Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The 72 hour NOEC for algae exposed to cyclohexane is 0.925 mg/L. The ErC50 was calculated to be > 4.425 mg/L. However, the authors used an extrapolation method to indicate an ErC50 of 9.317 mg/L with a confidence interval of 3.869 to 54.027 mg/L. Without further details of this calculation we consider the measured value of >4.425 mg/L to indicate the ErC50.

Key value for chemical safety assessment

EC50 for freshwater algae:
4.425 mg/L
EC10 or NOEC for freshwater algae:
0.925 mg/L

Additional information

A proprietary study (Exxon 1998) provided short term toxicity data. It showed 72 hour NOEC of 0.925 mg/L. The ErC50 was calculated to be > 4.425 mg/L. However, the authors used an extrapolation method to indicate an ErC50 of 9.317 mg/L with a confidence interval of 3.869 to 54.027 mg/L. Without further details of this calculation we consider the measured value of >4.425 mg/L to indicate the ErC50. The proprietary supporting study (Exxon 1998) was conducted to GLP based on a standard guideline. There were deviations from this method to ensure than loss of the test substance was minimised. The deviations are not believed to have influenced the reliability of the test. The study is therefore considered to be reliable for assessment. To support these data a QSAR model (Nabholz and Mayo-Bean 2009) provided an estimated 96 hour EC50 of 2.17 mg/L.