2,3-epoxypropyltrimethylammonium chloride

Hydrolysis

Description of key information

Based on the European GEMS database 50-percentile value for the pH of the European surface water is about 7.8. Therefore the half-live of 177 days at pH 7.8 will be used further in the regional and continental risk assessment.

Key value for chemical safety assessment

Half-life for hydrolysis:

177 d

at the temperature of:

12 °C

Additional information

The conversion of EPTAC, as cited by studies in the EU Risk assessment report, seems to be considerably slower than in the key study (10.5 days in pH 7). This could be partly explained by higher testing temperature in the key study, from where the results have been calculated. As other studies (EPTAC hydrolysis and CHPTAC conversion) are conducted in environmentally relevant conditions, results from these studies seem to be more reliable. CHPTAC (3 -Chloro-2 -hydroxypropyltrimethylammonium chloride, CAS# 3327 -22 -8) is used for the production of cationic starch. Thus, CHPTAC is always transformed to EPTAC before the cationisation. In addition, the hydrolysis half-lives for EPTAC calculated from these studies are close to each other i.e. 177 days and 138 days at pH 7.8. Furthermore these hydrolysis half-lives are clearly longer compared to CHPTAC conversion rate (21 days at pH 7.8) whereas in the first EPTAC hydrolysis test half-life is shorter compared to CHPTAC. Longer EPTAC hydrolysis half-lives compared to CHPTAC can be observed from two other tests, namely adsorption test to sludge and the chronic Daphnia test. In the sludge test abiotic removal of EPTAC was slower (4-6 % in 3 days in abiotic and sterile controls) compared to CHPTAC (22-27 % in 3 days). In the 21 day Daphnia sp. test with EPTAC no significant removal of EPTAC was observed after 2 days, but in the similar test with CHPTAC approximately 30 % of the total sum was converted to EPTAC after 2 days. Therefore results from the latter EPTAC hydrolysis study will be used in the assessment.