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The National Chemical Residue Monitoring Program (NCRMP)

• Plan Design - National Chemical Residue Monitoring Program
• Purpose and goals of the National Chemical Residue Monitoring Program
• Criteria used to identify compounds for inclusion in the annual monitoring program
• Evaluation of information and data generated by the NCRMP
  
  

Plan Design - National Chemical Residue Monitoring Program

The National Chemical Residues Monitoring Program NCRMP is implemented on a fiscal year basis (April 1 to March 31). The Food Microbiology and Chemical Evaluation Division (FMCE) develops the plan.

The 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 according to a schedule provided by the FMCE Division. The schedule will also identify to the laboratories the commodity types that are scheduled for submission to their facilities during the year, the time of year that the sample is to be expected and the tests to be completed on those sample submissions.

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. In addition, smaller sample sizes are severely restricted in their ability to show trends over a short time period. With a sample size of 300, seasonal trends may be evident especially if the seasonal variation is large. By comparison seasonal variations would not be as evident in sample sizes of less than 150 samples / year collected at random from the animal population.

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 and goals of the National Chemical Residue Monitoring Program

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 annual monitoring 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. Clearly, if the residue is not formed then there can be no inherent risk and monitoring would be useless. 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. This three year time period will be considerably longer for those programs in which the sampling frequency is less than 300 samples/year. 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. The risk associated with chronic exposure may not necessarily be related to the greatest acute toxicity and exposure; however, this is the only reasonable assumption available for assigning priority. 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.

Once the residue program content is identified and ranked from highest to lowest the limiting factors are considered. A major limitation is often the availability of an appropriate analytical method. If there are residues anticipated but their detection is not possible then clearly a monitoring program could not be implemented. This does not mean that the risk from such a residue is insignificant. However, without the ability to gather data about the occurrence of the residue, exposure and hence risk cannot be resolved. Under these circumstances the need for an appropriate analytical method would be identified as a research need leading to method development activities.

Evaluation of information and data generated by the NCRMP

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

Firstly, on a daily basis, the results reported under the testing program 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.

Secondly, 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.

Thirdly, on an annual basis, the 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 annual residue planning priorities.

The annual report is widely distributed to other federal departments, provincial health & agriculture departments, agriculture & environment associations, academia, trade partners, industry & trade associations, media and the general public.