Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Key values for acute aquatic toxicity

Algae: 72h-ErC50 (Desmodesmus subspicatus, growth rate) > 1000 mg a.i./L, pH 8.27 (nominal)

Daphnia: 48h-EC50 (Daphnia magna, immobilisation) > 100 mg a.i./ L, pH 7 (nominal)

Fish: 96h-LC50 (Danio rerio, mortality) > 100 mg a.i./L (nominal)

Key value for chronic aquatic toxicity

Algae: 72h-NOEC (Desmodesmus subspicatus, specific growth rate) >= 1000 mg a.i./L, pH 8.27 (nominal)

Toxicity to microorganisms

STP microorganisms: 3h-EC50 (STP microorganisms, respiration inhibition) = 844 mg a.i./L; 3h-NOEC (STP microorganisms, respiration inhibition) = 420 mg a.i./L

Additional information

Summary of aquatic toxicity

Aquatic algae

A reliable study was available on the toxicity of the submission substance to the unicellular freshwater green alga Desmodesmus subspicatus (RL2). The study was performed according to OECD 201 (adopted 1984) and in compliance with GLP. After 72 hours of exposure, inhibition of growth of the freshwater green alga Desmodesmus subspicatus was observed at nominal 250 mg a.i./L (biomass growth and specific growth rate), respectively. The derived EC50-values with 95% confidence intervals for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72h were 232 (226 - 239) and 253 (245 - 260) mg a.i./L, respectively. The NOEC for both biomass growth and specific growth rate was 125 mg a.i./L. Inhibition effects were found to be reversible up to 500 mg a.i./L (all effect levels given as nominal concentrations). With regard to the determinations in the pH-control it can be assumed that the effects on the cell growth were caused by the high pH. This is supported by the pH-control at 1000 mg a.i., adjusted to pH 8.27 where no inhibitory effects were observed. According to OECD 23 and ECHA guidance R.7b, pH should be adjusted to lie within the specified range for the test using a suitable buffer, where the substance itself causes a change to the pH of the test medium. This is the case for the test substance. Therefore, the valid 72h-EC50 for algal growth was considered > 1000 mg a.i./L, and 72h-NOEC = 1000 mg a.i./L.

 

Aquatic invertebrates

A reliable key study is available for the acute immobilisation of the test substance to Daphnia magna (RL1). Acute immobilisation of the test substance to Daphnia magna was determined according to OECD 202 (1984) and in compliance with GLP. After 48 hours, no effect of immobilisation was recorded in the lowest treatment group, the control and the pH-control. The derived 48h-EC50 was 28.6 mg a.i./ L (nominal) and 48h-EC10 was 8.9 mg a.i./L (nominal). No effect was observed at 100 mg a.i./L, neutralised to pH 7. The pH-value varied by slightly more than 1.5 units in the treatment groups and was in the acceptable range of 7.04 - 9.39 (guideline indicates the pH should be in the range of 6 to 9), which is related to the alkaline characteristics of the test substance. Observed effects of immobilisation are likely linked to pH-effect rather than inherent toxicity of the test substance. The assumption is supported by the pH control at 100 mg a.i./L and pH 7, where no immobilisation of daphnids occurred during 48 hours. According to OECD 23 and ECHA guidance R.7b, pH should be adjusted to lie within the specified range for the test using a suitable buffer, where the substance itself causes a change to the pH of the test medium. This is the case for the test substance. Therefore, the valid 48h-EC50 for the immobilisation of Daphnia magna was considered > 100 mg a.i./L.

Fish

A reliable key study is available on the acute toxicity of the submission substance (RL1). Acute toxicity of the test substance to fish (Zebrafish) was determined according to OECD 203 (1992) and in compliance with GLP. During the 96 hours exposure period, no mortality occurred in neither treatment group nor control. The derived effect concentration was 96h-LC50 (Danio rerio, mortality) > 100 mg a.i./L.

In conclusion, observed adverse effects were clearly linked to pH-effects instead of an inherent toxicity of the submission substance. Therefore, no hazard was identified for the submission substance with regard to aquatic organisms.

Microorganisms

A reliable key study is available on the activated sludge respiration inhibition of the submission substance (RL2). Respiration inhibition with activated sludge was performed with the test substance according OECD 209 (1984) and GLP principles. After 3 hours of exposure, respiration inhibition ranged from 0 to 100%. The derived 3h-EC50 was 844 mg a.i./L and the 3h-NOEC was 420 mg a.i./L. No adaptation of pH was performed and observed effects are likely related to pH rather than inherent toxicity of the submission substance. The additional validity criterion for the updated guideline from 2010 regarding the minimum respiration rate of the controls could not be met. However, this violation was not taken as reason to assume significant distortion of the result, also considering the conservative approach of the applied hazard assessment with regard to STP microorganisms (PNECstp was derived).