Abstract
ABSTRACT Methacrylic acid esters or methacrylates (with C1 to 8 alkyl side-chains) are a group of compounds used in the manufacture of resins and plastics. Releases to the atmosphere, surface waters, or soil can come about during manufacturing, use, transport, and storage activities. Given the potential for environmental exposures, an examination into factors that control the distribution, fate, and toxicity of methacrylates is warranted. Methacrylates are relatively volatile compounds that are easily and rapidly degraded in the atmosphere and in oxic surface waters and sediments, and so are not considered persistent. Aquatic organisms are also able to metabolize methacrylates as demonstrated by estimated bioconcentration factors of < 45 for the acid and the C1-4 esters, and a measured bioconcentration factor (BCF) for 2-EHMA. Thus, the methacrylates are not considered bioaccumulative. Acute and chronic aquatic toxicity data for the methacrylates were assembled. Quantitative structure–activity relationships (QSARs) were developed with the acute and chronic fish, invertebrate, and algal datasets to support the toxicity assessment of the methacrylates (with log octanol-water partition coefficients used as surrogates for structures). The data show the methacrylates to be of low to moderate toxicity with all acute LC/EC50 values and chronic no observed effect concentrations ranging from about 2 to 170 mg/l for the acid and C1-4 esters, and 0.1 mg/l up to the aqueous solubility limit (about 2 mg/l) for the C8 ester. The measured toxicity data and the data estimated from the QSARs were used to develop predicted no effect concentrations in water and sediment for methacrylic acid and the C1-C8 esters.
Published Version
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