can a toxic effect of cadmium cause a small elevation of blood or hair lead
above the average for that environment?
understand the behavior of metals it is necessary to look at their biochemical
behavior. Statistical correlations can
be misleading. It has been known for a long time that zinc and iron
deficiencies were associated with toxic effects of lead. These deficiencies are known to increase the absorption
and toxicity of cadmium. The inhibition
of the enzyme ALAD which is considered particularly characteristic of toxicity to
lead occurs with cadmium. Zinc protects this enzyme from inhibition. Cadmium
is an anti-metabolite of zinc. Zinc protects cells from cadmium toxicity. So
lead toxicity is not just a simple matter of exposure to a toxic metal and a
toxic effect that one can measure with blood lead levels or inhibition of
An excellent article is available regarding the
use of dietary strategies for the treatment of lead and cadmium toxicity.
Nutrients. 2015 Jan 14;7(1):552-71. doi:
Dietary strategies for
the treatment of cadmium and lead toxicity.
this article the effects of vitamins, minerals, herbs, and probiotics on toxic
effects of lead and cadmium are discussed. In most cases it is clear that a
reduction of blood lead with these strategies also reversed toxic effects of
One could consider that both
lead and cadmium are toxic but that elevation of blood lead is the indicator of
toxicity, not blood cadmium. Certainly
the toxicity is directly associated with deficiencies of vitamins and minerals.
However, one could also consider that lead exposure directly influences the
uptake of cadmium.
Cadmium is very interactive with all nutrient
and toxic metals and also with toxic chemicals. Lead is treated more like
calcium in the body and is stored in bone. Cadmium is stored in the lining of
blood vessels and in the choroid plexus surrounding the brain. It is in the
kidney, liver, ovary, testes, thyroid, and adrenals. With acute stress, like
handling an animal, cadmium is released into the body. Consequently, cadmium effects can occur
without directly adding cadmium to an experimental animal.
causes a stress response in all cells. Lead does so only through increasing the
absorption of cadmium. For instance,
lead in water increases metallothionein production in the liver. Metallothionein is part of the acute stress
response that cadmium produces. Cadmium
activates the promotor of metallothionein
whether cadmium has been added in the
experiment or not. When lead is directly added to liver cells there is no
increase in metallothionein production. Lead in drinking water increases the uptake of
cadmium which promotes the stress response resulting in increased metallothionein
production. It is not just that lead and
cadmium are both toxic. Toxic effects attributed
to lead are caused by cadmium.
is this effect of lead ingestion increasing the absorption of cadmium that is
directly related to the small but significant elevations in blood lead levels
and health effects. Cadmium increases resorption
of bone where lead is stored increasing blood lead levels. So the level of lead in blood is not a
measure just of exposure,but exposure plus a toxic effect of cadmium on bone.
Blood cadmium is not a helpful measurement because cadmium is taken up rapidly
into the blood vessels and the various organs.
The levels are highly variable through the day responding to various stresses. Blood hair, and urine cadmium levels are not
just measures of exposure but also of stressed induced releases.
Based on this information alone, it is clear
that cadmium is important. It should be measured accurately in air. New
approaches are needed to detect these volatile ultrafine fumes of cadmium. The US EPA needs to fund research on
effective ways to measure cadmium. Children with elevated blood lead levels
should be evaluated for toxic effects of cadmium. Their urine cotinine should be measured to determine
exposure to environmental tobacco smoke.
Children in tee highest quartile of urine cadmium have a three fold risk
for placement in special education. These children need the dietary strategies
suggested by Q Zhai et al. They need
stress reduction and excellent care both at home and at school. They are not permanently
damaged. It is neglect and indifference that
leads to permanent damage in most instances.