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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Persistence:

Dimethoxymethylsilane (CAS 16881 -77-9) is expected to hydrolyse rapidly in contact with water to methylsilanetriol (half-life approximately 0.3 h at 20-25°C and pH 7, see Section 4.1.1.1). Therefore, the substance is not persistent. A reliable ready biodegradation study is available for a structurally-analogous substance, which indicates that no significant biodegradationis is expected for the silanol hydrolysis product. Therefore, this hydrolysis product meets the criteria for persistence (P). Methanol is readily biodegradable and not persistent.

 

Bioaccumulation:

Dimethoxymethylsilane is expected to hydrolyse rapidly in contact with water to methylsilanetriol (half-life approximately 0.3 hours at 20-25°C and pH 7, see Section 4.1.1.1). Therefore, the parent substance will not bioaccumulate. The hydrolysis products methylsilanetriol 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 and is not B and not vB.

Toxicity: 

Due to the very rapid rate of hydrolysis, it was more appropriate to assess the toxicity of the hydrolysis products. The substance is not considered as T for the environment since based on read across data fro the hydrolysis product dimethylsilanediol the lowest measured EC50 value of > 100 mg/L and the lowest predicted EC50 of 2115 mg/L for the hydrolysis product methylsilanetriol do not meet the screening criteria for T for the environment (EC/LC50 <0.1 mg/L).

The substance is not classified for specific target organ toxicity, carcinogenicity, mutagenicity or reproductive and developmental toxicity in mammals (see Section 5.9). The criteria for “T” based on mammalian effects are therefore not met.