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PBT assessment

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PBT assessment: overall result

Reference
Name:
1112-39-6 Dimethoxydimethylsilane
Type of composition:
boundary composition of the substance
State / form:
liquid
Reference substance:
1112-39-6 Dimethoxydimethylsilane
PBT status:
the substance is not PBT / vPvB
Justification:

Persistence Assessment

Dimethoxydimethylsilane is expected to hydrolyse rapidly in contact with water to dimethylsilanediol and methanol (half-life 0.6 h at 25 °C and pH 7). Therefore, the substance is not persistent. Methanol is readily biodegradable and therefore not persistent. In contrast, dimethylsilanediol is neither readily nor inherently biodegradable. Therefore, the silanol hydrolysis product is expected to persist in the environment.

 

Bioaccumulation Assessment

Dimethoxydimethylsilane is expected to hydrolyse rapidly in contact with water to dimethylsilanediol and methanol (half-life 0.6 hours at 25 °C and pH 7). Therefore, the parent substances will not bioaccumulate.

The hydrolysis products dimethylsilanediol and methanol have low log Kow values (<3) and therefore, are not likely to bioaccumulate.

Therefore, the substance does not meet the criteria for bioaccumulation; it is not B and not vB.

 

Toxicity Assessment

Results of available long term data on the silanol hydrolysis product do not meet the definitive criteria for T for the environment (NOEC > 0.1 mg/L). In addition lowest measured E/LC50 were all >100 mg/L for the substance and its hydrolysis products. Therefore, also the screening criteria for T in the environment (E/LC50 <0.1 mg/L) is not met.

The substance is not classified for specific target organ toxicity, carcinogenicity, mutagenicity or reproductive and developmental toxicity in mammals. The criteria for “T” based on mammalian effects are therefore not met.

 

Summary and overall Conclusions on PBT or vPvB Properties

The substance is expected to hydrolyse very rapidly in the presence of water and therefore the substance does not meet the criteria for PBT or vPvB. The silanol hydrolysis product may persist in the environment but does not meet the criteria for B and T and therefore the hydrolysis product should not be concluded as PBT or vPvB.