The U.S. Government Accountability Office in a new report on USDA and Food and Drug Administration monitoring of pesticide residues in food has suggested that both agencies should improve their monitoring and data collection efforts in addition to further disclosing the limitations of those efforts.
The report, which took nearly two years to complete, reviewed data from as early as 1993 to identify how both agencies monitor for pesticide residue violations.
According to GAO, both FDA and USDA enforce pesticide residue thresholds, also called tolerances, that are determined by the U.S. EPA. USDA's Food Safety and Inspection Service monitors poultry, egg products and meat, while the FDA focuses its monitoring efforts on fruits, vegetables and other foods.
USDA's Ag Marketing Service is also involved in the process, though it only gathers residue data on some foods; it does not enforce violations.
GAO says FDA data, which shows low rates of pesticide residue violations, takes "relatively few" targeted samples for testing, and "detects what is likely to be a small percentage of the foods that have violative levels of residue."
GAO also said FDA doesn't test for some commonly used pesticides, and doesn't disclose that information. Those commonly used pesticides include glyphosate – the most commonly used pesticide in the U.S. – 2,4-D and methyl bromide, among others. All have established tolerances, though FDA is not required to test for all the pesticides that have tolerances.
Because FDA does not disclose which pesticide residues it does not test for in its reports on residue monitoring efforts, GAO argued that "users of the annual monitoring reports may not have accurate information and may misinterpret the results of the program, which, by not testing for certain pesticides, may be identifying fewer violations than occur."
Further, FDA does not use "statistically valid" methods to gather residue monitoring data, GAO says, leaving it unable to meet its objective of determining how many imported and domestic foods have pesticide residues.
Like the FDA, FSIS' monitoring efforts also show a low rate of pesticide residue violations on meat, poultry and egg products, though GAO says FSIS also did not test for all pesticides with established tolerances.
Despite the shortcoming, GAO reports that the number of pesticide residues FSIS tests for has increased. As of 2011, FSIS tests for 38 of the 191 pesticides with tolerance levels registered for indirect or direct use on food animals and 17 more that do not have established tolerances in animal products.
FSIS' reporting on the monitoring efforts, however, fall short of Office of Management and Budget standards, GAO says. This is because like the FDA, the agency does not disclose the pesticides with tolerances for which it does not test or the potential effect that its selection of pesticides could have on its results.
Margin of error information is also not provided, GAO says, which can skew interpretation of the monitoring results.
GAO recommended that the agencies each review monitoring and reporting efforts to design valid sampling methodologies and improve disclosures.
While USDA generally agreed with the recommendations and planned an implementation process, the Department of Health and Human Services said it would make some updates to add disclosures, but "it believes that disclosing pesticides for which FDA does not test would enable users to more easily circumvent the pesticide monitoring program."
HHS also said FDA would investigate adding more enhancements to the monitoring program, and will re-evaluate its PREDICT program, which targets violations on imported food.
Read the full report, FDA and USDA Should Strengthen Pesticide Residue Monitoring Programs and Further Disclose Monitoring Limitations, on the GAO website.