The Study on DEHP Exposure Analysis and Reproductive Hormones Disruption for PVC Workers

Abstract

The published studies had showed the troubling reports of high urinary metabolite levels and adverse reproductive health effects in workers exposed to di(2-ethylhexyl)phthalate (DEHP) in occupational settings and the contributions of different routes of exposure to DEHP are unclear After exposure most of the DEHP is rapidly metabolized to hydrolytic monoester (mono(2-ethylhexyl) phthalate: [MEHP]) and oxidative metabolites (mono (2-ethyl-5-hydroxyhexyl) phthalate: [MEHHP] mono (2-ethyl-5-oxohexyl) phthalate: [MEOHP]) which are associated with reproductive hormone interruption and testicular toxicity Some studies report that urinary concentrations of phthalate metabolites for plastics workers are significantly higher than for the general population However little is known about the disruption of reproductive hormones for workers exposed to DEHP There are two parts in this research: Part_I Estimating the Contribution of Inhalation Exposure to Di-2-ethylhexyl Phthalate (DEHP) for PVC Production Workers Using Personal Air Sampling and Urinary Metabolite Monitoring; Part_II: Relationship between urinary concentrations of di(2-ethylhexyl) phthalate (DEHP) metabolites and reproductive hormones in polyvinyl chloride production workers In part_I study we used personal air sampling and bio-monitoring to determine the contribution of inhalation exposure to the body burden of DEHP in the workplace Eighty-nine workers (high-exposure group: 66 raw-materials workers; low-exposure group: 23 administrative workers) were recruited from three polyvinyl chloride (PVC) factories Urinary levels of MEHP MEOHP and MEHHP were measured in pre-shift and post-shift samples The geometric means of airborne concentrations of DEHP were 5 3 μg/m3 (low-exposure group) and 32 7 μg/m3 (high-exposure group) (p <0 01) Correlation analysis showed a consistently significant association between airborne DEHP concentration and urinary DEHP metabolite levels in the high-exposure group Calculating daily DEHP intake based on total urinary metabolite levels showed that the geometric means of total daily urinary metabolite levels of DEHP were 9 2 μg/kg/day (low-exposure group) and 15 5 μg/kg/day (high-exposure group) (p <0 01) A quartile analysis of all workers showed a significant trend toward an association between the individual contribution of inhalation exposure to DEHP and urinary DEHP metabolite levels for which the mean inhalation contribution was 46 7% in the highest quartile We conclude that inhalation-absorbed airborne DEHP significantly increased the total body burden of DEHP in these occupationally exposed workers In part_II study the cross-sectional study of 82 male workers (seniority in current job > 1year) measured the biomarkers for their reproductive hormones and their exposure to DEHP Relationships between urinary concentrations of DEHP metabolites were estimated using multivariate linear regression and quartile analysis models The geometric means (GMs) of urinary creatinine-adjusted (μg/g-Cre) concentrations of MEHP MEOHP and MEHHP metabolites during the post-shift period were 23 9 66 9 and 84 6 respectively In multiple regression models adjusted for potential confounders there were significant positive associations between urinary concentrations of DEHP metabolites and estradiol (E2) (p <0 01) and in the ratio of E2 to testosterone (p <0 05) Moreover quartile analysis showed significant positive relationships between the total urinary concentration of DEHP metabolites and E2 (ptrend = 0 024) and in the ratio of E2 to testosterone (ptrend = 0 031) Relationships between reproductive hormones and the total urinary concentration of DEHP metabolites in male PVC production workers were significantly positive This indicated that aromatase activity had increased in male workers exposed to DEHP which is consistent with animal studies We suggest that workers with high urinary DEHP metabolite levels use personal protection equipment and be assigned to work areas well ventilated by local exhaust systems The potential harm these flexible PVC products pose to male workers could be considerable because of their wide use in myriad consumer products

Date of Award	2015 Aug 21
Original language	English
Supervisor	Ching-Chang Lee (Supervisor)