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Category name:
MAD_Lower Alkyl (C1-C8) Methacrylates

Justifications and discussions

Category definition:
chemical category name: Lower Alkyl (C1-C8) Methacrylate as defined as methacrylate esters of linear and branched C1 to C8 alcohols
Category description:
Currently included in the assessment are the methyl, ethyl, n-butyl, isobutyl, hexyl, octyl and 2-ethylhexyl esters of methacrylic acid
Category rationale:
Due to trends observed in environmental toxicity, distribution and fate, mammalian ADME (adsorption, distribution, metabolism and excretion), and toxicology between lower (C1-C8) unsaturated linear and branched alkyl methacrylates, a category approach was used for these compounds. The basic short chain (C1-C8) unsaturated linear and branched alkyl methacrylates included in this category show structure activity relationships with respect to environmental toxicity, distribution and fate, and mammalian toxicity. These esters are rapidly metabolised to methacrylic acid (CAS: 79-41-4) and the structurally corresponding alcohol by ubiquitous non-specific carboxylesterases in all organisms from bacteria to mammals. Methyl methacrylate (MMA) (CAS: 80-62-6), the C1 ester, is the largest volume methacrylate ester that has been studied extensively and reviewed in the OECD HPV Chemical Program. As such MMA provides a robust reference chemical for this category.

Methacrylic acid, while not being a member of the category is listed above as it is a common, primary metabolite and reference chemical that is referred to in the dossiers and the category document.