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Environmental fate & pathways

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Only screening level data on biodegradability are available:

In a ready biodegradability test according to OECD 301D (Closed Bottle) biodegradability of the test item was assessed (US-HPV program, study rated as highly reliable, original data not available). Due to inoculum toxicity at the test concentration of 2 mg/L active substance /L no biodegradation (1.19% within 28 days) could be observed. Under the conditions of this test the test item was not readily biodegradable.

This result is put into question by two other results of questionable reliability:

Based on secondary source (reliability category 4) a 5 -day BOD of 1.31 g/g had been determined for the test item with acclimated inoculum. Experimental details are not avialable. Together with the COD of 2.17 g/g reported in the same source this would mean that about 60% of the initial concentration was degraded under these conditions. Thus, concluding from these results biodegradability of the test item would be likely, reported data however too scarce for final judgement and use of acclimated inoculum is not compatible with ready biodegradability tests.

A further non-guideline result also points to biodegradability:

With the test compound as sole carbon-, nitrogen- and energy source for sewage sludge inoculum, a protein yield of 73 µg/mL culture medium (initially 0.05% of test compound) was obtained within 7 days following a 21-day adaption period with weekly culture transfers to fresh medium (3 transfers). Taking protein yield as a measure of successful metabolism of the test item and based on theoretical assumptions implicating that the estimated maximum achievable protein yield was 175 µg/mL (highest observed protein yield: 170 µg/mL for pyrrolidine), conclusions on the degree of biodegradation may be drawn from protein yield. Taking 175 µg/mL for 100% biodegradation, the test item reached 42% degradation within 7 days.

As no reliable information on biodegradability is available for the submission substance and available data are conflicting, no firm conclusion on biodegradability of the submission substance can be drawn.