以水蚤毒性試驗評估有機毒物之混合毒性研究

Abstract

本研究利用水蚤48小時急毒性試驗與21天慢毒性試驗來評估極性麻醉物-苯胺類和反應性有機物-腈類與殺蟲劑之混合毒性效應。 根據Chen & Yeh (1996)的研究，當兩毒性物質的劑量反應曲線之斜率甚小時，容易呈現協同作用；反之，若兩毒性物質之中有一個的劑量反應曲線之斜率甚大時，則易產生拮抗作用。在本研究的結果發現，小斜率的Aniline和大斜率的Chloroacetonitrile混合後卻呈現協同的效應，且三組的混合急毒性試驗都不符合混合預測模式的結果；isobologram中也發現Chloroacetonitrile+Malathion、Aniline+Malathion的混合呈現出不符合非交互作用理論的圖形。 慢毒性混合試驗中發現，Chloroacetonitrile+Malathion可能在極低的暴露濃度下，便會對環境生物造成影響。在環境風險評估方面，利用急毒性數據(EC10)取代慢毒性數據(NOEC)計算ACR值，可能會低估毒性物質在環境中的慢毒性影響。

This study is using Daphnia magna 48hr-acute toxicity tests and 21days-chronic tests to evaluate the combined toxic effects of polar narcotic toxicant aniline and reactive organics nitrile and insecticide. According to the study of Chen and Yeh(1996), greater- than-additive (synergistic) effects will perform when two toxicants have different mechanisms and the flat concentration-response curves mixed. By contrast, if one of the toxicants has steep curve, less-than-additive (antagonistic) will appear. We could find the toxicity test of this research are not corresponding with the above literature result. And the results of combined acute toxicity tests are not conform with the prediction by RA model. In the combined chronic toxicity tests, the group of Chloroacetonitrile and Malathion may perform danger effects to environmental organisms. The environmental risk assessments of the present study reveals the chronic toxicity effects may be underestimated by using EC10 value instead of NOEC value.