Twenty-eight week toxicity study of perlite powder in mice.

Groups of 21 male and 21 female mice were given diets containing 20%, 10%, 1% or 0% (control) perlite for 28 weeks. Appearance, behavior, mortality, and food consumption of mice of treated groups were not affected during the experimental period. Males of the 20% and 10% groups did experience slightly reduced growth rate. No significant drug-related changes were found in urinalysis, hematology, serum chemistry, and organ weight. No differences were found between control and treated groups in autopsy and histopathological findings. Therefore, the maximum no-effect level is considered to be 1% in the diet which developed no toxic changes in any items examined in mice treated orally with perlite for 28 weeks.