Dimethyl itaconate

Endpoint summary

Additional information

The testing program performed to assess the aquatic toxicity of the submission item deviated from the usual standard representative organisms in that duckweed was investigated instead of algae. Higher plants are not the standard test organisms for the trophic level of producers and generally protozoans are preferred. Nonetheless the choice of duckweed was required as literature data indicated significant effects of the submission item to the photosynthesis apparatus of higher (terrestrial) plants as shown in the experiments of Jordanov & Karanov (1977), Karanov, Vasilev & Pogoncheva (1975) an Karanov, Vasilev & Hristova (1975). These results are reported in section on toxicity to terrestrial plants.

Short-term toxicity

Regarding short-term toxicity the trophic level of producers can be assessed by the EC50 from the duckweed growth inhibition test (OECD TG 221, 2006), which is 45 mg/L. For the primary consumer level, pre-test data from the daphnid reproduction test (OECD TG 211, 2008) allow to approximate the LC50 to 27 mg/L. The fish embryo acute LC50 was 3.2 mg/L (OECD TG 236, 2013) indicating that the secondary consumers are most sensitive for intermittent releases. None of the short-term toxicity tests indicated L(E)C50 levels of 1 mg/L or below.

Long-term toxicity

For the submission item two long-term results (i.e. EC10) from species representing two trophic levels (producers and primary consumers) exist, which were derived from relevant, adequate, valid and thus conclusive guideline studies under GLP conditions. These are a duckweed (Lemna minor) growth inhibition test according to OECD TG 221 (2006) and a daphnid reproduction test according to OECD TG 211 (2008). These studies resulted in EC10 threshold levels of 15 mg/L for duckweed and 1.3 mg/L for daphnids.

In agreement with animal welfare legislation as expressed in the decision scheme for the conclusion on chemical safety assessment (PNEC Derivation), presented in Figure R.7.8-4 of the ECHA endpoint specific guidance R.7b (2014, p 57), no test using vertebrate fish was performed as with OECD TG 236 (2013) an alternative method was available. In this fish embryo acute toxicity (FET) test, zebra fish (Danio rerio) embryos served as test organisms. This study delivered the NOEC of 1.5 mg/L.

Using the data of these three tests the hazard assessment was performed using the lowest threshold concentration, i.e. the EC10 of the daphnid reproduction test of 1.3 mg/L, as point of departure. The submission item has no PBT or vPvB properties due to the low lipophilicity (Log Kow 0.9) and the experimental ready biodegradability and does not require environmental classification. As the risk is controlled no further testing was deemed necessary.

In the long-term studies the aquatic invertebrates, representing the trophic level of primary consumers (Daphnia magna), were clearly more sensitive than the aquatic plants, which represent the trophic level of producers. The short-term fish toxicity NOEC is only slightly higher than the long-term daphnid EC10. Therefore it cannot be finally concluded whether fish or aquatic invertebrates were most sensitive to the submission item. Due to animal welfare considerations long-term testing in fish is not supported, as risk control is demonstrated however an increased assessment factor applies due to the absence of the third long-term testing result.

• ECHA R.7b: European Chemicals Agency (2014). Guidance on information requirements and chemical safety assessment. Chapter R.7b: Endpoint specific guidance. Version 2.0., Document Reference ECHA-14-G-05-EN, ISBN 978-92-9244-759-5. Self-published, Helsinki, Finland, in November. 256 p.