You are here:
CHIRAL METHODS AND ANALYSIS OF PCB 95 AND CIS -PERMETHRIN IN ENVIRONMENTAL SAMPLES FROM THE CTEPP STUDY
Citation:
ULRICH, E. M., T. CUMMINGS, A. W. GARRISON, AND M. K. MORGAN. CHIRAL METHODS AND ANALYSIS OF PCB 95 AND CIS -PERMETHRIN IN ENVIRONMENTAL SAMPLES FROM THE CTEPP STUDY. Presented at Chirality 2007 - 19th International Symposium on Chirality, San Diego, CA, July 08 - 11, 2007.
Impact/Purpose:
To determine the environmental occurrences, fate, and effects of the enantiomers of selected chiral pesticides and other chiral pollutants.
Description:
The creation of chiral chromatography techniques significantly advanced the development of methods for the analysis of individual enantiomers of chiral compounds. These techniques are being employed at the US EPA for human exposure and ecological research studies with indoor samples, sediment, plants, and biota. A variety of chemicals including legacy persistent organic pollutants and current use pesticides are being investigated. One such project is the Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study. The CTEPP study focuses on measuring the exposures of preschool children to chemicals, including pesticides and polychlorinated biphenyls (PCBs), found in their everyday environments (i.e., homes and daycare centers). Chiral gas chromatographic mass spectrometry methods were developed and the enantiomer fractions of cis-permethrin and PCB 95 were measured in selected environmental samples. Enantiomer fractions [EF = chromatographic peak area (+) enantiomer / sum of (+) and (-) areas] can be used to implicate sources, distinguish between biological and other types of degradation, and give a more complete picture of environmental concentrations. cis-Permethrin has a racemic signature, or an EF of 0.5, in the three matrices analyzed (floor dust, hard floor surface wipe, and food preparation surface wipe). These results suggest that no enantioselective biological degradation of permethrin has occurred. PCB 95 EFs range between 0.48 and 0.69 in eight different matrices (transferable residues from surfaces; floor dust; food preparation surface, hard floor surface, and dermal wipes; indoor and outdoor air; and soil). The nonracemic EFs in the environmental samples indicate that some enantioselective biological degradation has occurred to this PCB over time, either in the indoor environment, or prior to translocation to the indoor environment. These results highlight the importance of the enantiomers of chiral compounds because some degradation pathways, usually biological ones, can change the distribution of enantiomers in the environment. This may lead to differential exposure to enantiomers, as is the case with PCB 95. The toxicity of enantiomers can also vary. When these two factors are combined, a differential risk to humans and other organisms may also be revealed.