Pesticide residues multiple exposure

Pesticide residues consist of chemicals that might occur in a commodity as a result of application of a pesticide. Such chemicals typically correspond to compounds for which a regulatory agency has or will set a tolerance, i.e., a maximum residue limit, specific to the commodity. In either a field study or a market basket survey, residues to be determined will be those which result from application of the specific pesticide that the study is intended to support. A market basket survey, however, might be intended to support not just one but several different pesticides of the same or different chemical classes. In addition, a market basket survey might include pesticides not used in the USA but for which import tolerances exist. For example, some uses of the parathion family of pesticides on food products have been abandoned in the USA but remain in other countries that export the products to the USA. A market basket survey offers a means to evaluate actual dietary exposures to residues of such pesticides. In addition, tolerance expressions frequently include multiple compounds, all of which must typically be determined in residue field trials. The sponsor of the market basket survey must decide whether to analyze for all compounds in the applicable tolerance expression or to restrict the program to selected analytes, such as the active ingredient. 

A unified safety standard for raw and processed foods This amends the Delaney clause in the FFDCA. Under the Delaney clause, a chemical that causes cancer in experimental animals (regardless of dose) shall not be allowed in processed food. Under the FQPA, pesticide residues shown to cause cancer in humans or animals are allowed on food if the EPA determines that the tolerance is safe, meaning that there is a reasonable certainty that no harm will result from exposure to the pesticide. This amendment is necessary mainly because of improved analytical capabilities. Under the Delaney clause, a carcinogen pesticide would be given a zero tolerance in processed food. However, zero tolerance caused many problems. As the analytical sensitivity increased, concentrations that were zero by old methods became measurable. A unified safety standard eliminates longstanding problems posed by multiple standards for pesticides in raw and processed foods. 

The limited EU guidance on risk assessment of chemical mixtures does not mean that the issue is not addressed by the EU member states. However, the level of detail and the status of the guidance vary considerably between the member states and the different policy areas. The UK Food Standards Agency established a special working group to formulate advice on risk assessment of multiple residues of pesticides and veterinary medicines in food, and of multiple sources of exposure to these... 

Aggregate exposure (multiple pesticides) The sum of exposures to pesticide chemical residues with a common mechanism of toxicity from multiple sources and multiple routes of exposure (Food Quality Protection Act, 1996) (USEPA, 1997a). 

Pesticide laboratories of food industries and regulatory agencies are continually faced with the problem of analyzing samples whose history of exposure to pesticides is unknown. More than one pesticide may be present in any of these samples and the residue of each may have to be determined. To help solve this problem of analyzing diverse sample types for exposure to different types of pesticides, effort has been made by the FDA scientists, among others, to develop methods for the multiple analysis of pesticides. 

U.S. tolerances is the responsibility of the U.S. Food and Drug Administration (FDA). In the absence of a specific tolerance, residues must be below detectable levels. Based on modifications to FFDCA mandated by the Food Quality Protection Act (FQPA) of 1996, several new elements were introduced to the EPA tolerance process. These include the need to consider the special sensitivity of infants and children, the potential exposure via multiple routes of exposure (i.e., aggregate exposure from dietary and non-dietary sources), and the potential for exposure to other pesticides and chemicals with a common mechanism of toxicity (i.e., cumulative exposure). Under FQPA, the EPA was also required to complete a reevaluation of all existing tolerances during a 10-year period. Domestically established M RLs apply also to imported commodities, but there is an established (if somewhat slow) process for evaluation of residue data from other countries in support of import tolerances. 

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