Chemical Residue Surveillance Program for Foods

The chemical residue surveillance program of the Canadian Food Inspection Agency (CFIA) consists of three well-defined components. The first is monitoring sampling, which probes the food supply for potential contamination and is managed under the National Chemical Residue Monitoring Program (NCRMP). The second is directed sampling which focuses on identified chemical contamination issues and the third is compliance sampling, which seeks removal of food in violation of standards from the marketplace.

Components of the Chemical Residue Surveillance Program for Foods

National Chemical Residues Monitoring Program (NCRMP)

Monitoring or data gathering is designed to provide profile information on the occurrence of chemical residues, food additives and microbiological organisms in predefined sampling populations. Monitoring information is normally obtained through a statistically based selection of random samples from normal appearing populations. The sampled lots are not held and are usually passed into consumer channels before the results are known. No direct enforcement action is taken on the basis of monitoring alone.

The National Chemical Residues Monitoring Program (NCRMP) is prioritized on the basis of estimated risk. As such, food items consumed in greater quantities by Canadians, those that are more contaminated or those, which are contaminated with more toxic components, are sampled and tested to the greatest extent. The general priorities lead to a well defined sampling schedule which identifies to CFIA operations staff the time and place that a sample is to be taken and the accredited laboratory which is to receive the sample and test it.

Although the monitoring program is not designed to provide highly accurate statistical estimates of the violative percentages of a population, such estimates are conveniently made available as auxiliary information. For example, if no violative samples are detected in a sample of 300 units it is convenient to infer with 95% confidence that the violative rate in the population falls at something less than 1.00%. Although precision becomes rapidly attenuated with smaller sample sizes, useful information can still be obtained from such sampling. Smaller annual samples must be carried out for longer periods before significant inferences can be drawn from the data.

When initial monitoring indicates that a contaminant in a given food commodity presents a potential risk, sampling plans may be adjusted, but only to the point that such effort will aid in the understanding of the problem or facilitate regulatory control. Such increased sampling may permit a study of trends, geographical variation and seasonal prevalence and thereby aid in the design of effective control strategies. Merely increasing the sample size without a strategy, that addresses the benefits of such an increase, is of little value. Once the monitoring program has identified a potential problem, an effective control strategy would not depend on increased rate of monitoring but rather on the implementation of effective directed sampling and compliance activities.

Purpose

The Canadian program has four purposes:

• The first is to determine the extent to which there is deviation from Good Agricultural Practices (GAP) or Good Practice in Veterinary Medicine (GPVM). This is assessed from the violations rates found in the monitoring phase When rates of violation exceed acceptable levels, usually 1 %, further control activities might be triggered.
• The second is to prevent the distribution of adulterated food products containing illegal residues. Growers and distributors of food which violate Canadian standards are placed on an enhanced inspection in order to identify causes and reduce or prevent re-occurrences
• The third is to provide data for calculation of comparative risk associated with domestic and imported sources of foods. This allows an estimation of equivalency of the various foreign residue control programs with our own.
• The fourth is to provide information on the effectiveness of control measures and more importantly the effectiveness of program modifications with respect to bringing about the desired changes. For example, if a training initiative for producers has been effective in bringing about a reduction in the violation rates or if a restriction in the accessibility to a specified drug has brought about an increase in the compliance rate, etc.

Criteria used to identify compounds for inclusion in the program

For inclusion, there must be a potential for the chemical, be it a veterinary drug, agricultural chemical or environmental pollutant to leave a residue in food. After testing programs have been in place for a minimum of three years the accumulated data is evaluated to determine if the continuation of the sampling and testing program is still warranted. Programs may be temporarily discontinued if the test results show no positive residue finding in three consecutive years of at least 300 test samples. Thus after an initial monitoring phase of three consecutive years, if a statistically valid sample size indicates no residue findings, then the annual program may be discontinued until there is a change in usage, tolerance or analytical sensitivity which would warrant re-institution the analysis.

In consideration of available resources, the residues for which monitoring will be instituted must always be prioritized. It is the model used throughout. The process assures that resources are allocated to higher priority items. Some lower ranking compounds will be included periodically or if they form part of a multiple residue test.

The CFIA NCRMP selects test areas from an extensive list of potential chemical contaminants, including but not limited to, veterinary drugs (both approved and not approved), agricultural chemicals (approved and not approved), toxic metals & elements, chlorinated p-dibenzo-dioxins & furans and other environmental pollutants. From this list the CFIA attempts to allocate its testing and inspection resources to the items of greatest potential health risks. To achieve this a two-fold calculation is used.

The first, which is applicable to new program areas or those program areas, which have only limited historic testing data available, employs the CES system. In this case risk is estimated on a scale of A-1 to D-4 where the letter designation refers to the health hazard identified from the toxicity testing on animals. This information is available in the scientific literature. The second element, the numeric designation refers to the estimated level of exposure of the population to the specific contaminant in question. This exposure is usually available from the literature, from Health Canada or from international organizations such as the Joint (FAO/WHO) Expert Committee on Food Additives (JECFA) or Joint (FAO/WHO) Meeting on Pesticide Residues (JMPR). For totally new compounds the exposure is estimated based upon the manner in which the product is used, the amount used per annum and the residue data provided by the registrant.

