Registration Dossier
Registration Dossier
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EC number: 221-916-9 | CAS number: 3279-27-4
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
The toxicity of o-tert-amylphenol to aquatic algae was estimated using a QSAR model. The 96 hr EC50 was 2.36 mg/L, while the 96 hr ChV was 0.93 mg/L with a calculated NOEC of 0.658 mg/L.
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 2.36 mg/L
- EC10 or NOEC for freshwater algae:
- 0.658 mg/L
Additional information
A reliable (Klimisch 2) modeled toxicity study with algae has been conducted for o-tert-amylphenol and is included in this dossier. Additionally, reliable toxicity studies with algae for the structural analogues o-tert-butylphenol and o -sec-butylphenol have been included for supporting evidence.
Sasol (2016) provided a reliable (Klimisch 2) study for o-tert-amylphenol using the QSAR model, Ecological Structure Activity Relationships (ECOSAR) Class Program to estimate toxicity to aquatic algae. 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 96 hr EC50 to be 2.36 mg/L based on the baseline toxicity equation. In addition, the 96 hr chronic value (the geometric mean of the NOEC and LOEC) was calculated as 0.930 mg/L for the neutral organic class. As per REACH Guidance Ch 10, a NOEC can be calculated from the chronic value. Therefore, the calculated NOEC is 0.658 mg/L. These results will be used as the key studies for toxicity to aquatic algae.
Schulz (1994) conducted a reliable (Klimisch 2) GLP compliant study according to OECD 201 methods using the structural analogue o-tert-butylphenol. In a 72 hr toxicity study, cultures of the green alga Scendesmus subspicatus (CHODAT 86.81 SAG) were exposed to o-tert-butylphenol at nominal concentrations of 1.2, 2.4, 5, 10, 20, and 40 mg/L under static conditions in accordance with EU method C.3 (Directive 92/69/EEC) and OECD guideline 201 (1984). The EC10 and EC50 values based on growth rate inhibition (ErCx) were 2.0 and 6.5 mg/L, respectively. The 72 hr NOEC is <1.2 mg/L, based on growth.
MOE Japan (1999) conducted a reliable (Klimisch 2) GLP compliant study according to OECD 201 methods using the read across substance o-sec-butylphenol. In a 72 hr toxicity study, cultures of the alga, Pseudokirchneriella subcapitata, were exposed to o-sec-butylphenol at nominal concentrations of 1.0, 1.8, 3.2, 5.6, 10, 18 and 32 mg/L under static conditions in accordance with OECD guideline 201 (1984). The 72 hr NOEC and EC50 values, based on growth rate inhibition (ErCx) were 1.8 and 6.9 mg/L, respectively.
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