Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability/Hydrolysis

Based on the hydrolysis as function of pH test (OECD guideline N°111), N,N'-bis(1,2,2-trimethylpropyl)-1,6-hexane diamine is considered as hydrolytically stable. Less than 10% hydrolysis occurred after 5 days when tested at pH 4, 7 and 9 at 50°C with an average initial concentration of 0.04 g/L. These results assessed by gas chromatography lead to half-life values greater than 1 year at 25°C.

Biodegradation

To assess the biodegradability of N,N'-bis(1,2,2-trimethylpropyl)-1,6-hexane diamine, the ready biodegradability test under aerobic conditions was performed (OECD guideline N°301B). After 28 days of exposure at 21°C, the test material attained 44% degradation after 28 days determined by measuring the carbon dioxide produced. In that context, the test substance is not considered as readily biodegradable. However, a degradation of 44% in a strignent ready test, indicates a potential for degradation in treatment plants that can be confirmed by a test on inherent biodegradability. In addition, the no ready biodegradability has also been supported through results given with BIOWIN3 AND BIOWIN5. The persistency status given by the results of BIOWIN2,6 and 3 were however at the borderline value leading to mixed results.

Bioaccumulation

According to the logKow determined by the shake-flask method, the substance (N,N'-bis(1,2,2-trimethylpropyl)-1,6-hexane diamine) does not have the property to bioaccumulate in living organisms (LogKow = 2.10).

Transport and distribution

Estimations of the logKoc indicate that N,N'-bis(1,2,2-trimethylpropyl)-1,6-hexane diamine can bind to solid surfaces. Indeed, log Koc estimate from KOCWIN v2.00 (US EPA, February 2009) gave a value of 4.47 which is in the same order of magnitude as the Koc estimate from the log Kow (log Koc = 4.06). The adsorption coefficient was not determined by HPLC due to the protonation of the amine groups at pH tested. At pH tested (5.5 -7.5), the amine groups are positively charged on the nitrogen which interacts with the column stationary phase by forces other than partitioning.

The Henry's law constant of 5.436 Pa.m3/mol determined by modeling (EPIWEB v4.1), demonstrates that the substance will not evaporate easly from the surface water.

In conclusion,

According data currently gathered on the substance, N,N'-bis(1,2,2-trimethylpropyl)-1,6-hexane diamine will adsorb on suspended matters or sediment in water, and will thus be removed from the water column to a certain extend reducing the direct toxicity of the test item to organisms remaining in the water column (fish, daphnia and algae). In soil, the substance is likely to remain adsorbed on soil particles and low losses are expected by run off to the groundwater.