| Summary: | 碩士 === 國防醫學院 === 公共衛生學研究所 === 95 === Foundry workers are exposed to silica and lead to an increased risk of silicosis and lung cancer. The development of silicosis has been considered to be associated with immunotoxicity pathway. In addition, silica may make DNA damage. The purpose of our study is to find out biomarkers of immunotoxicity and genotoxicity for silica exposure. We estimate DNA damage by comet assay. And the immunotoxicity of silica are presented by cytokines of plasma. To study the silica exposure level was associated with cytokine concentration and silicosis development, then conjectured the mechanism of silicosis development. Finally, we studied the changes of cytokine concentrations in the workers after an engineering control intervention to reduce the silica level.
Our study population is 103 male from 3 foundries in Taiwan. All subjects were categorized into high, medium, and low-exposure groups according to their job title and air silica concentrations. To collect the personal characteristic, personal habits and disease histories by questionnaire. Blood was collected to measure DNA damage and cytokine concentrations.
Our study found the L/H parameter presented silica exposure and DNA damage had dose-response effect(p<0.05). In addition, high exposure group’s DNA damage level was significantly higher than medium-low exposure group. After confounders were adjusted, high exposure group’s DNA damage was still significantly higher than medium-low exposure group. However, the result of cytokines showed that IL-4 level in high and medium exposure were both significantly than low exposure group, and showed a dose-response relationship (p<0.05). The concentration of cytokines were categorized into low and high levels according to the median concentration of low exposure group. The Odds ratios of having high IL-4 and IFN-gamma in the high exposure group were 7.42 and 9.56. The Odds ratios of having high IL-4 and IFN-gamma in the medium exposure group both were 4.27.
The longitudinal study’s result was different with our hypothesis. We found the IL-4,IL-6,IL-10 levels had significantly increased after engineering control intervention to reduce silica level. Finally, we had not find the association of cytokines and silicosis(p>0.05).
Our study showed that silica exposure level was increased, and the DNA damage level was increased. In addition, IL-4 can be a cytotoxicitic biomarker of silica exposure. IFN-gamma needs further studies in the future.
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