIA under the Health of Animals Act.

Concerns raised about the possible presence of antibiotics, hormones, or pesticides in meats include the following:

  • Allergic reactions are known to occur in sensitized persons. Penicillin causes the most severe adverse reactions and is implicated more frequently than all other antimicrobials combined. Small amounts of penicillin are metabolized in the body to penicilloic acid, which is a potent allergen. Allergy to the sulfa drugs is also common.
  • The development of antimicrobial resistance by bacteria has received widespread media attention. The concern has been raised that exposure of humans to low levels of antimicrobials through food could contribute to the development of resistant strains of pathogenic bacteria in the human population.
  • Residues could have direct pharmacologic effects if ingested. This is primarily a concern with the β-adrenergics.
  • Residues could have direct, acute toxic effects. This effect has been seen as a result of consuming fish and shellfish. The banned antibiotic chloramphenicol is known to cause aplastic anemia in some individuals. Most acutely toxic compounds are unlikely to pose a problem in meats, because levels high enough to affect the consumer will cause severe illness or death in the affected animal.
  • It has been postulated that chronic toxicity could occur from exposure to minute amounts of some chemicals over prolonged periods of time. This concern has been directed mainly at carcinogens and at compounds which are known to bio-accumulate.
  • Consumer confidence in our food supply may be reduced, even when there is little or no health risk.
  • Presence or suspicion of drug residues in a product can jeopardize export markets.

5.2.1.3 Causes

Veterinary drugs and agricultural chemicals used according to label directions should not result in residues at slaughter. Possible reasons for such residues include:

  • not following recommended label directions or dosage (extra-label usage);
  • not adhering to recommended withdrawal times;
  • administering too large a volume at a single injection site, resulting in the formation of a depot;
  • use of drug-contaminated equipment, or failure to properly clean equipment used to mix or administer drugs;
  • dosing, measuring, or mixing errors;
  • allowing animals access to spilled chemicals or medicated feeds;
  • animal effects - age, pregnancy, congenital, illness, allergies;
  • chemical interactions between drugs;
  • variations in water temperature for fish species;
  • environmental contamination; and
  • improper use of agricultural chemicals such as pesticides.

5.2.1.4 Legal authorities

5.2.1.4.1 Food and Drugs Act

Section 4(d) of the Food and Drugs Act prohibits the sale of "an article of food that ... is adulterated."

Section 23(1)(d) authorizes an inspector to detain any product which he "believes on reasonable grounds" does not comply.

5.2.1.4.2 Food and Drug Regulations

Maximum Residue Limits (MRLs) are set by Health Canada in the Food and Drug Regulations. MRLs for meat are set in Division 15, Sections B.15.001 to B.15.003, and the accompanying Tables. Table I deals with metals, Table II deals with agricultural chemicals and Table III deals with veterinary drugs.

Section B.15.002 sets a default MRL of 0.1 ppm for any agricultural chemicals not explicitly listed in Table II. Note that there is no equivalent provision for veterinary drugs; the MRL for veterinary drugs is therefore zero unless stated otherwise in Table III.

Section B.01.048 of the Food and Drug Regulations prohibits the sale, for food, of animals which have been treated with certain drugs, specifically:

  1. chloramphenicol and its salts and derivatives;
  2. 5-nitrofurans;
  3. clenbuterol and its salts and derivatives;
  4. 5-nitroimidazole compounds; and
  5. diethylstilbestrol and other stilbenes.

Health Canada has set "administrative" MRLs (aMRLs) for some compounds.

Product which contains a residue at a level less than or equal to an MRL in the Food and Drug Regulations, or an administrative MRL posted on Health Canada's Web site, is not considered adulterated, and may be released.

5.2.1.4.3 Meat Inspection Act

Section 13.(1)(b) authorizes an inspector to inspect and take samples of any meat product or other thing that the inspector believes on reasonable grounds does not comply with this Act or the regulations.

Section 15.(1) authorizes an inspector to seize and detain any meat product or other thing if he believes on reasonable grounds that the product is out of compliance.

5.2.1.4.4 Meat Inspection Regulations, 1990

Section 2(1) of the Regulations provides a definition of "adulterated".

Section 20(1) of the Regulations authorizes an inspector to detain an adulterated meat product until it can be brought into compliance, or condemn it if it cannot be brought into compliance.

Section 68(1) requires an operator to comply with an instruction from an official veterinarian to hold and segregate an animal.

Section 131(1) of the Regulations requires an operator or importer to provide any samples requested, free of charge.

5.2.1.4.5 Health of Animals Act

The Health of Animals Act empowers inspectors to deal with named "toxic substances." However, no toxic substances have been named under the Act. Therefore, powers of inspectors under this Act cannot be invoked. Regulations relating to this section of the Act and a list of substances are under development.

5.2.2 Individual exposure

5.2.2.1 Introduction

Some medications are deliberately administered to animals to treat specific disease conditions, by injection, bolus, or infusion.

In addition, animals may be exposed to agricultural chemicals or environmental contaminants through accidental ingestion or environmental exposure, and then culled because of signs of illness or impaired production.

Treatment or exposure may result in residues in edible portions of the animal.

5.2.2.2 Sample selection

Every animal which an inspector believes on reasonable grounds may have been treated with a medication or exposed to a chemical is a residue suspect, and must be detained until its status can be determined.

"Reasonable grounds" may include (but are not limited to):

  • the presence on ante mortem examination of signs of a disease condition for which a medical therapy is available;
  • the presence on ante mortem examination of pathological changes typical of a disease condition for which a medical therapy is available;
  • behavioural changes or clinical signs associated with exposure to or treatment with a particular substance or class of substances (such as dystonia with botulina toxin or pupillary constriction with organophosphates);
  • the presence on ante mortem or post mortem examination of anatomical changes associated with exposure to or treatment with a particular substance or class of substances (such as heavy muscling with β-agonists, or development of sexual structures with estrogens or androgens); and
  • a history of recent medical treatment, such that the animal may not have reached the withdrawal period, or such that slightly delayed clearance may result in residues still being present.

Additional guidance may be found in the following sections on specific compounds. The Area Program Specialist, Chemical Residues, may also be able to provide advice.

5.2.2.3 Testing

Appropriate testing is dependent on the particular compound. See the following sections on specific compounds for guidance. The Area Program Specialist, Chemical Residues, may also be able to provide advice.

5.2.2.4 Follow-up

Hold the carcass and all its parts until laboratory results are received. Alternatively, the company may elect, with the inspector's permission, to treat the held product as condemned material in accordance with Section 88 of the Meat Inspection Regulations, 1990, rather than incur the cost or inconvenience of storing it pending results. However, portions must be disposed of under inspectional control. It is also prudent to keep samples for repeat tests or additional testing. Additional guidance may be found in the following sections on specific compounds.

For most compounds, where only a single animal is involved, disposal of the carcass or portions via inedible rendering is permissible, due to the considerable dilution. This may not apply in the case of known or suspected carcinogens.

5.2.3 Exposure of a lot

5.2.3.1 Introduction

Note: Herdmates of animals which test positive on the Sulfa On Site test are dealt with under that section. See section 5.2.9, sulfonamides.

Section 5.2.2 deals with medications normally administered to individual animals.

Other medications are customarily administered to groups of animals, usually through medicated feed or water, for the purpose of:

  • growth promotion or other production enhancement;
  • disease prevention; and
  • treatment of a disease outbreak.

If an animal is found to have residues of medications normally administered to groups of animals, it is likely that other animals from the same production group (farm, herd, flock, barn, pen, etc.) or herdmates have similar residues.

Detection of a residue of a herd or flock medication in one animal of a lot is sufficient grounds to suspect presence of a residue in the other animals in the same lot presented for slaughter at the same time.

Occasionally, an owner may seek advice on a herd or flock known to have received treatment prior to slaughter, when doubt exists whether the observed withdrawal time was sufficient to clear the medication from tissues. All requests of this type which are submitted to the Veterinarian in Charge must be discussed with the Program Specialist, Chemical Residues. In general, the producer is responsible to ensure that animals he sends for slaughter are free of chemical residues, and the abattoir is required to have controls in place to assure this. If the situation warrants it, and the shipping of pre-test animals is indicated, the producer should send only the number of animals specified by the Program Specialist, usually six. The carcasses and all their parts must be held until the appropriate tissues have been analysed. Other samples may be collected at the time of slaughter of the production lot which the pre-test animals represent.

If a medication was administered extra label by a veterinary practitioner, that veterinarian can contact the Canadian Global Food Animal Residue Avoidance Database (CgFARAD) to obtain a recommended withdrawal time. For some antibiotics, rapid urine test kits are available.

The Veterinarian in Charge will consult the residue specialist to determine what measures are required in each case. The consultation process shall happen before the animals are brought to the plant, to permit preparation for the arrival of animals and avoid a premature or accidental kill of the lot before a decision is made. The CFIA will provide the operator with conditions to be met to allow the animals to be slaughtered. These shall be accepted by the plant operator before the kill actually occurs.

Operators are responsible to accept only animals which are free of harmful chemical residues for the preparation of meat. This should have been addressed by the plant's Hazard Analysis Critical Control Point (HACCP) plan. If an operator wishes to bring animals of uncertain status into his plant, he should provide all available information to the veterinarian in charge in advance, so that an assessment can be made and to avoid the need to hold large amounts of animals or product.

In cases in which the shipping of pre-test animals is not practical, such as poultry flocks, the producer may euthanize, or have euthanized, a number of animals and send them for residue testing in advance of the anticipated slaughter date. All testing of live animals or animals euthanized for the purpose of demonstrating freedom from residues will be done at the producer's expense. Samples should be selected by a competent, objective, independent third party, such as a private veterinary practitioner, and submitted to an accredited private laboratory.

The producer or veterinary practitioner should contact Standards Council of Canada (SCC)/CFIA accredited labs to schedule the testing and to confirm sampling, packaging and shipping requirements.

If the Veterinarian in Charge is not satisfied that the animals have been demonstrated to be residue-free, he still has the discretion to hold the carcasses and all their parts and submit samples for testing, in consultation with the Area Program Specialist, Chemical Residues.

5.2.3.2 Sample selection

Where a herd or flock is known to have received treatment prior to slaughter and doubt exists whether the observed withdrawal time was sufficient to clear the medication from tissues, several animals from that lot should be tested for the substance suspected. Animals selected for sampling should be the poorest of the lot, as these are the ones most likely to have a residue. Codex Alimentarius document CAC/GL 16, titled "Codex Guidelines for the Establishment of a Regulatory Programme for Control of Veterinary Drug Residues in Foods", section 6.4.1, Sampling suspect lots, states:

"A minimum of 6 to a maximum of 30 primary samples should be collected from a suspect lot. When the suspected adulteration is expected to occur throughout the lot or is readily identifiable within the lot, the smaller number of samples is sufficient."

Consult with your Area Program Specialist, Chemical Residues, to determine the appropriate sample size.

Medications are sometimes used "extra label", in other words not in accordance with the label instructions. This may include exceeding the label dose, or using the product in a species other than that for which the label provides directions. Withdrawal times can vary dramatically between species, even closely related ones.

