Water pipes can be a source of cadmium concentration. Cadmium is often used to protect metals from corrosion. Galvanized (zinc) pipes usually contain some cadmium, as does the solder used to hold them together. Soft or acid water is corrosive and causes the metals in the pipes to break down, releasing cadmium and other minerals from them. Hard water containing calcium and magnesium salts actually coats the pipes and protects against the leaching of other minerals.

Air pollution of cadmium comes from zinc mining and refining, and from the burning of coal. Cadmium is also an industrial contaminant from the steel-making process.

Soil levels of cadmium are increased by cadmium in water, by sewage contamination, by cadmium in the air, and by high-phosphate fertilizers. Coffee and tea may contain significant cadmium levels. Root vegetables such as potatoes may pick up more cadmium, and the grains can concentrate cadmium. Seafood, particularly crustaceans, such as crab and lobster, and mollusks, such as clams and oysters, have higher cadmium levels, though many are also higher in zinc, balancing the cadmium.

Methods of toxicity: Though cadmium has no known useful biological functions, it competes with zinc for binding sites and can therefore interfere with some of zinc's essential functions. In this way, it may inhibit enzyme reactions and utilization of nutrients. Cadmium may be a catalyst to oxidation reactions, which can generate free-radical tissue damage.

Symptoms of Toxicity: In his book Trace Elements and Man, the late expert in trace and toxic elements Henry Schroeder, M.D., described in detail cadmium's involvement in generating, or at least contributing to, high blood pressure. Cadmium concentrates in the kidney and can generate kidney tissue damage and hypertension, as well as an increased incidence of calcium kidney stones. Initially, protein and sugar may be spilled in the urine. Some patients with high blood pressure show elevated urine cadmium levels. This hypertension is likely related to the reduced zinc-cadmium ratio. The cadmium effect may contribute not only to hypertension but to heart disease as well. In rat studies, higher levels of cadmium are associated with an increase in heart size, higher blood pressure, progressive atherosclerosis, and reduced kidney function. And in rats as well as in humans, cadmium toxicity is worse with zinc deficiency and reduced with higher zinc intake.

Cadmium appears to depress some immune functions, mainly by reducing host resistance to bacteria and viruses. It may also increase cancer risk, possibly 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. It has been known to cause bone and joint aches and pains. This syndrome, first described in Japan, where it was termed the itai-itai ("ouch-ouch") disease, was caused by cadmium pollution there. It was also associated with weak bones that lead to deformities, especially of the spine, or to more easily broken bones. This disease was fatal in many cases.

We may be seeing an increase in emphysema due to cadmium exposure. Anemia also seems to be a problem. Most of these potential cadmium toxicity problems, including its immunosuppressant actions and its role in cancer, hypertension, and heart and kidney disease, need to be substantiated by more research.