Browsing by Author "Chen, Chung Yuan"

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Estimating low-toxic-effect concentrations in closed-system algal toxicity tests
(2009-07-01)
Chen, Chung Yuan
;
Wang, Yun Ju
;
Yang, Chao Fen
;
環境工程研究所
;
Institute of Environmental Engineering
The no-observed-effect concentrations (NOEC) and EC(10) values for 108 organic compounds were estimated, using multiple endpoints (i.e., biopopulation, growth rate, and dissolved oxygen production), from previous data obtained by a closed-system algal toxicity test (test alga: Pseudokirchneriella subcapitata). These low-toxic-effect concentrations are valuable to risk assessment of chemicals and protection of the aquatic environment as such information is quite scarce in existing toxicological databases. Furthermore, based on limited amount of available data, we found that the risk of organic toxicants to phytoplankton may be severely underestimated by existing databases, which are primarily derived by the conventional batch technique. Good correlation relationships between NOEC (or EC(10)) and EC(50) values were established. For polar and nonpolar narcotics, quantitative structure-activity relationships (QSARs) based on hydrophobicity, and/or the lowest unoccupied molecular orbital energy (Elumo) were developed with satisfactory predictive powers. The above statistical relationships can be applied to derive a preliminary estimation for the low-toxic-effect levels for other (or new) organic compounds that has no toxicological data available. (C) 2009 Elsevier Inc. All rights reserved.
Toxicity and quantitative structure-activity relationships of benzoic acids to Pseudokirchneriella subcapitata
(2009-06-15)
Lee, Po Yi
;
Chen, Chung Yuan
;
環境工程研究所
;
Institute of Environmental Engineering
The present study presents the toxicity data of benzoic acid and its derivatives on Pseudokirchneriella subcapitata, in terms of EC50 and NOEC values. Median effective concentrations (EC50) range from 0.55 to 270.7 mg/L (based on final yield) and 1.93 to 726.3 mg/L (based on algal growth rate). No-observed-effect concentration (NOEC) is within the range of <0.0057-179.9 mg/L. From both the NOEC and EC50 values, it was found that, 2,4,6-trihydroxybenzoic acid, 4-chlorobenzoic acid, 3-bromobenzoic acid, 4-bromobenzoic acid, 2,6-dihydroxybenzoic acid. and 2,3,4-trihydroxybenzoic acid possess much higher risks to the aquatic organisms as compared to the other benzoic acids. These data are useful for risk assessment and protection of the aquatic environments, because such information is not available in the existing toxicological databases. The toxicity of halogenated benzoic acids was found to be directly related to the compound's hydrophobicity (the logarithm of the 1-octanol/water partition coefficient, logKow). On the other hand, the number of hydroxyl groups (N(OH)) had a determinant influence to the toxicity of hydroxybenzoic acids. Quantitative structure-activity relationships were established to correlate the observed toxicity with logKow and N(OH) values. These statistical correlations are highly significant with the predictive power Q ranging from 0.896 to 0.955. Furthermore, in terms of the species sensitivity, the luminescent bacteria (Microtox) and the alga P. subcapitata appeared to be more susceptible to benzoic acids than the water flea and ciliate. (C) 2008 Elsevier B.V. All rights reserved.
Toxicity of propargylic alcohols on green alga-Pseudokirchneriella subcapitata
(2012-01-01)
Chen, Chung Yuan
;
Kuo, Kwan-Liang
;
Fan, Je-Wei
;
環境工程研究所
;
Institute of Environmental Engineering
The present study evaluates the toxicity of 34 propargylic alcohols, including primary, primary homo-, secondary, and tertiary alcohols, based on their effects on phytoplankton. A closed-system algal toxicity test was applied because the closed-system technique presents more realistic concentration-response relationships for the above compounds than the conventional batch tests. The green alga, Pseudokirchneriella subcapitata, was the test organism and final yield and growth rate were chosen as the test endpoints. Among all the propargylic alcohols tested, 1-pentyn-3-ol is the most toxic compound with its EC50 equal to 0.50 mg L(-1), which can be classified as a "R50" compound (very toxic to aquatic organisms, EC50/LC50 < 1 mg L(-1)), following the current practice for classification of chemicals in the European Union (EU). There are several other compounds including 2-decyn-1-ol, 3-decyn-1-ol, 1-hexyn-3-ol, 3-butyn-2-ol, and 3-hexyne-2,5-diol, which deserve more attention for their possible adverse impact on the aquatic environment, because these alcohols can be classified as "R51" compounds (toxic to aquatic organisms, EC50/LC50 between 1 and 10 mg L(-1)). Compared to the baseline toxicity relationship (narcosis QSAR) derived previously, tertiary propargylic alcohols can be identified as nonpolar narcotic chemicals, while secondary alcohols and primary alcohols with low molecular weight generally exhibit obvious excess toxicity in relation to the base-line toxicity. Finally, quantitative structure-activity relationships were established for deriving a preliminary estimation of the toxicity of other propargylic alcohols.