Zinc sulphide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Test substance	Method	Results	Remarks	Reference
Zinc sulphate	Mouselocal lymph node assay	Negative	2 (reliable with restrictions) key study	Ikarashi Y, Tsuchiya T and Nakamura A (1992)
Zinc sulphate	Guinea pig (Dunkin-Hartley) female Guinea pig maximization test	Negative	2 (reliable with restrictions) supporting study used in RAR, (EU 2004 e)	Van Huygevoort (1999 i)
Zinc oxide	Guinea pig maximization test	Negative	1 (reliable without restriction) key study used in RAR, (EU 2004 b)	Van Huygevoort AHBM (1999 g)
Zinc oxide	Guinea pig maximization test	Ambiguous	1 (reliable without restriction) key study	Van Huygevoort AHBM (1999h1) Van Huygevoort AHBM (1999h2)

Zinc sulphate (ZnSO₄•7 H₂O) was tested in a mouse local lymph node assay (Ikarashiet al., 1992), according to the testing methods developed by Kimberet al.,(1989 and 1990). After gentle dermal abrasion, 25ml of a 5% zinc sulphate solution in 20% ethanol was applied for three consecutive days at the dorsal side of both ears of 3 Balb/c mice. On the fourth day the animals were sacrificed and the ear-draining lymph nodes were collected. Lymph node lymphocyte proliferation was determined by tritiated thymidin incorporation. The results were compared to those of vehicle-treated controls. Zinc sulphate did not induce proliferative activity, whereas for potassium bichromate, nickel sulphate and cobalt chloride (known dermal sensitizers) positive results were obtained.

The skin sensitising potential of zinc sulphate (ZnSO₄•7 H₂O) was also investigated in guinea pigs. A well-performed maximisation test, conducted according to Directive 96/54/EC B.6 and OECD guideline 406, was carried out in female Dunkin Hartley guinea pigs. Based on the results of a preliminary study, in the main study 10 experimental animals were intradermally injected with a 0.1% concentration and epidermally exposed to a 50% concentration. Five control animals were similarly treated, but with vehicle (water) alone. Approximately 24 hours before the epidermal induction exposure all animals were treated with 10% SDS. Two weeks after the epidermal application all animals were challenged with a 50% test substance concentration and the vehicle. A second challenge followed one week after the first. In response to the 50% test substance concentration, in some experimental animals and controls skin reactions of grade 1 were observed 48 hours after the first (5/10 and 2/5, respectively) and the second challenge (4/10 and 2/5, respectively). As the skin reactions were comparable among the experimental and control animals, and as there was poor consistency of the skin reactions among individual experimental animals after the first and second challenge, the observed skin reactions can be considered to be non-specific signs of irritation. Hence, it can be concluded that zinc sulphate did not induce hypersensitivity in experimental animals (Van Huygevoort, 1999i).

The skin sensitising potential of zinc oxide (purity 99.69%) was investigated in female Dunkin Hartley guinea pigs in two well-performed maximisation tests, conducted according to Directive 96/54/EC B.6 and OECD guideline 406. Based on the results of a preliminary study, in the main studies experimental animals (10 in each test) were intradermally injected with a 20% concentration and epidermally exposed to a 50% concentration (i.e. the highest practically feasible concentration). Control animals (5 in each test) were similarly treated, but with vehicle (water) alone. Approximately 24 hours before the epidermal induction exposure all animals were treated with 10% SDS. Two weeks after the epidermal application all animals were challenged with a 50% test substance concentration and the vehicle. In the first study, in response to the 50% test substance concentration skin reactions of grade 1 were observed in 4/10 experimental animals 24 hours after the challenge (40% sensitisation rate), while no skin reactions were evident in the controls. In contrast, in the second study no skin reactions were evident in the experimental animals (0% sensitisation rate), while a skin reaction grade 1 was seen in one control animal. The skin reaction observed in one control animal is probably a sign of non specific irritation (Van Huygevoort, 1999h1, 1999h2).

In a third well-performed maximisation test, conducted according to the same guidelines and with the same experimental design, another analytical grade zinc oxide was tested (Zincweiß Pharma A; purity 99.9%). The only difference with the studies described above was the intradermal induction concentration, which was 2% as for Zincweiß Pharma A this was considered the highest concentration that could reproducibly be injected. In this test no skin reactions were evident in both experimental and control animals, hence a 0% sensitisation rate for Zincweiß Pharma A. White staining of the treated skin by the test substance was observed in some animals 24 and 48 hours after challenge (Van Huygevoort, 1999g).

Migrated from Short description of key information:
All available data suggests this compound does not have skin sensitisation potential.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Considering the absence of evidence of respiratory sensitization responses in, this endpoint is not expected to be of concern for zinc and zinc compounds.

Migrated from Short description of key information:
While is no particular study addressing respiratory sensitisation in experimental animals, there is no information suggesting zinc compounds to cause such effects animals.Taking into account the complete absence of skin sensitization potential of zinc compounds, respiratory sensitisation is not expected to be of concern for the zinc and zinc compounds considered in this chemical safety report.

Justification for classification or non-classification

The data on slightly soluble zinc oxide indicated no skin sensitising potential (negative in animal and human studies) therefore classification for skin sensitisation is not required according to EC criteria. Based on the assumption that zinc compounds with similar water solubility characteristics can be read across, it can be concluded that the other slightly soluble and insoluble zinc compounds are also expected to be non-skin sensitisers.

The data on soluble zinc sulphate indicates no sensitisation potential and therefore no classification is required according to EC criteria.Sensitisation is not expected from solublezinc chloride, zinc bis(dihydrogen phosphate), diammonium tetrachlorozincate and triammonium pentachlorozincate based on the data for zinc sulphate since the soluble zinc compounds share similar solubility characteristics.