Guidance on withdrawal times for extra label use can be obtained from the Canadian offices of the Global Food Animal Residue Avoidance Database (CgFARAD).

If gFARAD provides a written opinion regarding an appropriate withdrawal time for an extra label use, and the affected animals have met that withdrawal time, then they are deemed not to be residue suspects, and should not be detained. However, it may be appropriate, in consultation with the program specialist, to collect a check sample to validate our confidence in the advice.

5.2.3.3 Testing

For red meat species, if the residue suspected is an antibiotic, it may be possible to use the Swab Test On Premises (STOP) test to screen six carcasses from the suspect lot. If the STOP is negative, then the suspect herd can be released. This is only applicable if the STOP is known to be sensitive for the antibiotic suspected. Discuss this option with the Area program specialist, chemical residues, before proceeding. The STOP test is not valid for use in poultry. See section 5.2.7, Antibiotics.

Unscheduled samples must not be submitted without prior arrangement. Contact your Area Program Specialist to make the arrangements, and to determine what samples are required. As a general rule, unscheduled samples should go to a CFIA laboratory, and the cost of the analysis shall be charged to the operator. It will sometimes be necessary to use a private laboratory if the test is of a type not available "in house".

When analysing multiple tissues from a suspect herd, the CFIA will stop the analysis once a violation is demonstrated. Any further testing is the responsibility of the operator.

5.2.3.4 Follow-up

5.2.3.4.1 Herdmates alive

As a rule, no animal suspected of harbouring harmful residues should be brought to a registered establishment, so this should be a rare occurrence.

If the remaining herdmates are alive, they should be withheld from slaughter until they have had time to clear the residue from their system. Another six "pre-test" animals from the group should then be slaughtered and tested.

The suspect group may be held in the company's live receiving area. If so, precautions must be taken to ensure that the animals are not inadvertently slaughtered and their identity lost. Care must also be taken that the animals do not become a source of contamination for other animals in adjacent pens.

Alternatively, the suspect lot may be removed from the registered premises back to their farm of origin, or to any other suitable place, with the written permission of the veterinarian, to await clearance of the residue. In this case, the animals must be properly identified or otherwise controlled to ensure that they are not slaughtered elsewhere in the interim.

If the animals must be slaughtered, for humane or operational reasons, then they should be segregated during slaughter and handled in accordance with section 5.2.3.4.2, "Herdmates slaughtered".

5.2.3.4.2 Herdmates slaughtered

If a herd problem is suspected during slaughter, then all carcasses and offal from that herd should be held pending test results. This is much easier than attempting to locate the carcasses of herdmates following a violative result.

If a group of animals is not determined to be suspect until after they have been slaughtered, then every effort should be made to locate and detain the affected carcasses and offal. Samples of appropriate tissues from six animals should be selected at random and submitted for analysis to determine whether there are likely to be violative residues in the lot.

Where a flock or herd is deemed suspect, and has been sampled, the lot shall be deemed unacceptable if one animal or carcass exceeds the tolerance limit.

If the product has become mixed with other production and cannot be identified, then all product which might include the affected portions must be held.

If some or all of the carcasses or offal of herdmates has left the plant, a determination must be made whether a product recall is warranted. This decision will be made by the Area Program Specialist in consultation with the National Manager, Chemical Evaluation. The decision will be based on the tissues affected, the level of residue suspected, and the degree of hazard associated with exposure to the compound.

5.2.4 In-plant exposure

5.2.4.1 Introduction

Product in registered establishments is sometimes exposed to chemical contamination as a result of an accident in the plant, such as a fire, ammonia leak, or burst hydraulic line. In most cases, such exposure only affects the surface of exposed product. However, potentially contaminated product should be detained until its status can be determined.

Request the plant management to provide a detailed written description of the incident that led to the contamination, signed by the operator, to avoid any dispute at a later time as to what actually happened. The veterinarian or inspector in charge should add a statement that, to the best of his knowledge, the operator's statement is correct.

If the operator wishes to attempt to salvage any of the exposed product, he should also make a written request for risk assessment, including what use the operator wishes to make of the product for the purpose of this assessment.

Contact your Area Program Specialist, Chemical Residues, for guidance.

5.2.4.2 Sample selection

If the contaminant is a volatile agent, such as ammonia or chlorine, the operator should ventilate the area and allow time for the agent to dissipate.

In addition to the hazards of ingestion of residues, the possibility of product adulteration (off flavours or odours) must be considered. For some substances, organoleptic testing (smell and taste) is more sensitive than any laboratory assay.

Depending on the nature of the exposure, product may not have been uniformly exposed. If product is to be submitted for laboratory evaluation, collect a minimum of six samples, from various locations throughout the affected product.

5.2.4.3 Testing

Organoleptic testing should be conducted in the following order:

  • odour test of exposed product at room temperature;
  • odour test of exposed product after heating in a sealed plastic bag; and
  • taste test of cooked product.

Laboratory assays may not be available for the compounds of interest. Consult with your Area Program Specialist, Chemical Residues, for guidance. Where exposure involves a mixture of compounds (such as smoke exposure from a fire), it may be possible to test for an indicator substance, or a compound of particular concern (for example benzo-a-pyrene).

5.2.4.4 Follow-up

Any product which has been visibly affected (such as by smoke discolouration) must be trimmed or condemned.

Any product which has been detectably adulterated, as determined by the presence of off flavours or odours on organoleptic testing, must be condemned.

Any product which contains a chemical in excess of the maximum residue limit, as determined by laboratory analysis, must be condemned.

See Chapter 6 for guidance on disposal of condemned material containing chemical residues.

If the contaminant is volatile and could plausibly dissipate from the product surface, the company may, at its discretion, hold the product for a period of time and then submit further samples at its own expense. However, the product may not be restacked or mixed, in such a way that surfaces which were exposed to contamination become buried in the interior. The product may not be held in such a manner that it poses a contamination hazard to unaffected product.

5.2.5 National Chemical Residue Monitoring Program - Domestic

5.2.5.1 Introduction

The National Chemical Residue Monitoring Program is the CFIA's main program for monitoring various species to determine the prevalence of residues of various compounds of concern. The program consists of a statistical random sampling designed to detect a 1% incidence of violations at a confidence level of 95%. Sampling plans are prepared at headquarters, and distributed in the form of a sampling plan booklet, with one sample per page. One sample may consist of several tissues.

The National Chemical Residue Monitoring Program uses the Multiple Analysis Submission System (MASS), which permits the performance of several analytical operations on a single sample, in an attempt to keep sampling time and associated shipping costs to a minimum. Each sample is uniquely identified on the basis of a sample number by affixing the sample number to the bag using a CFIA/ACIA 1461, in such a fashion that it will not become detached in transit, and will remain legible. This number tells the laboratory which analyses to perform. The need for the inspector to list the desired tests is thus eliminated.

If a new establishment opens, or an existing establishment closes, or changes the main species it slaughters, it may be necessary to reallocate samples before the end of the fiscal year, in order to ensure that the samples continue to be representative of the entire slaughter population. In the event of an operational change, the Area Program Specialist, Chemical Residues, may assign additional samples to your establishment part way through the year.

5.2.5.2 Sample selection

Only normal (not suspect), domestic animals are to be sampled.

To ensure random sampling, the sampling plan specifies not only the day but also the hour of sampling to avoid bias or duplicate sampling from the same owner if more than one sample is required on the same day.

If an establishment is not slaughtering the applicable species on the day specified in the sampling plan, or for some reason a sample cannot be taken, the sample may be taken at random from one of the next day's production, or the next day on which the applicable species is available. However, do not carry scheduled samples over from one fiscal year to the next, in other words past March 31.

If your plant no longer slaughters the indicated species, notify your Area Program Specialist, Chemical Residues, and return copies of the applicable pages from your sample plan booklet, so that the samples can be reallocated. The original pages should be retained in the sampling plan booklet, and annotated to indicate that this has been done.

The owner's name and address and (where applicable) the national livestock identification number must be recorded in the space at the bottom of each page in the sampling plan. Also include any other identifying information, such as sale or auction backtags, Heath of Animals eartags, brands or tattoos, and the breed and sex of the animal. If residues are found on analysis, you will need to be able to provide this information to permit follow-up. At the end of each fiscal year, the booklet should be filed in the inspection office as a permanent record. Booklets must be retained for three years from the end of each fiscal year.

It is important to collect a sufficient weight of the correct tissues, as indicated in the sample plan booklet.

Where a sampling plan calls for samples of muscle, the requirement is for skeletal muscle. To the extent possible, the sample should be taken from low-value portions of the carcass, such as diaphragm or neck. Avoid sampling injection sites, or tissue which may have been subjected to post mortem contamination.

5.2.5.3 Testing

Only the laboratory which is scheduled to receive the sample will have all the necessary information to complete the testing. It is therefore absolutely essential to submit the sample to the correct laboratory. The name and address of the correct lab is provided on every sheet in the sampling plan booklet. The sampling plans for one establishment may make use of several different labs, so check each sheet carefully and ensure that the sample goes to the correct lab.

Since product is not held for monitoring programs, these samples will be processed as a low priority by the lab. Samples may be accumulated by the lab for several weeks or months, then processed as a batch, to make the most efficient use of lab resources.

To reduce shipping costs, several samples may be shipped together as a single package. However, do not hold samples at the plant for longer than one week. Samples held too long in storage may deteriorate, or be lost or forgotten.

After shipping the sample, record the date and waybill number on the page in the sampling plan booklet, as proof that the sample was submitted, and to permit tracing in the event that the sample is not received at the lab.

See section 5.7.3 for direction on sample submission.

5.2.5.4 Follow-up

Since product is not held for monitoring tests, product disposition will not normally be affected by any violative result. Otherwise, samples which are found to be violative under the National Chemical Residue Monitoring Program will be followed up in the same manner as any other violative test. The presence of a violative residue will trigger a farm visit, similar to that for antibiotics (see section 5.2.7.5). Based on the results of that inspection, the producer may be subjected to compliance testing.

5.2.6 National Chemical Residue Monitoring Program - Imports

5.2.6.1 Introduction

Like the domestic program, the imports program attempts to conduct statistically based sampling for residues in the population of interest. Because the arrival of shipments cannot be predicted in advance, it is not possible to produce a plan with specific sampling dates like that used in the domestic program. Instead, sampling frequencies are specified.

5.2.6.2 Sample selection

Sample selection is based on the country of origin and the type of product. Details are found in Annex M of Chapter 10. The main table specifies the country of origin, the frequency of sampling, and the amount of product to be sampled.

When Chapter 10, Annex M refers to sampling of "muscle", this means skeletal muscle only.

5.2.6.3 Testing

Annex M of Chapter 10 also specifies to which laboratory the samples are to be sent. Note that, in most cases, the laboratory is determined by the Area in which the product is received and reinspected, but that a few sampling programs are exceptions. Read the Annex very carefully before shipping the sample.

Whether the sample goes to a private lab or a CFIA lab, it should be accompanied by a form CFIA/ACIA 5164 "Food product sampling submission form", generated by the Sample Submission Form application.

Because private laboratories do not use Laboratory Sample Tracking System (LSTS), forms for submissions to private labs cannot be submitted or filled out electronically. Instead, click on the "Issue blank form" button to print a hard copy, and fill it out manually.

