Manganese dioxide

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral

In accordance with Column 1 of REACH Annexes VIII, IX and X, repeated dose toxicity testing on the most appropriate route of administration shall be conducted having regard to the likely route of human exposure. For the registered substance, inhalation is deemed to be the most likely route of human exposure and therefore repeated dose toxicity testing via the oral route is not considered scientifically necessary.

To expand, the substance is used in industrial settings where ingestion is extremely unlikely. In the event of ingestion – acute exposure; the acute oral toxicity test prescribed in REACH Annex VIII resulted in an LD50 in excess of 2000 mg/kg bw. Moreover, airborne exposure is the most likely the work place. Furthermore, on animal welfare grounds, adaptation is appropriate in consideration of the extensive use of experimental animals that would be required.

Inhalation

MnO2 will be proposed for classification as STOT RE2- target organ brain, on the basis of the Roels et al (1992) study on workers exposed to the substance without any confounders. The route of exposure in the study was inhalation and the sub-clinical effects seen at the exposure concentrations in the study, are believed to indicate that significant toxicity could occur at moderate exposure levels. On the basis of this proposal it is considered that conducting animal testing would be both scientifically unjustified and unethical. Therefore in accordance with Annex XI, section 1.1 this test is not considered necessary.

Dermal

In accordance with Column 1 of REACH Annexes VIII, IX and X, repeated dose toxicity testing on the most appropriate route of administration shall be conducted having regard to the likely route of human exposure. For the registered substance, inhalation is deemed to be the most likely route of human exposure and therefore repeated dose toxicity testing via the dermal route is not considered scientifically necessary.

The physiochemical properties of MnO2 suggest it is unlikely to be absorbed through the skin. It has a poor water solubility and inorganic ions do not pass easily through the dermal barrier. In addition, MnO2 is not acutely toxic by the oral route and therefore it is highly unlikely that it would be toxic via the dermal route which in general absorbs chemicals to a much lesser degree than the gastrointestinal tract. Furthermore, on animal welfare grounds, adaptation is appropriate in consideration of the extensive use of experimental animals that would be required.

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Annex I, Regulation (EC) No. 1272/2008, the substance is classified with respect to specific target organ toxicity following repeated exposure, and has the hazard phrase 'H373: May cause damage to the brain through prolonged or repeated exposure via inhalation'.

In accordance with the criteria for classification as defined in Annex VI, Directive 67/548/EEC (DSD), the substance is classified with respect to repeated dose toxicity and has the risk phrase 'R48/20 - Harmful: danger of serious damage to health by prolonged exposure through inhalation'.