Toxicological assessment of lower alkyl methacrylate esters by a category approach

Categories and read-across are essential tools for supplying information for assessments of endpoints without data while minimizing animal testing. This study is based on the guidance of ECHA in its Read-Across Framework (RAAF). A category of C1 - C8 alkyl methacrylate esters (methyl, ethyl, n-butyl, iso-butyl and 2-ethylhexyl) was constructed to fill in missing information for human health endpoints using read-across as a permitted adaptation under EU REACH. The esters form a series with common functional groups, small incremental changes of electrophilicity by molecular weight, and rapid hydrolysis by ester cleavage. Read-across is justified by two common specific modes of action, direct electrophilic reaction of the parent compounds and the potential inherent toxicities of the common metabolites methacrylic acid and the corresponding alcohols. The toxicological profile is very similar for all category members and not driven by the alcohol metabolites. Data gaps can be filled in with high confidence based on the number of studies available, the effects therein observed and the toxicological profiles of the hydrolysis products. The guidance provided by the RAAF enabled data gaps to be filled in a robust manner.