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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

No short-term toxicity in the classifiable range of CLP

Key value for chemical safety assessment

EC50 for freshwater algae:
65 mg/L
EC10 or NOEC for freshwater algae:
4 mg/L

Additional information

The toxicity of Guanidine carbonate (CAS 593-85-1) to aquatic algae was investigated in a GLP-compliant study (Bornatowicz 1998) using freshwater green algae (Pseudokirchneriella subcapitata) according to the EU C.3 (1992) protocol. Due to the properties of the test substance, the actual concentrations of the test substance in the test cultures could not be determined, but in view of the test item properties stability can be assumed. The raw data for the section-by-section specific growth rates are given, so that the mean coefficient of variation can be calculated and be compared with the more recent OECD TG 201 (2006) demand of ≤35 %. The experiment is deemed valid, conclusive and thus suitable for assessment without restrictions.

The test organisms were in 3 replicates exposed to nominal concentrations of 0, 12.5, 25, 50, 100 and 200 mg/L in a first experiment, were effects in all treatments were recorded, and 0, 1, 2, 4, 8 and 16.0 mg/L in a second experiment, the definitive study. The incubation was performed under constant illumination and shaking at a temperature of 22 ± 1 °C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Counter, model ZF.

Biomass (yield) was the most sensitive endpoint for the EC50, while the NOEC was equal for both, biomass and growth rate. Exposure to the test item resulted in an EbC50 of 15.1 mg/L and an ErC50 of 65 mg/L. The no effect level NOEC was 4 mg/L.

In conclusion the test item was found not toxic to aquatic algae up to the relevant levels considered for acute hazard to the aquatic life in the EU (i.e. 1 mg/L according to CLP, Regulation (EC) No 1272/2008) and no acute aquatic hazard classification is required by the results of this study.

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