Benzene, di-C10-14-alkyl derivs., sulfonated, sodium salts

Toxicity to aquatic algae and cyanobacteria

Key value for chemical safety assessment

EC50 for freshwater algae:

111 mg/L

EC10 or NOEC for freshwater algae:

111 mg/L

Additional information

A study was conducted to determine the toxicity to aquatic algae and cyanobacteria of the test substance according to OECD Guideline 201 and EU Method C.3, in compliance with GLP. The main test was performed based on the results of a preceding combined limit/range-finding test. Six exponentially growing algal cultures of Pseudokirchneriella subcapitata were exposed to an untreated control, whereas three replicates per group were exposed to Water Accommodated Fractions (WAFs) prepared at loading rates of 1.11, 3.55, 11.1, 35.5 and 111 mg/L. The initial algal cell density was 10E4 cells/mL. The total exposure period was 72 h and samples for It was not possible to implement a specific analytical method for analyses of samples taken from this test substance. Instead, TOC analysis was used as an alternative. Total Organic Carbon (TOC) analysis were taken at the start and the end of the exposure period. The theoretical carbon content of the test substance was determined to be 70.4% based on the organic carbon analysis of the pure test substance. A positive control (potassium dichromate) was added and gave results in the expected range. The study met the acceptability criteria prescribed by the study plan and was considered valid. Growth rates of loading rates prepared at concentrations between 1.11 and 35.5 mg/L were slightly higher than the growth rate of the control solutions. The growth rate of the highest loading rate of 111 mg/L was slightly below that of the control solutions. The inhibition was however not statistically significant or biologically relevant. Yield obtained in the loading rates prepared at concentrations between 1.11 and 35.5 mg/L were slightly higher than the average yield obtained in the control solutions. Only at the highest loading rate of 111 mg/L an inhibition of yield was observed. The inhibition of 19% was however not statistically significant which was likely due to the relatively high variation within the three replicates. Microscopic observations at the end of the test revealed a normal and healthy appearance of the algal cells exposed to the highest test group when compared to the control. Due to the very low solubility of the test substance in water, concentration levels significantly toxic for algae could not be reached. Under the study conditions, no statistically significant inhibition of growth rate or inhibition of yield in Pseudokirchneriella subcapitata was recorded at any of the loading rates of the test substance tested. Both the EL50 for growth rate inhibition (72 h-ERL50) and the EL50 for yield inhibition (72 h-EYL50) exceeded the highest loading rate tested, being 111 mg/L (Migchielsen, 2017).