Amines, N-(C16-18 and C18-unsatd. alkyl)-N,N',N'-trimethyltrimethylenedi-

Endpoint summary

Description of key information

N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 -diamine (diamine methylated) is protonated under ambient conditions and sorbs strongly to negatively charged surfaces like glassware, soil and sediment constituents. A mean Kd of 1763 L/kg was observed.

Biodegradation is considered to be the main removal mechanism of these substances as diamine methylated is readily biodegradable.

OECD 305-I, II and III testing is therefore considered not technically feasible and should be waived according to annex XI (section 2) of REACh regulation EC 1907/2006. No measured BCF fish is therefore available.

As an alternative the BCF was estimated using the observed log Kow of 4.06 (ratio octanol solubility and CMC). Using the BCFBAF v3.0 estimation program as included in EPIweb v4.0 a BCF is calculated of 70.8 L/kg ww. This value indicates a low bioaccumulation potential for diamine methylated.

Additional information

N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 -diamine (diamine methylated) has pKa's of 10.8, 9.7 and 7.2 which means that the amines are for the main fraction protonated under ambient conditions. As a consequence this molecule will sorb strongly to negatively charged surfaces like glassware, soil and sediment constituents.

Sorption of alkyl polyamines is mainly driven by ionic interaction and to a lesser extend by the hydrophobic interaction of the hydrophobic tail(s).

Diamine methylated is readily biodegradable

The half-life in the different environmental compartments will influenced by the bioavailability of the substances. No data is available for the determination of N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine in soil or sediment. In absence of half-life data in these compartments these can as a worst-case be estimated based on the readily biodegradability and the sorption data as determined in a sorption desorption test.

The Table below summarizes half-lives derived through default values and a simulation study.

Table Summary of degradation rate constants in various (eco) systems based the ready biodegradability of in soil or sediment. In absence of half-life data in these compartments these can as a worst-case be estimated based on the readily biodegradability and the sorption data as determined in a sorption desorption test.

(Eco) system	Method	Half-life
Surface water (fresh)	TGD default value	15 days half-life
Surface water (fresh) sediment	TGD default value	3000 days half-life (aerobic)
Marine water	TGD default value	50 days half-life
Soils	TGD default value	3000 days half-life*

 *As an alternative also read-across from a similar substance may be applied. For 14C hexadecylamine a half-life in three soils was measured according to an OECD 307 test. Although this C16 amine is strongly sorbing to soil (median Kp soil of 3875 L/kg at lowest measured concentration), half-life’s of 8.14 to 8.98 days were observed at 20 °C. These values can be recalculated (EUSES) to 12 °C a maximum half-life in soil of 16.9 days. As both primary alkyl amines and methylated alkyldiamines are readily biodegradable and have clear structural similarities, it is very likely that a much shorter half-life in soil and sediment than the default of 3000 days will be found when tested.

Diamine methylated has a short predicted half-life in air but because there are no important releases into the atmosphere and volatilisation is expected to be negligible, this removal mechanism is thought to be of low relevance.

Diamine methylated does not contain hydrolysable covalent bonds. Cleavage of a carbon-nitrogen bond under environmental conditions is only possible with a carbonyl group adjacent to the nitrogen atom. Degradation of diamine methylated through hydrolysis is therefore not considered.

Direct photolysis of diamine methylated in air/water/soil will not occur, because it does not absorb UV radiation above 290 nm. Photo transformation in air/water/soil is therefore assumed to be negligible.

Bioaccumulation potential

Standard OECD 305 tests are technically very complicated with strongly sorbing ready biodegradable substances. In addition is the route of exposure in a standard OECD 305 test via the aquatic route unrealistic for these substances because the substance will either be sorbed or biodegraded. OECD 305-I, II and III testing is therefore considered not technically feasible and should be waived according to annex XI (section 2) of REACh regulation EC 1907/2006. No measured BCF fish is therefore available.

In the absence of measured BCF data, the BCF was calculated using the BCFBAF v3.0 estimation program as included in EPIweb v4.0. The log Kow value available has been calculated from the ratio of the octanol solubility and CMC. This value can be used as a worst-case log Kow and is considered acceptable. Based on a measured log Kow of 4.06 a BCF is calculated of 70.8 L/kg ww for the protonated N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine and 9.36 L/kg for the non-protonated molecule.

The biodegradability is a strong indication that this substance is also metabolized in fish. In vitro biotransformation by rainbow trout hepatic subcellulair fraction has been observed for primary alkyl amines and alkyl propane-1,3-diamines. It is therefore likely that also for the methylated diamine biotransformation will be observed.

The calculated BCF indicates a low bioaccumulation potential. N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is almost completely protonated under ambient conditions. In addition, the bioavailable fraction of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is quickly degraded and a chronic exposure to a significant concentration in the aquatic compartment is therefore unlikely (the substance is either sorbed or degraded).