The enactment of the Food Quality Protection Act (FQPA) in 1996 resulted in major changes in the registration of pesticides. These included increased safety for infants and children, the reregistration of older pesticides including the use of aggregate and cumulative exposure assessments, and the expedited registration of reduced-risk (RR) pesticides. Special regulatory focus has been on three groups of pesticides: the neurotoxic organophosphate (OP) and carbamate (NMC) insecticides, and the B2 carcinogenic fungicides. Despite the pressure to substitute RR pesticides for these older, toxicologically suspect compounds, there has been little public analysis of changes in the pesticide use and residue levels or of changes in dietary risk resulting from FQPA. This study aims to assess these changes. The data were obtained from publicly-available databases, i.e. the USDA's Pesticide Data Program, the California Department of Pesticide Regulation, the CropLife Foundation, and the FDA's Total Diet Study.

The use and food residue detects of individual OPs showed a strong declining trend with an approximately 50% overall decline for the group from 1994 to 2006. The use of NMCs also declined approximately 70% from 1994 to 2006, but their residue detection trends were variable and did not clearly correspond to the decline in use. The use of the B2 fungicides declined less (10-20%) and there was no overall decrease in residue detects for most of these compounds. The RR insecticides and fungicides showed a steady increase over this time such that they are now central in pest management programs for fruits and vegetables but the residue data are too limited to establish a trend. It was estimated that approximately 50% (33-60%) of the RR pesticides were registered by USDA's IR-4 program. In some cases, residue detections were unexpectedly high and greater than those for the older compounds. Since the RR pesticides are applied at much lower rates than the older compounds, their adoption has resulted in lower levels of chemical use in fruit and vegetable production. This decreased environmental load, coupled with the improved toxicological profiles of the RR compounds, implies an increase in environmental and worker safety as well as a reduction in dietary risk.

The replacement of the B2 carcinogenic fungicide, iprodione, by the IR-4 registered RR compound, fludioxonil for use on stone fruits, was selected as a case study to illustrate changes in dietary risk after FQPA. Both the DEEM and Lifeline exposure assessment programs were used. The exposures were compared to the reference doses (RfDs). The percentage of the RfDs estimated for fludioxonil were lower than those for iprodione in both acute and chronic exposures, and the iprodione risks declined significantly after the passage of FQPA. These risks were highest for the 1-2 year old age group and declined rapidly thereafter with age. However, the largest contribution to food safety was through the reduction in carcinogenic risk due to reduced levels of exposure to iprodione and the lack of carcinogenicity of fludioxonil. A comparison of these risks at different tiers of analysis showed that both the acute and chronic dietary risks generally decreased from the lower to higher tiers (tier 1>tier 2>tier 3) which is expected since the input parameters become more realistic at higher tiers of analysis. Finally, a comparison of the DEEM and LifeLine programs in these analyses revealed comparable results despite considerable differences in their approaches to estimating dietary exposures.