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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

TNO (2004) reports a 72 hour EC50 of 2.2 mg/L and a 72 hour NOEC of 0.44 mg/L, both for p-xylene. The Draft Screening Assessment Report for ethylbenzene (Environment Canada 2014) reports a 48 hour EC50 of 1.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.3 mg/L
EC10 or NOEC for freshwater algae:
0.44 mg/L

Additional information

Data are available on the ecotoxicity of each of the xylene isomers and ethylbenzene to algae. The studies by Galassi et al (1988) and Oldersma (2004) followed OECD 201, whilst Herman et al (1990) used a non-standard method. All studies included analytical confirmation of the exposure concentrations.

The lowest results listed in the EU RAR (ECB 2007) for the toxicity of ethylbenzene to algae are a 72 hour NOEC of 3.4 mg/L and a 72 hour EC50 of 5.9 mg/L (Boeri 1987). The study is considered by the ECB to be reliable, and although results for 96 hours are also presented in the report, the algae were not in an exponential growth phase and therefore the results have not been used for effects assessment. The lowest results listed in the Draft Screening Assessment Report (Environment Canada 2014) for algal toxicity are a 48 hour EC50 of 1.3 mg/L (Tasi and Chen 2007).

The EC50 results reported from these studies for the different isomers and ethylbenzene are very similar, with a range of 1.3 - 4.9 mg/L. The lowest long-term result was reported by Oldersma et al (2004) for p-xylene. The lowest short-term result was reported in the EU Risk Assessment Report (ECB 2007) for ethylbenzene.