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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

For derivation of the Half-life of the registration substance in freshwater the 'ready biodegradability' result from an OECD 301D Closed Bottle Test was used. According to the REACH Endpoint specific guidance R.7b a half-life of 15d for a readily biodegradable substance was assigned. The half-life in freshwater sediment was read across from a results of aerobic soil degradation study (OECD 307) with Oleyl amine 2EO  (see read-across justification below).

Key value for chemical safety assessment

Half-life in freshwater:
15 d
at the temperature of:
12 °C
Half-life in freshwater sediment:
17 d
at the temperature of:
12 °C

Additional information

READ ACROSS JUSTIFICATION

OECD 303A

For the registration substance no Sewage Treatment Simulation Test OECD 303A is available and therefore the result from a similar substance is used instead. Read across substance: Bis(2-hydroxyethyl) oleyl amine (BOA), CAS No. 25307 -17 -9, EC No. 246 -807 -3, REACH Reg.No. 01 -2119510876 -0135 -0000 Read across justification: The registration substance Bis(2-hydroxyethyl) C12-18 alkylamine N-oxide (BANO) is similar to the read across substance BOA as it has the same bis(2-hydroxylethyl) group and has a long chain alkyl amine moiety. BANO has an amine oxide function whereas BOA is an amine. It is known that alkylamine N-oxides can be easily reduced to the alkyl amines (and vice versa) and therefore the inherent properties of each other can be used for read across (Reference; Crabbe et al, Microbial oxidation of amines, Bioachem. J. 1974, 140, 253-263; Barrett & Kwan, Bacterial reduction of trimethylamine oxide, Ann. Rev. Microbiol., 1985, 39, 131-149). BANO and BAO differ in the chain length as BANO is mostly C12/14 whereas BAO is mostly C18 which influences ecotoxicity meaning that BAO is more toxic. Both substances are cationic surfactant which means that the sorption properties are mainly determined by ionic interactions and to a lesser extent by unspecific van der Waal forces. Therefore the sorption properties of BANO can be deduced from the Kd values of BAO reasonably. In a Sewage treatment plant simulation test with cationic surfactants the biodegradation and the sorption properties are most relevant to estimate the mass balance of a substance in a Sewage treatment plant. BANO and BOA are readily biodegradable and have similar sorption properties. Based on the facts given before, it can be reasonably assumed that the results from an OECD 303A STP Simulation test of BOA can be used for BONA as well.

OECD 307 (Estimate sediment biodegradation from soil biodegradation, see REACH Guidance 7b)

Read across substance:

Hexadecanamine (HDA), CAS No. 143-27-1, is a component of C16-18-(even numbered)-alkylamines with the REACH Reg.No. 01 -2119473799 -015 -0000

Read across justification:

The registration substance Bis(2-hydroxyethyl) C12-18 alkylamine N-oxide (BANO) is similar to the read across substance HDA as both have a long chain alkyl amine moiety. BANO has an amine oxide function whereas HDA is an amine. It is known that alkylamine N-oxides can be easily reduced to the alkyl amines (and vice versa) and therefore the inherent properties of each other can be used for read across (Reference; Crabbe et al, Microbial oxidation of amines, Bioachem. J. 1974, 140, 253-263; Barrett & Kwan, Bacterial reduction of trimethylamine oxide, Ann. Rev. Microbiol., 1985, 39, 131-149). BANO and HDA differ in the chain length as BANO is mostly C12/14 whereas BAO is C16 Both substances are cationic surfactant which means that the sorption properties are mainly determined by ionic interactions and to a lesser extent by unspecific van der Waal forces. Therefore the sorption properties of BANO can be deduced from the Kd values of HDA or homologues e.g. Octadecylamine reasonably. According to the REACH Guidance Document R.7b the half-life of a substance in aerobic soil can be deduced from the biodegradation in a screening test on ready biodegradability and the sorption properties. BONA and HDA are both readily biodegradable and as they have similar sorption properties the result from an OECD 307 Aerobic soil transformation test of HDA can be used reasonably for read across to BONA.