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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Acute toxicity of ethylbenzene was tested with several species of algae and one species of cyanobacteria for varying durations ranging from 3 hours for Chlamydomonas and Chlorella to 96 hours for Selenastrum capricornutum and Skeletonema costatum. 

Key value for chemical safety assessment

EC50 for freshwater algae:
3.6 mg/L
EC50 for marine water algae:
7.7 mg/L
EC10 or NOEC for freshwater algae:
3.4 mg/L
EC10 or NOEC for marine water algae:
4.5 mg/L

Additional information

Two key algal studies were identified for ethylbenzene and includedSelenastrum capricornutum (now known asPseudokirchneriella subcapitata) and Skeletonema costatum. The 96-hr EC50 values for these two species were 3.6 and 7.7 mg ethylbenzene/L, while the 96-hr NOEC values were 3.4 and 4.5 mg/L. These two key studies were considered reliable without restrictions and each received a Klimisch score of 1. An additional S. capricornutum study reported a 72-hr EC50 of 4.6 mg/L and was rated a Klimisch score of 2. Twelve additional studies were considered supporting studies and five of these were considered reliable with a Klimisch score of 2. These studies included an 8-d algal study with S. capricornutum resulting in an EC50 of 4.8 and a 96-hr study with an EC50 value of 3.6 and a NOEC of 3.4 mg ethylbenzene/L, which supports the key study parameters selected. Additional species included Ulva pertusa, Chlamydomonas and Chlorella vulgaris. The endpoint forU. pertusa was photoaxis of zoospores and was not included, while the 3-hr EC50 values for Chlamydomonas and Chlorella were 51 and 63 mg/L.

Three of the remaining studies (data from secondary literature sources) were of questionable reliability and gave high NOEC/toxic threshold/EC50 values. The remaining four studies were identified as unreliable with Klimisch scores of 3.

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