2,2'-dithiobisethanol

Short-term toxicity to aquatic invertebrates

Description of key information

The 48h-EC50 was determined as 4.4 mg/L based on nominal concentrations with a 95% confidence interval between 3.6 and 5.4 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

4.4 mg/L

Additional information

Charles River Laboratories (2017) is a GLP-compliant study following OECD guideline 202 and is therefore reliable without restrictions (Klimisch 1). A range finding test was conducted with the concentrations of 0.10, 1.0, 10 and 100 mg/L. There was no immobility observed in the control and three lowest test concentrations at 24 or 48 hours. At 10 and 100 mg/L immobility of 60% and 70% was observed at 24 hours and, after 48 hours, immobility of 80 and 100% was seen. The concentrations used for the final test were 1.0, 2.2, 4.6, 10, 22 mg/L. Five daphnids were used for each concentration in a total of 4 replicates. The validity criteria for the study was fulfilled as no more than 10% of the dapnids in the controls became immobilised or showed any signs of disease/stress. The concentration of oxygen at the end of the test was≥3 mg/L in the control and test vessels. A reference test with potassium dichromate was conducted to check the sensitivity of the test system. The 48h-EC50 was 0.59 mg/L, which is within the historical ranges for the laboratory, conveying that the test system works.

The analytical method of UPLC-RID was used to measure concentrations at the start (0 hrs) and end of test (48 hrs). The tested concentrations of 1.0, 2.2 and 4.6 mg/L could not be quantified. The nominal concentrations of 22 and 10 mg/L showed stability throughout the exposure period (84% and 96% of initially measured). Therefore, the results were reported as nominal concentrations.

In conclusion, the 48h-EC50 was determined as 4.4 mg/L based on nominal concentrations with a 95% confidence interval between 3.6 and 5.4 mg/L.