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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Based on the available studies on biodegradation of aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts, is degraded partly. Due to the persistence of some dimethylnaphthalenesulphonate isomers and nonyl methylnaphthalenesulphonate and nonyldimethylnaphthalenesulphonate as observed in a SCAS test (van Ginkel et al, 2012), aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts cannot be considered as readily biodegradable. It is very unlikely that the biodegradation of sulphonates resistant to biodegradation in the SCAS test will occur in sediment. Further testing in sediment is therefore not expected to deliver more information. For sediment therefore the default half life value of 30000 days is used until better soil/sediment data become available.

Key value for chemical safety assessment

Half-life in freshwater sediment:
30 000 d

Additional information

Based on the available studies on biodegradation, aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts, only part of the isomers present in the substance are degraded in sediment i.e. water soluble methylnaphthalenesulphonate, and dimethylnaphthalenesulphonate. Nonyl methylnaphthalenesulphonate and nonyldimethylnaphthalenesulphonatewill be recalcitrant in sediment. Further testing in sediment is not expected to deliver more information. For sediment therefore the default half life value of 30000 days is used for the sediment based on the log Koc of 3.4 until better data become available.

The half-life of the biodegradable fraction of aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts, in the water phase of sediment is expected to be a few days.