From the soil, certain plants tobacco, rice, other cereal grains, potatoes, and other vegetables take up cadmium more avidly than they do other heavy metals such as lead and mercury Satarag et al.
Cadmium is also found in meat, especially sweetmeats such as liver and kidney. In certain areas, cadmium concentrations are elevated in shellfish and mushrooms Jarup Cadmium can also enter the food chain from water.
In Japan, zinc mining operations contaminated the local water supplies with cadmium. Local farmers used that water for irrigation of their fields. The soil became contaminated with cadmium which led to the uptake of cadmium into their rice Jarup Skip directly to site content Skip directly to page options Skip directly to A-Z link.
Environmental Health and Medicine Education. Section Navigation. Facebook Twitter LinkedIn Syndicate. Cadmium Toxicity. Examples are liver, mushrooms, shellfish, mussels, cocoa powder and dried seaweed. An exposure to significantly higher cadmium levels occurs when people smoke. Tobacco smoke transports cadmium into the lungs. Blood will transport it through the rest of the body where it can increase effects by potentiating cadmium that is already present from cadmium-rich food.
Other high exposures can occur with people who live near hazardous waste sites or factories that release cadmium into the air and people that work in the metal refinery industry.
When people breathe in cadmium it can severely damage the lungs. This may even cause death. Cadmium is first transported to the liver through the blood. There, it is bond to proteins to form complexes that are transported to the kidneys. Cadmium accumulates in kidneys, where it damages filtering mechanisms. This causes the excretion of essential proteins and sugars from the body and further kidney damage.
It takes a very long time before cadmium that has accumulated in kidneys is excreted from a human body. Other health effects that can be caused by cadmium are: - Diarrhoea, stomach pains and severe vomiting - Bone fracture - Reproductive failure and possibly even infertility - Damage to the central nervous system - Damage to the immune system - Psychological disorders - Possibly DNA damage or cancer development. Cadmium waste streams from the industries mainly end up in soils.
The causes of these waste streams are for instance zinc production, phosphate ore implication and bio industrial manure. Cadmium waste streams may also enter the air through household waste combustion and burning of fossil fuels.
Therefore cadmium discards will end up in municipal waste and disposed of in landfills , incineration, open burning or indiscriminate dumping. Some of the cadmium in these products will be released to the environment. The critical health effect of cadmium is on the kidneys where it damages the blood filtration system of the kidneys, which results in proteins being excreted in urine. The severity of the effects depends on duration and magnitude of exposure.
Skeletal damage is another critical effect of long term exposure to cadmium at levels somewhat higher than those for which kidney problems occur. When it is breathed in, cadmium can cause lung cancer.
Cadmium is mainly stored in the liver and kidneys. Excretion is slow, with a very long half-life decades in the human body. Cadmium concentrations in most tissues increase with age. Cadmium is a non-essential heavy metal , meaning that it is not used by biological systems. Both in aquatic and terrestrial ecosystems it tends to bioaccumulate , particularly in vertebrates, and specifically in organs such as the kidney and liver , and it also accumulate builds up in invertebrates, algae and plants.
Effects on birds and mammals are mainly due to kidney damage. Cadmium air concentrations may be elevated in certain industrial settings, but these exposures are closely controlled today by national occupational exposure standards. Historically, average exposure levels and regulatory permissible exposure limits have decreased markedly in the past 40 years in recognition of the importance of cadmium inhalation to human health and with the significant improvements in air pollution control technology over that period Elinder , WHO Tobacco leaves naturally accumulate and concentrate relatively high levels of cadmium, and therefore smoking of tobacco is an important source of air cadmium exposure for smokers.
It has been reported that one cigarette contains about 0. Smokers generally exhibit significantly higher cadmium body burdens than non-smokers. Higher levels have been noted around certain coastal areas Elinder and variations of cadmium concentration with the ocean depth, presumably due to patterns of nutrient concentrations, have also been measured WHO , OECD Even greater variations are quoted for the cadmium contents of rainwater, fresh waters, and surface waters in urban and industrialised areas.
Cadmium is a natural, usually minor constituent of surface and groundwater. It may exist in water as the hydrated ion, as inorganic complexes such as carbonates, hydroxides, chlorides or sulphates, or as organic complexes with humic acids OECD Cadmium may enter aquatic systems through weathering and erosion of soils and bedrock, atmospheric deposition direct discharge from industrial operations, leakage from landfalls and contaminated sites, and the dispersive use of sludge and fertilisers in agriculture.
Much of the cadmium entering fresh waters from industrial sources may be rapidly adsorbed by particulate matter, and thus sediment may be a significant sink for cadmium emitted to the aquatic environment WHO Some data shows that recent sediments in lakes and streams range from 0. Partitioning of cadmium between the adsorbed-in-sediment state and dissolved-in-water state is therefore an important factor in whether cadmium emitted to waters is or is not available to enter the food chain and affect human health.
Rivers containing excess cadmium can contaminate surrounding land, either through irrigation for agricultural purposes, dumping of dredged sediments or flooding. It has also been demonstrated that rivers can transport cadmium for considerable distances, up to 50 km, from the source WHO Nonetheless, studies of cadmium contamination in major river systems over the past twenty to thirty years have conclusively demonstrated that cadmium levels in these rivers have decreased significantly since the s and s Cook and Morrow , Elgersma et al.
Cadmium in soils is derived from both natural and anthropogenic sources. Natural sources include underlying bedrock or transported parent material such as glacial till and alluvium.
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