| Summary: | 碩士 === 國立成功大學 === 環境醫學研究所 === 98 === Phthalates (PAEs) are primarily used as plasticizers in the manufacture of flexible vinyl. According to survey of Taiwan EPA, there are 200 thousand tons of Di (2-ethylhexyl) phthalate (DEHP) and 5 thousand tons of Dibutyl phthalate (DBP) were manufactured or used between 2005 and 2007. And there are about 14 thousand workers working in polyvinylchloride processing industries. Polyvinylchloride (PVC) processing workers may expose to phthalates, the main exposure routes may via ambient air and airborne dust exposure. Some studies revealed that PAEs exposure in male may be resulted in abnormal blood biochemistry, decreased testosterone level and reduced sperm counts. In the past, no comprehensive study conducted for worker exposed to PAEs in PVC leather processing industries. Therefore, we will find out PAEs exposure levels and routes for workers in PVC leather processing industries. Screening criteria such as raw materials, products, used quantities of PAEs, and number of workers were set up to identify the high exposure potential factories. 30 workers in a selected polyvinylchloride leather processing industry were selected as study subjects. The examinations of blood biochemistry and hormones, personal and occupational exposure data, time activity pattern, airborne exposure sampling and DEHP analysis, and urine sampling and urinary DEHP metabolites of pre- and post- workshift analysis for all selected workers has been completed.
In the first day of working shift, the highest airborne DEHP concentration was 3.91 mg/m3 in mixing roll of the process 2, and followed by 1.63 mg/m3 in mixing roll of the process 3, and the lower airborne DEHP concetrations were found in four airborne samples of office (0.0113 - 0.0157 mg/m3) which were lower than banbury mixer and mixing roll (0.0203-3.9120 mg/m3). In the fifth day of working shift, the highest airborne DEHP concentration was 1.5818 mg/m3 in the winder of process 1, and followed by 1.1187 mg/m3 in mixing roll of the process 4, and the lower airborne DEHP concetrations were found in four airborne samples of office (0.005-0.0105 mg/m3). According to the airborne DEHP concertration, job categories and time activity data, 30 workers were categorized to two groups: high exposure group (banbury mixer and mixing roll workers, n=15), low exposure group (winder workers and officers, n=15).
The urinary MEHHP levels of high exposure group in the preshift of first and fifth day were 116.8, 151.15μg/g creatinine and in the postshift of first and fifth day were 190.53, 256.77μg/g creatinine. The urinary MEHHP levels of low exposure group in the preshift of first and fifth day were 46.03, 44.63μg/g creatinine and in the postshift of first and fifth day were 78.62, 63.68μg/g creatinine. The urinary MEHHP (P = 0.0327, 0.001) and MEOHP (P=0.0443, 0.005) levels of high exposure group were significant higher than low exposure group in the preshift of first and fifth day. The urinary MEHHP and MEOHP levels of high exposure group were significant higher than low exposure group (P=0.01, 0.008) in the postshift of first day. The urinary MEHP and MEOHP levels of high exposure groupwere significant higher than low exposure group in the postshift of fifth day. And the urinary MEHHP levels of high exposure group were marginal significant higher than low exposure group (P=0.07) in the postshift of fifth day. The urinary MEHP, MEHHP, MEOHP levels of high exposure worker in the postshift of first and fifth day were higher than in the preshift of first and fifth day (P＜0.05). But no significant difference was found in urinary DEHP metabolites in low exposure worker. Due to occupational exposue, the urinary DEHP metabolites levels in high exposure group higher than low exposure group. The urinary MEHP, MEOHP levels of high exposure worker in the postshift of fifth day were higher than first day (P＜0.05). But no significant difference was found in urinary MEHHP level between the postshift of first day and fifth day. So, the high exposure worker has higher exposure levels, and cause to accumulate.
In the first day, R-Square of the airborne DEHP concentration and urine MEHHP concentration was 0.205, it’s median correlation. In the fifth day, the R-square was 0.449, it shows to highly correlatied. We concluded the airborne DEHP exposure maybe one of the mainly exposure route.
We found the T3 concentration of higher exposure group was significant lower than low exposure group (110.5 vs. 125.1 ng/dL, p=0.0075). And we also found the T4/FT4 ratio of higher exposure group was significant lower than low exposure group (median 5.39 vs. 6.05, p=0.0023).
Beside, the urinary MEHHP levels of high exposure worker have widly range (Min=13.04, Max=524.24 ng/mg creatinine). So, we rechange the group. First, we divide to high and low level group by air levels and job title. Then, according the median of the urinary MEHHP level (171.34 ng/mg creatinine), we divide high exposure to two groups. In the Result, we found the inhibin b concentration in higher exposure group (68.6 pg/ml) were lower than those in the median (74.8pg/ml) and low exposure (102.3 pg/ml) groups (P=0.0275; Ptrend=0.006).
We analyse the correlation coefficients between with urinary metabolites of DEHP and serum reproductive and thyroid hormone. We found the correlation coefficients were positive significant between in the posshift of fifth day and reproductive hormorne FAI, testosterone, E2(correlation coefficients=0.405, 0.393, 0.443, p＜0.05). And there are the same result in the simple regression analysis.
In conclusion, the workers were truly exposed to higher concentration of DEHP emitted from polyvinylchloride leather processing industry. The usage of personal protective measures was suggested to effectively reduce the concentrations of urinary metabolites of DEHP. Although the hightest airborne DEHP (3.91 mg/m3) was lower than Permissible Exposure Limit (5 mg/m3), the daily expsoure doses of DEHP in 15% workers were higher than the reference doses of EU and US EPA. In addition, DEHP is known endocrine disruptor, further studies are suggested to determine the long-term health effects of DEHP exposure, and to verify the availability of protection of PEL for workers.
|
|---|
