| Measurement of Organophosphate Metabolites in Postpartum Meconium as a Potential Biomarker of Prenatal Exposure: A Validation Study Robin M. Whyatt1 and Dana B. Barr2 1Columbia Center for Children's Environmental Health, Division of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
2Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA Abstract
Experimental data have linked exposure to prenatal organophosphates to adverse neurocognitive sequalae. However, epidemiologic research has been hampered by lack of reliable dosimeters. Existing biomarkers reflect short-term exposure only. Measurements of pesticides in postpartum meconium may yield a longer-term dosimeter of prenatal exposure. As the initial step in biomarker validation, this research determined background levels, detection limits, and stabilities of six organophosphate metabolites in meconium: diethylphosphate (DEP) , diethylthiophosphate (DETP) , diethyldithiophosphate (DEDTP) , dimethylphosphate (DMP) , dimethylthiophosphate (DMTP) , and dimethyldithiophosphate (DMDTP) . Calibration curves were also constructed. The meconium was collected from 20 newborns at New York Presbyterian Hospital ; analyses were undertaken at the Centers for Disease Control and Prevention (CDC) . DEP was detected in 19/20 samples (range 0.8-3.2 µg/g) and DETP was detected in 20/20 (range 2.0-5.6 µg/g) . DMP and DEDTP were each detected in 1/20 (at 16 and 1.8 µg/g, respectively) . DMTP and DMDTP were not detected. Detection limits were comparable to or lower than those in urine ; levels were similar to those seen in adult urine in population-based research. Metabolites were stable at room temperature over 12 hr. Calibration curves were linear over the range tested (0.5-400 µg/g) ; recoveries ranged from 18% to 66%. Using isotope dilution, recoveries of each analyte in individual samples can be corrected automatically based on the recovery of the respective stable isotope-labeled analogue, making this method fully quantitative. Results indicate that measurements of organophosphate metabolites in meconium have promise as biomarkers of prenatal exposure. Further research is needed to determine the time frame of exposure represented by pesticide levels in meconium and to evaluate the dose-response relationship. Key words: biomarkers, meconium, organophosphates, pesticides, prenatal exposures. Environ Health Perspect 109:417-420 (2001) . [Online 29 March 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p417-420whyatt/ abstract.html Address correspondence to R.M. Whyatt, Division of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 60 Haven Avenue, B-1, New York, NY 10032 USA. Telephone: (212) 304-7273. Fax: (212) 544-1943. E-mail: rmw5@columbia.edu We thank R. Bravo and D. Whitehead of the CDC for technical assistance and P. Holahan and A. Viade of New York Presbyterian Hospital for assistance in the meconium collection. This work was supported by the National Institute of Environmental Health Sciences (NIEHS) P50 ES09600 ; NIEHS P30 ES09089 ; U.S. Environmental Protection Agency R827027 ; the Gladys and Roland Harriman Foundation ; the W. Alton Jones Foundation ; and the New York Community Trust. Received 10 August 2000 ; accepted 13 October 2000.
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