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The health of workers exposed to cadmium.


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Gill, Peter Francis 1976 , 'The health of workers exposed to cadmium.', Coursework Master thesis, University of Tasmania.

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Cadmium has been described as being toxic in all living species. At
no level of intake does it appear to have a useful biological function.
Although it was not recognised until 1817 as a separate element man has
been polluting his environment with it for centuries - from the time the
early Greek metallurgist began working with "bronzes". Widely distributed
in the earths crust in low concentrations it remains "locked in"
unless other more important resources are extracted and refined.
Erosion and weathering of the earths crust contributes little to the
level of environmental cadmium.
In nature it is closely associated with zinc. It is also found in many
other polymetallic ores, particularly those containing copper and lead.
Fossil fuels, coal and oil, as well as phosphate rock also contain
significant quantities of cadmium. When mankind refines and utilises
and purifies these materials cadmium is released. It is a relatively
unimportant resource, a by-product of far more important resources.
Whether needed or not it is being separated and recovered in greater
quantities annually. Many uses have been found to make it marketable.
Little recycling of the end product occurs. Consequently an increasing
quantity of "free" cadmium is available for contamination of the environment.
Water, air, food chains, foodstuffs are providing an increasing
load to all living things. It has been claimed it poses a threat to all
life on earth.
Almost 150 years passed from the time cadmium was recognised to the
time it was generally accepted as a dangerous substance. 19th century
industry provided many examples of its acute toxicity but it was the
mid twentieth century before it was established that the metal could
accumulate in the body over many years and ultimately reach a concentration
which interfered with the function of the host cell.
Those most at risk are those who handle the material in their occupation.
But heavy pollution of some Japanese waterways has resulted in death and
chronic disability to the population living along the shores. Chronic
obstructive airways disease and renal tubular disease are common in
those whose working conditions expose them to high concentrations.
Anaemia, bone disease, general malaise have also been found.
Animal experimentation has shown that cadmium, though poorly absorbed,
can enter the body via the skin, lungs and alimentary canal. Its
entry stimulates the formation of a special protein, Metallothionein,
which acts both as a carrier and a receptacle. Cells of many tissues
take up cadmium - in particular the liver, kidney, pancreas, gonads,
salivary and intestinal glands. Because of its environmental ubiquity
and its slow excretion - mainly via the kidney, lifelong accumulation
occurs. How much can the body accumulate before signs of toxicity
appear? Just how toxic is it to various organs?
I have compared the health of 34 workers at the Electrolytic Zinc
Company of Australasia, Risdon, Tasmania who have spent many years
working in a moderately contaminated atmosphere with fellow workers
exposed only to environmental cadmium. I restricted my investigation to the clinical field and avoided invasive investigational procedures..
I found no evidence of any serious ill health specific to the exposed
group. In particular this group did not manifest any of the disabilities
found in similar surveys by others. My group of workers were different
in that they were working in levels well below accepted tolerable
levels. This group therefore could be used as representatives of a
middle group between those environmentally at risk and those seriously
at risk because of heavy occupational exposure.
I found cadmium did cause chronic pulmonary symptoms even in these
low concentrations but without objective pulmonary disease. Some of
those with the longest exposure and presumably the largest body burden
did show evidence of altered haemoglobin and protein synthesis without
obvious clinical manifestations.
I found no evidence of any of the conditions - hypertension, malignancy
endocrine disorders speculatively linked to cadmium by epidemiologists
using results of animal studies on environmental studies and disease
patterns. Though definitely toxic to cells cadmium can be tolerated up
to a certain body burden for a "no effect". I was not able to establish
this burden but the study may provide areas for further research into
this very important question.

Item Type: Thesis - Coursework Master
Authors/Creators:Gill, Peter Francis
Keywords: Cadmium, Cadmium
Copyright Holders: The Author
Copyright Information:

Copyright 1976 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (M.D.)--University of Tasmania, 1977. References: l. 224-229

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