Abstracts: ISEE 20th Annual Conference, Pasadena, California, October 12–16, 2008: Contributed Abstracts
Carbaryl and Naphthalene Exposures Among a Pregnant Latina Population Living in an Agricultural Area
Naphthalene, a respiratory carcinogen, is a component of vehicle exhaust, cigarette smoke and mothballs. Carbaryl, a potential neurotoxicant, is commonly used in agriculture and for landscape maintenance. 1- and 2-hydroxynaphthalene (1- and 2-naphthol) are metabolites of naphthalene; 1-naphthol may also derive from carbaryl.
We measured 1- and 2-naphthol in urine samples collected in the first and third trimester from over 500 pregnant women living in the Salinas Valley, CA (1999–2001). The women were participants in a community-based cohort study (Center for the Health Assessment of Mothers and Children of Salinas-CHAMACOS) led by the University of California at Berkeley.
The CHAMACOS detection frequencies for 1- and 2-naphthol ranged from 66% to 75%. Median concentrations for both compounds were similar to median concentrations among U.S. national reference data for 118 pregnant women (NHANES). Correlation analyses indicate moderate correlations between the two metabolites within each sampling time point (rho = 0.42– 0.56, P < 0.001), and between the two sampling time points for 2-naphthol (rho = 0.56, P < 0.001). If exposure to only naphthalene was occurring, we would expect similar amounts of both metabolites. The average of the women's 13-week metabolite ratios of 1-naphthol to 2-naphthol was 5 to 1, suggesting that exposure to both carbaryl and naphthalene may be occurring in this cohort. By contrast, the average ratio of 1-naphthol to 2-naphthol among pregnant women participating in NHANES was 2 to 1. Among CHAMACOS women working in agriculture during their first trimester of pregnancy, median 1-naphthol levels were slightly higher (2.3 μg/L) compared to women not employed in agriculture (1.8 μg/L) (Kruskal-Wallis P-value = 0.05). Additional analyses of metabolite levels and potential risk factors of exposure such as number of farmworkers living in the home, distance of home to agricultural fields, smoking, etc., and diet will be presented. Finally, a comparison of the estimated maternal doses to U.S. EPA health-based reference values will provide a basis to interpret the health significance of these exposure levels.© 2008 Lippincott Williams & Wilkins, Inc.