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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Inherently biodegradable, not fulfilling specific criteria: 41% after 28 d based on O2 consumption (OECD 301C)

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria

Additional information

One study is available investigating the ready biodegradability of 2-(1-methylethoxy)ethyl acetate (CAS 19234-20-9). The study was performed according to OECD 301C under GLP conditions using a mixed population of activated sewage sludge microorganisms (Clarke, 2012). A biodegradation of 41% based on O2 consumption was attained after 28 d indicating that the substance is not readily biodegradable but can be considered as inherently biodegradable (not fulfilling specific criteria). Chemical analysis of the test item concentration at 0 h showed measured test concentrations to be 97% of nominal. A decline in measured test concentration was observed after 28 d giving measured concentrations of less than the limit of quantitation (LOQ) of the analytical method employed which was determined to be 0.51 mg/L. Given that, this decline was observed in the test item vessels with and without inoculum it was considered in the report that the decline in measured test concentrations was due to instability, hydrolysis and/or adsorption to glassware and not degradation. Adsorption and hydrolysis are unlikely to occur based on available QSAR results. Decline in test concentrations might have been resulted due to analytical deficiencies. The toxicity control attained 63% degradation after 14 d and 67% after 28 d indicating that the test substance is not inhibitory to the inoculum. In conclusion the test substance is not readily biodegradable according to the OECD criteria.

An additional QSAR calculation was performed using the BIOWIN v4.10 program (Müller, 2012). The results for the BIOWIN 1 (Linear Model Prediction), BIOWIN 2 (Non-Linear Model Prediction), BIOWIN 5 (MITI Linear Model Prediction) and BIOWIN 6 (MITI Non-Linear Model prediction) models predict fast biodegradation of the substance. The time-frame for primary degradation (BIOWIN 4) and ultimate biodegradation (BIOWIN 3) was estimated to be within days and weeks, respectively. The overall conclusion as a result of all model calculations is that 2-(1-methylethoxy)ethyl acetate is readily biodegradable.