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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Tert-butyl acrylate can be expected to be ultimately biodegradable in the environment. Formation of persistent breakdown products is not expected. Thus, simulation tests in water and sediment are not required for the environmental hazard assessment of tert-butyl acrylate.

Key value for chemical safety assessment

Additional information

There are no simulation tests in water and sediment available for tert-butyl acrylate.

In a CO2-Headspace test according to ISO 14593 which is identical to OECD 310 (Ready Biodegradability - CO2 in sealed vessels) tert-butyl acrylate was moderately (or partly) biodegradable. The 10-day-window criterion for ready biodegradability was not fulfilled, and after 28 days a biodegradation degree of 50 - 60 % (mean value of three test assays: 59 % TIC/TOC) was determined. Thus, the criterion for biodegradability was missed by a narrow margin. The members of the acrylate category are all readily biodegradable according to OECD criteria with tert-butyl acrylate being the only exception due to the steric inhibition caused by the highly branched tert-butyl moiety. Biodegradation kinetics for tert-butyl acrylate are considerably slower than for the other acrylate members as demonstrated by the longer lag-phase. Nevertheless, in two out of three test assays the required biodegradation degree of 60 % TIC/TOC was reached within 28 days indicating complete albeit slower mineralization of tert-butyl acrylate.

Primary degradation products predicted for tert-butyl acrylate by Q(SAR) modeling (OASIS, Catalogic v5.10.5) are acrylic acid and tert-butanol. Acrylic acid is readily biodegradable according to OECD criteria. The biodegradability of tert-butanol was investigated in a CO2-Headspace test according to ISO 14593 (non-GLP). After 28 days a biodegradation degree of 70 - 80 % was determined (BASFSE, 1997). Due to a longer lag-phase, the 10-day-window criterion for ready biodegradability was not met. Based on these test results, tert-butanol was considered to be biodegradable.

Taking all these data into consideration, tert-butyl acrylate can be expected to be ultimately biodegradable in the environment. Formation of persistent breakdown products is not expected. Thus, simulation tests in water and sediment are not required for the environmental hazard assessment of tert-butyl acrylate.