Trichloro(vinyl)silane

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.34 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

3.4 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.034 mg/L

Assessment factor:

5 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

1.24 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.12 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.043 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

3.71 mg/kg food

Assessment factor:

90

Additional information

Due to the very rapid hydrolysis of trichloro(vinyl)silane, it is appropriate to calculate PNEC_freshwateron the basis of data for the hydrolysis product vinylsilanetriol. There are no measured data for trichloro(vinyl)silane but data can be read across from the substance trimethoxyvinylsilane (2768-02-7) which rapidly hydrolyses to the same product, vinylsilanetriol. The relevant values are:

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

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

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

The standard approach to PNEC calculation when acute data are available for three trophic levels is to apply an assessment factor of 1000 to the lowest lethal or effect concentration (E(L)C₅₀). However, this assessment factor may be reduced by up to a factor of 10 if this is justified by the available data, for example:

• Evidence from structurally similar compounds which may demonstrate that a higher or lower factor may be appropriate.
• Knowledge of the mode of action as some substances by virtue of their structure may be known to act in a non-specific manner. A lower factor may therefore be considered. Equally a known specific mode of action may lead to a higher factor (ECHA 2009).

 

Vinylsilanetriolis part of a category of organosilicon substances containing only hydrocarbon, halogen, alkoxy or silanol groups attached to the Si atom. The category has a low hazard profile and data are consistent with a simple polar narcosis mechanism. It is considered that the weight of evidence for the number of substances (ca.40 substances have reliable measured data) justifies a reduction of the assessment factor from the normal value of 1000. A value of 500 is used, to reflect the increased confidence in the individual values due to the low variability across the category.

The lowest L(E)C50 value forvinylsilanetriolis 169 mg/l for invertebrates. Therefore, PNEC_aquatic is 169/500 = 0.34 mg/l. Where releases are intermittent, it may be appropriate to reduce the assessment factor to 50.

Conclusion on classification

It is proposed that trichloro(vinyl)silane should not be classified in the EU for acute or chronic toxicity on the grounds that appropriate read-across indicates that it is not toxic at an initial loading rate of the substance of 100 mg/l. The substance hydrolyses very rapidly and the hydrolysis product has a low Log Kow.