Cadmium has the atomic number of 48 and is found together with zinc
in natural deposits and they are similar in structure and function in the human body.
Cadmium may displace zinc in some of its important enzymatic and organ
functions; thus, it interferes with these functions or prevents them from being
completed. The zinc-cadmium ratio is very important, as cadmium toxicity and
storage are greatly increased with zinc deficiency which is a common condition
for alcohol drinkers as alcohol expels zinc in the urine. Good levels of zinc
protect against tissue damage by cadmium. The refinement of grains reduces the
zinc-cadmium ratio, so zinc deficiency and cadmium toxicity are more likely when
the diet is high in refined grains and flours.
There may be as much as 40 mg of
cadmium in the human body and consumption from foods can be at least 40 mcg
daily. Levels vary according to region, as most comes from soil by way of food.
There may be some in water from contamination and water pipes and cigarette
smoke plus industrial burning of metals puts some cadmium into the air. Cadmium
levels in the atmosphere are much higher in industrial cities.
Cadmium is not easily eliminated.
Besides faecal losses, it is excreted mainly by the kidneys. This mineral is
stored primarily in the liver and kidneys. As zinc has an affinity for the
testes, cadmium is also stored there in higher concentrations than in other
tissues. With zinc deficiency, more cadmium is stored. With aging, cadmium
accumulates in the kidneys and may predispose to hypertension.
Cadmium can depress some immune
functions by reducing resistance to bacteria and viruses. It may also increase
cancer risk, for the lungs and prostate. Cadmium toxicity has been implicated in
generating prostate enlargement, possibly by interfering with zinc support.
Cadmium also affects the bones because
zinc improves the absorption of
vitamin D, the vitamin which aids in the absorption of
calcium and cadmium’s displacement of zinc has been known to cause bone and joint aches and pains. This was first
described in Japan caused by cadmium pollution there. It was also associated
with weak bones that lead to deformities, especially of the spine or to fragile
and easily broken bones and was fatal in many cases.
Cadmium, copper and lead concentrations increase in the lens of the eyes in tobacco smokers leading to cataracts and vision impairment.
Long term cadmium exposure can also
lead to cancer, hypertension, heart and kidney disease, emphysema and anaemia.
No cadmium is present in newborns
because it does not cross the placenta-foetal barrier nor the blood-brain
barrier as lead and mercury do, so it is not toxic to foetuses, nor does it
cause the mental and brain disorders associated with lead and mercury.
During the growth of grains such as wheat and rice, cadmium (from the soil) is
concentrated in the core of the kernel, while zinc is found mostly in the germ
and bran coverings. With refinement, zinc is lost, increasing the cadmium ratio.
Refined flours, rice, and sugar all have relatively higher ratios of cadmium to
zinc than do the whole foods.
One pack of cigarettes contains about 20 mcg of cadmium or about 1 mcg per
cigarette. About 30 percent of that goes into the lungs and is absorbed and the
remaining 70 percent goes into the atmosphere to be inhaled by others or to
contaminate the environment. With long-term smoking, the risk of cadmium
toxicity is increased. Though most of it is eliminated, a little bit is stored
every day. Marijuana may also concentrate cadmium, so regular smoking of
cannabis may also be a risk factor for toxicity from this metal.
Reducing alcohol intake and stopping
smoking tobacco and cannabis plus consuming
rich foods can help reduce cadmium toxicity and
vitamin D and calcium
deficiency. High intake of zinc as well as of
will protect against further cadmium absorption and adequate body levels of zinc
may displace some tissue cadmium.
vitamin C have been shown to increase cadmium elimination as can be measured
by urine levels. Hair analysis is a good way to follow cadmium levels.
Sources of cadmium
Cadmium is also a component of alloys,
used in electrical materials and is present in burning coal, ceramics, dental materials, storage batteries and water pipes.
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