NEW LABORATORY METHODS FOR IDENTIFYING HUMAN EXPOSURE TO NON-PERSISTENT PESTICIDES

Abstract

ISEE-451 Introduction: Low-level exposure to pesticides does not typically induce acute toxic effects; however, the potential effects of chronic, low-level exposures are topics of many current research studies. In order to properly classify exposures in these studies, accurate and reliable methods for determining individual and population exposures must be used. Biological monitoring is a useful tool for assessing exposure to pesticides. However, biological monitoring data, along with other exposure assessment tools, are inherently complex. If these data are not properly interpreted, erroneous conclusions can be drawn from them. Methods: We have developed methods to measure concentrations of pesticides and/or their metabolites in biological media including blood serum or plasma, urine, saliva, amniotic fluid and meconium. The pesticide classes that can be measured include organochlorine, organophosphate, carbamate and pyrethroid insecticides, herbicides and fungicides. Our methods use high resolution or tandem mass spectrometry and isotope dilution quantification. They are highly selective and sensitive, with the ability to measure general population exposures with great precision. We have used these methods to assess exposure in many large prospective cohort studies. Although these data have provided useful exposure assessment information, interpreting the data has become a complex issue that is the topic of much debate. For example, if metabolites can be derived from multiple pesticides, how is the correct exposure identified? Are creatinine-corrected data from spot urine samples reliable? Is a single spot urine sample sufficient to evaluate transient exposures to nonpersistent pesticides? Should all blood pesticide data be adjusted for lipid content? These questions among others will be addressed. Discussion: Biological monitoring is a useful tool for exposure assessment if the data are properly handled and interpreted. We describe our comprehensive approach to biological monitoring of pesticides in multiple biological matrices using innovative mass spectrometry-based methods. In addition, we present case examples of the complexity of interpreting biological monitoring data.