Speaking Topics

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), generally known as dioxins, are highly lipophilic and resist environmental degradation. Endocrine-disrupting chemicals (EDCs) are natural or human-made chemicals that may mimic, block, or interfere with the body’s hormones, which are part of the endocrine system. These chemicals are associated with a wide array of health issues in working environment. Public concern about the impact of EDCs on workers is growing steadily. In present researches, we focused on the PCDD/F exposure assessment of workers of electric arc furnaces, secondary copper-melting plants, and secondary aluminum smelting plants, the phthalates exposure assessment of PVC production workers and occupational phthalates exposure for workers in printing industry. 

In the first study, we aimed to elucidate the serum PCDD/F levels of 134 workers and ambient air levels around electric arc furnaces (EAF), secondary copper smelters and secondary aluminum smelters (ALSs) in Taiwan. The highest serum PCDD/F levels were found in the ALSs workers (21.9 pg WHO-TEQ/g lipid), with lower levels in copper smelter workers (21.5 pg WHO-TEQ/g lipid), and the lowest in the EAF plant workers (18.8 pg WHO-TEQ/g lipid). This was still higher than the levels for residents living within 5 km of municipal waste incinerators (14.0 pg WHO-TEQ/g lipid). For ambient samples, the highest ambient air PCDD/F level was in the copper smelters (12.4 pgWHO-TEQ/Nm3), with lower levels in ALSs (7.2 pgWHO-TEQ/Nm3), and the lowest in the EAF industry (1.8 pgWHO-TEQ/Nm3). The congener profiles were consistent in serum and in air samples collected in the copper smelters, but not for ALSs and EAF. In secondary copper smelters, the air PCDD/Fs levels might be directly linked to the PCDD/Fs accumulatedin the workers due to the exceedingly stable congener pattern of the PCDD/F emission.

In the second study, we aimed to investigate the urinary metabolite levels of di(2-ethylhexyl)phthalate (DEHP) and adverse reproductive health effects for PVC production workers. However, the contributions of different routes of exposure to DEHP are unclear. We used personal air sampling and biomonitoring 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 mono(2-ethylhexyl) phthalate (MEHP), (mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) were measured in pre-shift and post-shift samples. The biomarkers for their reproductive hormone were measured. The geometric means of airborne concentrations of DEHP were 5.3 g/m3 (low-exposure group) and 32.7 g/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 g/kg/day (low-exposure group) and 15.5 g/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 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 also found sperm concentration and motility were significantly affected in the high-exposure group. The percentage and intensity of sperm ROS generation were higher in the high-exposure group than those in the control group. After adjustment for age, smoking status, and coffee consumption, the decrease in sperm motility was inversely associated with the concentration of MEHP (b = -0.549, P = 0.0085), MEHHP (b = -0.155, P = 0.0074), and MEOHP (b = -0.201, P = 0.0041). Moreover, sperm apoptosis and ROS generation were positively associated with MEHHP and MEOHP concentration, respectively.