Trichloro(ethyl)silane

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.2 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1.7 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.02 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.74 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.074 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

equilibrium partitioning method

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.032 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Additional information

Short-term ecotoxicity data for three trophic levels can be read-across from trimethoxyvinylsilane. This substance hydrolyses rapidly to vinylsilanetriol, which is a close structural analogue of the hydrolysis product of the trichloro(ethyl)silane, ethylsilanetriol. The test organisms in each test with trimethoxyvinylsilane were primarily exposed to the hydrolysis product vinylsilanetriol. The rapid hydrolysis of trichloro(ethyl)silane means it is appropriate to calculate a PNECfreshwater on the basis of data for this hydrolysis product. The relevant short-term values are:

Fish:LC50 (96 h): 191 mg/l

Daphnia:EC50 (48 h): 169 mg/l

Algae:EC50 (7 d): 210 mg/l

In addition, a 21-day NOEC value of ≥100 mg/L has been determined for the effects of trichloro(ethyl)silane on survival and reproduction ofDaphnia magnawhen expressed in terms of nominal concentrations. When expressed in terms of mean measured TOC concentration in the test medium the NOEC was ≥10 mg/L. A NOEC of 25 mg/l was determined in the algal test for trimethoxyvinylsilane. It is again likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

The standard approach to PNEC calculation when long-term data are available for two trophic levels, including that which was found to be most sensitive in the short term tests, is to apply an assessment factor of 50 to the NOEC.

Therefore, PNECaquatic is≥10/50 =≥0.2mg/l.

Conclusion on classification

It is proposed that the substance should not be classified in the EU for the environmental because reliable data for a suitable read-across substance indicate that the substance is not toxic at a loading rate of 100 mg/l. The substance hydrolyses rapidly and the silanol hydrolysis product has a low log Kow.