Benzene, ethylenated, residues, distn. lights

Short-term toxicity to aquatic invertebrates

Description of key information

An acute toxicity test to Daphnia magna according to OECD Guideline 202 and EU Method C.2. Daphnia magna were exposed to Ethylbenzene, manuf. of, distn. residues, distn. lights. in a static freshwater system over a period of 48 hours. The 48-Hour EL 50 for Ethylbenzene, manuf. of, distn. residues, distn. lights. to Daphnia magna based on nominal loading rates was 1.3 mg/L with 95% confidence limits of 1.0 – 1.8 mg/L.  The No Observed Effect Loading rate was 1.0 mg/L.
 - Water Solubility: slightly soluble 
 - Biodegradation in water: The test material attained 15 % degradation after 28 days and therefore cannot be considered to be readily biodegradable.

Additional information

The acute toxicity of Ethylbenzene, manuf. of, distn. residues, distn. lights. to the freshwater invertebrateDaphnia magnahas been investigated and gave a 48-Hour EL₅₀value based on nominal loading rates of 1.3 mg/L with 95% confidence limits of 1.0 – 1.8 mg/L loading rate WAF. The No Observed Effect Loading rate at 48 hours was 1.0 mg/L loading rate WAF.

In view of the difficulties associated with the evaluation of aquatic toxicity of poorly water soluble test materials, a modification of the standard method for the preparation of aqueous media was performed. An approach endorsed by several important regulatory authorities in the EU and elsewhere (ECETOC 1996, OECD 2000 and Singer et al 2000), is to expose organisms to a Water Accommodated Fraction (WAF) of the test material in cases where the test material is a complex mixture and is poorly soluble in water and in the permitted auxiliary solvents and surfactants. Using this approach, aqueous media are prepared by mixing the test material with water for a prolonged period. Pre-study work showed that a preparation period of 24 hours was sufficient to ensure equilibration between the test material and water phase. At the completion of mixing, the test material phase is separated by siphon and the test organisms exposed to the aqueous phase or WAF (which may contain dissolved test material and/or leachates from the test material). Exposures are expressed in terms of the original concentration of test material in water at the start of the mixing period (loading rate) irrespective of the actual concentration of test material in the WAF.

It is assumed that the Effective Loading rate (EL) is equivalent to the Effective Concentration (EC). According Directive 67/548/EEC, Ethylbenzene, manuf. of, distn. residues, distn. lights. should be classified as R51/53: Toxic to aquatic organisms and May cause long-term adverse effects in the aquatic environment. According to Regulation (EC) No. 1272/2008, Ethylbenzene, manuf. of, distn. residues, distn. lights. should be classified as Acute Category 2.