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Environmental fate & pathways

Biodegradation in water: screening tests

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No biodegradation data is available for HiMO LAB. Data from LAB (CAS No: 67774-74-7), LAB alkylate bottoms (CAS No: 85117-41-5) and HAB (CAS No: 84961-70-6) as structural analogues were used to understand the biodegradation profile of substance . Based on the biodegradation studies of structural analogues, although LAB is readily biodegradable, the substance considered to be not readily biodegradable.

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Benzene, C16-24 alkyl derivatives are also known as High Molecular Weight Linear Alkylbenzenes (HiMo LAB).  The substance is a UVCB. Because of their high molecular weight, they are very similar in composition and properties to the heavy alkylate bottoms (HAB). Based on these structural and functional similarities, data on LAB (CAS no: 67774-74-7) being registered under REACH, LAB Alkylate Bottoms (CAS no: 85117-41-5) described in OECD SIDS dossier, and HAB (CAS no: 84961-70-6) being registered under REACH are suitable as supporting studies in case where specific data on the HiMo LAB is lacking. 

To assess the biodegradation profile of the substance, woe approach were used from LAB (CAS No: 67774-74-7), LAB alkylate bottoms (CAS No: 85117-41-5) and HAB (CAS No: 84961-70-6) as supporting data. The biodegradation of substances was determined in OECD 301F guideline studies (manometric respirometry test) and BODIS test.

The ready biodegradation of LAB with initial concentration of 141.9 mg/L was tested in OECD 301F guideline study (manometric respirometry test). The test substance was 64.1% degraded at the end of 28 days. The test substance met the 10 -day window and is therefore considered readily biodegradable.

 

The ready biodegradation of LAB alkylate bottoms with initial concentration of 100 mg/L was tested in OECD 301F guideline study also. The result is the mean of 24 separate assays, using four different inocula, three different ways of test substance application,and two different calculation techniques. These studies were carried out during four separate test series in the fall of 1984. The test substance was consistently poorly biodegradable (less than 20% in 28 days).

The biodegradation of HAB was determined in BODIS test (BOD-test for insoluble substances). Samples of activated sludge were exposed to 5.4, 5.8, and 6.0 mg/flask of HAB. Diethylene glycol was used as the reference substance. Oxygen measurements were taken at 7, 14, 21, and 28 days. The MULTIPLAN PC program was used to analyze results. The test substance was only 28% degraded at the end of 28 days. Results with the reference substance were valid. The test substance was not readily biodegradable.

Based on the biodegradation studies of structural analogues, although LAB is readily biodegradable, the substance considered to be not readily biodegradable.

 

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