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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable: 78% in 28 days (OECD 301C, Modified MITI Test)

Key value for chemical safety assessment

Additional information

No experimental data evaluating the biodegradation potential of methyl hexanoate (CAS No. 106-70-7) are available. Therefore, biodegradation data from a structurally related category member, methyl laurate (CAS No. 111-82-0) are used as read-across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Both methyl hexanoate and methyl laurate are fatty esters esterified with methanol, differing only on the length of the fatty acid C-chain (C6 and C12 respectively). Since the potential for biodegradation is expected to decrease at increasing C-chain lengths, read-across from methyl laurate to methyl hexanoate will represent a worst-case for this substance as the biodegradation of C6 will probably be underestimated. Nevertheless, based on the structural similarities between both substances this read-across possibility is justified.

One study evaluating the biodegradation potential of methyl laurate (CAS No. 111-82-0) is available (Japanese Ministry of Economy, Trade and Industry, 1995). In this GLP-study, conducted according to OECD 301C, a mixture of sewage, soil and natural water was used as inoculum and O2 consumption monitored as indicator of biodegradation. After 28 days of incubation, the test substance reached 78% biodegradation. Since the 10-day window concept does not apply to the MITI method, methyl laurate is readily biodegradable according to OECD criteria.

Based on the results obtained for a structurally related category member (in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5) methyl hexanoate can be considered as readily biodegradable.