Silicon dioxide

Endpoint summary

Description of key information

For the assessment of skin sensitisation of untreated SAS, a weight of evidence approach was used compiling data from repeated dose toxicity via the dermal route, absence of reported skin sensitization case during the past 20 years associated to monitoring of workers health and the use of this form of the substance in cosmetics products as reviewed by the Cosmetics Ingredients Review. Based on the long history of use and the absence of reported cases in humans and some studies, the generation of new data appears not required and no classification is warranted.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

In accordance with section 1.2 of REACH Annex XI, the available information for skin sensitization toxicity of unsurfaced treated synthetic amorphous silica was assessed in a “Weigh-of-Evidence” approach to identify potential concerns. In the case of untreated SAS adequate information is available in more than one study and therefore we applied a WoE based on the following data:
- Repeated dose toxicity : dermal exposure in vivo study
- Monitoring of workers in Germany exposed to SAS and the absence of reported case of skin sensitization.
- Long track record of use of untreated SAS in cosmetics products, including creams without reported case of sensitization.
- Several published studies were summarized in the last submission to the Cosmetics Ingredient Review Expert Panel Members, all the available sources showed no skin sensitization potential with studies on non-surface treated SAS at concentration ranging from 21 up to 45%
In a limited 3-week study from 1958, no systemic toxicity and no gross pathological or microscopic change was reported. No sign of sensitization was described in this study.
Additionally a study performed by Du Pont de Nemours from 1970 using patches has also been reviewed by the panel with the following summary reported:
Patches were applied for six days to the arms of 10 men and the arms or legs of 10 women. After a two-week interval, new patches were applied for 48 hours as a challenge test. Skin under the patches was examined at one, two, three and six days after the first application and on removal of the challenge patch. No skin reactions were seen at any examination on any subject.
Altogether, none of these studies showed any potential for skin sensitization of non-surface treated Silica. Additionally, and an additional source of information the Informationsverbund Dermatologischer Kliniken (Information Network of Departments of Dermatology) which is a network funded in 1988 of currently 58 dermatological departments in Germany, Switzerland and Austria prepared and extensive literature search on their internal database which is composed of datasets of about 285 000 patients. This research only highlighted two “potential” cases which could not be directly convincingly linked to untreated Synthetic Amorphous Silica as reported in the statement attached to this entry. This is also consistent with the long history of use of untreated SAS in cosmetics products like creams without reported case of sensitization to the substance which was also confirmed by reports published in the Cosmetics Ingredient review report where Hydrated Silica (up to 45%) and in formulation at 21.74% were not sensitizing in human repeat insult patch tests (HRIPT) or in guinea pig sensitization tests.
As an additional source of information, this conclusion is also supported by the absence of positive skin sensitization in the 7 studies performed on silanized SAS test materials.

Reference 1:
W.R. Grace & Co. 1981. Supplement to GRAS affirmation petition No. 1G0270: Silica gel for use as a carrier for flavors.
Reference 2:
1984. Safety data of hydrated silica - contact allergenicity (Translated into English in 2009). 5 pages
Reference 3:
KGL, Inc. 2003. An evaluation of the contact-sensitization potential of a topical coded product (facial mask containing 17% Hydrated Silica) in human skin by means of the maximization assay. KGL Protocol #5384. Unpublished data submitted by the Council June 3, 2009. 12 pages.
Reference 4:
KGL, Inc. 2004. An evaluation of the contact-sensitization potential of a topical coded product (face powder containing 21.7436% Silica) in human skin by means of the maximization assay. KGL Protocol #5632. Unpublished data submitted by the Council June 3, 2009. 12 pages.
Reference 5:
E. I. du Pont de Nemours and Company, Inc., unpublished, Report No.: 484-70 (1970)

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 2

Endpoint:

skin sensitisation: in vitro

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Justification for classification or non-classification

No skin sensitization potential was identified for the different forms of the test material in the studies that are published and case have been reported during the long track record of workers or consumers exposed to untreated synthetic amorphous silica. According to Annex I of the Regulation (EC) 1272/2008 and GHS (Globally Harmonized Classification System), the test substance therefore requires no classification and has no mandatory label requirement