醛類有機毒物之單一及混合毒性

Abstract

本研究利用密閉式藻類毒性試驗，以11種醛類有機毒性物質為主要對象，探討其單一毒性效應，並選用Acetonitrile及Malnonotrile兩種腈類化合物與五種簡單醛類化合物:Formaldehyde、Acetaldehyde、Butyraldehyde、Propionaldehyde及Glutaraldehyde進行混合毒性試驗研究。 在單一試驗的結果顯示，除了2-Pyridinecarboxaldehyde外，皆在以溶氧變化量為試驗終點時得到較敏感之EC50值。而在物種間的比較則發現以藻類為受體進行毒性試驗之敏感性較Carp及水蚤差，可是較哺乳類動物:老鼠及兔子，以及水體生物:Minnow、綠藻類、Microtox都佳，顯示其存在被選擇為受體之優越性。進行QSARs模式分析得到去除outlier後迴歸式之相關係數有大幅提升的現象，在採用兩個參數：log P及Elumo進行三維之response-surface迴歸分析則觀察到相同之狀況，相關係數R2在去除outlier後可由0.24上升至0.83。 在混合毒性部分，毒性效應最強的協同作用主要出現在以溶氧變化量為試驗終點的情況下並佐以大斜率(斜率大於2)加上小斜率(斜率小於2)的組合時最易觀察到。若將兩種腈類化合物分開來觀察其混合後之效應，結果顯示：若是以Acetonitrile混合醛類有機物，則混合效應多是拮抗效應；而在醛類毒物和Malononitrile混合所生之效應則是以相加作用為主。這與Microtox之試驗結果並不一致，探討其原因可能是和不同物種對毒性物質之容忍度亦不相同所導致。此外，去除在兩種試驗終點表現一致的組別後，亦發現剩下的組別裡有75%的實驗結果是以溶氧變化量為試驗終點時較為敏感。

The aim of this study is to use a close system algal toxic test to assess the toxicity of aldehyde chemicals, and evaluate the joint action of aldehyde toxicants with cyanogenic organic chemicals. In aldehyde chemicals, experimental results indicated that more sensitive outcomes were based on DO. When compared to other species, our results were more sensitive than Minnow, other green algal, Microtox, rat and rabbit but carp and daphnia, apparently it is a great microorganism for toxic test. Quantitative structure-activity relationships (QSAR)showed that toxicity values were highly correlated with log P and a two parameter QSAR model was obtained with the inclusion of Elumo. In binary toxicity test, the results indicated that great than additive effect always occurred when these mixed chemicals with steep slope and flat slope. If combined Acetonitrile and aldehyde chemicals, antagonism effect were found; when aldehyde chemicals mixed with Malononitrile got more additive effect. The different outcomes between Microtox and Raphidocelis subcapitata toxic test maybe result from different tolerance to difference microorganism.