Manganese dioxide

Endpoint summary

Description of key information

Manganese dioxide is of low acute toxicity. The inhalation LC50 is > 1500 mg/m^3 for 4-hr exposure in rats [OECD TG 423]. 
The dermal LD50 is > 2000 mg/kg bw in rats [OECD TG 402]. 
The oral LD50 is > 3478 mg/kg bw in male rats.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

3 478 mg/kg bw

Quality of whole database:

Study conducted according to internationally accepted testing guidelines.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

1 500 mg/m³ air

Quality of whole database:

Study GLP compliant and conducted according to internationally accepted testing guidelines.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Study GLP compliant and conducted according to internationally accepted testing guidelines.

Additional information

Manganese dioxide is of low acute toxicity. The inhalation LC50 is > 1500 mg/m^3 for 4-hr exposure in rats [OECD TG 423]. The dermal LD50 is > 2000 mg/kg bw in rats [OECD TG 402]. The oral LD50 is > 3478 mg/kg bw in male rats.

Oral exposure:

As reported by Holbrook et all in the article Studies on the evaluation of the toxicity of various salts of lead, manganese, platinum and palladium, Environmental Health Perspectives, 10:95-101, 1975, the oral LD50 on rat for MnO2 is major than 40 mmol/kg equivalent to major than 3478 mg/kg. The test was performed on male Sprague-Dawley rat and the observation period was 14-days.

According to CLP Regulation (EC n. 1272/2008) and based on LD50 comes from the study of 1975, the substance would be not classified for acute oral toxicity. However Manganese dioxide is included in annex VI of CLP Regulation (EC n.1272/2008) and it is classified H302 (acute oral toxicity cat.4). The study of 1975 is not GLP but it meets generally accepted scientific principles.

Inhalation exposure:

As reported in SIDS Dossier of MnO2 approved at SIAM 25 (17 -18 October 2007) with reference to unpublished report of National Institute of Environmental Research (NIER), Korea, 2006, The Acute inhalation toxicity of manganese dioxide to rat (Report No. ICRC/2006/010), tested by Chemical Safety and Health Center Korea Occupational Safety and Health Agency, the inhalatory LC50 on rat is more than 1500 mg/m^3. 30 laboratory rats (15 males & 15 females/5 sex/group) were exposed to the substance via inhalation route at the following concentrations 375, 700, 1500 mg/m^3 for 4h . No abnormalities were noted during the 14 -day post-exposure period. Gross pathological observations showed no significant macroscopic findings. No mortality has been seen at tested concentration. The study was conducted according OECD TG403.

According to CLP Regulation (EC n.1272/2008) and based on LC50 comes from the study of 2006, the substance would be not classified for acute inhalatory toxicity). However Manganese dioxide is included in annex VI of CLP Regulation (EC n. 1272/2008) and it is classified H332 (acute inhalation toxicity cat.4). The CLP classification annex VI may be justifed by inhalation study on human (see section 7.10 IUCLID Lloyd-Davies, 1946).

Dermal exposure:

As reported in SIDS Dossier of MnO2 approved at SIAM 25 (17 -18 October 2007) with reference to unpublished report of National Institute of Environmental Research (NIER), Korea, 2006, The Acute dermal toxicity of Manganese dioxide to rat (Report No. G06022), tested by KRICT, the dermal LD50 on rat is more than 2000 mg/kg. 20 laboratory rats (10 males & 10 females/5 sex/group) were exposed to the substance via dermal route at the following concentrations 500, 1000, 2000 mg/kg bw for 24 h.No abnormalities were noted during the 14 -day post-exposure period. No mortality has been seen at tested concentration. The study was conducted according OECD TG402.

Justification for classification or non-classification

From studies reported in SIDS Dossier approved at SIAM 25 (17 -18 October 2007) manganese dioxide is of low acute toxicity.

However, Manganese dioxide is included in annex VI of CLP Regulation (EC n.1272/2008) and it is classified H302 (acute oral toxicity cat.4) and H332 (acute inhalation toxicity cat.4).