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Environmental fate & pathways

Biodegradation in water: screening tests

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Based on results of the analogue substance Di-(2-ethylhexyl)amine (CAS 106-20-7), the compound is not readily, but moderately biodegradable. Due to the structural similarity with tris-2-ethylhexylamine (CAS 1860-26-0), read across is considered appropriate. This is confirmed by four QSAR models (BIOWIN v4.10, CATALOGIC v5.11.15: OECD 301B, 301C, 301F). 

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Based on the available data, tris-2-ethylhexylamine (1860-26-0) can be considered as moderately biodegradable (not readily biodegradable) and is not persistent. Since no reliable data were available for tris-2-ethylhexylamine (CAS 1860-26-0), a read across to the analogue substance di-(2-ethylhexyl)amine (CAS 106-20 -7) with structural similarity was performed.

Two results from ready biodegradability tests are available for CAS 106-20-7. Both studies were performed under GLP conditions according to OECD 301B (CO2 Evolution Test), but indicating different biodegradation potential. In the most recent study and based on CO2/ThCO2, no biodegradation was observed, even after prolonged exposure of 60 days in total (BASF, 2012). Based on DOC removal, 83% of the substance was eliminated after 28 days, which is, however, interpreted to be likely due to adsorption to the sludge and/or test vessels. I

n the older study and based on CO2/ThCO2, the substance was degraded by ca. 30 % after 28 days and by ca. 50% after 39 days, respectively (BASF, 1997). One study with the target substance following OECD 301F (BASF, 1988) was not considered due to toxicity in the inhibition control (validity criteria not fulfilled).

 

In addition to the read-across approach, the ready biodegradability was assessed using four QSAR models. The substance was within the applicability domains of the used models. The substance was predicted to be not readily biodegradable by all four models. Based on the estimated degree of degradation, moderate biodegradability is a reailistic assumption.

- BIOWIN v4.10 (EPI Suite v4.11): not readily biodegradable

- CATALOGIC Kinetic OECD 301B v.02.08: 28% in 28 d, not readily biodegradable

- CATALOGIC OECD 301C v.08.11: 7% in 28 d, not readily biodegradable

- CATALOGIC Kinetic OECD 301F v.11.14: 20% in 28 d, not readily biodegradable