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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

One ready biodegradability test has been carried out: according to OECD 301B (CO2 evolution test) mineralization was 46% of the parent substance, which clearly supports the inherently biodegradable conclusion with regards to the stringency of this test.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria

Additional information

Partial mineralization of the substance was observed in ready biodegradability test. Not enough to consider it ready biodegradable, but yet significant, therefore for risk assessment purpose, substance will be considered as inherently biodegradable.

The aerobic degradation of benzyltoluene has been examined during 29 days according to EU test Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test) and GLP requirements. The validity criteria were fulfilled.

The use of EU test Method C.4 -C for volatile substances may lead to underestimate the level of biodegradation due to the non-bioavailability of the test substance to the medium and thus to microrganisms. The level of biodegradation is calculated from the amount of carbon dioxide produced from the test substance. The volatilisation of the test substance in the flasks cannot be detected and quantified. The volatility of the test substance cannot lead to a higher percentage of degradation but can only decrease the measurement of degradation. EU test Method C.4 -C for volatile substances can thus be considered as a worst case of degradation level because the best conditions are not fulfilled with this guideline for such substances.

Biodegradation of ca. 46% after 29 days for benzyltoluene (estimated Henry's law constant of 3165 Pa.m3/mol) can be used as a minimum of result of ready biodegradability. Therefore, the substance can be considered at least as inherently biodegradable.