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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Half-life in surface water: 15 d (based on ready biodegradability); half-life in bulk-sediment: 169 d (based on 10x half-life in aerobic soil at 12 °C)

If no data are available on a salt, effects may be read-across from the anion or cation, whichever has the most toxic effect (according REACH guidance document R7b v4, June 2017 p81). It was considered that environmental fate and ecotoxicity of the registered substance as driven by properties of the dissociated alkylammonium part. Alkylammonium moieties come from the raw UVCB material C16 -C18 Alkylamines (CAS 90640 -32 -7) which is used as such to manufacture the alkyl phosphate and stearyl amine salts (EC = 952-252-4) and released when dissociated. 

Key value for chemical safety assessment

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

Additional information

The registered substance is an Alkyl phosphate and stearyl amine salts (EC = 952-252-4). It is mainly composed by primary alkylamines (CAS 90640-32-7, UVCB), Monoalkyl dihydrogenophosphate and Dialkyl hydrogenophosphate salts (CAS 39471-52-8, Multi-Constituent). This different chemical structures are constituted by variable chain lenght with C16 and C18. The salt under its solid form will be non dissociated and totally insoluble. Progressively, under certain condition the salt may dissociate in differents combination of cation/anion. The different constituents of the alkyl phosphate and stearyl amine salts are all quite insoluble and are not expected to solubilise in water above 0,1 mg/L (see read-across justification document).

The salt is composed by two parts which individually, encompass two differents biodegradation pathway and is considered as not readily biodegradable. It is of importance to note that new studies on the registered substance (Alkyl phosphate and stearyl amine salts, EC = 952-252-4) are ongoing according the appropriated TG OECD to verify the solubility, partition coefficient and biodegradability potential of this salt. 

It was considered that environmental fate and ecotoxicity of the registered substance as driven by properties of the dissociated alkylammonium part. Alkylammonium moieties come from the raw UVCB material C16 -C18 Alkylamines (CAS 90640 -32 -7) which is used as such to manufacture the alkyl phosphate and stearyl amine salts (EC = 952-252-4) and released when dissociated.

Amines, C16-18-alkyl simulation test in water and sediment:

No simulation tests for degradation rates under environmental conditions are available. Therefore, for the aquatic environment the default value suggested by the REACH Guidance based on ready biodegradability results is used. A Half-life in surface water: 15 d was determined for primary alkylamines C16-C18.

 

For aerobic sediments, based on the result of the study on aerobic transformation in soil and in line with the REACH Guidance R16. (2016) A.16 -3.2.2, a DT50 freshwater sediment (aerobic) of 16.9 d at 12 deg. C is assigned (value equal to half-life in soil). Further, for bulk sediment, a 10-times higher half-life is assumed, in accordance with the R.16 guidance.

 

Phosphoric acid, octadecyl ester simulation test in water and sediment:

Although an OECD Guideline 308 study would demonstrate that radioactivity detected in bound residues can be mineralised to CO2 in two aerobic sediment systems, the results of this feasibility study demonstrate that conducting a full study would not generate any further information and it is unlikely that a full study would meet the objectives of the OECD Guideline 308 in aerobic or anaerobic aquatic sediment systems.