Bureau REACH conducted a substance evaluation for synthetic amorphous silica dioxide. This substance is registered in various forms.
These forms vary greatly in physical and chemical properties. There was insufficient data available to assess the safe use of all forms of this substance. Another concern was that the substance consists of nanoparticles, the effects of which are not well understood.
Therefore, Bureau REACH requested additional inhalation studies from the REACH registrant. In these studies, rats were repeatedly exposed to multiple forms of synthetic amorphous silica dioxide. The test results showed that inhalation of synthetic amorphous silica dioxide particles causes severe lung effects at concentrations that require classification.
However, the REACH registrants do not provide this classification for synthetic amorphous silica dioxide. As a result, users do not receive warnings for these effects via the label or safety data sheet. Therefore, in 2023, Bureau REACH prepared and submitted a proposal for harmonized classification. The proposal concerns the classification of synthetic amorphous silica dioxide for specific target organ toxicity category 1 (STOT RE 1).