Changes in Oral LD50 Values for Heavy Metals by Pretreatment with the Same Metals

Abstract

Oral LD50 values (at 24- and 168-hr) for eight metal salts were determined in female ICR mice pretreated orally with small doses (1/10 of the challenge doses) of the same metal ions or with deionized water at 24hr prior to the challenge doses. The LD50 values for Cd²⁺ or Mn²⁺ increased with pretreatment by the same ion, but those for Hg²⁺ decreased. Pretreatment with Cu²⁺, Fe²⁺, Fe³⁺, Pb²⁺ or Zn²⁺ had little effect on the lethality of the same ion. Cd²⁺ pretreatment was the most effective in reducing the acute toxicity of the same ion. Pretreatment with Cu²⁺ Hg²⁺ or Zn²⁺ protected mice against the toxic action of Cd²⁺.