Urinary concentrations of 2,5-dichlorophenol and diabetes in US adults

Para-dichlorobenzene (p-DCB) products are widely used in the home and public buildings, leading to exposure to this chemical in indoor environments. In this study, we explored potential relationships between p-DCB exposure and diabetes in US adults by analyzing a nationally representative subsample of 3063 adult participants aged 20-79 years randomly selected for measurement of urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the major metabolite of p-DCB, in the 2007-2010 National Health and Nutrition Examination Survey. Median urinary 2,5-DCP concentration was 7.0 μg/l (interquartile range: 2.1-29.9). Of the participants, 560 (13.6%) were diabetic. A dose-dependent increase in the prevalence of diabetes was observed in the study participants across quartiles of urinary 2,5-DCP (P-trend<0.0001). After adjusting for potential confounders, individuals in the highest quartile of urinary 2,5-DCP had an increased odds of diabetes (OR=1.59 (95% CI: 1.06, 2.40)) compared with individuals with the lowest quartile. The highest quartile of urinary 2,5-DCP was also positively associated with insulin resistance (adjusted β=0.75; 95% CI: 0.27, 1.24). This study demonstrated a potential association between exposure to p-DCB, measured as urinary concentrations of 2,5-DCP, and diabetes in US adults. Additional epidemiologic and mechanistic studies would further explore these interactions.