The sampling plan number is the fiscal year, followed by an underscore and "M8IMP", for example "2009_M8IMP". Use the "import control number" as the laboratory sample number.

Please ensure that the Food Product Sampling form is completed in sufficient detail to permit a rapid and efficient identification of the production lot sampled. For imported products the Import Inspection Report number must also be entered in the "identification code" field.

In the case of an unsatisfactory laboratory result, the submission form must provide all necessary product information to initiate a recall or follow up investigation and in the case of imported products, to advise the foreign country.

The specific tests which will be performed are based on the country of origin and the type of product. The laboratory will have this information.

5.2.6.4 Follow-up

Product sampled under this program is not detained, unless there are other problems with the shipment. All violative laboratory results from monitoring samples of imported meat are followed by intensified inspection. This means that the next 15 shipments, of a weight at least equal to that of the shipment found in violation, will be held and tested for the compound. Rather than wait for the test result, the exporting establishment has the option to have the product pre-tested, in an accredited private laboratory, and have the certificate accompany the shipment.

5.2.7 Antibiotics

5.2.7.1 Introduction

Antibiotics may be administered for growth promotion, for disease prevention, or for the treatment of infections. They may be administered via feed or water, by injection, or via timed-release boluses.

5.2.7.2 Sample selection

The Veterinarian in Charge will determine whether an animal is considered a suspect or not and whether to initiate testing for the possible presence of antibiotic residues. Practitioner certification that an animal has not been given antibiotics does not override this authority or this responsibility.

Antibiotic use should be suspected in any animal in which an injection site is found, and any animal affected with a septic condition, which might have been treated with antibiotics. The following is a partial list of pathologies and conditions that warrant retention and testing of carcasses.

  • Mastitis – carcasses with inflammatory ventral edema in the perineal area resulting from mastitis. Hemorrhages and yellow serous infiltrate, located ventrally, are typically present.
  • Metritis – carcasses with acute metritis. Associated pathology includes enlargement of the uterine body, distension of the uterine horns with a fetid brown, red brown, or black fluid; thinning of the uterine wall; and lack of evidence of normal uterine involution (no lines of contracture in the myometrium).
  • Peritonitis and surgery – carcasses with active peritoneal inflammation associated with fibrinous exudate or fetid ascitic fluid, no matter how limited the extent of the lesions, or with ventral abdominal cellulitis secondary to percutaneous abomasal surgery. Findings of surgical devices (suture, toggles, fistula devices, etc.) are only significant if they are associated with active peritoneal inflammation (the presence of fibrin as opposed to chronic peritonitis with fibrous adhesions).
  • Injection sites – carcasses with lesions associated with injections. Injection sites are likely to be found in a variety of locations including the neck, shoulder, thorax, axilla, ventral abdomen (along the subcutaneous abdominal vein), flank, hindquarter, pelvic area (perirectal) and tail. Also, look for cellulitis that is away from pressure points (e.g., tuber ischii, hip joint, stifle joint). These are generally found in the semimembranosus and semitendinosus muscles.
  • Pneumonia – carcasses with acute, subacute, or chronic active pneumonia; with pleural cellulitis resulting from reticuloperitonitis complex; or with embolic pneumonia.
  • Pericarditis – carcasses with fibrinous or fibrinosuppurative pericarditis.
  • Endocarditis – carcasses with endocarditis and acute pulmonary, renal or other embolic lesions. Also, test carcasses that are condemned due to septicemia, toxemia, or other reasons.
  • Abomasal or intestinal disease – carcasses with abomasal displacement, abomasal torsion, intussusception, mesenteric torsion, or cecal torsion.
  • Nephritis or cystitis.
  • Septicemia and toxemia – carcasses that are being condemned for septicemia, toxemia, or other inflammatory/infectious conditions.
  • Diamond skin or other skin conditions associated with generalized or systemic infection.
  • Animals identified during ante mortem inspection that were determined to be suspect for residues.
  • Animals identified during ante mortem inspection showing signs of generalized infection (such as depression, a body temperature above or below the normal range, hyperemic skin, congested mucous membranes, dehydration or poor body condition), in association with an injury or inflammatory condition.
  • Carcasses with acute cellulitis or other acute inflammations associated with a fibrinous or fibrinosuppurative exudate in any location on the carcass or viscera.

Animals which were non-ambulatory prior to loading would also be suspects, but transportation of this class of animal is not permitted under the Health of Animals Regulations.

Even if the animal is condemned because of the pathology, a STOP test should still be conducted, so that residue violations may be detected and traced back.

Antibiotic use may also be reported by the producer.

Any animal suspected of having been treated with an antibiotic, especially if there is a suspicion that the withdrawal time was not observed, should be held for testing. It should be noted that some antibiotics have withdrawal times of up to 30 days.

Testing should also be done on a proportion of normal animals, both to maintain proficiency in plants which receive few suspects, and to use up old kit supplies before they expire. In an establishment where suspect animals are rarely available for testing, having each inspector perform the test at least once a week on a normal animal should be sufficient to maintain this proficiency.

5.2.7.3 Testing

Initial screening of animals suspected of having antibiotic residues is conducted using the Swab Test On Premises (STOP). STOP kits are normally supplied twice a year, Spring and Fall.

The STOP test is performed in accordance with the procedure described in the self-instructional guide, "Performing the Swab Test On Premises (STOP) for antibiotic residues", dated May 2002. This procedure must be followed exactly. Variations in the technique have not been tested for reliability, so could result in false test results, and could be challenged in court or by foreign auditors.

Keep the STOP report (CFIA/ACIA 1479) on file at the establishment. These reports should be reviewed regularly by the Regional Veterinary Officer. Send a copy to your Area Program Specialist, Chemical Residues. If a laboratory result is pending for a held carcass, wait for the lab report before sending the completed CFIA/ACIA 1479.

If an animal is suspected of having antibiotic residues, all costs for the initial screening test (STOP) will be charged to the establishment according to the regulations, regardless of whether the result is positive or negative. The fees are specified in the Canadian Food Inspection Agency Fees Notice, Part 10. Random tests on normal animals are not cost recovered.

If the sample is collected from an establishment operating under a federal-provincial agreement, one copy of the STOP report (CFIA/ACIA 1479) must be forwarded to the responsible Regional Office for cost recovery to the applicable province.

Note: If it is discovered that a substantial amount of offal or viscera from animals with residues has been sent for rendering, the Veterinarian in Charge will immediately notify the Office of Food Safety and Recall; and the Feed Section, Animal Health and Production Division. It is important to note that raw material delivered to a rendering plant can be rendered into feed and reach farms within 24 hours.

5.2.7.4 Confirmation

The STOP test is only a presumptive test for the presence of microbial inhibitors, and must be confirmed by laboratory testing before a disposition can be made.

If the initial screening result is negative, the carcass is released. If the result is positive, the carcass remains under detention. The company may elect to discard the offal.

The company has the option to accept or decline laboratory confirmation. Explain to the company that, should the laboratory confirmation fail to detect violative residues, no further charges will be levied. If violative residue levels are detected in skeletal muscle, then the costs of the laboratory work will be charged. The charges can vary, depending on the amount of work that needs to be done. In addition, the carcass will be condemned should the muscle sample contain violative levels. The company should indicate its choice by completing the "Submission Form - Cost Recovered Antibiotic Confirmation" (See Annex A).

Statistics on the results of screening and confirmatory testing must be kept at all establishments so that the program results can be reviewed periodically and to aid future decision-making.

The sampling plan number is the fiscal year, followed by an underscore and "M8STP", for example 2009_M78STP.

5.2.7.4.1 Company agrees to confirmation

Submit 500 g of skeletal muscle. Samples of muscle should be selected from a location well away from any suspected injection site, such as the diaphragm. For carcass disposition, skeletal muscle must be used, as smooth and cardiac muscle are metabolically different, and levels detected there cannot be extrapolated to the carcass.

Do not submit the injection site from a STOP positive carcass. Because injection sites often contain high levels of the antibiotic, the residue can contaminate the equipment and the laboratory environment. The laboratory will not analyse these samples.

When the Report of Analysis is received from the laboratory, the Veterinarian in Charge should review it to determine which analyses were performed, then consult the Canadian Food Inspection Agency Fees Notice, Part10, to determine the cost of the testing. If it is a federally registered establishment, the Veterinarian in Charge will invoice the abattoir by the methods currently in use. In the case of establishments under inspection under federal-provincial agreements, a copy of the submission form (Annex A) should be sent to the Regional Office so that the appropriate provincial government can be invoiced.

5.2.7.4.2 Company declines confirmation

If the operator refuses to accept these conditions, then the operator must make a request in writing to treat the held carcass as condemned (section 88 of the Meat Inspection Regulations, 1990). The carcass should be discarded and recorded as screening test positive but not laboratory confirmed. No condemnation certificate shall be issued since it was the choice of the company to take this course of action.

In the event that the carcass is condemned at the operator's request, a kidney should be submitted to the Centre for Veterinary Drug Residues, Saskatoon, regardless. This will serve to identify the compound which resulted in the positive test, both to validate the STOP result and to determine whether a residue concern exists. Because the carcass is not held in this case, the lab will treat the sample as low priority.

5.2.7.5 Follow-up

Carcasses and organs may not be released until laboratory reports are received. The dressed carcass and all organs derived from the carcass shall be condemned if the skeletal muscle from that carcass gives a violative result. When a liver or kidney or both are found violative (in excess of the MRL) but the skeletal muscle is negative or non-violative, then only the organs shall be condemned.

See Chapter 6 for guidance on disposal of condemned material containing chemical residues.

Where a violative result is confirmed in kidney or muscle, the Program Specialist will arrange for an inspection of the farm of origin, in accordance with the Animal Health manual on Chemical Residues. Based on the results of that inspection, the producer may be subjected to compliance testing.

Compliance testing is conducted on the basis that, because of the previous violation, any animal from the same producer is deemed suspect until demonstrated otherwise. Subsequent shipments from the same producer will be held for STOP testing until the Program Specialist deems that residue-free status of the herd of origin has been established.

5.2.7.6 Disposal of STOP kit components

5.2.7.6.1 Introduction

The STOP kit uses a culture of Bacillus subtilis. This organism is widespread in the environment, and the strain used in our test kits is susceptible to a wide range of antimicrobial agents. It is not considered to be a human pathogen. However, although this kit has been in use for over 20 years, and no problems have been documented from its use, cases of infection with B. subtilis have been documented in individuals with impaired immune systems.

Discarding used plates, swabs, etc. into the normal dry waste stream is not considered good laboratory practice. The standards are set out in the Laboratory Biosafety Guidelines 3rd Edition 2004.

5.2.7.6.2 Disposal options

The following are acceptable options for disposal of kit components (culture plates, spore suspensions, used swabs), in descending order of preference.

5.2.7.6.2.1 Plant hazardous waste stream

If the establishment operates a microbiology laboratory of its own, the components may be discarded in the establishment's laboratory waste stream in accordance with their laboratory protocols.

