Calcium bis[4-[[1-[[(2-chlorophenyl)amino]carbonyl]-2-oxopropyl]azo]-3-nitrobenzenesulphonate]

Endpoint summary

Additional information

The acute tests on fish (OECD 203) and algae (OECD 201) as well as the study on the toxicity to microorganisms (OECD 209) did not reveal any toxic effects of the substance in the range of its water solubility. The study on daphnids was performed as chronic toxicity study according to OECD guideline 211 with nominal test concentrations of 0, 0.46, 1, 2.2, 4.6 and 10 mg/L.The analytically determined water solubility in the test medium is clearly below 1 mg/L (please refer to the endpoint summary of the long-term daphnia study for more detailed information on specific water solubilites in the different media). Thus, the 10 mg/L concentration group clearly exceeded the water solubility in the test medium. The stock solution of 10 mg/L was used to prepare the lower concentrations by serial dilution. No effects could be observed in the lower concentration groups (0.46, 1, 2.2, 4.6 mg/L), however, the highest concentration of 10 mg/L had a minor effect on Daphnia reproduction after 21 days of exposure (13%). It is assumed, the observed effect is due to better soluble impurities present in the test substance rather than the pigment itself, which is expected to be not toxic. The impurities listed in the certificate of analysis of the batch used for the study are all well below 1 % and therefore not relevant for classification purposes. However, some of them are known to have toxic effects on aquatic organisms and the observed effects in the highest concentration group are expected to be caused by these better soluble impurities.To clarify this aspect, it was decided to conduct a second experiment using a saturated solution of the test substance prepared at a loading rate of 1 mg/L. This loading rate still clearly exceeds the water solubility in the test medium, thus, it can be guaranteed that the additional study was conducted at the highest concentration of test substance possible. Furthermore, the loading rate of only 1 mg/L lowers the amount of better soluble impurities in the test medium by a factor of 10 and therefore allows a clearer statement of the toxic potential of the pigment itself. At this loading rate, no effects could be observed which is regarded as clear proof, that the observed effects at 10 mg/L in the first experiment are caused by better soluble impurities and therefore, the pigment itself is not toxic to aquatic invertebrates.

Acute toxicity to fish:

With high probability acutely not harmful to fish. No toxic effects occur within the range of water solubility.

Chronic toxicity to aquatic invertebrates:

With high probability not harmful to aquatic invertebrates. No toxic effects occur within the range of water solubility.

Toxicity to aquatic algae:

With high probability acutely not harmful to aquatic algae. No toxic effects occur within the range of water solubility.

Toxicity to microorganisms:

The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriate low concentrations.