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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The QSAR model predicts a 96 hour EC50 value of 30.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
30.3 mg/L
EC10 or NOEC for freshwater algae:
7.07 mg/L

Additional information

The Mattock (1996) study is a GLP, near guideline proprietary experimental study; however there are limitations in the study due to loss of the test substance. Ethylene is a gas at standard temperature and pressure and it was technically difficult to maintain aqueous concentrations of the gas during the study. The reported 72 hour EC50 for Selenastrum capricornutum was 40.5 mg/L based on biomass and 72.2 mg/L based on growth rate. The 72 hour NOEC was 13.9 mg/L for both biomass and growth rate. The results are based on the mean measured concentrations, though the ErC50 should be treated with caution as it lies outside the measured concentration range. This study was conducted to GLP standards and followed standard guidelines with minor deviations and a large proportion of the ethylene was lost during the test. Due to this limitation the study was used as a supporting study.

The key study for the endpoint is a QSAR prediction using the ECOWIN v1 ECOSAR (Nabholz and Mayo-Bean 2009) model. This model predicts a 96-hour EC50value of 30.3 mg/L and a ChV of 7.07 mg/L.

The aquatic toxicity of this substance was estimated using the Target Lipid Model based on methologies described by Mcgrath et al. (2015). The estimated LL50 for this substance is 119.325 mg/L and the NOELR was 22.859 mg/L.