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Environmental fate & pathways

Endpoint summary

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Description of key information

The test substance is expected to rapidly biodegrade in a variety of environments.

Additional information

The ready biodegradability of the test substance was determined using the Manometric Respirometry Test according to Annex of EEC-Directive 92/69; corresponds to OECD Guideline 301 F and ISO Standard 9408. This test employed biodegradation reaction mixtures containing a non-adapted activated sludge inoculum, which was suspended in a defined mineral medium, at a concentration of 30 mg/L (dry solids). The test substance was added into each reaction mixture at a concentration of 50 mg/L (103 mg/L theoretical oxygen demand). Biodegradation of the substance began at Day 4, and reached 95 ± 9.2 % (mean ± 1 standard deviation) based on biological oxygen demand (BOD), at the end of the 28 -day test. The test substance met the 10-day window criteria as the biodegradation reached 83.3 ± 5.9 % (mean ± 1 standard deviation) based on BOD at Day 14 since the onset of the biodegradation at Day 4. Since the pass level of 60 % biodegradation was achieved within the 28 -day test period and 10 -day window criteria was satisfied, the substance meets OECD criteria for “ready biodegradability” in the Manometric Respirometry test.

The results of this test met or exceeded each of the OECD-specified criteria for validation of its ready biodegradability tests. These include parameters such as viability of the inoculum, control of pH and temperature, and precision in percentage biodegradation recorded among replicate test mixtures. Biodegradation of a reference substance (aniline) reached 90 - 100 % in 14 days, and thus verified the viability of the inoculum employed in this test. An Inhibition (Toxicity) Control mixture, containing both aniline (50 mg/L) and the test substance, showed no evidence for inhibition of the microbial inoculum. An Abiotic Control mixture, containing the test substance and a chemical sterilant (HgCl2), verified that the observed test substance degradation was due solely to biological activity. Thus, the test substance is considered “readily biodegradable” according to OECD criteria. Therefore, the test substance is expected to rapidly biodegrade in a variety of environments.