5.2.7.6.2.2 Disinfection – Sodium Hypochlorite

Plates and swabs may be disinfected by flooding the plate with a 0.5% solution of sodium hypochlorite. This is prepared by mixing 1 part household bleach (5.25%) with 9 parts water. Bottles of spore suspension may be disinfected by adding 3 mL of the bleach solution to the bottle, recapping, and shaking. In both cases, materials should be allowed to sit in contact with the disinfectant for 30 minutes before discarding.

The lids should be secured to the plates with celluloid tape or other suitable means prior to discarding.

Containers and bags must be adequate to prevent leakage of disinfectant.

Note: Most commercial disinfectants are ineffective against bacterial spores.

5.2.7.6.2.3 Disinfection – Virkon™

Virkon™ (Antek International) is a general purpose bactericide and virucide. Although it is not registered as a sporicidal or chemosterilant agent, the manufacturer considers it sporicidal with sufficiently long exposure times. Because its ingredients have low environmental toxicity, it may have some appeal for sterilizing the STOP plates.

Plates and swabs may be disinfected by flooding the plate with a 1% solution of Virkon™. This is the concentration obtained by mixing the product according to the manufacturer's directions. Bottles of spore suspension may be disinfected by adding 3 mL of Virkon™ to the bottle, recapping, and shaking. In both cases, materials should be allowed to sit in contact with the disinfectant for at least eight hours before discarding.

Virkon™ is sold as a powder, and is not stable once dissolved. Therefore, a fresh supply must be made up each time it is needed.

5.2.7.6.2.4 Autoclave

Autoclave at 121°C for 30 minutes. Plates should be packaged in standard "biohazard" bags with indicator markings prior to autoclaving.

The autoclave should go through a load test to verify that the time and temperature are adequate, in accordance with the manufacturer's instructions, the first time the autoclave is used, and then regularly thereafter depending on use.

5.2.7.6.3 Other details

Kidneys and other readily degradable material may be disposed of in the establishment's inedible waste. Plastic plates and glass bottles would contaminate the rendering process, and may not be discarded by this means.

5.2.8 Tetracyclines

5.2.8.1 Introduction

Tetracyclines (tetracycline, oxytetracycline, chlortetracycline) may be used for either prevention or treatment of bacterial infections. Oxytetracycline and chlortetracycline may be added to feed in accordance with Medicating Ingredient Brochures, alone or in combination with other antimicrobials.

Oxytetracycline is also available for administration by injection. Oxytetracycline and tetracycline may be administered via drinking water. Tetracycline is available as a bolus.

The tetracyclines form insoluble complexes with calcium. Animals treated with tetracyclines therefore acquire permanent deposits of tetracycline in the bones, which are visible as a yellow discolouration which fluoresces under ultraviolet light.

A yellow discolouration in the bones of market hogs is probably due to tetracycline; however, other compounds can cause this.

5.2.8.2 Testing

The presence of the discolouration in bones is not an indicator of tetracycline residues in muscle. Because the deposits are essentially permanent, the medication may have long since been cleared from other tissues. Meat from hogs with yellow bones does not appear to be at an increased risk of having unacceptable tetracycline residues, and residue testing is not warranted unless there are other indications of recent treatment.

5.2.8.3 Follow-up

The yellow discolouration is to be solely considered a quality defect. Operators of hog slaughter and processing establishments are responsible for ensuring that discoloured products, including yellow bones, are not offered for sale to consumers. No action or special inspection activity is to be undertaken by CFIA during post-mortem procedures as this is an operator quality managed defect. Furthermore, considering that the yellow colouring of bones may disappear after the carcass has remained a certain time in the cooler, operators can decide that the removal of parts of bones that showed a yellow discoloration at the time the carcass was dressed, is no longer justified once the carcass is ready to be boned at the establishment or shipped. Should the removal of these bones from the carcass take place at another Federally Registered Establishment a control program acceptable to the Veterinarian in Charge shall be put in place.

Yellow bones may not be used for mechanically separated meat or any other edible purpose. These bones must be disposed of in a manner that meets the requirements of section 54 of the Meat Inspection Regulations, 1990.

5.2.9 Sulfonamides

5.2.9.1 Introduction

Sulfonamides are used primarily in the prophylaxis and therapy of bacterial diseases. In combination with antibiotics, notably of the tetracycline and penicillin group, they are widely employed as medicated feeds to increase the rate of weight gain in livestock.

In hogs, these compounds serve as an aid in maintaining growth rate and feed efficiency in the presence of atrophic rhinitis, and in the prevention of bacterial enteritis, including hog cholera (Salmonella enterica) and swine dysentery.

In beef cattle, sulfonamides are used to maintain weight gain and feed efficiency during periods of stress due to weaning, shipping or handling.

In poultry, sulfonamides form a valuable aid in preventing or in reducing mortality due to coccidiosis, fowl typhoid and acute fowl cholera.

Injectable and bolus sulfonamides may be administered alone or formulated in combination with a synergist such as trimethoprim. Such products may contain more than one sulfa.

Sulfonamides may therefore be administered to a single animal, or as a mass medication. Only sulfamethazine is licensed for use as a medicated feed ingredient. Sulfaquinoxaline may be administered to poultry via water.

The rationale for testing dressed carcasses and organs for sulfonamide residues is largely analogous to that of antibiotics.

Rapid screening for sulfamethazine in market hogs is performed using the Kidney Inhibition Swab (KIS) test manufactured by Charm Sciences Inc.

5.2.9.2 Sample selection

Sampling frequencies for the KIS test are set for each establishment by the National Manager, Chemical Residues. The frequency specifies how many tests are to be performed per week, and how many are to be performed in each batch.

If samples are not being taken every day, avoid falling into a pattern, such as testing only on certain days of the week, or every second day. Also avoid taking samples only at certain times of the day. This is to prevent producers from evading testing by predicting when it will occur.

Animals should be selected from different truckloads or sale lots. Since sulfonamides are normally administered to an entire lot, there is no point in testing more than one animal from a single barn.

5.2.9.3 Testing

The presence of sulfamethazine residues in swine is monitored by the use of the Kidney Inhibition Swab (KIS) rapid in-plant test.

The KIS test is performed in accordance with the procedure described in Meat Hygiene Training Module E-8, PS# I6D252, Version 1 - October 2010. This procedure must be followed exactly. Variations in the technique have not been tested for reliability, so they could result in false test results, and could be challenged in court or by foreign auditors.

All costs associated with sulfonamide testing, including both in-plant screening and confirmatory testing, are to be charged to the establishment. Fees are to be calculated according to Part 10 of the Meat Products Inspection Section, Canadian Food Inspection Agency Fees Notice.

5.2.9.4 Follow-up procedures on positive KIS test

The KIS test is not specific for sulfamethazine, but only detects the presence of microbial inhibitors. Therefore, a positive KIS test cannot be assumed to affect the herdmates.

Laboratory confirmation of presumptive positives is mandatory. One 500 g sample of skeletal muscle and 500 g of liver must be frozen and shipped to the Centre for Veterinary Drug Residues, Saskatoon accompanied by a completed CFIA/ACIA 5165 form (Meat Product Inspection Sample Submission Form).

The sample plan number is the fiscal year, followed by an underscore and "M8KIS", for example "2011_M8KIS".

The carcass, viscera, and offal from the test animal must either be held pending laboratory confirmation or treated by the operator as condemned. The condemned carcass and offal may be sent for normal rendering.

5.2.9.5 Follow-up procedures on notification of confirmatory lab results

5.2.9.5.1 Disposition

Upon notification of confirmatory lab results, the following action shall be taken on the tested animal and its herdmates:
Case # Liver Muscle Immediate action Future shipments:
1 ≤ 0.1 ppm ≤ 0.1 ppm pass carcass, viscera and offal no restriction
2 > 0.1 ppm ≤ 0.1 ppm pass carcass, condemn Table Note 1 viscera and offal pre-testing
3 > 0.1 ppm > 0.1 ppm condemn Table Note 1 carcass, including viscera and offal pre-testing
4 Table Note 2 ≤ 0.1 ppm > 0.1 ppm condemn Table Note 1 carcass, including viscera and offal pre-testing

Table Notes

Table note 1

May be sent for normal rendering.

Return to table note 1  referrer

Table Note 2

Case 4 is a rare occurrence that warrants further investigation at the discretion of the National Manager, Chemical Evaluation.

Return to table note 2  referrer

5.2.9.5.2 Pre-testing

Producers who supply animals found to be in violation of the Maximum Residue Limit for sulfonamides will be subject to pretesting.

Pre-testing consists of sampling six hogs sent in advance of the next production lot. These animals will be screened by KIS, and if the results are negative the carcasses will be released and the rest of the herd can proceed to slaughter. Any positive test is handled in the same manner as described in section 5.2.9.4 above.

Viscera from pre-test animals can be sent for inedible rendering, regardless of the presence of residues.

Where they exist, provincial Marketing Boards will advise inspection personnel and management of the establishment when pre-test animals are being shipped. A minimum period of ten days must have expired from the date of the violation before pre-test hogs can be presented for slaughter, in order to allow time for the animals on farm to clear the drug.

Violative results obtained while on pretest will require a submission of a further set of pre-test hogs upon the expiration of a minimum of ten days following the date of the previous submission.

5.2.9.5.3 On-farm inspection

In all cases of violative residues, an on-farm inspection is conducted by animal health or feeds inspectors.

5.2.9.6 Company testing

Some companies perform considerable Sulfa On Site testing in order to meet customer requirements.

If the company uses a screening test other than KIS, it cannot substitute for CFIA's testing program. Results of the company's testing shall be made available to CFIA inspectors in accordance with Section 13(1) of the Meat Inspection Act. The company's HACCP plan should describe what action the company will take in the event of a positive test.

5.2.10 Steroid hormones

5.2.10.1 Introduction

5.2.10.1.1 Use of hormonal substances

  • as anabolic agents (to increase feed efficiency, accelerate attainment of market weight and improve carcass quality);
  • as estrus regulators; and
  • for the treatment of specific disorders.

5.2.10.1.2 Steroidal growth promotants

There are various endogenous hormone preparations and two exogenous hormone preparations (zeranol and trenbolone) which are licensed for use as implanted pellets for growth promotion in calves, heifers and steers. In all cases, the recommended implant site is the ear.

