Chapter 5 - Sampling and Testing

5.2 Chemical Residues

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 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, 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_M8STP.

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 carcasses. 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.

See section 5.8.4, Samples for antibiotic confirmation.

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, Part 10, 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 Government of Canada's Laboratory Biosafety Guidelines 3rd Edition - 2004, available at http://www.phac-aspc.gc.ca/publicat/lbg-ldmbl-04/index-eng.php

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

Tetracycline deposits in bones can be released under acidic conditions. Therefore, the discoloured bones should be removed from the carcasses and considered not suitable for human consumption unless the company can prove that they are not a chemical residue hazard.

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