Ethylbenzene

Toxicity to aquatic algae and cyanobacteria

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.