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Toxicological information

Acute Toxicity: oral

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Administrative data

Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Method appears to have been conducted to good scientific standards, although not to GLP. However, in one part of the report it states oral dosing is via stomach intubation, but then the rest of the report appears to indicate ad libitum. It is difficult to know how an insoluble MnO2 would have been administered this way, so this lack of clarity makes it difficult to assign the results as reliable.

Data source

Reference
Reference Type:
publication
Title:
Studies on the evaluation of the toxicity of various salts of lead, manganese, platinum and palladium
Author:
Holbrook DJ, Washington ME, Leake HB and Brubaker PE
Year:
1975
Bibliographic source:
Environmental Health Perspectives, 10:95-101

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Rats were exposed to MnO2 via drinking water for an unspecified period of time. Bodyweights and food/water consumption were measured at 7 day intervals (results not reported).
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): MnO2

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
4 rats per cage, food (Purina Laboratory Chow; 56 ± 5 mg Mn/kg feed) and water available ad libitum.

Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
water
Doses:
No data
No. of animals per sex per dose:
No data
Control animals:
yes

Results and discussion

Effect levels
Sex:
male
Dose descriptor:
LD50
Effect level:
> 3 480 mg/kg bw
Based on:
test mat.

Applicant's summary and conclusion

Interpretation of results:
practically nontoxic
Remarks:
Migrated information
Conclusions:
The result of this study indicating an LD50 >> 3480 mg/kg for MnO2 conflicts directly with the current classification of MnO2 which indicates acutely harmful by the oral route. Given the insoluble nature of MnO2 and low bioavailability due to this, it is easier to believe that MnO2 should not be classified as acutely harmful by the oral route and there is no published data which supports this classification. Although assignment of a reliability of 1 or 2 is not possible for this study, the conclusion from this study, that MnO2 is not acutely harmful by the oral route, is very believable.