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Administrative data

Key value for chemical safety assessment

Additional information

The tested synthetic amorphous silicas showed no mutagenic or clastogenic activity in standard test systems under valid test conditions. In one non-standard test, the mutagenic potential was investigated following inhalation exposure to rats, as inhalation has to be considered to be the exposure route of highest toxicological significance for humans. For that purpose, the test design had to be modified and adjusted such as to meet relevant physiological needs: Therefore, the target cells were isolated after in-vivo exposure and cultivated ex vivo. Selection of possible mutants followed the standard method of the HPRT assay (see for details under 7.6.2: Johnston et al. 2000). This study gave no evidence of a mutagenic potential for Aerosil 200 when inhaled at a high exposure concentration of 50 mg/m3for 13 weeks.

Read-across based on the fact that synthetic magnesium silicate and silicon dioxide have similar basic physicochemical properties and are highly stable, inert substances can justify the use of silicon dioxide data in this endpoint. In addition, it will eliminate the need for further vertebrate studies that are unwarranted on ethical and animal welfare grounds.

Overview of the most relevant studies

      Test                  

      Test system

Substance/ Result

Reference

         In-Vitro Assays

Ames

S. typh. (strains TA98, TA100, TA1535, TA1537, TA 1538)

Cab-O-Sil EH5 (pyrogenic): negative with and without metabolic activation

San and Springfield 1989
(Microbiol. Associates)

Ames

S. typh. TA 98, TA 100, TA 1535, TA 1537, TA 1538, E. coli WP 2

Silcron (silica gel):

negative with and without metabolic

Mortelmans and Griffin 1981

Gene mutations (mammalian cell)

Chinese hamster ovary cells  / HGPRT assay

Cab-O-Sil EH5 (pyrogenic): negative with and without metabolic activation

Sigler and Harbell 1990 (Microbiol. Associates)

Chromosomal

aberrations

Chinese hamster ovary cells /  cytogenetic assay

Cab-O-Sil EH5 (pyrogenic): negative with and without metabolic activation

Putman and Morris 1990 (Microbiol. Associates)

Chromosomal

aberrations

Human embryonic lung cells (WI-38) / cytogenetic assay

Syloid 244 (silica gel):

negative
without metabolic activation

Litton Bionetics, Inc. 1974

Short description of key information:

The REACH data profile for this endpoint has been covered for synthetic amorphous silica:

Result: not mutagenic and not clastogenic in three valid in-vitro tests

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on experimental evidence, no classification for genotoxic potential is required under DPD (Directive 67/548/EEC) or CLP/GHS (Regulation 1272/2008) legislation.