Utilization of drinking water quality index by bioassays detecting initiation and promotion activity

在癌变过程中，除了起始活性外，还需要促进活性。本研究采用小鼠成纤维细胞转化试验作为促进活性指标，采用中国仓鼠肺细胞染色体畸变试验作为起始活性指标。本研究的目的是通过考察生物测定结果与产生的氯化副产物之间的关系来显示水质管理中的水质指标。另一方面，如果是基因破坏致癌物，则以终生致癌率为基础制定了水质标准值。也就是说，它最初不应该评估某一化学物质的瞬间浓度，而应该评估其综合毒性。从这个角度来衡量本财政年度水域的时间序列波动。除琵琶湖南部地区外，还选定了Yodo河附近的1处（大阪府平方市）为污染较严重的地区。这项检查是通过每月抽取一次水来进行的。测定结果表明，氯仿适宜作为促进活性的指标。同时，琵琶湖水加氯后，其起始活性降低，促进活性升高。非两步转化试验表明，饮用水的致癌性在配水系统中会降低。结果表明，MX可以代替三卤甲烷作为配水系统的水质指标。

Promotion activity in addition to initiation activity is needed for the process of the carcinogenesis. Transformation test using the mouse fibroblast cell is carried out in this study as an index to promotion activity, and chromosomal aberration test using Chinese hamster lung cell is carried out as an index to initiation activity. The purpose of this research is to show water quality index in the water quality management by examining the relationship between bioassay result and produced chlorination by-products. On the other hand, a water quality standard value has been set on the basis of a lifetime carcinogenic rate in case of a gene damaging carcinogen. That is to say it should originally evaluate not moment concentration of a chemical but an integrated toxicity. The time-serial fluctuation in waters was measured in this fiscal year from this viewpoint. One site (a site in Hirakata City of Osaka Prefecture) in Yodo River was selected as the site where pollution a little is advanced, in addition to southern part of Lake Biwa. The examination was carried out by sampling water once a month. As a result of measurement, it was shown that chloroform was suitable as an index to the promotion activity.In the meantime, there were reduction of the initiation activity and increase in the promotion activity after chlorination of Lake Biwa water. Non-two step transformation test shows that carcinogenesis of dinking water would decrease in water distribution systems. The obtained results show that MX would be an appropriate water quality index in water distribution systems instead of trihalomethanes.