The following are approved in Canada.
Registered trade name Ingredient Species Dose
Component E-C (Elanco) 100 mg progesterone
10 mg estradiol benzoate
Suckling beef calves up to 185 kg. Should not be used in veal calves intended for slaughter. Do not use in calves under 45 days of age or more than 185 kg body weight. 1 implant
(4 pellets)
Component E-C with Tylan (Elanco) 100 mg progesterone
10 mg estradiol benzoate
29 mg tylosin
Suckling beef calves up to 185 kg. Should not be used in veal calves intended for slaughter. Do not use in calves under 45 days of age or more than 185 kg body weight. 1 implant
(5 pellets)
Component E-H (Elanco) 200 mg testosterone
20 mg estradiol benzoate
Heifers 185 to 365 kg 1 implant
(8 pellets)
Component E-H with Tylan (Elanco) 200 mg testosterone
20 mg estradiol
29 mg tylosin
Heifers 185 to 365 kg 1 implant
(9 pellets)
Component E-S (Elanco) 200 mg progesterone
20 mg estradiol benzoate
Steers 185 to 365 kg 1 implant
(8 pellets)
Component E-S with Tylan (Elanco) 200 mg testosterone
20 mg estradiol
29 mg tylosin
Steers 185 to 365 kg 1 implant
(9 pellets)
Component TE-H (Elanco) 140 mg trenbolone acetate
14 mg estradiol
Feedlot heifers 300-450 kg 1 implant
(7 pellets)
Component TE-H with Tylan (Elanco) 140 mg trenbolone acetate
14 mg estradiol
29 mg tylosin
Feedlot heifers 300-450 kg 1 implant
(8 pellets)
Component TE-S (Elanco) 120 mg trenbolone acetate
24 mg estradiol
Feedlot steers 250-450 kg 1 implant
(6 pellets)
Component TE-S with Tylan (Elanco) 120 mg trenbolone acetate
24 mg estradiol
29 mg tylosin
Feedlot steers 250-450 kg 1 implant
(7 pellets)
Compudose Estradiol
  • Suckling and growing steers greater than 80 kg
  • Heifers and steers over 260 kg
1 implant (24 mg)
Ralgo 36 mg Zeranol Suckling, weaned and growing beef cattle, feedlot steers and heifers 1 implant (3x12 mg pellets)
Ralgo Magnum 72 mg Zeranol Feedlot steers 1 implant (6x12 mg pellets)
Revalor 200 200 mg trenbolone acetate
20 mg estradiol
Feedlot steers and heifers 1 implant (10 pellets)
Revalor - G 40 mg trenbolone acetate
84 mg estradiol
Pasture steers 195-320 kg 1 implant
(2 yellow pellets)
Revalor - H 140 mg trenbolone acetate
14 mg estradiol
Feedlot heifers 300-450 kg 1 implant
(7 pellets)
Revalor - S 120 mg trenbolone acetate
24 mg estradiol
Feedlot steers 1 implant
(6 pellets)
Synovex - C 10 mg estradiol benzoate
100 mg progesterone
Calves. Synovex - C implants should not be used in veal calves intended for slaughter. Do not use in calves under 45 days of age or more than 185 kg body weight. 1 implant
(4 pellets)
Synovex Choice 100 mg trenbolone acetate
14 mg estradiol benzoate
Feedlot steers 1 implant
(8 pellets)
Synovex - H 20 mg estradiol benzoate
200 mg testosterone propionate
Heifers 180-400 kg 1 implant
(8 pellets)
Synovex - S 20 mg estradiol benzoate
200 mg progesterone
Steers 180-450 kg 1 implant
(8 pellets)
Synovex Plus 28 mg estradiol benzoate
200 mg trenbolone acetate
Feedlot steers and heifers 1 implant
(8 pellets)

Note that none of these products is approved for use in calves intended for veal production. The presence of any hormonal growth promotant (implant) in a calf presented for slaughter constitutes adulteration. Carcasses of such animals shall be condemned. No testing is required.

If an implant is detected in a calf on ante mortem, the operator may elect to return it to an off-site facility for grow-out to a full weight beef animal. Note that prior to the removal of any animal from the facility, written permission from the veterinarian in charge is required, in accordance with Section 43(1) of the Meat Inspection Regulations, 1990. The CCIA identification tag number should be recorded, and measures taken to ensure that the animal will not be simply transported to a different slaughter facility.

Steers and heifers slaughtered at an unusually early age must be considered as suspect for the presence of an implant because some are approved for use on beef calves. If a steer or a heifer of a beef breed is presented at such an early age that the carcass will likely show the maturity characteristics of a veal calf described in Chapter 17, care must be taken to verify that no implant was used, as described above. The meat from an implanted steer or heifer slaughtered at an unusually early age cannot be marketed as veal if the use of a hormonal implant is suspected. If it can be demonstrated through veterinary certification, examination, and inspection that an implant was used according to the label, the meat will be allowed on the market as ungraded beef.

Only one steroidal growth promotant, melengestrol acetate (MGA) is approved as a feed additive. It has a withdrawal time of 48 hours, and must not be fed to heifers implanted with or being fed other hormone drugs. See Medicating Ingredient Brochure 46.

5.2.10.1.3 steroidal drugs

Several steroidal hormones or their analogs are available for use by veterinarians. These fall into three major categories.

Estrus Regulators:

  • Regumate (altrenogest)
  • Veramix (medroxyprogesterone)

Anti-inflammatories:

  • Azium (dexamethasone)
  • Betasone (betamethasone)
  • Flucort (flumethasone)

Anabolics:

  • Equipoise (boldenone)
  • Winstrol-V (stanozolol)

5.2.10.1.4 DES

The use of the synthetic stilbene derivative diethylstilbestrol (DES) has been prohibited in Canadian food producing animals since 1974. Use of this compound in other countries has been reported.

5.2.10.2 Sample selection

5.2.10.2.1 Implants

According to Health Canada, "the use of an implantation site other than what is recommended would unlikely be sufficient proof of adulteration under the Food and Drugs Act. While acknowledging the probable absence of harmful residue, the Drugs Directorate recommended that liver and kidney of animals implanted with these drugs in areas other than the ear not be permitted for sale as food. As well, all the area of implantation and any adjacent areas showing evidence of inflammation are to be completely destroyed." Should implanted pellets of any description be found in any area other than the ear, the above policy is in effect.

Should an inspector have any reason to believe that implanted pellets may be other than those licensed for use in Canada, then the carcass and offal should be detained. Collect the implant site into a plastic bag, freeze, and submit to the Centre for Veterinary Drug Residues in Saskatoon for analysis.

Because the ears are removed along with the hide, animals must be inspected for the presence of implants prior to hide removal.

During ante mortem screening, the operator must segregate all calves which have a missing ear, an ear with an incision indicating recent surgery, or a mutilated ear. The producer or operator must provide an acceptable written explanation for this anomaly. If the veterinary inspector is unable to determine that an implant was not present, the carcass and all its parts shall be condemned, on the basis that there are reasonable grounds to believe that the derived meat products are adulterated from the use of hormonal growth promotants.

5.2.10.2.2 DES

Since illegal use of DES in Canada could be attempted, inspectors in calf slaughter establishments should check for precocious sexual development in veal calves on ante and post mortem inspection. Special attention should be paid to the mammary gland and teat development in males and females, uterine and ovarian enlargement in females, and testicular and prostatic enlargement in males.

The following samples should be taken from suspected carcasses and submitted for laboratory testing.

  • 500 g of liver that is immediately frozen and sent to the laboratory as per section 5.7.3.
  • The sexual organs of the pelvic cavity, specifically prostate or Bartholin glands, as well as mammary glands or teats are required for histological examination. Sexual organs are to be immersed in 10% formalin. Care should be taken to avoid large pieces of tissue, as formalin will only penetrate a quarter of an inch of tissue.

The prostate in calves is located in the pelvic portion of the penis at the junction of the ureter, seminal vesicles, and corpus peni and the end of the urethral muscle. It straddles the dorsal side of the ureter in the form of a horseshoe the size of a large pea. The Bartholin glands are found on the caudo-ventral side of the vagina, on each side of the end of the ureter and clitoris. As a sample, the caudo-ventral portion of the vagina should be taken.

5.2.10.3 Testing

Do not submit unscheduled samples to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residue Monitoring Program (Section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

5.2.10.4 Follow-up

Carcasses and organs are to be held until laboratory reports are received. The laboratory result will determine the disposition of the carcass or offal, based on the applicable Maximum Residue Limit (MRL) in the Food and Drug Regulations. The dressed carcass and all organs derived from the carcass shall be condemned if the skeletal muscle from that carcass is violative. When a liver or kidney or both are found to be violative but the level in the skeletal muscle is below the applicable MRL, then only the organs shall be condemned. Contact your Program Specialist, Chemical Residues, for guidance.

Because the use of DES is prohibited in food producing animals, the presence of a residue of DES in any tissue constitutes adulteration. The carcass and all its parts will be condemned.

See Chapter 6 for guidance on disposal of condemned material containing chemical residues.

The presence of a violative residue will trigger a farm visit, similar to that for antibiotics (see section 5.2.7.5). Based on the results of that inspection, subsequent animals sent to slaughter by that producer may be subjected to compliance testing.

Compliance testing requires that, because of the previous violation, any animal from the same producer is deemed suspect until demonstrated otherwise. The Program Specialist, Chemical Residues, will determine whether a check sample (carcass not held), a compliance sample (carcass held), or a series of compliance samples is warranted; and, in the last case, how many times the producer's animals will be sampled.

5.2.10.5 Surveillance program for hormones in veal

5.2.10.5.1 Introduction

Since January 5, 2005, producers of veal calves have stopped the extra-label use of hormonal implants approved for growth promotion in market cattle. Since then, a few cases have been found in which hormones were administered by injection in calves intended to be sold as veal.

Suspect veal fall into three categories, depending on whether the lot or individual animals are suspect or not. The conformation of the animals and the history of the producer are the criteria used to establish suspicion.

In all cases, pay close attention to the following points:

  1. When a large quantity of product must be placed under detention, contact your Program Specialist, Chemical Residues, or your Regional Veterinary Officer to confirm that this approach is appropriate to the situation. The Agency must, among other things, decide whether samples should be collected for possible legal proceedings and adapt the method of collection accordingly.
  2. The offal and blood of held carcasses must also be held.
  3. Product suspected of containing residues of hormones is to be detained on the grounds that it is an adulterated food under the Food and Drug Regulations, or meat product under the Meat Inspection Regulations, 1990. The condemnation of product found in violation will be done under the authority of sections 20(1) and 54 of the Meat Inspection Regulations, 1990.

5.2.10.5.2 Entire lot is suspect

A lot is suspect if:

  • the calves originate from a producer who has previously presented calves with injection sites containing hormone residues; and
  • the lot has a conformation suggesting the use of hormones (very pronounced muscular development, changes in the genital organs); and
  • multiple carcasses have injection sites in a location where it is unusual to find signs of injection of common products such as vitamins or antibiotics.

In the event of a suspect lot:

  1. Seize and detain the entire lot, including offal.
  2. Consult your Program Specialist, Chemical Residues, or your Regional Veterinary Officer to determine the number of samples needed for laboratory confirmation and whether samples must be taken according to the protocol for legal samples. Usually, six samples are required to evaluate a lot, regardless of the size of the lot.
  3. Sample the injection sites and normal muscle (250 g of diaphragm from the same animal) from each sample carcass.

If hormones are detected in a sample at a level which cannot be explained by the natural variation in the level of a hormone, the entire lot will be condemned.

5.2.10.5.3 Suspect carcass

Carcasses are in this category if:

  • the calves originate from a producer who has previously presented calves with injection sites containing residues of hormones; and
  • some carcasses carrying marks suggestive of an injection at a location where it is uncommon to find traces of injections for common products such as vitamins or antibiotics.

In this case:

  1. Seize and detain individual carcasses with marks suggestive of injections, including offal.
  2. Consult your Program Specialist, Chemical Residues, if more than six carcasses are affected.
  3. If six or fewer carcasses are affected, sample the injection sites and normal muscle (250 g of diaphragm from the same animal) from each held carcass.

