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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Three biodegradation studies have been conducted on the substance H-MI Ammonium salt, two on the readily biodegradability of the the substance and one on it's inherent biodegrability. 
All studies have been ranked 'reliability 1' according to the Klimisch et al scale as they were conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.
In the key study (OECD Guideline 301 B) the test material attained 21% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301 B.
In the supporting ready biodegradability study (OECD Guideline 301 F)
49.1% degradation occurred within 14 days and the value exceeded 25% based on total ThOD, which indicated that the test substance can be assumed to be not inhibitory under the conditions of the test.

In the supporting inherent biodegradation study (OECD Guideline 302 C) the percentage biodegradation after treatment of 28 days averaged (n=3) 8.4%. H-MI Ammonium Salt did not exhibit a percentage biodegradation exceeding the pass level of 20% within 28 days.

Key value for chemical safety assessment

Additional information

Although all studies were considered to be equally reliable according to the Klimish scale, the Ready Biodegradability Study conducted to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) was selected as the key study overall. This decision was made based on the level of detail contained within this study report when compared to the supporting study reports.

The pass criteria for ready biodegradability (OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)) and (OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)) is 70% DOC and 60% ThOD and as such both studies indicated that H-MI Ammonium salt is not readily biodegradable.

The pass criteria for inherent bidegradability (OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))) was 20% in 28 days with the conclusion that H-MI Ammonium salt is not inherently biodegradable.