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OCCURRENCE OF CHIRAL PESTICIDES IN HUMAN BREAST MILK AND OTHER MEDIA
Citation:
Falconer, R L. AND M K. Morgan. OCCURRENCE OF CHIRAL PESTICIDES IN HUMAN BREAST MILK AND OTHER MEDIA. Presented at Society of Environmental Toxicology and Chemistry 22nd Annual Meeting, Baltimore, MD, November 11-15, 2001.
Impact/Purpose:
The goal of this task is to contribute to a better understanding of human exposure to pesticides, especially for small children by developing methods to characterize sources and pathways in and around the residential environment. We will support the science behind FQPA and assist the Office of Pesticide Programs (OPP) in the development of guidelines for the assessment of residential exposure to pesticides. Specific research objectives include: (i) to evaluate and develop methods for measuring pesticides in air using passive/diffusive samplers. Assess and refine devices for the collection of surface transferable pesticide residues and to establish transfer efficiencies; (ii) to develop and apply analytical methods for new and emerging pesticides using both gas and liquid chromatographic methods in support of the National Exposure Research Laboratory's (NERL) Human Exposure Measurement Project; and, (iii) to conduct pilot studies investigating chiral chromatographic methods.
Description:
Enantiomers of chiral pesticides have the same physical and chemical properties; therefore transport processes, such as leaching and volatilization, and abiotic reactions, such as hydrolysis and photolysis, do not discriminate between the enantiomers. Since enzymes themselves are chiral molecules, however, they can react selectively with one of the enantiomeric forms. Thus, metabolism by microorganisms in water and soil and in higher organisms often leads to non-racemic residues. Examining the enantiomeric patterns of pesticides can thus provide a sensitive indicator of biological degradation. Numerous studies have been done looking at chiral pesticides and their metabolites in the environment and several researchers have reported preferential degradation/accumulation of pesticide enantiomers in biota. Unfortunately, very little work has been done to date on chiral pesticides in the human body and indoor environment even though past research has shown that enantiomers of biologically active chiral molecules can differ in potency, pharmacological action, metabolism, toxicity and kinetics. This study looks at the enantiomeric patterns of chiral pesticides and their chiral metabolites in human breast milk and adipose tissue as well as in indoor media including house dust. Several human breast milk samples showed selective degradation for o,p'-DDT, trans-chlordane, cis-chlordane, oxychlordane and -hexachlorocyclohexane, although pesticide levels were near or at detection limits for most compounds.
This work has been funded wholly or in part by the United States Environmental Protection Agency and has been subjected to Agency review and approved for publication.