The Study of Toxicity Assessment of Aromatic Aldehydes(Benzaldehydes) Using a Closed-System Algal Test and The Quantitative Structure-Activity Relationship

• Main Authors: Din-Yu Tsai, 蔡定裕
• Other Authors: Chung-Yuan Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/83548615052654470341

碩士 === 國立交通大學 === 環境工程系所 === 94 === The objective of this study is to study the toxic effect of aromatic aldehydes (benzaldehyde) on Pseudokirchneriella subcapitata using a closed system test. The effects of benzaldehydes were evaluated by three kinds of response endpoints, i.e., cell density, algal growth rate, and the dissolved oxygen production. Median effective concentratons (EC50s) were estimated using the Probit model with a test duration of 48hr. The quantitative structure-activity relationships (QSARs) were established based on the 1-octanol/water partition coefficient (logKow) and an electronic parameters-Lowest unoccupied molecular orbit (ELUMO). The result shows that the algae would make three types of benzaldehydes (benzaldehdye、vanillin and 3,4-dihydroxybenzaldehyde) into benzoic acid, and this reaction is called the dismutation. Special attention should be paid to that the oxygen produced by algae and toxicity of benzaldehydes will be decreased in the dismutation. The highest toxicity in different kinds of hydroxyl- benzaldehydes is 5-bromo-2-hydroxybenzaldehyde. In addition, the toxicity of para-hydroxy-benzaldehydes is lower than that of ortho-hydroxy- benzalde- hydes, exept 3-bromo-4-hydroxybenzaldehyde. The results also reveal that the value of the lower effect concentration (EC10、LOEC、NOEC and NEC) of the benzaldehydes is NOEC <EC10< NEC<LOEC. This demonstrates that the relative sensitivity is NOEC >EC10> NEC>LOEC. Besides, the experiment results (EC50) are compared with literature data derived by various toxicity tests. The order of the relative sensitivity is then obtained as follows : algae(Final yield)>algae(DO prod- uction)>algae(Grwoth rate)>Fathead minnow>Daphnia magna> Microtox >Tetrahymena pyriformis. On the other hand, the toxicity of hydroxy-benzaldehydes is demonstrated to be higher than that of other benzaldehydes, and a single parameter (logKow) is used to estabilish QSAR of the hydroxy-benzaldehydes, except the one outlier (2,5-dihydroxybenzaldehyde).[log(1/EC50)G.R = 0.8457X - 0.34 96, R2 = 0.9152, n=7]