Quaternary ammonium compounds, C12-14 (even numbered) alkyl(hydroxyethyl)dimethyl, C12 alkylbis(hydroxyethyl)methyl, chlorides and amines, C12-14 (even numbered) alkyldimethyl, chlorides

Toxicity to aquatic algae and cyanobacteria

Description of key information

Based on the results of the study, the 72 h ErC50 and ErC10 values of 67.22 and 8.4 µg a.i./L (nominal) respectively determined for the test substance for effects on growth rate of Desmodesmus subspicatus has been considered further for hazard/risk assessment.

Key value for chemical safety assessment

EC50 for freshwater algae:

67.22 µg/L

EC10 or NOEC for freshwater algae:

8.4 µg/L

Additional information

A study was conducted to determine the acute toxicity of the test substance, C12 -14 HEDMAC (39.6% active) to freshwater green algae (Desmodesmus subspicatus) OECD guideline 201, in compliance with GLP. Six concentrations of test substance ranging from 0.32 to 100 μg/L (nominal concentration test substance) resp. 0.13 – 39.6 μg/L (nominal concentration of the active surfactant content of the test substance) were used in the study with an incubation time of 72 h. The cell concentration of each replicate was determined by measuring the cell numbers every 24 h with an electronic particle counter. Growth rate μ and the yield 1 were determined from the cell number at the respective observation times. Significant inhibition of algal growth was observed in the 3 highest concentrations: 10, 32, 100 μg/L (nominal) resp. 3.96 – 39.60 μg/L (nominal concentration of the active surfactant content of the test substance). At the start and at the end of the test and every 24 h, the content of the test substance in the test solutions was determined using LC-MS. After 72 h, the test substance was detectable only in the 4 highest nominal concentration exposure groups (treatments). Therefore, only the 4 highest nominal concentration exposure groups were used for statistical evaluation. Because the measured concentrations were not in the range of ± 20 % of the nominal concentrations, the biological results were based on the geometric mean of the measured concentrations of the test subsatnce. Additionally, the results are presented based on the active surfactant content of the test substance (39.6 %). The 72h-EC50 values of potassium dichromate were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.65 - 1.10 mg/L, yield 0.21 – 0.66 mg/L). The EC50, EC10 and NOEC values for test substanace based on growth rate was found to be 169.74, 21.20 and 1.89 µg/L respectively. The EC50, EC10 and NOEC values for test substanace based on yield was found to be 26.83, 4.4 and 1.89 µg/L respectively. Under the study conditions, the 72 h EC50, EC10, LOEC and NOEC for test substance for effects on growth rate were determined to be 169.74, 21.20, 7.47 and 1.89 µg/L (nominal) (equivalent to 67.22, 8.4, 2.96 and 0.75 µg a.i./L) respectively (Muckle, 2019).