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Environmental fate & pathways

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Fate of C4 sulfonamido methacrylate is addressed by a mixture of experimental data, calculation, and readacross of data from C4 acrylate. The Target chemical and the Source chemical both contain the nonafluorobutylsulfon-N-methylamidoethoxyl (i.e., C4 sulfonamido alcohol) functionality. The Target chemical contains this structure esterified with methacrylic acid. The Source chemical contains the same group esterified with acrylic acid. The Source chemical and the Target chemical have similar molecular weight. Water solubility differs between the two chemicals by approximately a factor of ten, while octanol-water partition coefficient differs by less than one log unit. Acrylate and methacrylate functionalities are electrophilic and both may participate in Michael addition reactions. Metabolism occurs through the same pathways, hydrolysis by carboxylesterases and conjugation to gluthathione. Hydrolysis is similar across the acrylate family and enhances the elimination of the chemical upon exposure (McCarthy & Witz (1997), Toxicol. 116, 153). Enzymatic hydrolysis kinetic constants for methacrylate and acrylate esters are similar. Because the source and target substances exhibit similarity in their structures physicochemical properties and metabolic properties, data gaps for biodegradation can be addressed by read across. C4 acrylate was not readily biodegradable in a test conducted under test guideline OECD301B. C4 sulfonamido methacrylate is also expected not to be readily biodegradable, but instead to be persistent in the environment. The reason for lack of biodegradation is not clear given the extensive in vivo hydrolysis observed in toxicokinetic studies of both C4 acrylate and C4 sulfonamido methacrylate. C4 acrylate showed no toxicity to microorganisms in an OECD 209 study, and C4 sulfonamido methacrylate is similarly expected. Had hydrolysis occurred during the 301B test, the resulting acrylic acid would have been metabolized easily to carbon dioxide and detected. Abiotic hydrolysis results are also read across from C4 acrylate. C4 sulfonamido methacrylate is expected to have hydrolysis half-lives of 0.6049 years at pH 7 and 25°C, 15.14 years at pH 4 and 25 °C, and 1.608 years at pH 9 and 25 °C. Owing to extensive water treatment technologies at the production facility, neither biodegradation nor abiotic hydrolysis are expected to have a significant impact on fate. Larger releases are expected to the air compartment. A modeled rate constant of 3.19E-011 cm³/molecule∙s for reaction with hydroxyl radical indicates a projected atmospheric half-life of 12 hours for C4 sulfonamido methacrylate.  

C4 sulfonamido methacrylate has a measured log Kow of 4.68. However, owing to extensive in vivo metabolism in the toxicokinetic studies, no bioaccumulation is expected. The metabolic products are themselves far more hydrophilic than the parent and are also not expected to be subject to bioaccumulation.

C4 sulfonamido methacrylate has an organic carbon normalized soil:water adsorption coefficient of 11,500 L/kg calculated from the log Kow. It is expected to sorb to surfaces.

Please see Analogue Reporting Format, IUCLID Section 13, for further information justifying the readacross.