Agricultural pesticide use and food safety:California's model

Pesticides have been an essential part of agriculture to protect crops and livestock from pest infestations and yield reduction for many decades. Despite their usefulness, pesticides could pose potential risks to food safety and the environment as well as human health. This paper reviews the positive benefits of agricultural pesticide use as well as some potential negative impacts on the environment and food safety. In addition, using the case of California, we discuss the need for both residue monitoring and effective pest management to promote food safety. Twenty years＇ pesticide residue data from California＇s pesticide residue monitoring program were analyzed. Results showed that more than 95% of food samples were in compliance with US pesticide residue standards （tolerances）. However, certain commodities from certain sources had high percentages of residues above tolerance levels. Even when residues above tolerance levels were detected, most were at levels well below 1 mg kg^-1, and most posed negligible acute health risk. However, a few detected residues had the potential to cause health effects. Therefore, establishing an effective food residue monitoring program is important to ensure food quality throughout the marketplace.

Pesticide food safety standards as companions to tolerances and maximum residue limits

Allowable levels for pesticide residues in foods, known as tolerances in the US and as maximum residue limits （MRLs） in much of the world, are widely yet inappropriately perceived as levels of safety concern. A novel approach to develop scientifically defensible levels of safety concern is presented and an example to determine acute and chronic pesticide food safety standard （PFSS） levels for the fungicide captan on strawberries is provided. Using this approach, the chronic PFSS level for captan on strawberries was determined to be 2 000 mg kg-1 and the acute PFSS level was determined to be 250 mg kg-1. Both levels are far above the existing tolerance and MRLs that commonly range from 3 to 20 mg kg-~, and provide evidence that captan residues detected at levels greater than the tolerance or MRLs are not of acute or chronic health concern even though they represent violative residues. The benefits of developing the PFSS approach to serve as a companion to existing tolerances/MRLs include a greater understanding concerning the health significance, if any, from exposure to violative pesticide residues. In addition, the PFSS approach can be universally applied to all potential pesticide residues on all food commodities, can be modified by specific jurisdictions to take into account differences in food consumption practices, and can help prioritize food residue monitoring by identifying the pesticide/commodity combinations of the greatest potential food safety concern and guiding development of field level analytical methods to detect pesticide residues on prioritized pesticide/commodity combinations.

Determination of organophosphorus pesticide residues in vegetables by an enzyme inhibition method using α-naphthyl acetate esterase extracted from wheat flour

The widespread use of organophosphorus pesticides(OPs) poses a great threat to human health and has made the detection of OP residues in food an important task,especially in view of the fact that easy and rapid detection methods are needed.Because OPs have inhibitory effects on the activity of α-naphthyl acetate esterase(ANAE) in plants,in this work we evaluated the possibility of detecting OPs in vegetables with ANAE extracted from commercial flour.The limits of detection(LODs) obtained for methamidophos,dichlorvos,phoxim,dimethoate,and malathion in lettuce samples with crude ANAE were 0.17,0.11,0.11,0.96,and 1.70 mg/kg,respectively.Based on the maximum residue limits(MRLs) for OPs in food stipulated by Chinese laws which are 0.05,0.20,0.05,1.00,and 8.00 mg/kg for methamidophos,dichlorvos,phoxim,dimethoate,and malathion,respectively,the esterase inhibition method with crude ANAE had sufficient sensitivity to detect the residues of dichlorvos,dimethoate,and malathion in lettuce,but it could not be used to guarantee the safety of the same samples if methamidophos or phoxim residue was present.The sensitivity of the method was improved by the use of esterase purified by ammonium sulfate salting-out.The LODs obtained for methamidophos and phoxim with purified esterase were lower than the MRLs for these OPs in food.This is a very promising method for the detection of OP residues in vegetables using crude or purified esterase because of its cheapness,sensitivity,and convenience.