Reaction mass of tetramethylammonium hypochlorite and tetramethylammonium chloride

Toxicity to microorganisms

Description of key information

The activated sludge respiration study was conducted according to the OECD 209 and in compliance with GLP.

Key value for chemical safety assessment

EC50 for microorganisms:

251.5 mg/L

Additional information

 The key value for CSA was selected from the GLP compliant activated sludge respiration inhibition study conducted for the target substance. The study was done according to the OECD 209. Samples of test medium were not collected during the exposure period for the analytical verification of the test solutions. Halo Salt could not be quantified in the test system due to the nature of the material being unstable under the test conditions and the fact that no suitable analytical technique with the required sensitivity could be determined. Therefore the results of this study were based on nominal test concentrations.

The pH of the test media was between 8.68-8.75 with the highest test substance concentration of 1000 mg/L. Therefore the pH in samples with concentration of 1000 mg/L was adjusted to 8.07-8.13 with 1 mL 5% Acetic acid before test initiation. Nominal concentrations used in both pre-test evaluation and in final test were 10 mg/L, 100 mg/L and 1000 mg/L. The EC50 value for test substance was determined as 251.5 mg/L, with 95 percent confidence limits of 100 mg/L and 1000 mg/L.

 

In general, target substance should have minimal effect on the microbes of municipal waste water treatment plant, as because of its high reactivity and rapid degradation is expected to disappear very rapidly in sewer (Modelling results by Vandepitte & Schowanek 2007). Activated sludge flocs are also not very sensitive to hypochlorite probably because they have polysaccharide glycosalix that protects them (EU Risk Assessment Report 2007).