2-isopropoxyethanol

Biodegradation in water: screening tests

Description of key information

OECD 301F study: BOD28=23%
OECD 301C study: BOD28=8%
Surrogate substance (n-propoxyethanol): BOD20=100% (APHA test method)
QSAR prediction: Readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

In an approved guideline OECD301F study conducted to GLP, isopropyl glycol ether was only 23% biodegraded at 28 days in a predominatly unadapted domestic sewage sludge and therefore failed to meet the criteria for ready biodegradability. The result may have been better in an adapted industrial sludge rather than an unadapted domestic sludge. In an OECD301C guideline and GLP study, a test with activated sludge of 2-isopropoxyethanol resulted in 8% degradation after 28 days cultivation period. Part of 2 -isopropoxyethanol was converted to 2 -(1 -methylethoxy)ethanoic acid during the cultivation period. Biodegradation testing with the isomer of isopropoxyethanol (n-propoxyethanol) conducted under a modified guideline method showed the latter to be readily biodegradable at 20 days under aerobic conditions with non-acclimated sewage microorganisms. The US EPA Biowin v. 4.10 QSAR model predicts that both n and isopropoxyethanol will be readily biodegradable. The results in 6 of the 7 models within the QSAR gave identical predictions and in only one did it predict that n-propoxyethanol would be readily biodegradable but isopropoxyethanol would not be. The data suggests that isopropoxyethanol is less readily degradable than n-propoxyethanol and cannot, on present information, be considered readily biodegradable The overall available data suggests however that it is likely to be inherently biodegradable.