Investigating Pesticide Tolerance

By Dr. Bill Reeves, EAS Regulatory Consultant

Consistent, scientifically justified regulations enable over $1.5 trillion in global agricultural exports every year. The world economy depends on these regulations to ensure whatever goes onto a ship is legal to sell when it reaches port. One key requirement for agricultural commodities that have received pesticide applications is that any remaining residues are within legal limits for their destination country or region.

Pesticide tolerances (known as maximum residue levels or import tolerances in some world areas) are the maximum amount of a pesticide ingredient or metabolite that can remain on the crop at harvest when the pesticide is applied according to label instructions. A tolerance is specific to the combination of a pesticide and a crop or crop group. If pesticides are present at levels greater than their tolerance or do not have a tolerance, the crop is adulterated and cannot be sold.

The Federal Food, Drug and Cosmetic Act granted the Environmental Protection Agency (EPA) the authority to establish tolerances for pesticides and their metabolites. It also granted the Food and Drug Administration (FDA) the authority to enforce tolerances. The 1996 Food Quality Protection Act (FQPA) updated EPA’s approach for setting tolerances to allow a more detailed accounting of potential human exposures.

Under FQPA, EPA considers requests for new tolerances in the context of existing tolerances for the pesticide in question as well as exposures from drinking water and residential use. To set a tolerance, EPA must be able to conclude that there is a “reasonable certainty of no harm” from the pesticide across all exposure routes. If the pesticide in question is part of a broader class of molecules that also have pesticidal uses, EPA conducts a cumulative risk assessment for all members of the class to determine whether there is still a reasonable certainty of no harm. FQPA also established a default ten-fold safety factor to protect children that applies to all pesticides unless EPA has data demonstrating that exposures are unlikely to result in developmental harm.

The Food and Drug Administration is responsible for enforcing tolerances and determining whether a particular commodity is adulterated. FDA relies on data it collects through the Pesticide Residue Monitoring Program as well as data from the U.S. Department of Agriculture’s Pesticide Data Program. FDA monitors for more than 800 pesticides and includes those that do not have approved tolerances in the U.S. and may be present on imported foods. According to FDA, more than 95% of the violations it discovers are the result of a pesticide being present without a tolerance. Violations can result in recalls or other enforcement action.

When comparing residue data to tolerances, it is important to remember that tolerances are not stand-alone safety standards. Violative residues do not equate to a threat to public health but rather serve as a reminder that EPA has not accounted for the presence of a pesticide on a commodity at a certain level in its dietary risk assessment. Remaining vigilant about what pesticides are present in a supply chain reduces the potential for recalls and ensures the continued flow of agricultural goods around the world.