Exposure and health assessment of 1,4-dichlorobenzene

• Main Authors: Pao-Kuei Hsiao, 蕭寶桂
• Other Authors: Yi-Chang Lin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/51375390262847373705

博士 === 國立臺灣大學 === 環境衛生研究所 === 97 === 1,4-Dichlorobenzene (1,4-DCB) is widely used as a deodorizer because of it’s volatility (vapor pressure is 1.08 mg/m3 at 25℃). It is also used as a moth repellent and toilet deodorizer. Many studies have showed that human exposed to 1,4-DCB mainly by inhalation. Human inhale high 1,4-DCB concentration may cause eye and upper respiratory tract irritation, abnormal liver/kidney function and lung disorders. In this study, we conduct an exposure assessment to clarify the relationship between 1,4-DCB exposure profile and the related health effects. The human internal dose can be analyzed by the concentrations of 1,4-DCB, 2,5-dichlorophenol (2,5-DCP), 2,5-dichlorophenol glucuronide (2,5-DCPG), and 2,5-dichlorophenol sulphate (2,5-DCPS) in urine. However, chemical standards of 2,5-DCPG and 2,5-DCPS are not commercially available, therefore, 2,5-DCPG and 2,5-DCPS were synthesized in our study. In the present study, we developed a method to analyze urinary 2,5-dichlorophenol (2,5-DCP), 2,5-dichlorohydroquinone, 2,5-DCPS, and 2,5-DCPG simultaneously by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC/MS/MS). Our method has been successfully used to detect urinary metabolites of 1,4-DCB with high throughput and represented a good sensitivity. After analysis method was established, we conducted an assessment of human 1,4-DCB exposure in three major moth repellent product plants, plant A and C are in northern Taiwan as well as plant B is in southern Taiwan. Plant C has the highest output of 1,4-DCB repellent product, and plant B has the smallest one. In our evaluated plants, samples of workers’ personal air and urine were simultaneously collected; in addition, we also collected workers’ questionnaire and biochemical test results. Our data has demonstrated the concentration of free form 2,5-DCP/2,5-DCPS in urine was generally lower (70 ~ 1050 ng/mL) than 2,5-DCPG (20 ~ 350 mg/L). Therefore, 2,5-DCPG was found to be the major metabolite after human exposed to 1,4-DCB. For air sampling, we used 3M 3500 passive sampler to evaluate repellent workers’ exposure profile. The sampling time included 8 hours daytime, and 16 hours overnight. After sampling, the air samples were analyzed by Gas Chromatography Flame Ionization Detector (GC-FID). Our results demonstrated that the highest air concentration (9.15 ± 6.37 ppm in daytime and 0.84 ± 0.68 ppm in over night) wad found in plant C, and plant B had the lowest concentration (1.19 ± 0.84 ppm in daytime and 0.08 ± 0.04 ppm in over night ). From the statistical results, the 1,4-DCB concentration in air was significantly higher in on-site workers than in non-on-site workers (p < 0.05). Moreover, the air concentration was also found to be higher in raw material operator than in semi-finished product collector (p < 0.05). The air concentration was higher in who has the habit of using mothball contained 1,4-DCB in home (p < 0.05). Once the worker has the higher air concentration of 1,4-DCB, their metabolite concentration in urine was also found to be higher (p < 0.05). In health effect, the biochemical indices such as white blood cell count (WBC), blood urea nitrogen (BUN) level and BUN/creatinine ratio are positively correlated with the air concentration and urinary metabolite concentration (p < 0.05). This study employed solid-phase extraction (SPE) to extract 1,4-DCB metabolites from urine and the metabolites were then subsequent to analysis by UPLC/MS/MS coupled with negative electrospray ionization. This method has successfully measured urinary metabolites of 1,4-DCB with high throughput and represented a good sensitivity. We found the major metabolite of 2,5-DCP in urine is 2,5-DCPG. From air sampling results, the 24 hours sampling data is much closer to the real exposure situation than 8 hours sampling. The concentration of 1,4-DCB in air and major metabolite in urine are positively correlated with WBC count, BUN concentration and BUN/creatinine ratio, but these indices is still in the normal range.