Temporal variability of pesticide concentrations in homes and implications for exposure misclassification in cancer epidemiology

Thursday, October 11, 2012 — Poster Session III
10:00 a.m. – Noon	Natcher Conference Center, Building 45	NCI	EPID-8

* FARE Award Winner

Authors

• N.C. Deziel
• M.H. Ward
• E.M. Bell
• T. Whitehead
• R.B. Gunier
• M.C. Friesen
• J.R. Nuckols

Abstract

Background: Residential pesticide use has been linked to childhood and adult cancers. High-quality exposure estimates are critical for confirming these associations. A few epidemiologic studies have used one measurement of pesticide concentrations in carpet dust to characterize an individual’s usual exposure. If concentrations vary over time, this approach could substantially misclassify exposure and attenuate risk estimates. Methods: We collected up to 7 carpet dust samples from 21 homes in Fresno County, California from 2003-2005. Dust was analyzed for 13 pesticides using gas chromatography/mass spectrometry. We used mixed-effects models to estimate between- and within-home variance. We computed intraclass correlation coefficients [ICC=between-home variance/(between-home variance+within-home variance)] and the expected attenuation of odds ratios in a hypothetical case-control study collecting a single dust sample. Results: The median ICC was 0.79 (range=0.38-0.95), demonstrating higher between-home than within-home variability for most pesticides. The expected attenuation in odds ratios using one dust sample would be expected to be <25% for 9 of the 13 compounds evaluated. Conclusions: For most pesticides studied, use of one dust sample to represent an exposure period of ~2 years would not be expected to substantially attenuate odds ratios. Further study is needed to determine if our findings hold for longer exposure periods.

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