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Environmental fate & pathways

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Primary alkyl amines released into the atmosphere are likely to be degraded by reaction with hydroxyl radicals, with a half-life around 7.5 h.Because there are no important releases into the atmosphere and volatilisation is expected to be negligible, this removal mechanism is considered not to be relevant.

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 substances 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 (see IUCLID Chapter 5.2.3) 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 for the exposure assessment are summarized.

  

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.