Calcium tin trioxide

Endpoint summary

Description of key information

In vitro studies were performed on
- skin corrosion and irritation, with the Reconstructed Human Epidermis (RHE) Model
- eye irritation with the Bovine Cornea Opacity and permeability Assay (BCOP)
All the test are recent (2010) and were performed according to standard OECD Test Guidelines and GLP standards.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

As indicated in OECD 404 and 405 test guidelines, screening for existing data indicating irritation or corrosion potential should precede testing. Screening for skin and eye corrosion/irritation potential by Toxtree (Cramer rule) analysis was performed (see attachment), but only resulted in unknown or no classification. Literature and data on pH and buffering capacity testing are attached, demonstrating that pH in 10% suspension was 12,1-12,3 and buffering capacity was 4,48 g NaOH/100 g Calcium stannate. The conclusions are that, despite the extreme pH, the buffering capacity is too low to expect corrosive properties. Hence, in vitro testing was needed.

A key  in vitro skin corrosion   study with a three-dimensional reconstructed human epidermis (RHE) model was conducted with Calcium stannate according to GLP and the OECD 431 test guideline(Hey S., Evonik Industries, 2010).The study was considered reliable, adequate and relevant and considered as key study for skin corrosion testing.
Two RHE cultures were topically exposed to 30.8 mg (±2.3 mg) Calcium stannate. Corrosive effects were determined after 3 min and 1 h exposure by determining cell viability using the standard MTT Assay.Application of Calcium stannate resulted in a mean cell viability of 91.0 % (±9.2 %) after 3 min exposure period and 93.9 % (±14.5 %) after 1 h exposure period. It is concluded that Calcium stannate has to be predicted as non corrosive to skin.

A key   in vitro skin irritation   study with a three-dimensional reconstructed human epidermis (RHE) model was conducted with Calcium stannate according to GLP and the OECD 439 test guideline (Heisler E. , Evonik Industries,2010). Three RHE cultures were topically exposed to 61.6 mg (±4.6 mg) Calcium stannate for a 60 min (±1 min) period time. The cell viability was determined after an additional 42 h (±1 h) post incubation period. For the analysis of the tissue viability, the standard MTT Assay was used. The viability of the negative control was set to 100%. The acceptance criteria for the study with negative and positive controls were met and the study was considered reliable, adequate and relevant. Application of Calcium stannate resulted in a mean cell viability of approximately 66 % after 60 min (±1 min) exposure. It is concluded that Calcium stannate has to be predicted as not irritating to skin according to the OECD Test Guideline 439.

A key   in vitro study for eye irritation   was conducted with Calcium stannate according to GLP and the OECD 437 test guideline (Bovine Cornea Opacity and permeability Assay (BCOP) (Heppenheimer A., 2010). The background opacity of fresh bovine corneas (t0) was determined, followed by application of a 20% (w/v) Calcium stannate to corneas incubated for 240 minutes at 32±1°C. After the incubation phase, Calcium stannate was rinsed from the corneas and opacity was measured again (t240). Thereafter, the permeability of the corneas was determined while application of 1 mL of sodium fluorescein for 90 minutes at 32±1°C. The acceptance criteria for the study with negative and positive controls were met and the study was considered reliable, adequate and relevant. Calcium stannate did not cause opacity of the corneas compared with the results of the negative control, but increased the permeability of the corneas. The calculation mean in vitro score was 18.75. According to the criteria mentioned in the report, Calcium stannate was considered as a mild irritant. According to OECD 437, Calcium stannate is considered as not corrosive or severe eye irritating. On the SDS it should be mentioned that Calcium stannate is mildly irritating to eyes based on the precautionary principle.

Effects on eye irritation: slightly irritating

Justification for classification or non-classification

Calcium tin trioxide does not fulfill the classification criteria for skin corrosion or irritation, based on negative results in studies with a three-dimensional reconstructed human epidermis (RHE) model.

Calcium tin trioxide does not fulfill the classification criteria for eye corrosion or severe eye irritation, based on negative results in the BCOP test.

Calcium tin trioxide is inconclusive on non classification for eye irritation because negative results in the BCOP test are not conclusive for a non classification; for a final conclusion in vivo testing is needed but this is not required in REACH for this kind of dossier.