3H-Pyrazol-3-one, 2,4-dihydro-5-methyl-2-phenyl-, 4-[(4-C7-17-branched alkylphenyl)azo] derivs.

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

Justification for type of information:

According to QSAR estimation methods for 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone, the water solubility was 1.04E-04 mg/L. Using the flask method, the water solubility of 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone was empirically determined to be less than 0.05 mg/L at 20°C. Using the HPLC method, the log (base 10) n-octanol/water partition coefficient was determined to be greater than 6.5. This was also similar to the Log Kow estimates for 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone according to KOWWIN (v. 1.43) which predicted a log (base 10) Kow value of 7.99.

Using the ECOSAR program (developed by the US Environmental Protection Agency’s Office of Chemical Safety and Pollution Prevention, v 1.11), the predicted effect levels for acute toxicity to Daphnia exceeded the estimated water solubility of 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone. Toxic effects were predicted at concentrations ranging from ~ 5-fold to 300-fold greater than the predicted water solubility limit for both acute and chronic toxicity to Daphnia. Thus, no acute or chronic effects at water saturation were predicted for the test material, and the study was deemed scientifically not necessary.

Description of key information

No acute or chronic effects at water saturation were predicted for the test material, therefore acute testing with Daphnia is waived since the study is scientifically not necessary.