The development of biological indexes to assess risk of carcinogenicity among workers exposed to dioxins

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Dioxin is well known that it causes cancer in human and the issue is of great concern among the public. On the other hand oxidative stress is now widely recognized that it closely relates to carcinogenicity. To know whether excessive oxidative stress is induced among workers exposed to dioxins will be useful information for preventing cancer induced by dioxins. This research is aimed to develop new methods or validate newly appearing methods to measure oxidative stress level and to establish the method for assessing the risk of causing cancers among workers exposed to dioxins. To accomplish this research we first have to develop indexes that could effectively evaluate exposure level of dioxins and oxidative stress level and then to validate whether afore mentioned indexes will possibly of our research is as follows.Summary of our research is as follows.1)Development of indexes that surrogate the exposure level of incinerator workers to dioxins : On the base of the preliminary study abo … More ut job class which has possible exposure to fly ash in the target factory, interview on the job history, especially concerning on the work inside the incinerator, inside the electrical precipitator, and at fly ash solidifying machine. According to the result of the interview, we calculated the duration that each worker engaged in jobs, which includes works that had possible exposure to fly ash. We classified workers into three groups those are long term exposure group, short term exposure group and control group. We also corrected blood samples from a part of workers in each group and measured blood dioxin levels. Comparing these two indexes we found that the duration of exposure to fly ash correlated well with blood dioxin levels. We showed that the index constructed by the duration of engagement in job related to possible exposure to fly ash would be surrogate index to the exposure level of dioxins.2)Development of effective methods to evaluate oxidative stress level : We developed the method to detect genome DNA damage induced by oxidative reaction using electrophoresis. We then validated the ELISA method to detect urinary substance that is related to genome DNA damage induced by oxidative reaction and proved that the method was well quantitative and cost efficient measurement to be applied to epidemiological studies. And also showed that the target substance was stable enough to be good indicator for oxidative stress level of each subject.3)Application of our methods to epidemiological study : Investigation of incinerator workers revealed that among several indexes of oxidative stress, urinary 8-OHdG level had good correlation with the duration engaged in work that has possible exposure to fly ash. Our results suggested that the exposure to fly ash induced oxidative stress to workers. Less