1-(2-methyl-4-(2-methylphenylazo)phenylazo)-2-naphthol

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur

Description of key information

Determination of the inhibition of the mobility of daphnids was carried out with the substance 1-(2-Methyl-4-(2-methylphenylazo)phenylazo)-2-naphthol. Test was conducted according to OECD Guideline 202 (Experimental study report, 2017). The stock solution 2 g/L was prepared by dissolving brown powder in acetone. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 0, 0.6, 1.2, 2.5, 5, 10 mg/l nominal concentrations. Effects on immobilisation were observed for 48 hours. The median effective concentration (EC50) for the test substance, 1 -(2 -Methyl-4 -(2 -methylphenylazo)phenylazo)-2 -naphthol, in Daphnia magna was determined to be 3.9 mg/L. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 2 as per the CLP criteria. But as the chemical was readily biodegradable in water so on the basis of biodegradability, it can be concluded that the chemical 1 -(2 -Methyl-4 -(2 -methylphenylazo) phenylazo)-2 -naphthol was nontoxic and can be consider to be not classified as per the CLP classification criteria.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.9 mg/L

Additional information

Determination of the inhibition of the mobility of daphnids was carried out with the substance 1-(2-Methyl-4-(2-methylphenylazo)phenylazo)-2-naphthol. Test was conducted according to OECD Guideline 202 (Experimental study report, 2017). The stock solution 2 g/L was prepared by dissolving brown powder in acetone. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 0, 0.6, 1.2, 2.5, 5, 10 mg/l nominal concentrations. Effects on immobilisation were observed for 48 hours. The median effective concentration (EC50) for the test substance, 1 -(2 -Methyl-4 -(2 -methylphenylazo)phenylazo)-2 -naphthol, in Daphnia magna was determined to be 3.9 mg/L. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 2 as per the CLP criteria. But as the chemical was readily biodegradable in water so on the basis of biodegradability, it can be concluded that the chemical 1 -(2 -Methyl-4 -(2 -methylphenylazo) phenylazo)-2 -naphthol was nontoxic and can be consider to be not classified as per the CLP classification criteria.

Short term toxicity to aquatic invertebrate endpoint can also be considered for waiver as per ccordance with column 2 of Annex VIII of the REACH regulation, testing for this end point is considered scientifically not necessary since there are mitigating factors indicating that aquatic toxicity is unlikely to occur as the test chemical is highly insoluble (solubility: 0.023 mg/L at 25° C) in water and also having the partition coefficient value ranging from 6.66 to 6.87, respectively. Thus, test chemical can be considered to be hydrophobic in nature.