Amines, N-C16-18-alkyltrimethylenedi-

Endpoint summary

Additional information

Biodegradation screening tests are available for various structurally related alkyl-1,3-diaminopropanes. All alkyl-1,3-diaminopropanes under consideration consist of carbon, hydrogen and nitrogen only. The basic structure of all alkyl-1,3-diaminopropanes consists of a hydrocarbon chain with a 1,3-propanediamine group at the end of the chain. The only difference consists of differing chain lengths and slight variations in the degree of saturation in the alkyl chain. Since the majority of the alkyl chains consist of C₁₂to C₁₈units, and the unsaturated part is mainly located in the more central part of the alkyl chain, significant changes in chemical behavior and/or reactivity is not to be expected. Therefore the experimental data available for this group of alkyl-1,3 -diamines are used for the evaluation of the biodegradability of  N-C_{12 -14}–propane-1,3-diamine.

Based on the available studies on biodegradation, all alkyl 1,3 -diaminopropanes (C10 - C18) are considered to be readily biodegradable. The 10-days-window criterion does not need to be evaluated as the alkyl 1,3 -diaminopropanes are UVCB substances. No simulation tests for degradation rates under environmental conditions are available, therefore the default values suggested in the REACH guidance may be used. Because of the observed ready biodegradability there is no requirement for performing a soil biodegradation test (Annex IX. 9.2.1.3).However a soil biodegradation test is performed with the structurally related¹⁴C hexadecyl amine. The observed half-life of ¹⁴C hexadecylamine of 8.98 days at 20 °C as determined according to an OECD 307 test is used for read-across to the diamines as both the primary alkyl amines and diamines are structurally related, readily biodegradable and have a similar sorption to soil. This means that for the risk assessment a half-life for soil and sediment of 17 d at 12°C are considered realistic for diamines.

A waste water treatment simulation test was performed with amines, N-C16-18-alkyl (even-numbered) propane-1,3-diamine (133779-11-0). 99.4% removal was observed using specific chemical analyses (LCMS/MS) of the effluent during day 56 to 60 (n=5). In addition, sorption to sludge was measured and this accounted for 4.1% of the total removal which means that 95.3% was removed by biodegradation.

Summary table of degradation rate constants in various (eco) systems based on the ready biodegradability of alkyl-1,3-diaminopropanes:

 

(Eco)system	Method	Half-life
Surface water (fresh)	TGD default value for readily biodegradable substances	15 days
Surface water (fresh) sediment	Read across from half-life hexadecylamine	17 days
Marine water	TGD default value for readily biodegradabl substances	50 days
Soils	Read across from half-life hexadecylamine	17 days^a
Degradation in sewage treatment plants	Determined in STP simulation test	99.4% removal primarily by biodegradation

^aHalf-life of the fraction dissolved in the water phase is expected to in the order of a few days.