N-[3-(trimethoxysilyl)propyl]butylamine

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Data waiving:

exposure considerations

Justification for data waiving:

other:

Description of key information

A long-term toxicity study on fish is not necessary as

- exposure considerations in accordance with Annex XI, Section 3, indicate that exposure of aquatic organisms to N-[3-(Trimethoxysilyl)propyl]-1-butanamine is absent or not significant

and

- the substance has a low hazard potential based on the available toxicity data.

Additional information

In accordance with Annex XI, Section 3, exposure of aquatic organisms to N-[3-(Trimethoxysilyl)propyl]-1-butanamine(CAS No. 31024-56-3) is absent or not significant. 

The environmental hazard assessment, PNEC derivation and risk characterization is based on the silanol hydrolysis product, 3-(N-butylamino)propylsilanetriol, as the substance is expected to hydrolyse rapidly under environmental conditions (DT50 = 4.0 h at pH 7 and 20-25 °C). The other hydrolysis product, methanol, is known for its absence of environmental toxicity at levels up to the highest tested concentrations (OECD SIDS, 2004), and thus not relevant for the assessment of aquatic toxicity.

Short-term aquatic toxicity data is available for all three trophic levels (fish, algae, aquatic invertebrates) on the registered compound. The hazard assessment showed no short-term aquatic hazard to all three trophic levels (all acute effect values > 1 mg/L). However, the tested concentrations were well below the predicted solubility of the substance (1.3E+04 mg/L) and therefore does not provide an accurate representation of the likely toxicity of the substance. Thus, it was considered appropriate to read across from the structurally analogue substance N-ethyl-3-trimethoxysilyl-2-methylpropanamine (CAS No. 227085-51-0). The source substance is also expected to hydrolyse rapidly in the aquatic environment (DT50 = 4.7 h at pH 7 and 20-25 °C, QSAR) to form a structurally similar silanol hydrolysis product, N-ethyl-3-trihydroxysilyl-2-methylpropanamine, and the common alcohol hydrolysis product methanol. Short-term aquatic toxicity data is available for all three trophic levels. No short-term toxicity effects up to the highest concentrations tested were observed in any of the three organism groups (EC/LC50 > 100 mg/L, equivalent to > 81 based on molecular weight corrections). However, for the purpose of exposure-based adaptation as in the present endpoint, PNECs were derived in the Chemical Safety Report (CSR, Chapters 9 and 10) for the required risk characterization even though no hazard was identified in the available aquatic toxicity studies. The PNECs aqua (freshwater/marine water) were derived using a worst-case threshold value of 100 mg/L (equivalent to 81 mg/L based on molecular weight corrections) in combination with the standard assessment factors of 1000 and 10000, respectively, as outlined in ECHA guidance R.10 (2008).

Taking into consideration the fast hydrolysis time of the source compound, the study design (static), and the duration of the acute toxicity tests (48 to 96 h), it can be assumed that the organisms were predominantly exposed to the hydrolysis products. The registered compound and its silanol hydrolysis product are well soluble. Significant deviations from this overall ecotoxicity profile are not expected and greater long-term toxicity in an additional test with fish is considered unlikely.

The risk characterization for the silanol hydrolysis product of the registered compound indicated no risk to the aquatic environment (RCR < 1).

For detailed information on the risk assessment please refer to the attached documentation in Section 13.

 

References:

OECD, 2004: SIDS Initial Assessment Report for Methanol, SIAM 19, Berlin, Germany, 19-22 October 2004, Methanol, CAS 67-56-1