Public Hygienic Study of Replacemented A type-zeolite by Ag, Zn, NH₃ Part I -Subchronic Toxicity Test

Abstract

Silver-containing zeolite has been introduced into the market being mixed into plastic. Because of its antimicrobial effect, this material is now variously applied to cookwared and sanitation products in hospitals. As for A-type zeolite, it has been used as a detergent builder and was cleared by the United States Food and Drug Administration per their safety standard for long-term oral intake. However, little is known about the toxicity of zeolite of which antimicrobial metal is substituted. In light of the drastic expansion of antimicrobial plastic products, we conducted a three-month aral subchronic toxicity test by using FISHER-344 rats from the viewpoint of public hygiene. Currently, more than ten companies manufacture antimicrobial zeolite products. These products are completely different in performance and characteristics; hence Zeomic (manufactured by Shinagawa Fuel Co., Ltd.) -a major product of this kind in the Japanese market-was adopted as the sample. Results indicate growth inhibition and atrial thrombus in the 5.0% Zeomic intake mouse group and the mice died in seven weeks. In the 2.5% and 1.25% intake groups, the dosage-reaction correlative pigmentation was observed. Also several changes of blood components were observed such as increase of white blood cells at 5.0% intake group. In the case of rats, growth inhibition and mid-way death were observed in the 5% Zeomic intake group. A change in the vascular walls was also observed presumably caused by silver sedimentation. In the 2.5% and 1.25% intake rat groups, pigmentations of pancreas, liver and kidney were observed, which was the same as in the 5% group. The non-effective dosage of Zeomic for mice and rats was estimated at 0.125%.