The second calculation, which is used for programs that have generated statistically significant data, involves the estimation of potential health risk associated with the contamination levels of the food items included in the NCRMP. If the evaluation indicates insignificant long term health risk from such exposure the testing may be discontinued until there is a change in usage of the chemical which might effect the exposure estimates.

Evaluation of information and data generated by the NCRMP

The data from the NCRMP is reviewed in a number of ways:

• The results reported are compared to Canadian standards. If found in violation, the owner of the food items in question is identified for further action via the compliance-testing phase. This might mean the initiation of a "Hold and Test" program wherein subsequent lots are held until tests show that they are if full compliance with the current Canadian standards.
• Data is reviewed on a periodic basis, usually quarterly, in order to determine if an emerging residue issue is developing. This preliminary evaluation might lead to the introduction of directed sampling, blitzes or special pilot surveys.
• Data is compiled for the preparation of the annual report. This information is used to determine the ongoing status of the food supply. This permits the assessment of gradual changes in the compliance rate, the effectiveness of introduced control measures and it augments the available databases, which are utilized for the planning priorities.of the NCRMP.

Directed sampling

Directed sampling is to verify any suspected problems of potential health risk, suggested in the monitoring program and is directed at targeted populations (e.g. commodity types or geographical areas). This component verifies violations of Canadian Acts & Regulations and triggers further inspections as part of compliance action. If warranted, product is detained until test results indicate the appropriate course of action. The approach for directed sampling is referred to as biased or directed, and follows Codex Alimentarius specifications. Directed sampling results leading to further compliance action (violative results) must be verified by prescribed confirmatory techniques before any follow-up control action is taken. Education is an important element in correcting identified problems.

Compliance

Compliance action is taken as a regulatory control measure to prevent the marketing or remove from the market a contaminated or adulterated food product. It presupposes that enforceable regulations or guidelines relevant to the situation are in existence. The compliance action is always directed at a specific source, (i.e. the party felt to be legally responsible). The product is detained until the test results indicate the appropriate disposition. The approach for compliance testing is referred to as in-depth sampling and follows Codex Alimentarius specifications. The establishment of a chain of custody of the sample is essential if legal proceedings are expected to ensue.

Other sampling

Special or pilot surveys are used to gather information about the occurrence of residues not meeting the requirement of the other program components, above. For example, initial surveys or surveys for components outside of the health and safety criteria such as feed mix up might be included here. These are usually limited in scope and duration.

Blitzes are used to obtain a snapshot in time at some point during the fiscal year. The scheduling of blitzes is unannounced. A blitz may allow for the sampling of every herd presented for slaughter for a specified, usually short, period of time not exceeding 2 to 6 weeks.

Legal sampling is undertaken for specific conditions where legal action is the anticipated follow up action. Certain additional criteria are demanded during the sampling submission and laboratory testing of these samples. Adherence to all quality assurance is essential. Legal advice should be sought prior to the initiation of such activities.

Implementation of the Chemical Residue Surveillance Programs

The requirements of the monitoring portion of the NCRMP are developed with input from the CFIA commodity program groups. The sampling information is forwarded to the CFIA operations in a very detailed format. It specifies the date, time, commodity, species, tissues, country of origin, testing facility and pre assigned sample number for every submission.

For non scheduled follow up samples or samples taken at the discretion of the inspector a Food Product Sampling Report form must be completed and submitted with the sample to the receiving laboratory responsible for the testing. The inspector has the authority to select a sample whenever there is reasonable suspicion of a problem.

Laboratory result availability

One of the reasons that the CFIA, in its Residue Plan Design, categorizes the program components by designations such as monitoring, directed sampling, compliance, special and pilot surveys, blitzes and legal sampling is to maximize laboratory testing capacity. Samples for which there is higher likelihood of finding a positive have a shorter turnaround time in order to facilitate follow up actions. Thus for surveillance, compliance and special request samples generated at the inspectors discretion the reporting time is 5, 3 and 3 days respectively, including transit time to laboratory.

For samples generated as a result of blitzes and pilot surveys reporting times are longer. Blitzes are held at the laboratory until all the samples are collected, typically 2 to 6 weeks, and then analysis proceeds as rapidly as possible until all samples are completed. Pilot and special surveys usually are reported within 90 days of sampling.

For monitoring samples reporting time is dependent on the type of residue being tested. It ranges from 3 days for antibiotics to 45 days for toxic metals and elements. The average for monitoring samples is 21 calendar days.

Enforcement actions and records available

The CFIA reviews each violation and appropriate action is requested, as necessary. Such action includes; the notification of program and operation divisions within the CFIA to initiate follow up inspections. These activities are initiated, tracked and closed using the Residue, Anti-Microbial and Micro-Organism System (RAMS). If there is still product on the marketplace a Food Recall will be initiated. This recall will be classified and managed in a manner consistent with the level of risk associated with consumption of the food items.

If the violation is feed related, the on farm follow up inspections would be requested. Feed inspectors, possibly with assistance from provincial agriculture personnel would carry out an on farm investigation, notifying the producer of the violation, identifying any actions on future shipments and advising on means to avoid further violations. In the case of a violation believed to be due to drug injections, notification is similar except an animal health inspector will conduct the on farm follow up inspection.

If a prohibited drug is involved, in addition to the above actions, Health Canada's Veterinary Drugs Directorate will be advised and the assistance of the Drug Enforcement Division of Health Canada will be requested. This group might investigate the sources and distribution of the illegal drug product.