Levels of dialkylphosphate metabolites in urine among general U.S. population

• Nonsmokers had higher levels of urinary DMTP than smokers for adolescents and adults.
• Exposure to SHS at home was associated with higher levels of DMP among children.
• Children had higher levels of DMTP than both adolescents and adults.
• Children had higher levels of DETP than both adolescents and adults.
• Age was negatively associated with the levels of DMTP among children.

Data from National Health and Nutrition Examination Survey for years 2003–2008 were used to study the factors that affect urinary levels of dialkylphosphate (DAP) metabolites in urine. Separate regression models were fitted for children aged 6–11 years, adolescents aged 12–19 years, and adults aged ≥20 years. Specifically, DAP metabolites that were analyzed were: dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP). Males had statistically significantly lower adjusted levels than females for DMP for adolescents, for DEP for adults, for DMTP for both adolescents and adults, and for DETP for both children and adults. Nonsmokers had statistically significantly higher adjusted levels than smokers for DMTP for adolescents and for DMP and DMTP for adults. Exposure to second hand smoke at home was associated with relatively higher levels of DMP among children (p = 0.01) but the reverse was found to be true for DMTP (p < 0.01) among adolescents as well as adults (p = 0.02). Children had higher levels of DMTP than both adolescents and adults (p < 0.01) and higher levels of DETP than adolescents (p = 0.02). Age was found to be negatively associated with the levels of DMTP (p = 0.01) among children and positively associated (p < 0.01) with the levels of all four metabolites among adults.