Urinary concentrations of dichlorophenol pesticides and obesity among adult participants in the U.S. National Health and Nutrition Examination Survey (NHANES) 2005-2008.
Accumulating evidence from recent studies has suggested a possible link between exposure to environmental pesticides and obesity. In this study, we assessed the potential associations between exposure to dichlorophenol pesticides and obesity in adults. Study participants aged 20-85 years were selected from the 2005 to 2006 and 2007 to 2008 U.S. National Health and Nutrition Examination Survey, and were categorized as obese and non-obese based on body mass index. Creatinine-corrected urinary concentrations of dichlorophenols were determined to assess level of exposure to environmental pesticides. Multivariate logistic regression was performed using SAS 9.3 to assess the association between 2,4-dichlorophenol (2,4-DCP) and 2,5-dichlorophenol (2,5-DCP) levels in urine and obesity with adjustment for potential confounders. Significantly higher geometric means of urinary concentrations of both 2,5-DCP (p<0.0001) and 2,4-DCP (p=0.0170) were seen in obese adults, compared to that in non-obese adults. A dose-dependent increase in the prevalence of obesity was observed in the study participants across increasing levels of urinary 2,5-DCP (p-trend<0.0001). Urinary concentrations of 2,5-DCP were significantly associated with obesity among the second (AOR: 1.47, 95% CI: 1.12, 1.93), third (AOR: 1.41, 95% CI: 1.07, 1.87), and fourth (AOR: 1.62, 95% CI: 1.21, 2.17) inter-quartiles after adjustment for age, gender, race, education, total fat intake, and physical activity. A statistically significant association was not seen between urinary 2,4-DCP and obesity. Our findings suggest a potential relationship between exposure to the fumigant insecticide paradichlorobenzene, measured as urinary concentrations of 2,5-DCP, and obesity in adults. Because we cannot rule out the possibility of reverse causality in our study, prospective studies measuring exposure during etiologically relevant periods are warranted.