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 four species representing three taxonomic groups and two trophic levels (decomposers and consumers): earthworms, springtails, plants and soil microorganisms

 

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.

In addition, a soil microorganism toxicity test in accordance with OECD TG 216 nitrogen transformation test has been conducted with D5 (Smithers Viscient, 2019).

No effects at the highest test concentration were observed. A 28-day EC10 value of >100 mg/kg dry weight based on nitrogen transformation rate was determined.

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.