利用密閉式藻類毒性試驗對氨基甲酸酯類化合物進行毒性評估

Abstract

有機化合物的種類與數量於近代迅速地增長，傳統的水質監測項目已經不足以預防新興汙染物造成的危害，因此藉助生物毒性試驗進行評估。新興汙染物在環境裡的濃度相當微量，初級之處理單元無法完全將其移除，殺蟲劑屬於其中之一。本研究以月芽藻（Pseudokirchneriella subcapitata）作為試驗物種對氨基甲酸酯類化合物進行密閉式藻類毒性試驗，並使用三種反應終點（溶氧變化量、藻類細胞密度、藻類細胞生長率）求得其毒性影響，各反應終點之EC50以藻類細胞密度（Final yield）最為敏感。本研究分析NOEC、LOEC與EC10何者能為水體環境提供良好之保護，並求取合理之急慢毒性比。

本研究將試驗之十一種氨基甲酸酯類化合物根據歐盟所訂定之危害物質法規分類標準進行分類，其中有六種（Aldicarb, Dioxacarb, Isoprocarb, Metolcarb, Mexacarbate and Propoxur）屬於R51等級（對水體生物具有毒性），其餘四種（Phenyl Carbamate、Benzyl Carbamate、Methyl phenyl Carbamate與Ethiofencarb）被分類為R52等級（對水體生物有危害性）。本研究選用七種不同之物化參數透過迴歸分析建立定量結構反應關係模式（QSARs），包括常使用之親脂性參數與親電性參數，單參數之迴歸分析結果顯示Dipole、Electronic Energy與Core - Core Repulsion為最佳的三種迴歸參數。並與過去本實驗室所建立的基線毒性進行比較，所產生之超量毒性現象驗證氨基甲酸酯類化合物為反應性物質。

關鍵字：氨基甲酸酯類、月芽藻、定量結構反應關係

Toxicity Assessment of Carbamates on Pseudokirchneriella subcapitata Using a Closed - System Testing Technique Student : Yu - Chen, Chen Professor : Dr. Chung - Yuan, Chen Institute of Environmental Engineering National Chiao Tung University Abstract This study evaluated the toxic effects of various carbamates on Pseudokirchneriella subcapitata using a closed algal toxicity testing technique with no headspace. Three response endpoints, i.e., DO production, final yield, and algal growth rate, were used to evaluate the toxicity of carbamates. Overall speaking, final yield is the most sensitive response endpoint with respect to Carbamates. In addition, no-observed-effect concentrations (NOECs) and concentrations that caused 10% responses were derived to provide safe estimates for these carbamates in the aquatic environment.

Among the eleven carbamates tested in the present study, six of them (Aldicarb, Dioxacarb, Isoprocarb, Metolcarb, Mexacarbate and Propoxur) were identified to be toxic to aquatic organisms (R51 class according to the European Union risk specification), and the rest of the test compounds (Phenyl Carbamate, Benzyl Carbamate, Methyl phenyl Carbamate and Ethiofencarb) were found to be harmful to the aquatic environment (R52 class). Various physical/chemical descriptors were applied to establish quantitative-structure-activity rela-tionships (QSARs) by regression analysis. The result shows that Dipole, Electronic Energy and Core - Core Repulsion are optimal descriptors. By comparing observations with the baseline toxicity, this study verifies that carbamates are reactive compounds according to the excess toxicity for the test compounds.

Keywords：Carbamates、Pseudokirchneriella subcapitata、QSAR、Toxicity