If hormones are detected at a level which cannot be explained by normal variation in hormone levels, the carcasses will be condemned.

If several carcasses are placed under detention, the CFIA laboratory may decide to stop the analyses when the first violative sample is found.

5.2.10.5.4 Other situations

Carcasses are in this category if:

  • the carcasses have a normal appearance (normal muscling);
  • there are marks suggestive of a possible injection site in a location where it is unusual to find traces of injections; and
  • the calves originate from a producer which has never presented calves bearing injection sites which contain hormone residues.

In these situations, in which there is a need to verify a possible injection site:

  1. Sample the lesion. It is critical to follow the protocol for legal samples. If you have not been trained in this, contact your Regional Veterinary Officer (RVO) or Program Specialist for guidance.
  2. The CFIA will not routinely hold these products because the suspicion is not strong enough to justify it, but the operator may decide not to distribute the product pending the results of the analysis.
  3. Notify the operator that the tissues are being submitted to be tested for hormones, and that if hormones are detected at a level which cannot be explained by natural variation in the level of the hormones, the CFIA may use the results to initiate legal action.

5.2.11 Prostaglandins

5.2.11.1 Introduction

Prostaglandins are hormones derived from fatty acids, which regulate reproduction and inflammation. Prostaglandins approved for veterinary use include:

  • Estrumate™, Planate™ (cloprostenol)
  • Lutalyse™ (prostaglandin F2α)

5.2.11.2 Sample selection

Although these products carry a 48-hour label withdrawal time, their tissue half-life is on the order of minutes, and they should not cause a residue concern. If in doubt, contact your Area Program Specialist, Chemical Residues, for guidance.

5.2.12 Somatotropin

5.2.12.1 Introduction

Somatotropins are large molecular weight proteins which regulate growth and maturation in normal animals. They have been manufactured commercially through recombinant DNA technology.

Bovine somatotropin has been approved in the United States for the enhancement of milk production in dairy cattle, under the trade name Posilac™. Research is underway for the development of porcine somatotropin as a growth promotant in market hogs.

5.2.12.2 Sample selection

Bovine and porcine somatotropin are not pharmacologically active in primates. Treated animals do not have circulating somatotropin levels outside the range of physiological variation. Somatotropins are ineffective if administered orally. These compounds are not a residue concern.

5.2.13 Beta agonists

5.2.13.1 Introduction

The β-agonists (β-adrenergics) are synthetic analogues of adrenalin. Members of this family of medications include clenbuterol, salbutamol, and terbutaline. β-agonists may be used illegally as growth promotants or repartitioning agents, particularly in veal.

Clenbuterol is a β-agonist approved by Health Canada for use in horses only. Specifically, clenbuterol is approved for use as a bronchial dilator in horses that are not to be slaughtered for food (Ventipulmin™, Boeringer). It is an extremely potent β-agonist with preferential affinity for bronchial and uterine smooth muscle. Veterinarians have been known to prescribe this drug, in an off label manner, as an agent for the delaying of parturition. The Food and Drug Regulations, Section B.01.048, prohibits the sale of any animal intended for consumption as food, which has been treated with clenbuterol.

Clenbuterol is illegally distributed in many countries as a growth promotant. This is an unapproved usage and has severe adverse health consequences. Outbreaks of poisoning have been reported in other countries, and at high enough concentrations (parts per billion), death can occur. Manifestations of poisoning include heart palpitations, tachycardia, dizziness, headaches, and tremors.

One β-agonist (ractopamine) is licensed for use as a repartitioning agent in hogs in Canada (Paylean™, Elanco). See Medicating Ingredient Brochure #82.

5.2.13.2 Sample selection

Veal calves showing heavy muscling should be deemed suspect. Collect eyes, liver, and muscle.

5.2.13.3 Testing

Detain the carcass and offal of suspect animals. β-agonists have an affinity for neural tissue, and residues will persist in the retina after they have been cleared from other tissues. Contact your Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number. Ship the eyes and 500 g each of liver and skeletal muscle, frozen, to the Centre for Veterinary Drug Residues, Saskatoon. Ensure that you collect as much identifying information as possible, such as live weight, eartag or backtag numbers, sale lot numbers, breed, and National Livestock Identification Number.

5.2.13.4 Follow-up

If an animal tests positive (retina test), the carcass and offal shall be condemned.

See Chapter 6 for guidance on disposal of condemned material containing chemical residues.

The Area Program Specialist will notify the producer, in writing, that clenbuterol residues have been detected in the retina of one of his lot, and that this constitutes an adulteration under the Meat Inspection Act and Regulations and the Food and Drugs Act and Regulations (see Annex B for Letter of Notification).

Prior to presenting his next lot for slaughter, and each time after, until five (5) consecutive lots test negative, the producer must notify the Canadian Food Inspection Agency's (CFIA) area office by telephone, of the date and place of the next intended slaughter. This applies whether the slaughter establishment is in the home province of the producer or another province.

If the producer sells his animals to an intermediary or a commercial agent or at auction he must inform the buyer that they must contact the CFIA's regional office and provide the date and place of the intended slaughter.

These animals will undergo the normal ante mortem and post mortem examination and will then be placed under detention. One (1) out of six (6) of the lot will be sampled and tested (skeletal muscle, liver and retina).

  • If the retina is negative, the lot will be released.
  • If the retina is positive, the corresponding carcass will be condemned. The producer will then have the option of proving, at his cost, that the retinas from each of the other carcasses are negative, or they will be condemned.

The National Chemical Residue Monitoring Program will continue to randomly select animals for retina sampling and testing. All positive findings will be subject to the aforementioned procedure.

5.2.14 Other therapeutic agents

5.2.14.1 Introduction

Therapeutic agents not covered previously in this chapter form a heterogeneous group of chemical substances. The persistence of residues varies accordingly and very few statements can be made that would have general applicability.

This group includes medicating feed ingredients as well as veterinary drugs for direct administration. Medicating feed ingredients include anti-microbial and antiprotozoan agents, coccidiostats, hypotensives, and anthelmintics. Some of these can be administered without veterinary prescription. For more details, consult the Compendium of Medicating Ingredient Brochures (MIB).

Some compounds are typically administered to individual animals with specific medical conditions. Others are typically administered as mass medications through feed or water, and may require use of the herdmates policy (see section 5.2.3). CFIA veterinarians may be able to make this determination through knowledge of the specific medications or by reference to the Compendium of Veterinary Products. If you require assistance, contact your Area Program Specialist, Chemical Residues.

5.2.14.2 Sample selection

You may detain any product which you believe, on reasonable grounds, may contain residues. This may be based on the presence of a disease condition or a physical or physiological change; or a report or allegation by a producer, transporter, or other source.

Ensure that you hold all organs and by-products, as well as the carcass and its parts.

The selection of tissues for analysis depends on the suspected substance. Contact your Area Program Specialist, Chemical Residues, for guidance.

The presence of a recent injection site in an animal which is negative on the STOP test may indicate the use of a therapeutic agent other than an anti-microbial, such as an anti-inflammatory. In these cases, submit a sample of the injection site. Ensure that it is clearly labelled, and that the submission form clearly indicates the reason for submission.

5.2.14.3 Testing

Do not submit unscheduled sample to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residues Monitoring Program (section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Area Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

5.2.14.4 Follow-up

Carcasses and organs are to be held until laboratory reports are received. The laboratory result will determine the disposition of the carcass or offal, based on the applicable MRL in the Food and Drug Regulations. The dressed carcass and all offal derived from the carcass shall be condemned if the skeletal muscle from that carcass is violative. When a liver or kidney or both are found to be violative but the level in the skeletal muscle is below the applicable MRL, then only the offal shall be condemned. Contact your Program Specialist, Chemical Residues, for guidance.

See Chapter 6 for guidance on disposal of condemned material containing chemical residues.

The presence of a violative residue will trigger a farm visit, similar to that for antibiotics (see section 5.2.7.5). Based on the results of that inspection, the producer may be subjected to compliance testing.

Compliance testing requires that, because of the previous violation, any animal from the same producer is deemed suspect until demonstrated otherwise. The Area Program Specialist, Chemical Residues, will determine whether a check sample (carcass not held), a compliance sample (carcass held), or a series of compliance samples is warranted; and, in the last case, how many times the producer's animals will be sampled.

5.2.15 Insecticides

5.2.15.1 Introduction

Insecticides are widely used in agriculture, both to protect crops from insect predation and to treat animals affected with insect pests or ectoparasites. Most insecticides are compounds which have a much higher acute toxicity for insects than for mammals. Residues may result from accidental environmental exposure (overspray, improperly stored containers, improper disposal), or from improper use of insecticides to treat animals (extra label use, failure to observe withdrawal).

Insecticides may be classed according to their chemical composition:

  • Organohalogens (Halogenated Hydrocarbons)
  • Organophosphates
  • Organosulfur Compounds
  • Organonitrogen Compounds
  • Pyrethrins and Analogues

5.2.15.1.1 Organohalogens

Organohalogens are organic chemicals containing one or more halogen substituents. In the majority of cases, these substituents are chlorine atoms (organochlorine pesticides), with bromine and fluorine substituted chemicals (organobromine and organofluorine pesticides) comprising the balance. Typical representatives of this group of compounds are aldrin, dieldrin, benzene hexachloride (BHC), lindane, chlordane, dichlorodiphenyltrichloroethane (DDT) and its metabolites, dicofol, heptachlor and its epoxide, methoxychlor and toxaphene.

Organohalogen insecticides are relatively stable compounds, broken down under normal environmental conditions at a very slow rate with half-lives ranging from a few months to well over a hundred years. They are practically insoluble in water, but soluble in fat and organic solvents. Because of their solubility in fat, intermittent or continued exposure to relatively low concentrations can result in residue accumulation in adipose (fatty) tissues. As a result, these compounds reach higher levels in older animals, and become more concentrated as they migrate upwards in the trophic food chain. Pharmacological effects on mammalian species, including man, are usually chronic in nature, although delayed semi-acute symptoms can appear if stress or disease causes an animal to rapidly mobilize its lipid reserves.

5.2.15.1.2 Organophosphates

Organophosphates are organic chemicals containing a central phosphorus atom (normally pentavalent), linked to aliphatic or aromatic side chains by oxygen or sulphur bridges. Typical representatives of this group are dimethoate (Cygon™, American Cyanamid), chlorpyrifos (Dursban™, DowElanco), diazinon, ethion, fenthion (Spotton®, Bayer), malathion and parathion. Halogenated compounds for direct application to livestock and facilities include coumaphos (Co-Ral™, Bayer), tetrachlorvinphos (Gardona™, American Cyanamid), trichlorfon (Dipterex™, Dylox™, Bayer) and dichlorvos (Vapona™, Shell).

The organophosphates are water soluble, quickly broken down in the environment, and rapidly metabolized in the body. Oxidative reactions in metabolism are usually detoxification mechanisms, but with organophosphates, oxidation can form a metabolite which is more toxic than the original pesticide. Certain hydrolytic metabolic processes, known to destroy the actual or potential activity of the chemical, continue under post mortem conditions. As these are temperature dependent processes, it is of utmost importance to have a sample for analysis frozen immediately and have it arrive at the laboratory in a frozen state.

