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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Acrylic acid is readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The biodegradability of acrylic acid was investigated in several batch tests for ready biodegradability.

 

Huntington Research Center Ltd. conducted a closed bottle test according to OECD TG 301D and GLP regulations with acrylic acid at a test substance concentration of 3 mg/L. The inoculum used in this study was a supernatant obtained by filtering activated sludge from the aeration stage of a sewage treatment plant treating predominantly domestic sewage. Acrylic acid attained 81 % biodegradation (O2 consumption) within 28 days. The pass level of 60 % was reached within 10 days of exceeding the 10 % level and, consequently, acrylic acid was readily biodegradable in this test (10-day window criterion fulfilled) (BAMM 1991).

 

In a DOC-Die-Away assay according to 92/69/EEC, part II, C.4-A and GLP acrylic acid was readily biodegradable reaching 95 % DOC removal within 9 days. The test was performed with a test substance concentration of 15.08 mg/L (DOC) and activated sludge from a domestic sewage treatment plant as inoculum (Huels AG 1995).

 

These test results are supported by a Modifed MITI Test (I) according to OECD TG 301C in which a biodegradation degree (O2 consumption) of 68 % was determined after 14 days (JETOC/CITI 1992).

 

Based on the presented evidence, acrylic acid is considered to be readily biodegradable under aerobic conditions.

  

Acrylic acid is also susceptible to degradation by anaerobic microbes. In a screening study using 10 % sludge from a secondary digester as inoculum, acrylic acid was estimated to be degradable with > 75 % of theoretical methane being produced within 8 weeks of incubation (Shelton and Tiedje, 1984).

 

In an OECD 302 Zahn-Wellens test, the test item reached 100 % degradation after 5 days of eyposure (BASF AG 1992). This result supports the already obtained results on the ready biodegradability.

Several publications reported that the test item was readily biodegradable with different inoculum and test conditions.