芳香族化合物之毒性評估及QSAR研究

Abstract

藻類在水體食物鏈中處於初級生產者之位置，在水體生態影響評估中佔重要之地位，近年來，藻類毒性試驗已被廣泛使用於評估危害性化學物質對環境之影響研究，由於一般藻類毒性試驗皆為開放系統，故對於揮發性有機毒物之敏感度不佳，根據本研究群之密閉式毒性試驗結果顯示，現有的藻類毒性資料庫數據嚴重低估有機毒物之毒性，故有必要以密閉式毒性試驗重新建立新的藻類毒性資料庫。。 本研究以50種芳香族化合物（20種苯甲醛類、15種硝基苯胺類以及15種硝基甲苯類）為研究對象，以密閉式毒性試驗探討上述有機毒物對月芽藻 (Pseudokirchneriella subcapitata)之毒性， Pseudokirchneriella subcapitata為藻類中最為廣泛使用之指標物種，US EPA、 OECD、及 ISO皆以Pseudokirchneriella subcapitata為標準物種，本研究以藻細胞的產氧量（ΔDO）、藻細胞生長率及藻細胞數 (Final yield)為觀測終點，分析毒性物質之半抑制濃度 (50% Effect concentration，EC50)及低影響濃度(NOEC、LOEC、EC10、NEC)，以瞭解這一類化學物質對於藻類的生長情形有何影響。除此之外，將針對此類化學物質毒性試驗結果之log(1/EC50)值與該毒化物之物化特性進行回歸分析，求出毒性方程式並建立QSAR（Quantitative Structure-activity Relationships）模式以作為毒性評估之用途。

Toxicity testing with microalgae has been used extensively in ecotoxicogical studies for assessing the impact of chemical substances on water quality. Our previous studies indicated that current standard algal toxicity tests (protocols) significantly underestimated the toxicity of various organic toxicants, because of their open test environment. The proposed study attempts to assess the toxicity of three types of aromatic compounds; Aromatic Aldehydes, Nitroanilines, and Nitrotoluenes. The toxic effects of the above compounds, on Pseudokirchneriella subcapitata (alga), will be evaluated by a closed-system test technique. The test endpoints include dissolved oxygen production, algal growth rate, and algal population. Toxicity data will be in the form of median effective concentrations (EC50s) and low toxic effect concentrations (NOEC, EC10, and NEC). In addition, quantitative structure-activity relationships (QSARs) will be developed for predicting the toxicity of chemicals of similar structure or alike chemical properties.