Tris(2-methoxyethoxy)vinylsilane

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.63 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

6.3 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.063 mg/L

Assessment factor:

5 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

200 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

2.3 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.23 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.09 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

1.7 mg/kg food

Assessment factor:

300

Additional information

PNECaqua-freshwater is derived from short term aquatic toxicity data for the toxicity of tris(2-methoxyethoxy)vinylsilane to fish, invertebrates and algae. The relevant short-term values are:

Fish:LC50 (96 h): >100 mg/l

Daphnia:EC50 (48 h): 314 mg/l

Algae:EC50 (7 d): 611 mg/l

It is likely that the test organisms were predominantly exposed to the hydrolysis products of the substance, vinylsilanetriol and 2-methoxyethanol.

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).

Tris(2-methoxyethoxy)vinylsilane and vinylsilanetriolare 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. This is discussed further in PFA, 2010. The lowest L(E)C50 value for tris(2-methoxyethoxy)vinylsilane is 314 mg/l for invertebrates. Therefore, PNECaquatic is 314/500 =0.63 mg/l.

Conclusion on classification

It is proposed thattris(2-methoxyethoxy)vinylsilaneshould not be classified in the EU for acute or chronic toxicity, on the basis that available data indicates that it is not toxic at an initial loading rate of the substance of 100 mg/l. The substance hydrolyses rapidly and the log K_owof the silanol hydrolysis product is low.