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Environmental fate & pathways

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Biodegradation studies in freshwater and in soil are available for propylene glycol methyl ether.

In freshwater, propylene glycol methyl ether meets the criteria for ready biodegradation according to all aerobic biodegradation screening studies except in the “Closed Bottle Test” (OECD Guide Line 301D) where a biodegradation of only 2 to 4% occurred after 28 days (the biodegradation is expressed as theoretical oxygen demand). However, a modified Sturm test (Directive 84/449/EEC, C.5) was performed in the same series along with a microbial inhibition test on a pure strain of Ps. fluorescens. A degradation of 65 to 69% after 28 days was observed. The absence of degradation in the “Closed Bottle Test” could result from incapability of the particular strain of microorganism to adapt to the substance. This assumption is confirmed by the presence of lag periods in all of the tests. In conclusion, propylene glycol methyl ether can be considered as readily biodegradable under aerobic conditions.

Only one study on anaerobic biodegradation is available. A biodegradation of 38% after 81 days was reported and the presence of the test substance did not appear to inhibit gas production indicating no apparent toxicity to the anaerobic sludge inoculum.

Rapid biodegradation of propylene glycol methyl ether was observed in two different sandy loam soils under aerobic conditions at 25±2 Deg. C.