Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The following data are available describing the short-term toxicity of the registration substance to marine organisms:

  • Fish: A 96-h LL50 value of >1000 mg/l and NOELR of 560 mg/l have been determined for effects on mortality of Cyprinodon variegatus.
  • Invertebrates: A 48-h LL50 value of 272 mg/l and NOELR of 100 mg/l have been determined for effects on mobility of Acartia tonsa.
  • Algae: A 70.5-hour EL50 of >988 mg/l and NOELR of ≥988 mg/l have been determined for effects on growth of Skeletonema costatum.

These values are all well above the water solubility limit of Vi4 -D4 (0.0073 – 0.0088 mg/l at 23°C). However, the results as reported do provide strong evidence of the absence of short-term toxicity at the solubility limit of the substance.

Data for short-term toxicity to fish, invertebrates and algae have been read-across from trimethox(vinyl)silane (CAS 2768-02-7), which also contains a vinyl side chain. L(E)C50 values are reported in the range of >89 -191 mg/l, indicating that the side chain is not contributing significant short-term toxicity to the substance. It is therefore also unlikely to contribute significant toxicity to this substance.

A 14 -day NOEC of 0.0044 mg/l has also been determined for effects of the structurally-analogous read-across substance, octamethylcyclotetrasiloxane (D4, CAS 556-67-2) on mortality of the freshwater fish, Oncorhynchus mykiss.

There are no long-term toxicity data for fish and invertebrates for the registration substance. However, the following data are available for D4:

  • A 93-day NOEC of ≥0.0044 mg/l has been determined for the effects of the substance on embryo viability, hatching success, larval survival and growth of early life stages of Oncorhynchus mykiss.
  • A 21-day NOEC of 0.0079 mg/L has been determined for the effects of the test substance on survival and reproduction of Daphnia magna.

Reliable long-term ecotoxicity conclusions are read across from a structural analogue of higher water solubility (see above). These long-term no observed effect concentrations for aquatic organisms are very close to the limit of water solubility for the registration substance, and it is not possible to conclude with confidence whether the NOECs will be above or below the limit of solubility for the registration substance. Therefore, toxicity may or may not be expressed in long-term studies for the registration substance. This is key for concluding on classification and labelling; therefore, testing proposals are put forward. However, the assumption that toxicity would be expressed and the use of the read-across NOECs for PNEC derivation and risk characterisation is a worst-case and the read-across is sufficient for the chemical safety assessment.

An activated sludge respiration inhibition 3hr EC50 value of >1000 mg/l and NOEC value of ≥1000 mg/l (nominal) were determined in a reliable study.  

Refer to IUCLID Section 6 endpoint summary (CSR Section 7.0) for further discussion of the approach to chemical safety assessment and justification for read across.