Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Testing for toxicity to terrestrial organisms has been carried out with species that are representative of three taxonomic groups; earthworms, springtails and plants.

A 28-day LC50 value of >4074 mg/kg dry weight and a 56-day NOEC of ≥4074 mg/kg dry weight have been determined for the effects of the test substance on mortality, and on reproduction and growth, respectively of the earthworm, Eisenia andrei.

A 28-day LC50 value of 813 mg/kg dry weight and a 28 -day IC50 value of 767 mg/kg dry weight have been determined for the effects of the test substance on mortality and reproduction of the springtail, Folsomia candida. A NOEC of 377 mg/kg dry weight has been determined by the reviewer on the basis of a visual examination of the data for both mortality and reproduction.

A 14-day IC50 value of 209 mg/kg dry weight has been determined for the effects of the test substance on root dry mass of Barley, Hordeum vulgare. IC50/EC50 values for effects on seedling emergence, root and shoot length and shoot dry mass determined in the same test were ≥248 mg/kg dry weight. 14-day EC50 values of >4054 mg/kg dry weight have been determined for the effects of the test substance on seedling emergence, root and shoot length and root and shoot dry mass of Red Clover, Trifolium pratense. NOECs were not determined in the tests.

The D5 terrestrial studies are considered to be non-standard. They have been conducted by spiking surrogate biosolids mixed into natural soil rather than by direct spiking of soil. However, the studies are considered to be suitable to derive a hazard and risk assessment under REACH.

Terrestrial studies with siloxanes are considered to be difficult to conduct due to their high volatilisation potential (high HLC) and the potential for degradation in soil. Decamethylcyclopentasiloxane (D5, CAS 541-02-6) is the only substance with terrestrial toxicity data from which it has been possible to derive a PNEC. An OECD TG 222 study on the earthworm Eisenia andrei, (and a pre-test on stability under OECD 222 conditions) has more recently been conducted with D5 (Smithers Viscient, 2015). No effects were observed.

Effects on soil microorganisms are not anticipated. In aquatic toxicity testing, activated sludge (sewage treatment plant microorganisms) do not appear to be affected by siloxanes. However, a nitrogen transformation test (OECD TG 216) is contracted and will be carried out in accordance with ECHA decision number TPE-D-2114422497-46-01/F. Testing has been delayed due to difficulties in obtaining radiolabelled test material.The result of the study is expected by July 2019 and it is anticipated that a further dossier update will be submitted by October 2019.

Long-term toxicity with terrestrial plant studies have not been carried out as the chemical safety assessment according to Annex I indicate that this is not necessary.