Organophosphates are acutely toxic, inducing typical symptoms of acetylcholinesterase inhibition (e.g. salivation, lacrimation, diarrhea, nervous twitching and trembling). Because they are water-soluble, these compounds are not normally bio-accumulated. Notable exceptions are, however, a few representatives of this group used as systemic pesticides, which contain halogen-substituted side chains and exhibit some of the characteristics of the organohalogen group.

5.2.15.1.3 Organosulfur compounds

Organosulfur compounds are organic chemicals containing one or more sulphur atoms bound to oxygen to form a sulfoxide or sulphone. Typical examples are phenylsulphone and technical sulfoxide. Since the majority of pesticides in this group are also halogenated (e.g. endosulfan), they have the characteristics of the halogenated hydrocarbons, and are normally listed as representatives of that group.

Sulphur compounds of the classical sulphate and polysulphide type find little application in modern agricultural practice.

5.2.15.1.1.4 Organonitrogen compounds

Organonitrogen compounds are organic chemicals containing one or more nitrogen atoms in characteristic locations within the aliphatic or aromatic part of the molecule. The site and configuration of the nitrogen permits a broad subdivision into two groups, aliphatic and aromatic.

5.2.15.1.4.1 Aliphatic compounds

Carbamates, carbonates, carboxylates and substituted ureas are generally water soluble and characterized by a low persistence in the environment and animal body. Typical representatives of this group of insecticides are propoxur (Baygon™, Bayer), carbaryl, dimetilan, and methomyl. All of these are permitted for use on animal facilities, and carbaryl is also used in topical applications to livestock, but the primary use is for crop protection.

The insecticidal efficacy of these compounds parallels mammalian toxicity and, in the case of carbamates, acute symptoms due to a moderate acetylcholinesterase inhibition have been observed. Terminal residues in meat products are rarely seen due to the rapid in vivo metabolization and continued chemical and enzymatic breakdown in post mortem tissues.

5.2.15.1.4.2 Aromatic compounds

These include pyridine and diazine (pyrimidines and uracils) derivatives. Both sub-groups are usually characterized by the simultaneous presence of phosphorus (e.g. chlorpyrifos - Dursban™, diazinon) or halogen, permitting their classification with those groups.

5.2.15.1.5 Pyrethrins and their analogues

Pyrethrins are derivatives of chrysanthemumic acid, the oldest and best known representative being a natural pyrethrum extract, which due to cost consideration has met with a large competition from synthetic pyrethrin analogues. Typical representatives of this group are permethrin, allethrin and technical pyrethrin.

Together with piperonyl butoxide (which acts as a synergist), pyrethrins have been licensed for use as an insecticide in feed and food establishments, as well as for systemic and topical application to livestock. Pyrethrins are insoluble in water and easily destroyed by the application of heat. Their insecticidal properties are attributable to their action on the respiratory system (contact insecticide). The mammalian toxicity is generally low and absorption by normal pathways minimal.

Terminal residue formation has been reported as being negligible.

5.2.15.2 Sample selection

The above considerations are important for deciding on sample selection for testing and checking for clinical signs in suspected animals. If insecticides are not used carefully and in accordance with label directions, accidental contamination of feeds or direct exposure of livestock is possible. In certain cases, animals may be suspected of heavy exposure to a particular insecticide, either from reports of owners or other people connected with the livestock industry, or from observation on ante mortem and post mortem inspection. Such indications of exposure must be followed up. All available information, including ante and post mortem signs, should be reported to your Area Program Specialist, Chemical Residues, who will decide whether further investigation and sample submission will be necessary. It is important to identify the suspected chemical at least by group. Any reasonable suspicion should be checked out by laboratory tests, but it should be borne in mind that analyses are costly and laboratory facilities are limited.

The tissue of choice for regular halogenated hydrocarbons residue analyses is perirenal fat. In cases where a topical dorsal application may be suspected, the subcutaneous fat from that region is more suitable.

The tissues of choice for most organophosphate residue assays are liver and kidney, but perirenal or dorsal fat should be included if the application of a systemic compound is suspected. To keep the residue from being broken down by enzymes before testing, it is of utmost importance to have a sample for analysis frozen immediately and have it arrive at the laboratory in a frozen state.

For aliphatic organonitrogen compounds, liver tissue is considered the best choice for sampling purposes because the liver is one of the transient target organs.

5.2.15.3 Testing

If samples are submitted for laboratory analysis, then the carcass and all parts of the index animal and any herdmates suspected of being exposed must be detained pending the results of analysis.

Do not submit unscheduled samples to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residue Monitoring Plan (section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

Monitoring for organochlorine pesticides insecticides is carried out to assess their prevalence in the major slaughter populations, as part of the National Chemical Residue Monitoring Plan (see sections 5.2.5, 5.2.6).

5.2.15.4 Follow-up

Insecticide exposure should be dealt with as for any other herd or flock exposure. (see section 5.2.3)

5.2.16 Other pesticides

5.2.16.1 Introduction

Pesticides form a class of agricultural chemicals which, if applied correctly, serve to increase the efficiency of food production through the control of pests affecting both plant and animal life. Besides the insecticides, the general class of pesticidal chemicals thus includes: attractants, defoliants, fungicides, herbicides, molluscicides, nematocides, ovicides, plant bactericides, plant growth regulators, repellents, rodenticides, sterilants, and others. An extremely wide scope of chemicals is needed to fulfil this multiplicity of functions. For analytical purposes, it is therefore convenient to divide pesticides according to their general chemical structure:

  • Triazines
  • Phenoxyacid derivatives
  • Organometallic compounds
  • Other inorganic and organic compounds

5.2.16.1.1Triazines

Triazines find widespread application as herbicides. While practically insoluble in water, triazine herbicides exhibit a relatively low mammalian toxicity. Accumulation in the trophic food chain has not been observed to any appreciable degree.

5.2.16.1.2 Phenoxyacid derivatives

Phenoxyacid derivatives are very efficacious herbicides and are frequently applied as such. Typical examples of this group of compounds are 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 4-(4-chloro-o-tolyloxy)butyric acid (MCPB).

They are generally water soluble and quickly metabolized. Their mammalian toxicity is relatively low. Of primary interest are, however, residual constituents and metabolic end products of the polychlorinated aromatic type, such as chlorinated dibenzo-p-dioxins (CDD) and chlorinated dibenzofurans (CDF). See the section on polyhalogenated hydrocarbons (5.2.18).

5.2.16.1.3 Organometallic compounds

This group of compounds includes organomercurials and arsenicals. Organomercurials find application as fungicides for seed treatment, while arsenicals are used as medicating feed ingredients for poultry and swine in the control of coccidiosis, hexamitiasis, blackhead and to improve pigmentation and weight gain. Copper chromated arsenate (CCA) was widely used as a preservative on pressure-treated lumber, but is being phased out in favour of less toxic compounds.

Any hazard with these compounds is associated with the metal (mercury or arsenic) component. See section 5.2.19.

5.2.16.1.4 Other inorganic and organic compounds

Several pesticidal substances, notably rodenticides and special purpose formulations, do not fit any of the above categories and are equally unsuited to multiple residue approaches. Residues of this nature can only be analysed for on special request using compound specific techniques.

5.2.16.2 Sample selection

Where an animal is suspected of exposure to a pesticide, collect 250 g each of liver, kidney, and fat. Samples should be immediately frozen to stop the break-down of compounds by enzyme activity.

5.2.16.3 Testing

The above considerations are important for deciding on sample selection for testing and checking for clinical symptoms on suspected animals. If pesticides are not used carefully and in accordance with label directions, accidental contamination of feeds or direct exposure of livestock is possible. In certain cases, animals may be suspected of heavy exposure to a particular pesticide, either from reports of owners or other people connected with the livestock industry, or from observation on ante mortem and post mortem inspection. Such indications of exposure must be followed up. All available information, including ante and post mortem signs, should be reported to your Area Program Specialist, Chemical Residues, who will decide whether further investigation and sample submission will be necessary. It is important to identify the suspected chemical at least by group. Any reasonable suspicion should be checked out by laboratory tests, but it should be borne in mind that analyses are costly and laboratory facilities are limited.

Do not submit unscheduled samples to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residue Monitoring Plan (section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

Monitoring for polyhalogenated hydrocarbons (PCBs, dioxins) is carried out to assess their prevalence in the major slaughter populations, as part of the National Chemical Residue Monitoring Plan (see sections 5.2.5, 5.2.6).

5.2.16.4 Follow-up

Pesticide exposure should be dealt with as for any other herd or flock exposure (see section 5.2.3).

5.2.17 Chlorine

5.2.17.1 Introduction

Chlorine compounds are used in registered establishments as antimicrobial agents in the plant environment, on product contact surfaces, and on carcasses via either spray or immersion. These compounds may include dissolved chlorine gas (Cl2), chlorine dioxide (ClO2), and sodium hypochlorite (NaClO). The antimicrobial action is exerted through the strong oxidizing ability of free chlorine.

In contact with organic matter, chlorine will react to form various organochlorine compounds. Those of greatest health concern in drinking water are the chloramines (monochloroamine, NH2Cl; dichloramine, NHCl2; and trichloramine, NCl3) and the chloromethanes (methyl chloride, CH3Cl; methylene chloride, CH2Cl2; chloroform, CHCl3; and carbon tetrachloride, CCl4). Chloroform is a carcinogen, dichloromethane is a mutagen, and several of these compounds can cause liver or kidney damage.

Chloramines and chloromethanes are volatile, so will not leave persistent residues in the finished product. However, higher molecular weight organochlorine compounds with carcinogenic potential may be formed. See section 5.2.18, polyhalogenated hydrocarbons.

Health Canada has issued a letter of no objection to the use of chlorine at levels up to 50 ppm in poultry, and up to 20 ppm in red meat. In the case of red meat, a rinse with potable water is always required after such use. Operators who wish an exemption from the potable water rinse must request it in writing from Health Canada.

5.2.17.2 Sample selection and testing

As specific compounds of concern have not been identified, laboratory analysis is not practical.

5.2.17.3 Follow-up

All product exposed, or potentially exposed, to chlorine in excess of the Health Canada limits should be detained until its status can be determined. Notify your inspection manager, and your Area Program Specialist, Chemical Residues.

If chlorine levels are not monitored continuously, such as by an automated in-line sensor with an alarm, then all product exposed since the last acceptable test is deemed suspect.

Companies using chlorine as an antimicrobial product treatment, either by spray or by immersion, must have measures in place to prevent exceeding the approved limit. On the first occurrence of exposure in excess of the limit, affected product may have the contact surfaces removed. Alternatively, the producer may choose to dispose of any suspect product to inedible rendering or landfill. The company must produce an action plan to prevent recurrence.

On the second occurrence of exposure in excess of the limit, the corrective action plan should be reviewed to determine why it failed, and a letter of advice issued to the company. Product may again be either reworked or discarded.

In the event of any subsequent exposures, the product shall be condemned. In addition, a third occurrence constitutes failure of the HACCP plan, and must be addressed accordingly.

