Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

While animal studies on skin sensitisation for silicic acid, lithium salt are lacking, reliable data for different structurally analogue test substances are available for assessment.

Silicic acid, lithium salt contains depending on its molar ratio 3.4 - 7% lithium (MR: 2.8 - 6.3). No sensitising potential have been reported for lithium for more than 50 years, in which lithium has been used therapeutically.

The dermal sensitisation potential of the read-across substance AgSil™ 25 Potassium Silicate Solution (active ingredient: 30%)

was determined in a Buehler test according to U.S. EPA Health Effect Test Guideline OPPTS 870.2600 (Durando, 2004). The undiluted test substance was topically applied to 20 guinea pigs, once a week for a three-week induction period. On day 28 the test animals as well as ten naïve control rabbits were treated with a 75% (w/w) challenge dose. Very faint erythema, which was not considered a positive reaction, was observed in some animals (test group: 8/20; naïve control group: 4/10) when examined 24 hours after the challenge application. Similar irritation persisted in one test animal through 48 hours, the naïve control animals were free of irritation by 48 hours after challenge application. Thus, based on the test results, the potassium silicate solution were not considered to be a skin sensitiser.

 

A local lymph node assay according to OECD Guideline 429 was conducted to determine the skin sensitisation potential of the read-across substance disodium metasilicate (Karrow et al., 2002). No significant effect on cell proliferation in the auricular lymph nodes was detected in female mice after treatment with 2, 4 and 6% test substance for 3 consecutive days.

 

In conclusion, based on the skin sensitisation tests performed on the read-across substances AgSil™ 25 Potassium Silicate Solution and disodium metasilicate and the many years of experience of lithium in bipolar disorder therapy, in which no sensitising potential for lithium have been noted, silicic acid, lithium salt is not considered to be a skin sensitiser.


Migrated from Short description of key information:
skin sensitisation (EPA OPPTS 870.2600, Bühler test): not sensitising (RA from AgSil™ 25 Potassium Silicate Solution)

Justification for classification or non-classification

Based on available data on skin sensitisation from read-across substances, silicic acid, lithium salt does not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC.