Predicting the relative toxicity of metal ions using ion characteristics: Microtox{reg_sign} bioluminescence assay

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Environmental Toxicology and Chemistry

DOI:https://doi.org/10.1002/etc.5620151011· OSTI ID:474293

McCloskey, J T; Newman, M C; Clark, S B ^[1]

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1. Univ. of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.

Quantitative structure-activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox{reg_sign} bioassay was predictable using ion characteristics. Median effect concentrations (EC50s) were determined for 20 metals in a NaNO{sub 3} medium, which reflected freshwater speciation conditions, using the Microtox bacterial assay. The log of EC50 values was modeled using several ion characteristics, and Akaike`s Information Criterion was calculated to determine which ion characteristics provided the best fit. Whether modeling total ion or free ion EC50 values, the one variable which best modeled EC50s was the softness index, while a combination of {chi}{sub m}{sup 2}r ({chi}{sub m} = electronegativity, r = Pauling ionic radius) and {vert_bar}log K{sub OH}{vert_bar} was the best two-variable model. Other variables, including {Delta}E{sub 0} and {chi}{sub m}{sup 2}r (one-variable models) and (AN/{Delta}IP, {Delta}E{sub 0}) and ({chi}{sub m}{sup 2}r, Z{sup 2}/r) (two-variable models), also gave adequate fits. Modeling with speciated (free ion) versus unspeciated (total ion) EC50 values did not improve fits. Modeling mono-, di-, and trivalent metal ions separately improved the models. The authors conclude that ion characteristics can be used to predict the relative toxicity of metal ions whether in freshwater (NaNO{sub 3} medium) or saltwater (NaCl medium) speciation conditions and that this approach can be applied to metal ions varying widely in both valence and binding tendencies.

• Sponsoring Organization: USDOE
• OSTI ID: 474293
• Journal Information: Environmental Toxicology and Chemistry, Journal Name: Environmental Toxicology and Chemistry Journal Issue: 10 Vol. 15; ISSN 0730-7268; ISSN ETOCDK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOASSAY
BIOLOGICAL INDICATORS
MATHEMATICAL MODELS
METALS
PHOTOSYNTHETIC BACTERIA
TOXICITY
WATER POLLUTION