Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

The registered substance is Alkyl phosphate and stearyl amine salts (EC = 952-252-4), a Multi-constituent. 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 saturated and variable chain lenght with C16 and C18.

 

Whereas the primary alkylamine part of the registered substance has proved to be readily biodegradable (under OECD 301D, 75 % of biodegradation after 28 days), the Phosphoric acid, octadecyl ester is not readily biodegradable (20% degradation after 28 days, OECD 301B). Therefore the Alkyl phosphate and stearyl amine salts (EC = 952-252-4) cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline 301/310. It is of importance to note that a new study on the Alkyl phosphate and stearyl amine salts (EC = 952-252-4) will be performed according the TG OECD 301/310 to verify the biodegradability potential of this salt.

 

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.

 

The sorption behaviour of the registered salt is dominated by ionic interactions rather than hydrophobic partitioning with organic matter. The alkyl ammonium cations present under environmental conditions can interact with the surfaces of mineral particles or with negatively charged humic substances.

 

Primary alkyl amines are unlikely to undergo photolytical or hydrolytic degradation. Thus abiotic degradation in the environment is not expected. Based on the available studies on biodegradation, the primary alylamines are estimated to be readily biodegradable, fulfilling the 10-days-window criterion.

 

An OECD 307 aerobic soil transformation study (3 soils) was carried out with [1-14C]-Hexadecanamine (Harlan, 2010). Although this C16 amine is strongly sorbing to soil (median Kpsoil of 3875 L/kg at lowest measured concentration) half-lives between 8.1 and 9 days at 20 degree C were determined. The median Half-life of 8.9 d at 20 degree C corresponds to a median Half-life of 16.9 d at an environmental temperature of 12 degree C (see REACH Guidance). No other 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. 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 would be assigned (value equal to half-life in soil). In the table below, the degradation rates used the exposure assessment are summarized for primary alkylamines (CAS 90640-32-7, UVCB)

 

Table:Degradation rates used in the exposure assessment:

 

k

DT50

 

kdegfreshwater

4.62.10-2d-1

15 d

kdegseawater

1.39.10-2d-1

50 d

kbiosed(aerobic)

4.10.10 -2d-1

16.9 d

kbiosed(bulk)

4.10.10 -3d-1

169 d

kbiosoil

4.10.10 -2d-1

16.9 d

kdegair

2.22d-1

7.5 h

N-Primary alkyl amines are rapidly metabolised not only by microorganisms but also by other biota like fish.