reaction mass of ethylbenzene and xylene

Short-term toxicity to aquatic invertebrates

Description of key information

The lowest result is a 24 hour EC50 of 1 mg/L for o-xylene.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 mg/L

Additional information

Data are available on the acute toxicity of each of the xylene isomers and ethylbenzene to aquatic invertebrates. The study by Galassi et al (1988) follows OECD 202 and uses Daphnia magna, whilst Holcombe et al (1987) used a flow through system to expose different species (including Daphnia magna) simultaneously. Niederlehner et al (1998) used Ceriodaphnia dubia as the test organism. All studies included analytical confirmation of the exposure concentrations.

The lowest result listed in the EU RAR (ECB 2007) and the Draft Screening Assessment Report (Environment Canada 2014) for acute toxicity of ethylbenzene to invertebrates is a 48 hour EC50 of 1.8 mg/L (Vigano 1993). The ECB report that the study investigated the toxicity of ethylbenzene to Daphnia magna in completely filled, closed bottles, with results based on mean measured concentrations. The results were taken from a larger study on the effects of different food rations on juvenile Daphnia. Although lower results are reported by Benville and Korn (1977) are reported in the EU RAR, the test result is not considered valid as it is not known how the mean exposure concentration over the whole test duration was calculated and no attempt was made to supplement the toxicant.

The 24 and 48 hour EC50 results reported from these studies for the xylene isomers and ethylbenzene are very similar, with a range of 1 - 4.7 mg/L. In the study by Niederlehner et al (1998), the highest concentration tested did not result in effects on mortality, so the EC50 is > 3.4 mg/L. The lowest result will be used in the risk assessment.