Estimated daily intake of phthalates in occupationally exposed groups

Abstract

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 mg/kg/day, with the two highest geometric mean (GM) intakes in polyvinyl chloride (PVC) film manufacturing (17 mg/kg/day) and PVC compounding (12 mg/kg/day). All industries, except phthalate manufacturing, had some workers whose DEHP exposure exceeded the U.S. reference dose (RfD) of 20 mg/kg/day. A few workers also exceeded the DEHP European tolerable daily intake (TDI) of 50 mg/kg/day. DEP intake estimates were 0.5-170 mg/kg/day, with the highest GM in phthalate manufacturing (27 mg/kg/day). DBP intake estimates were 0.1-76 mg/kg/day, with the highest GMs in rubber gasket and in phthalate manufacturing (17 mg/kg/day, each). No DEP or DBP intake estimates exceeded their respective RfDs. The DBP TDI (10 mg/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.

Relationship between urinary concentrations of di(2-ethylhexyl) phthalate (DEHP) metabolites and reproductive hormones in polyvinyl chloride production workers

“…Conversely, our findings were inconsistent with other studies of non-occupationally exposed groups. There is reason to believe that occupational exposure is generally much higher than non-occupational exposure through diet and the activities of daily living 48. In the present study, we found that the GMs of creatinine-adjusted concentrations of MEHP, MEOHP and MEHHP during the post-shift periods were 23.9, 66.9 and 84.6, respectively.…”

Occupational exposure to diisononyl phthalate (DiNP) in polyvinyl chloride processing operations

“…We also did not have information on non-occupational DiNP exposure, such as diet, off-the-job activities, and at home. Although the method we used to estimate DiNP daily intake from urinary metabolite concentrations has been commonly used, the method has certain limitations, including temporal variability in metabolite concentrations, source variability, variability in model input parameters (F UE and CE), and within-and between-person variability in metabolism (discussed more fully in Hines et al 2011); thus, our DiNP intake estimates should be interpreted with caution. No occupational exposure standards have been established for DiNP metabolites in urine; hence, we compared our estimated DiNP daily intake to intake limits recommended by the U.S. CPSC and the European FSA.…”

“…Workers were recruited as part of a NIOSH study of occupational phthalate exposure (Hines et al 2009, Hines et al 2011. Two companies in the study used DiNP during the sampled period; one company manufactured PVC film (n = 25, recruited in 2004), and one company performed custom PVC compounding (n = 12, recruited in 2005).…”

“…We used end-shift creatinine-adjusted (CR-adjusted) MCiOP concentrations and the method of David (2000) as previously described in Hines et al (2011) to estimate each participant's daily intake of DiNP (Eq. 1).…”

The role of human biological monitoring in health risk assessment

“…The DEHP DI can be estimated by using the individual concentration of the metabolite (and corresponding FUE values) in equationslisted in Table 4. For example, DI of DEHP has been estimated using the sum of the concentrations of three metabolites (Wittassek et al, 2007a;Hines et al, 2011) and five metabolites (Wittassek et al, 2007b;Frederiksen et al, 2011) in population level biomonitoring studies.…”