Comparison of exposure assessment guidelines for pesticides

The field of exposure assessment of pesticides has become well established in the past decade. Consequently, government agencies and industry groups have identified the need for guidelines for conducting studies that assess mixer/loader/applicator exposure to pesticides, as well as the exposure of individuals to residues. This paper reviews guidelines on mixer/loader/applicator exposure studies issued by the International Group of National Associations of Manufacturers of Agrochemical Products, the National Agricultural Chemicals Association, the U.S. EPA, and the World Health Organization. Mention is also made of Canadian exposure guidelines in preparation. Also reviewed are two guidelines for conducting indoor occupant exposure studies, one by the National Agricultural Chemicals Association and one by Health and Welfare Canada. The only available guideline (EPA) on assessing pesticide exposure to workers upon reentry into treated fields is also reviewed. These guidelines are reviewed and compared as to criteria for requirements of exposure studies, methodologies recommended for dermal, inhalation, and biological monitoring, quality assurance and quality control, the use of surrogate data, data reporting, and exposure calculations. From this comparison, it is evident that there has been little significant progress in the area of methodologies used for dermal exposure monitoring. The use of patches as suggested by Durham and Wolfe (1962) is still accepted and widely used, despite its limitations. However, relatively recent research in this area has shown that the fluorescent tracer technique (Fenske et al. 1986a,b) and use of full-body dosimeters may help in overcoming some of these limitations. The tracer technique is mentioned in the EPA guidelines and full-body dosimeters are addressed by EPA, WHO, and NACA. Biological monitoring can also overcome many of the limitations of passive dosimetry, but all guidelines stress the need for extensive knowledge of the pharmacokinetics and metabolism of the pesticide before this approach can be used. Rapid advancement has been made in quality assurance/quality control and analytical techniques. This has increased the level of confidence placed in exposure estimates and is evidenced by the detailed requirements of quality assurance and quality control in most of the guidelines reviewed. Guidelines on conducting indoor occupant exposure studies deal extensively with methodologies for collecting residue samples, but do not make concrete recommendations for estimating human exposure based on these residues. More research is required before the subject can be adequately dealt with in guidelines. It is encouraging that this research is being coordinated among industry, academia, and government. Further research is also needed in determining exposure to pesticides during reentry into treated areas in order to develop further guidelines.(ABSTRACT TRUNCATED AT 400 WORDS)