5.2.18 Polyhalogenated hydrocarbons

5.2.18.1 Introduction

Polyhalogenated hydrocarbons comprise several families of compounds, of varying toxicity. Groups of interest include:

  • Pentachlorophenol (PCP)
  • Polychlorinated Biphenyls (PCB)
  • Chlorinated Dibenzo-p-dioxins (CDD)
  • Chlorinated Dibenzofurans (CDF)

PCBs, dioxins, and dibenzofurans are homologous series of derivatives varying in the degree of halogen substitution, which together with isomers, form an entire spectrum of individual compounds. Members of each family vary from highly toxic to relatively non-toxic, so doses and maximum residue levels are normally expressed as "toxic equivalents" (TEQ) of the most toxic compound.

5.2.18.1.1 Pentachlorophenol (PCP)

PCP is widely used as a fungicide and wood preservative. PCP in higher concentration is toxic. The compound is to an extent lipophilic and accumulates in fat. The use of wood treated with PCP in barns or wood shavings as litter has caused concern in two areas:

  • PCP present in chicken litter is converted through bacterial action into chlorinated anisoles, which impart a musty odour and taste to chicken meat.
  • Commercial PCP may be contaminated with chlorinated dibenzodioxins (CDD) and chlorinated dibenzofurans (CDF). See section 5.2.18.1.3. CDD and CDF have higher chemical stability than PCP and may persist in tissues after PCP is metabolized.

5.2.18.1.2 Polychlorinated biphenyls (PCBs)

Polychlorinated biphenyls were developed as heat exchangers in electrical transformers, and were widely used in plastics and paper manufacturing. Their high chemical stability, which was a desirable property in their industrial applications, also made them an environmental contaminant. Trace levels of PCBs are found universally in nearly every species of land and aquatic animals tested. PCBs were never manufactured in Canada, and their manufacture in the United States was terminated voluntarily in 1977, but they may still be found in older equipment. Accidental spills have resulted in serious contamination of feed in isolated areas. PCBs have similar chemical characteristics to those of organochlorine pesticides. (See section 5.2.15.1.1) They are lipid soluble and accumulate in the fat of animals.

5.2.18.1.3 Dioxins

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are often referred to simply as "dioxins". They are very stable and fat-soluble, and therefore accumulate in the food chain. They may be present as contaminants or by-products in the manufacture of other halogenated compounds. They are also found in fly ash from incinerators, and produced naturally in forest fires. As a result, they are a ubiquitous environmental contaminant, found at very low levels in all living organisms.

Depending on the degree of chlorination (1-8 chlorine atoms) and the substitution pattern, one can distinguish between 75 PCDFs and 135 PCDFs, called "congeners". The toxicity of dioxins varies considerably. Of the 210 congeners, only 17 are of toxicological concern. Exposure levels or residues are expressed in toxic equivalents (TEQ) of the most toxic congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD).

Exposure to a concentrated source, or to an unusually contaminated environment, may result in measured dioxin levels significantly above the background level.

These compounds produce a syndrome characterized by a delayed onset and involving widespread degenerative changes in several organs, in particular liver, thymus, and skin. CDD and CDF are formed during manufacture of chlorinated hydrocarbons and are also present in PCBs, organochlorine pesticides and phenoxyacid herbicides.

5.2.18.2 Sample selection

If any reasonable suspicion exists about the possible presence of residues due to industrial accidents or localized environmental contamination, the matter should be brought to the attention of the Area Program Specialist, Chemical Residues, for further action.

Monitoring for PCP and dioxins is conducted as part of the National Chemical Residue Monitoring Program. (See sections 5.2.5, 5.2.6)

A sample submission shall consist of fat and liver. In the case of birds, the sample can be pooled from several birds of the same flock.

PCBs are detected by the same analytical method as the organochlorine pesticides, and monitoring for PCBs is conducted within the program for pesticides.

5.2.18.3 Testing

Do not submit an unscheduled sample to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residue Monitoring Program (Section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Area Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

5.2.18.4 Follow-up

The Area Program Specialist, Chemical Residues, will likely request a check sample from the same producer, to determine whether the residue was transient or represents an on-farm problem. A visit to the farm of origin may be conducted to attempt to determine the route of exposure.

5.2.19 Heavy metals

5.2.19.1 Introduction

Contamination with heavy metal residues has occurred from seeds treated with fungicides or disinfectants containing mercury or arsenic, and subsequent use in feedstuffs. Contamination has also occurred as a result of accidents in formulations of feeds with arsenicals or from environmental contamination by lead, cadmium, or mercury.

Arsenic poisoning is no longer common, because most farm chemicals and veterinary medications containing arsenic are no longer in use. Arsanilic acid is still employed at low levels as a medicating feed ingredient for pork and poultry. (See Medicating Ingredient Brochure 4.) Main sources for environmental access are discarded cans of arsenicals, areas of industrial pollution (smelters), and ashes from the burning of treated fence posts. Animals will develop a tolerance to arsenic if it is fed at sublethal doses over a period of time.

Cadmium is present in areas of high industrialization as an environmental pollutant and finds widespread use as a plating metal. It is also present as a natural soil component in some areas. It accumulates in liver and kidney as a function of age, while muscle tissue levels remain constant. Kidney levels are generally somewhat higher than corresponding liver levels. Horses are particularly prone to concentrating cadmium in their organs; for this reason, horse kidneys and livers are not considered edible.

Copper is a ubiquitously distributed element essential to the animal at trace mineral levels. It is normally poorly absorbed, and not all copper circulating in the blood is available to the animal. Deficiency is a greater problem than excessive dosage. The distribution of copper in the liver is very uneven, the caudate lobe having higher concentrations than those found in the dorsal or ventral lobes.

Lead levels in ditchbank vegetation due to automobile exhaust have dropped significantly with the introduction of lead-free gasoline. Current sources of access to livestock include industrial pollution, waste engine oil, putty, roofing tiles, old lead-based paint, and lead batteries. So-called lead-free paint may contain up to 1% of lead.

Mercury as a general environmental pollutant is strictly controlled by legislation, making high level occurrences less frequent. Distribution of mercury in the body depends on the form in which it is ingested. Organic mercurials lead to high blood and brain levels with equal amounts in liver and kidney, while inorganic mercury tends to exhibit higher levels in the kidneys. Organic mercurials are more toxic than inorganic mercury.

Selenium, aside from extremely localized areas of industrial pollution, is introduced primarily with the feed. Bound forms of selenium, such as selenomethionine, are available in the majority of vegetable diets. Deficiency is a greater problem than excessive dosage. Absorption and utilisation is extremely variable and highly dependent on the type of diet and antagonistic effect of other trace elements. Even animals with clinical signs due to selenium toxicity do not usually demonstrate tissue selenium levels above the normal range.

Zinc finds widespread application as a plating and galvanizing metal and can be found in high concentration in areas of industrial pollution (smelters). Toxicity is uncommon, young animals being more susceptible than older ones. Zinc is an essential trace element and deficiency represents a problem. Infectious diseases are known to lower liver and serum levels while increasing corresponding kidney levels.

5.2.19.2 Sample selection

For metals, skeletal muscle, liver, and kidney are sampled. Metals are monitored for under the National Chemical Residue Monitoring Program (see sections 5.2.5, 5.2.6). Animals originating from sources with suspected or known access to heavy metals, if not condemned on ante mortem inspection for clearly visible symptoms, shall be held and sampled, and samples submitted to the laboratory. Contact your Area Program Specialist, Chemical Residues, for guidance.

5.2.19.3 Testing

Do not submit unscheduled sample to the lab without prior authorization. The assay that you require may not be available at all labs. Private labs which process samples for the National Chemical Residue Monitoring Program (section 5.2.5, 5.2.6) can only perform the tests, and the number of samples, for which they have a contract.

Contact your Area Program Specialist, Chemical Residues, to determine where the sample must be submitted, and to obtain a sample submission number.

5.2.19.4 Follow-up

Animals found with elevated levels will be traced to the farm of origin. An inspection may be conducted by a feed inspector to determine the source of elevated levels. Subsequent shipments from the producer should be checked.

The accompanying sample submission form should, if at all possible, state the specific heavy metal suspected. The additional remark "special request" will avoid confusion with regular monitoring and assure the priority status for the sample submitted.

5.2.20 Hydraulic fluid

5.2.20.1 Introduction

Hydraulic fluids may be used in various places in registered establishments, such as adjustable stands, restrainers, and forklift trucks. These fluids are usually long-chain hydrocarbons. Because the presence of hydraulic fluids in the establishment can be a source of incidental, undetected contamination of edible product, such as by contact with hands or clothing, these fluids must be of an acceptable type. Please refer to Chapter 3.6, Pre-requisite Programs, for the requirements for acceptable packaging materials and non-food chemical products.

However, extensive exposure such as from a burst hydraulic line poses a greater risk. Over time, hydraulic fluids, even though acceptable, may become heavily contaminated with heavy metals or other chemicals from the equipment. In areas where there is exposed product, pneumatic equipment, which uses compressed air instead of liquid is preferable.

5.2.20.2 Assessment

As described under "In plant exposure" (section 5.2.4), exposed product must be either condemned for adulteration or detained pending assessment and appropriate corrective action. It may be difficult to see the extent of contaminated meat that needs to be removed, and also difficult to demonstrate by means of a meaningful sample that the method of decontamination, for example trimming, has effectively eliminated all contamination.

If the company wishes to attempt to salvage exposed product, contact your Program Specialist, Chemical Residues, who will request a risk assessment from the National Manager, Chemical Evaluation. In order to conduct the assessment, the following information will be required.

Provide a short description of the events that occurred just before, during, and immediately after the discovery of the spill, to allow understanding of the situation. As precisely as possible, answer each of the following questions:

  • How was the spill detected? For example, during routine inspection, equipment held, after a fire, etc.
  • What was the brand of oil or fluid? If the Material Safety Data Sheet is available, this should be included.
  • What amount of fluid escaped?
  • Was the fluid under pressure?
  • For fluids under pressure, at what temperature and pressure is the fluid normally maintained when the equipment is operating?
  • How often is the fluid normally replaced in the equipment, and when was it last changed?
  • How much time passed between the start of the spill and the time it was detected? It may be necessary to estimate the time. State "unknown" if it is possible that the spill continued for some time before being discovered.
  • What products were exposed to the fluid? A description of all the exposed products is required.
  • How did the fluid come into contact with the product? For example, "by dripping", "vaporised under pressure", "smoke produced when fluid burned", etc.
  • Was the product that the operator wants evaluated packaged? If yes, describe the packaging. (Plastic or paper? Sealed or not? What thickness?)
  • Was the product fresh or frozen at the time of exposure?
  • How was the product stored, stacked, etc.

And, concerning the control of the contaminated product:

  • Have actions been taken to reduce the risks? (For example, visible contamination trimmed immediately)
  • Is the product currently under detention and segregated?
  • What has the company proposed for reducing the risk? (For example, remove the skin then rinse; discard one hour's production)
  • What has the company proposed for testing the product? (For example number of samples, which laboratory, which method)
  • Has the company requested the advice of the CFIA about methods of reducing the risk and of testing the product?

5.2.20.3 Follow-up

Appropriate corrective actions will be determined based on the risk assessment. Affected product may need to be condemned or reworked under inspectional control.

Date modified: