Toxicity of MnCl 2 .4H 2 O when Fed to Rats

Abstract

Findlay 1 claims that addition of manganese chloride to the “ordinary” diet of rats produces cirrhosis of the liver and death in from 6 to 10 weeks. He fed 0.3 to 0.4 g manganese chloride per rat per day but failed anywhere to indicate the composition of the diet used. McCarrison 2 fed rats 0.889 mg of MnO per day. He compared their weights with those of a similar group receiving no manganese other than that contributed by the salt mixture and the other constituents of the diet. He states “There was no difference in the percentage weight curves of the 2 groups up to the 32nd day. Thereafter the curves diverged gradually and increasingly; that of the group receiving manganese being at the lower level.” The experiment lasted 135 days. To another group of rats he fed MnCl₂ at a level of .0327 mg per rat per day. A control group received no MnCl₂. He states, from the outset the rate of growth of the group receiving 0.327 mg MnCl₂ daily per rat surpassed that of the control group.” The experiment lasted 53 days. Unfortunately, the diets used in these 2 sets of experiments were not identical either in the source of the manganese, amounts of manganese, or sources of fat or vitamins.

Orent and McCollum³ demonstrated the need of the rat for manganese for normal reproduction. On manganese-free diets females fail to suckle their young, and males show testicular degeneration after 100 days or less. The addition of .005 to .05% manganese in the form of MnCl₂4H₂O promotes normal functioning of males and females.

As a result of these observations further experiments were conducted where manganese was added to the blasal ration at the following levels of MnCl₂.4H₂O: 0.18%, 0.36%, 0.9%, 1.8%, 3.6%. Thus there was added to the diets .0499, .0998, .2495, .4990, and .9980 g of manganese respectively. Thle basal ration had the following composition: Table