Reaction mass of tetramethylammonium hypochlorite and tetramethylammonium chloride

Toxicity to aquatic algae and cyanobacteria

Description of key information

Key study on the 72-h toxicity to algae (Pseudokirchneriella subcapitata) was determined according to the OECD 201 and in accordance with GLP. 

Key value for chemical safety assessment

EC50 for freshwater algae:

449 µg/L

EC10 or NOEC for freshwater algae:

125 µg/L

Additional information

Key study on the 72-h toxicity to algae (Pseudokirchneriella subcapitata) was determined according to the OECD 202 and in accordance with GLP. Since the target substance is analogue to the inorganic household agents (e.g. sodium hypochlorite) the literature data from sodium hypochlorite was used as a supporting read-across data to evaluate the aquatic toxicity to algae.

The key study was conducted for the target substance by using the nominal concentrations. Because the substance is a multi-constituent and the intrinsic properties are related to the available chlorine content, the most feasible method to measure the test concentrations is to use titration. However, since the test concentrations were very low the detection limit of the analysing method caused limitations and the nominal concentrations were used instead of measured ones. In addition, the pH adjustment was not feasible because the target substance will decompose if the pH is adjusted. Based on the key study results, the key value for the 72-h EC50 is 449 µg/L (growth rate). No NOEC value was achieved.

 

Based on the supporting studies on analogue household bleaching agents (sodium hypochlorite) the intrinsic properties are similarly related to the available chlorine and the aquatic toxicity determined for these analogue substances indicate long-term toxicity to algae. No short-term or long-term studies conducted by standard methods have been found by the literature search. The following conclusions on hypochlorite long-term toxicity to algae have been presented in the EU Risk Assessment Report for sodium hypochlorite in 2007:

 

Cairns et al. (1990) examined the chronic effects of sodium hypochlorite in a laboratory multispecies microcosm (alone or together with ammonia) to naturally derived periphytic communities exposed for 7 days to sodium hypochlorite in a flow-through system. The reduction in protozoa species richness was statistically significant (LOEC) at 6 μg TRC*/L, while for a reduction of 20 %, (IC 20) considered biologically significant, a concentration of 2.7 μg TRC/L was calculated. At 6 μg TRC/L, the composition of protozoa communities (number of taxa) changed significantly. Since the effect was about 10 %, for this endpoint a NOEC (LOEC/2) = 3 μg TRC/L could be calculated. Non-taxonomic responses were also measured. In vivo fluorescence, used as an index of algal biomass, was significantly reduced (22 %) at 6 μg TRC/L (the lowest tested concentration). This data can be used to calculate a NOEC of 3 μg TRC/L equivalent to 2.1 µg FAC**/L as an indication of long-term toxicity to algae.

 

In addition to this key value selected for the sodium hypochlorite in the EU risk assessment (2007), the biomass microcosm studies and mesocosm studies by Pratt et al. (1988) were given as the supporting information in the report. The 28 d EC50 of 2.1 μg TRC/l equivalent to 2.1 μg FAC/l (FAC (100%) for biomass microcosm study and the 24 d NOEC of 1.5 μg TRC/l equivalent to 1.5 μg FAC/l (FAC 100%) indicated similar toxicity levels to algae.

 

For brackish water and sea water the 21d EC50 of 1-10 μg TRC/l for sodium hypochlorite has been selected from the study by Sanders et al. 1981 conducted for periphytic community, intermittent exposure (first cited at the EU Risk Assessment Report 2007).

 

**FAC= free available chlorine

*TRC= total residual chlorine