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Environmental fate & pathways

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Environmental fate data of various ethoxylated alkyl-1,3 -diaminopropanes have been used for the evaluation of the environmental fate of this category. The justification for the read-across is based on the similarities in their chemical structure, physico-chemical and environmental fate properties. All ethoxylated alkyl-1,3-diaminopropanes under consideration consist of carbon, hydrogen, oxygen and nitrogen only. The basic structure includes a hydrocarbon chain with an ethoxylated (3EO) 1,3-propanediamine group at the end of the chain. Due to the identical position of the functional ethoxylated diamine group and the identical CH2 -groups adjacent to the diamine group, no difference in chemical reactivity is expected for the functional group. 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 C12 to C18-units, 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.

 

Ethoxylated alkyl-1,3 -diaminopropanes are protonated under ambient conditions. This means that they will sorb strongly to negatively charged surfaces like glassware, soil and sediment constituents. Distribution constants ranging from 6219 to 91157 L/kg were observed in an OECD TG 106 test. When comparing the results for the different soils, there seems to be no relationship between the organic carbon content of the soils and the measured distribution coefficients. The observed distribution coefficients seem to increase with with the clay content and CEC of the soils. F

rom the three distribution constants a mean Kd of 43274 L/kg is calculated.

Biodegradation is considered to be the main removal mechanism for this substance. The half-life in the different environmental compartments is expected to be short. No measured data is available which quantifies the half-life of ethoxylated diamines in soil or sediment. These values can therefore be estimated as a worst-case based on the readily biodegradability and the sorption data as determined in a sorption desorption test.

A waste water treatment simulation test was performed with ethanol, 2,2’-[[3-[2-hydroxyethyl]amino]propyl]-iminobis-, N-(hydrogenated tallow alkyl) derivatives. A removal of >99.97% was observed using specific chemical analyses (LC-MS/MS) of the effluent. Also the sorption to sludge was measured and this accounted for 3.8 % of the total removal. Biodegradation is therefore responsible for 96.2% of the removal.

Environmental degradation rates for the exposure assessment

 

DT50(days)

Degradation in water

15

Degradation in seawater

50

Degradation in sediment

30000

Degradation in soil

30000

 Removal in an STP >99.97 

 

Ethoxylated diamines have 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. Ethoxylated diamines do 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 diamines through hydrolysis is therefore not considered.

Direct photolysis of diamines 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.

 

Standard OECD 305 tests to assess the bioaccumulation are technically not feasible with these strongly sorbing easily degradable substances. Several attempts have been made with comparable substances, which demonstrated that maintaining a steady state exposure at the low aquatic concentrations required is impossible for this type of substances. Furthermore, the route of exposure in a standard OECD 305 test is unrealistic for these substances because the substance will either be sorbed or biodegraded. The bioaccumulation potential of diamines was therefore assessed based on a measured log Kow. These log Kow values were measured using the slow stirring method according to OECD 123. This test was performed for Amines, N-(C18 saturated, alkyl) trimethylenedi-, ethoxylated (NLP)

Substance

Log POW

N. N', N'-tris(2 -hydroxyethy1)-tallow-l,3-diaminopropane

2 .8

with the following results of its components

N, N', N'-tris (2-hydroxyethyl)-tetradecyl-l,3-diaminopropane

1.7

N, N', N'-tris (2-hydroxyethy1)-hexadecylene-l,3 -diaminopropane

2.1

N, N', N'-tris (2-hydroxyethy1)-octadecyldiene-l,3 -diaminopropane

2.7

N, N', N'-tris (2-hydroxyethy1)-hexadecyl-l,3 -diaminopropane

2.7

N, N', N'-tris (2-hydroxyethy1)-octadecylene-l,3 -diaminopropane

3.3

N, N', N'-tris (2-hydroxyethy1)-octadecyl-l,3 -diaminopropane

3.6

Log Kow values below 3 indicate a low bioaccumulation potential. For substances with a log Kow >3 but <4 a moderate bioaccumulation potential is anticipated.