Cadmium, a naturally occurring heavy metal, is found in the Earth’s crust. Human activities significantly increase its environmental presence, making it a recognized pollutant. When present in water, cadmium is a concern due to potential health implications. This element has no odor or taste, making it undetectable without testing.
How Cadmium Enters Water
Cadmium enters water sources through natural processes and human activities. Natural pathways include the erosion of cadmium-containing rocks and soils, and atmospheric deposition from volcanic activity and forest fires.
Human activities are a major contributor to cadmium contamination. Industrial discharges from mining, smelting, battery manufacturing, metal plating, and textile production release cadmium-containing waste. This waste can contaminate surface water and groundwater if not properly managed. Agricultural runoff also contributes, primarily from phosphate fertilizers and sewage sludge, which can contain elevated cadmium levels. The corrosion of galvanized pipes, common in older plumbing, can also leach cadmium into drinking water supplies.
Impacts on Health
Chronic exposure to cadmium through contaminated water can lead to adverse health effects due to its long half-life (25-30 years) and accumulation in the body. The kidneys are the primary target organ for cadmium toxicity, where it can damage kidney cells, leading to kidney dysfunction. This damage can lead to tubular proteinuria, an early sign of impaired tubular resorption, and in severe cases, reduced kidney function or renal failure.
Cadmium also impacts bone health by interfering with calcium metabolism. This can lead to osteoporosis (reduced bone density) and osteomalacia (softening of bones). Individuals may experience joint and back pain, an increased risk of fractures, and, in severe cases, bone deformities. The skeletal effects are often secondary to kidney damage, as impaired kidney function can lead to increased urinary calcium and phosphorus loss and inhibit vitamin D activation.
The International Agency for Research on Cancer (IARC) classifies cadmium as a human carcinogen, with associations observed for lung, kidney, and prostate cancers. Other potential effects from long-term exposure include liver and blood damage, such as anemia, and reproductive or developmental issues, although human studies on the latter are inconsistent.
Reducing Exposure
Protecting oneself from cadmium exposure in water involves several steps. Testing water is a primary measure, which can be done through home testing kits or professional laboratory analysis, particularly for private wells. For those on municipal water supplies, accessing water quality reports provides information on contaminant levels. The U.S. Environmental Protection Agency (EPA) has established a Maximum Contaminant Level (MCL) for cadmium in public drinking water at 0.005 milligrams per liter (mg/L) or 5 parts per billion (ppb), a standard designed to protect public health.
If cadmium is detected above safe levels, effective water treatment technologies can be employed. Reverse osmosis (RO) systems are highly efficient, utilizing a semi-permeable membrane to remove up to 99% of heavy metals, including cadmium. Ion exchange is another method where unwanted ions like cadmium are exchanged for less harmful ions using a solid resin. Activated carbon filtration and distillation can also reduce cadmium levels in water. Beyond treatment systems, flush stagnant water from pipes, especially if water has been sitting for several hours, as cadmium levels can increase in water stagnating in household pipes.