2-ethylhexyl methacrylate

Short-term toxicity to aquatic invertebrates

Description of key information

WoE evaluation based on two valid acute studies with Daphnia magna (MoE, 1998) and (Safepharm 1995): 48 h-EC50 = 2.18 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

2.18 mg/L

Additional information

Acute toxicity data of the substance to daphnia are available from four different test reports, 2 acute guideline studies with Daphnia magna and 48 h toxicity data from two chronic invertebrate studies. The two acute studies have deficiencies because of the use of /solvent/dispersant in order to overcome the limited solubility of the test material. In addition, the two results are not very consistent.

In the first one (MoE 1998) several of the concentrations tested were above the solubility limit in pure water, and the obtained EC50-48h is about 5.6 mg/L. In the second one (Safepharm 1995), a solvent (DMF) was used to help to dissolve the substance in the medium. Although use of solvent is not encouraged, DMF is among those listed in the OECD "Guidance document on aquatic toxicity testing of difficult substances and mixtures" (OECD, 2000). The EC50 -48h in this study was 0.85 mg/L.

As the two results are not very consistent, further information can be drawn from the two chronic studies in order to gain more confidence in the evaluation. In both studies the toxicity of 2-EHMA to the parental Daphnia was monitored. In one reproduction toxicity test (Fraunhofer 2004, see section 6.1.4) there was no toxicity to parental daphnia after 48 h of exposure up to the highest test concentration of 2.75 mg/L. At the same concentration 80 % of the parental daphnids were immobilised after 72h. This is consistent with the results of the other Daphnia reproduction study where no immobilisation was observed after 48 h at 2.2 mg/L (nominal/1.51 mg/L(measured) while 40 % immobilisation of the parental daphnids were observed at 5 mg/L (nominal) /3.82 mg/L(measured). The results of these two tests are consistent and indicate that the 48h-EC50 is more likely in a range between 2 and 3 mg/L. Therefore, the geometric mean of the two acute studies is used as the relevant parameter for the assessment: 2.18 mg/L.

There are no data on the toxicity of 2-EHMA to marine invertebrates, but studies with the common metabolite of the category, methacrylic acid, indicate that marine species are not expected to be more sensitive to methacrylates than freshwater species (Sverdrup, 2001).