Triethoxy(vinyl)silane

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.4 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1.21 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.04 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

PNEC marine water (intermittent releases):

1.21 mg/L

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

1.5 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.15 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.06 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Conclusion on classification

Key parameters for classification:

The registered (parent) substance triethoxy(vinyl)silane (CAS No. 78 -08 -0) hydrolyses rapidly in contact with water under environmentally relevant conditions (DT50 = 0.9 h at 20 -25 °C and pH 7, QSAR). Therefore, the environmental hazard and risk assessment is based on the silanol hydrolysis product, i.e. vinylsilanetriol. The other hydrolysis product, i.e. ethanol, is assumed to have a negligible impact on the environmental hazard profile of the parent substance based on a low environmental hazard profile for ethanol itself (OECD SIDS, 2004a). As there is no data available for the registered substance or its silanol hydrolysis product, a read across to the analogue substance trimethoxy(vinyl)silane (CAS 2768-02-7) has been applied to support the environmental hazard assessment of triethoxy(vinyl)silane (CAS 78 -08 -0). The read across source substance trimethoxy(vinyl)silane (CAS 2768-02-7) also rapidly hydrolyses in the aquatic environment (DT50 = 0.1 h at 20 -25 °C and pH 7, QSAR) to form the same silanol hydrolysis product as the target substance, vinylsilanetriol; the other hydrolysis products being methanol instead of ethanol, which is readily biodegradable and has an overall low environmental hazard profile (OECD SIDS 2004b).

 

Abiotic degradation – Hydrolysis

DT50 = 0.9 h (20-25 °C and pH 7, QSAR)

 

Biodegradation in water, sediment, and soil

Not readily biodegradable; 51% biodegradation within 28 days (OECD 301 F, RA CAS No. 2768-02-7)

 

Bioaccumulation

Log Kow (parent): 3.0 (QSAR)

Log Kow (silanol hydrolysis product): -2.0 (QSAR)

 

Aquatic acute toxicity

Fish

LC50 (96 h) > 92.2 mg/l (meas., TWA, Danio rerio, OECD 203, RA CAS No. 2768-02 -7)

Aquatic invertebrates

EC50 (96 h) = 168.7 mg/l (nominal, Daphnia magna, EU Method C.2, RA CAS No. 2768-02 -7)

Algae

ErC50 (72 h) > 89 mg/l (meas., TWA, Pseudokirchneriella subcapitata, Circular on Test Methods of New Chemical Substances (Japan), RA CAS No. 2768-02 -7)

 

Aquatic chronic toxicity

Aquatic invertebrates

NOEC (21 d) = 28.1 mg/l (meas.TWA, Daphnia magna, OECD 211, RA CAS No. 2768-02 -7)

Algae

NOErC (72 h) ≥ 89 mg/l (meas., TWA, Pseudokirchneriella subcapitata, Circular on Test Methods of New Chemical Substances (Japan), RA CAS No. 2768-02 -7)

 

Classification assigned according to GLP

Triethoxy(vinyl)silane is expected to hydrolyse rapidly under environmental conditions (DT50 = 0.9 h at 20-25°C and pH 7) to form the hydrolysis products vinylsilanetriol and ethanol. The silanol hydrolysis product is not considered to be readily biodegradable, while the second hydrolysis product ethanol is readily biodegradable (OECD SIDS, 2004a). Due to a low log Kow of the silanol hydrolysis product, a low potential for bioaccumulation is expected. As there is no data available for the registered substance on the toxicity towards aquatic organisms, good quality data has been read across from a structural analogue substance, trimethoxy(vinyl)silane (CAS 2768-02-7). The source substance hydrolyses rapidly under environmental conditions (DT50 = 0.1 h at 20-25 °C and pH 7) to form the same silanol hydrolysis product, vinylsilanetriol, as the target substance and a second hydrolysis product, methanol. Both alcohol hydrolysis products of target and source substance, ethanol and methanol, respectively, are not expected to be hazardous at concentrations relevant to aquatic toxicity studies (OECD SIDS, 2004a; OECD SIDS, 2004b). Acute aquatic toxicity data for the source substance trimethoxy(vinyl)silane are available for all three trophic levels (fish, aquatic invertebrates, algae). No effects on aquatic organisms were recorded in the available studies, all LC/EC50 effect values are >100 mg/L. Chronic aquatic toxicity studies are available for two trophic levels (aquatic invertebrates and algae). Only moderate effects were observed in daphnids (21-day NOEC = 28.1 mg/L, equivalent to 20 mg/L vinylsilanetriol) and no effects were observed in algae up to the highest concentrations tested (NOErC (96-h) ≥ 89 mg/L. On this basis, the parent substance triethoxy(vinyl)silane (CAS No. 78-08-0) does not need to be classified and labeled according to the consolidated version of Regulation (EC) No 1272/2008 including all further amendments (ATPs).

 

References:

OECD SIDS, 2004a. Ethanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.

OECD SIDS, 2004b. Methanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.