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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) does not meet the OECD criteria for ready biodegradability (<10 %)

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Additional information

Four guideline studies investigating the ready biodegradability of Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) are available.

The first study was conducted in accordance to OECD Guideline 301B using domestic non-adapted activated sludge (Bogers & Coenen, 1988) and a concentration of 20 mg test material /L applied. The biodegradation of the test substance was determined to be 7.1 % at test termination after 28 days. In a second Modified Sturm Test according to OECD Guideline 301B again domestic non-adapted activated sludge was used and 20 mg test material/L (Coenen, 1991). The biodegradation of the test substance was determined to be 6.3 % at test termination after 28 days. A third biodegradation screening test - a Closed Bottle Test according to OECD Guideline 301D - with a mixed microbial population taken from the bottom of aquaria in the laboratory as inoculum (Benijts, 2002) also recorded a low biodegradation potential (8.7 % after 28 d). Finally, a test according to ASTM guideline 5864-95 for lubricants or their components (O'Leary, 1999) using domestic activated sludge which was pre-adapted with the test substance is available. Despite the pre-adaptation of the activated sludge, the biodegradation was very low with less than 3.8 %.

In all four studies the biodegradation of the test substance was < 10 % at test termination after 28 days. Thus, Fatty acids, C18-unsaturated., dimers is not readily biodegradable under conditions tested according to OECD criteria.