Health Risk Estimation of Dichlorobenzene Exposure Workers by Using Computer Models

1,4-Dichlorobenzene (DCB), widely used as a moth repellent and a space deodorant, is one kind of chlorobenzene that is classified by the International Agency for Research on Cancer among chemicals possibly carcinogenic to humans on the basis of a sufficient evidence for carcinogenicity to rodents. DCB has been found to cause renal tubular-cell adenocarcinomas in rats and hepatocellular carcinomas in mice but without their clastogenic and genotoxic effects. In this study, we investigated the health risk of DCB workers from three steps. Firstly, we investigated the cytotoxicity of 1,4- dichlorobenzene and its metabolite 2,5-dichlorophenol in human lymphoma Jurkat cells, human colon adenocarcinoma cells and human hepatocellular carcinoma cells. The LD50 of DCB were 1.34 mM, 5 mM and 2 mM in Human lymphoma Jurkat cells, human colon adenocarcinoma cells and human hepatocellular carcinoma cells respectively. DCB was found to cause apoptosis itself and reduced the staurosporine-induced apoptosis in all three cells. Secondly, works in four factories were investigated to examine their blood cells. Two items, their apoptosis rate and their anti-apoptosis rate, were investigated on the work's blood. In an investigation on Dec, 2004, we found a significant higher apoptosis rate of exposure workers comparing with nonexposure workers. The blood cells of workers were significantly resistant to the staurosporine-induced apoptosis. In the other three investigations in 2005, we found similar phenomenon that the blood cells of exposure workers had higher apoptosis rate and higher resistant rate to staurosporine-induced apoptosis. Thirdly, the DCB content in the urine and blood of workers were analyzed. Based on the low to high level of DCB content, the workers were grouped into 10 degrees. The correlation of the level of DCB and apoptosis rate and anti apoptosis rate was analyzed by Pearson Correlation Program. The apoptosis rate and anti-apoptosis rate of worker's blood were both significant negatively correlated with the DCB content in their urine and air. Based on this computer program analysis, we suggest that the exposure of DCB induced significant changes of the blood cell of exposure workers and need to be concerned.

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