Most contaminants that make their way into our water supply occur there as a byproduct of their industrial use or due to their natural abundance. The transition metal cadmium is an exception to both of these rules – sort of. Cadmium appears in the environment in such trace amounts that traditional mining of the element is nearly impossible. This is a lucky coincidence, being that the metal is recognized as highly toxic, yet water supplies remain unsaved from the contaminant’s intrusion. This tricky metal frequently occurs in deposits of zinc, a metal whose industrial use is cited at an average of 12 million tons per year. With zinc’s high levels of use, co-occurring cadmium is able to invade water supplies, both as a side effect of zinc mining and as a result of its own industrial use, made possible by its presence in zinc ores. In its own right, cadmium is most often used in:
While industrial waste from the manufacture of cadmium products, as well as the mining process for cadmium and zinc, are significant sources of cadmium’s introduction to ground and surface water sources, the use of cadmium as an alloy is a more direct source of contamination. Cadmium and zinc alloys are often used within the structures that are in direct contact with our water supply – pipes, plumbing fixtures, even water heaters and coolers. Overtime, the cadmium alloyed metals or zinc alloyed metals, which inevitably contain trace amounts of cadmium, begin to break down, releasing amounts of the contaminant into water as it passes through. The chemical nature of cadmium causes these alloys to break down faster in water with a low pH level by increasing the contaminant cadmium’s water solubility. This property complicates cadmium contamination, as contamination levels are subject to vary geographically, due to local pH levels, and even from home to home, based on the types of plumbing fixtures and water temperature controllers used in each household.
The Environmental Protection Agency has recognized cadmium as a harmful contaminant and legally set its maximum level of occurrence in drinking water at .005 milligrams per liter (mg/L) or 5 parts per billion (ppb). Though cadmium’s health effects from water consumption are not as thoroughly understood as other forms of its consumption, the contaminant is still recognized as harmful. The confirmed side effects of continued cadmium consumption include bone loss as well as damage to the intestinal tract, liver, and kidneys. In fact, studies conducted by the World Health Organization have found that consumed cadmium can be stored in the kidneys for up to 35 years. Carcinogenic effects have also been suggested through multiple studies, but direct evidence in humans is difficult to document, resulting in cadmium’s classification as a ‘probable human carcinogen’. The European Union has taken these health concerns to heart with the recent decision to ban Cadmium based pigments:
While public water supplies are obligated to maintain the 5 ppb standard for the water that they supply, it is possible for additional cadmium contamination to occur between public supply and personal consumption, due to its common occurrence in plumbing structures. Due to this fact, as well as the associated risks of cadmium consumption, it is wise for consumers to take their water’s health into their own hands by implementing a home filtration system. Reverse-osmosis filtration systems are an approved method for reducing cadmium contamination. These filters use a semi-permeable membrane to filter water. The nature of this membrane allows for water molecules to pass through while contaminants like cadmium are unable, leading to reduced contaminant concentration. Ion-exchange systems are also helpful in contaminant removal and use specialized resin to attract impurities like cadmium while replacing the harmful additive with a less harmful substitute, such as hydrogen ions.
Another option for cadmium decontamination is coagulation/filtration. This kind of system removes contaminants by precipitation. In coagulation/filtration, aluminum or iron compounds are introduced, which lead to a number of chemical processes between the additives and the contaminants present in the water supply. Ultimately, the added aluminum or iron compound precipitates and attracts certain contaminants, like cadmium, to its suspended mass, reducing the water’s contamination. For more details on cadmium’s industrial uses, natural occurrence, and health effects, visit: https://www.atsdr.cdc.gov/phs/phs.asp?id=46&tid=15
In order to safeguard yourself from serious waterborne problems or risks to health, consider using water filters at home or at institutions. Water filtration for all uses can easily provide protection from contaminants. It is highly recommended to adopt a convenient and affordable water filtration method to fight potentially harmful elements found in Water supply caused due to Water pollution.