2-(1,1-dimethylpropyl)phenol

Short-term toxicity to aquatic invertebrates

Description of key information

The 48-hr EC50 for Daphnia magna was determined to be 1.77 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.77 mg/L

Additional information

A reliable short-term toxicity study with aquatic invertebrates has been conducted for o-tert-amylphenol, is included in this dossier and is summarized below. Additionally, reliable toxicity studies with aquatic invertebrates with the structural analogues o-tert-butylphenol and o -sec-butylphenol have been included for supporting evidence. In the key study Hermes, 2015, t

he 48 -hr acute toxicity of o-tert-amylphenol to Daphnia magna was studied under static conditions. Daphnids were exposed to control and test chemical at nominal concentrations of 0.05, 0.11, 0.24, 0.53, 1.2 and 2.6 mg/L for 48 hr. Stability of the test substance over the study period was confirmed by photometric analysis. Immobilisation and sublethal effects were observed daily. The 48 hr EC50 was reported to be 1.77 mg/L. S

asol (2014) provided a reliable (Klimisch 2) study for o-tert-amylphenol using the QSAR model, Ecological Structure Activity Relationships (ECOSAR) Class Program to estimate short-term toxicity to aquatic invertebrates. The ECOSAR model estimates aquatic toxicity based on the structural similarity to chemicals for which aquatic studies are available. In addition, the log Kow and molecular weight of o-tert-amylphenol are within the criteria (max log Kow = 7 for acute, 8 for chronic and max molecular weight = 1000) and domain of the model. The measured log Kow of 4.0 was used in the model. Model results indicate a daphnid 48 hr LC50 to be 1.47 mg/L based on the neutral organic class equation. Schulz (1995) conducted a reliable (Klimisch 2) GLP compliant study according to OECD 202 methods on the structural analogue, o-tert-butylphenol. The 48-hr acute toxicity of o-tert-butylphenol to Daphnia magna was studied under static conditions. Daphnids were exposed to control and test chemical at nominal concentrations of 0.3, 0.6, 1.3, 2.5, 5.0, and 10 mg/L for 48 hr. Stability of the test substance over the study period was confirmed by photometric analysis. Immobilisation and sublethal effects were observed daily. The 48 hr EC50 was reported to be 3.4 mg/L. MOE Japan (1999) conducted a reliable (Klimisch 2) GLP compliant study according to OECD 202 methods. The 48 hr acute toxicity of the structural analogue, o-sec-butylphenol, to Daphnia magna was studied under static conditions. Daphnids were exposed to control and test chemical at nominal concentrations of 1.0, 1.8, 3.2, 5.6, and 10 mg/l for 48 hr. Immobilisation was observed at 48 hours. The 48 hr EC50 was reported to be 4.0 mg/L. McLeese et al (1981) conducted a reliable (Klimisch 2) toxicity study on both structural analogues, o-tert-butylphenol and o-sec-butylphenol, using the shrimp, Crangon septemspinosa, under static conditions in saltwater. Shrimp were exposed to control and test chemical at nominal concentrations for 96 hr. The 96 hr LC50 for o-tert-butylphenol was reported to be 2.4 mg/L while the 96 hr LC50 for o-sec-butylphenol was 1.3 mg/L. Reliable (Klimisch 2) measured and modeled short-term toxicity studies with invertebrates have been conducted for o-tert-amylphenol and the structural analogues o-tert-butylphenol and o-sec-butylphenol and are included in this dossier. The key study, Hermes (2015), provides a 48 hr LC50 of 1.77 mg/L for daphnids for o-tert-amylphenol. Consequently this value will be taken as the short-term toxicity to aquatic invertebrates endpoint for o-tert-amylphenol.