Urinary DEHP metabolites and fasting time in NHANES

J Expo Sci Environ Epidemiol. 2011 Nov-Dec;21(6):615-24. doi: 10.1038/jes.2011.28. Epub 2011 Aug 17.

Abstract

Exposure assessment analyses conducted in Europe have concluded that the primary pathway of exposure to di(2-ethylhexyl) phthalate (DEHP) is through the diet. The purpose of this study is to evaluate whether urinary DEHP metabolite data from the 2007-2008 National Health and Nutritional Examination Survey (NHANES) demonstrate relationships with reported food-fasting time consistent with diet as the predominant exposure pathway. Previous controlled-dosing data demonstrate that DEHP metabolite concentrations in urine first rise and then decline over time, with first-order elimination becoming evident at about 6 h post exposure. Regression of the concentrations of four key DEHP metabolites vs reported fasting times between 6 and 18 h in adults resulted in apparent population-based urinary elimination half-lives, consistent with those previously determined in a controlled-dosing experiment, supporting the importance of the dietary pathway for DEHP. For fasting times less than about 6 h, sampling session (morning, afternoon, or evening) affected the measured metabolite concentrations. Evening samples showed the highest metabolite concentrations, supporting a hypothesis of recent daily dietary exposures from multiple meals, whereas morning and afternoon samples for fasting times less than 6 h were similar and somewhat lower than evening samples, consistent with less-substantial early day dietary exposure. Variations in children's bodyweight-normalized creatinine excretion and food intake rates contribute to a strong inverse relationship between urinary DEHP metabolite concentrations and age under age 18. Finally, a previously published pharmacokinetic model for DEHP demonstrates that time since previous urinary void, a parameter not measured in NHANES, is predicted to result in non-random effects on measured urinary concentrations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Diethylhexyl Phthalate / pharmacokinetics
  • Diethylhexyl Phthalate / toxicity
  • Diethylhexyl Phthalate / urine*
  • Environmental Exposure / analysis*
  • Environmental Exposure / statistics & numerical data
  • Female
  • Humans
  • Male
  • Nutrition Surveys
  • Plasticizers / analysis*
  • Plasticizers / pharmacokinetics
  • Plasticizers / toxicity
  • Risk Assessment / methods
  • Risk Assessment / statistics & numerical data
  • Time Factors
  • United States / epidemiology

Substances

  • Plasticizers
  • Diethylhexyl Phthalate