Estimated daily intake of phthalates in occupationally exposed groups

Improved analytical methods for measuring urinary phthalate metabolites have resulted in biomarker-based estimates of phthalate daily intake for the general population, but not for occupationally exposed groups. In 2003-2005, we recruited 156 workers from eight industries where materials containing diethyl phthalate (DEP), dibutyl phthalate (DBP), and/or di(2-ethylhexyl) phthalate (DEHP) were used as part of the worker's regular job duties. Phthalate metabolite concentrations measured in the workers' end-shift urine samples were used in a simple pharmacokinetic model to estimate phthalate daily intake. DEHP intake estimates based on three DEHP metabolites combined were 0.6-850 μg/kg/day, with the two highest geometric mean (GM) intakes in polyvinyl chloride (PVC) film manufacturing (17 μg/kg/day) and PVC compounding (12 μg/kg/day). All industries, except phthalate manufacturing, had some workers whose DEHP exposure exceeded the U.S. reference dose (RfD) of 20 μg/kg/day. A few workers also exceeded the DEHP European tolerable daily intake (TDI) of 50 μg/kg/day. DEP intake estimates were 0.5-170 μg/kg/day, with the highest GM in phthalate manufacturing (27 μg/kg/day). DBP intake estimates were 0.1-76 μg/kg/day, with the highest GMs in rubber gasket and in phthalate manufacturing (17 μg/kg/day, each). No DEP or DBP intake estimates exceeded their respective RfDs. The DBP TDI (10 μg/kg/day) was exceeded in three rubber industries and in phthalate manufacturing. These intake estimates are subject to several uncertainties; however, an occupational contribution to phthalate daily intake is clearly indicated in some industries.