Some Studies on the Chronic Toxicity
of Cadmium and Hexavalent Chromium
in Drinking Water
RICHARD U. BYERRUM, Professor of Chemistry
Kedzie Chemical Laboratory
Michigan State University
East Lansing, Michigan
Acute toxicity of chromium and cadmium has been recognized as an industrial hazard for many years. The toxicity of cadmium from inhalation of
cadmium oxide or cadmium sulfide fumes in certain industries has been well
established, and experimental studies in which cats and dogs were similarly
exposed have also shown cadmium to be toxic. Topical exposure or inhalation of chromium has been shown to result in ulcer-like lesions and exposure
to chromium containing mists has been suggested as contributing to the high
incidence of lung cancer in certain industries.
Oral administration of chromium or cadmium has also been shown to be
toxic both to humans and experimental animals. For instance, rats receiving
50 ppm of cadmium in drinking water exhibited reduced blood hemoglobin
and stunted growth when compared with controls. Similarly ingestion of
chromium, particularly hexavalent chromium, has been shown to result in a
diminished growth rate, and liver and kidney damage in experimental animals (1,2).
Both cadmium and chromium have been found in the past few years in
drinking water. The occurrence of both of these is largely attributable to
contamination by industrial wastes although cadmium has heen found to occur
naturally in several locations. The concentrations at which these substances
occur in drinking water is below the level which causes acute toxicity-, up to
about one ppm of both cadmium and chromium. In a few instances of sudden
contamination, hexavalent chromium has risen to 50 ppm in drinking water,
but this level is also below the concentration which causes acute toxicity.
There are virtually no data available on the effects on people or animals of
long-term ingestion of small quantities of cadmium and chromium. The present study reports results of experiments concerned with the effect on rats and
dogs of concentrations of cadmium and chromium which might be expected
to occur in drinking water.
CHRONtC TOXICITY OF CADMIUM
Albino rats, 34 days old, (Sprague-Dawley strain) were housed in individual raised cages, and divided into a control group containing 10 males and
10 females, and six other groups containing eight rats of each sex. The ani -
mals were maintained at a temperature between 75 and 79 F. Food and water
were given ad libitum. Composition of the diet, in percentage by weight,
was as follows-, ground yellow corn meal, 32.5; ground whole wheat, 25.0;
powdered whole milk, 22.5; linseed oil meal, 10.0; alfalfa, 6.0; brewer's
yeast, 3. 0; and sodium chloride, 1.0. Controls received distilled drinking
water. Other rats were given water containing cadmium at the following
levels: 0.1, 0.5, 2.5, 5.0, 10.0, and 50.0 ppm cadmium. These solutions
were prepared by diluting a stock solution of cadmium chloride with distilled
water. Weekly records were kept of body weight and food and water consumption.
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