Cadmium poisoning occurs when a person is exposed to excessive amounts of cadmium, a toxic heavy metal that is not naturally required by the human body. The primary causes of cadmium poisoning stem from environmental, occupational, and dietary exposures where cadmium accumulates in the body over time, leading to harmful health effects.
Cadmium is commonly found in industrial settings such as mining, smelting, battery manufacturing, and welding, where workers may inhale cadmium fumes or dust. Inhalation is a major route of exposure in these environments because cadmium particles can enter the lungs and cause direct respiratory damage. Chronic inhalation can lead to lung inflammation, pulmonary edema, bronchitis, and even lung cancer, as cadmium is a known human carcinogen.
Another significant source of cadmium exposure is through contaminated food and water. Cadmium can enter the food chain when plants absorb it from polluted soil or water, especially near industrial sites or areas with heavy use of phosphate fertilizers that contain cadmium impurities. Common foods that may contain cadmium include rice, leafy vegetables, shellfish, and some grains. Long-term dietary intake of cadmium leads to its accumulation primarily in the kidneys and bones.
Once cadmium enters the body, it is absorbed and transported mainly to the kidneys, where it accumulates in the renal cortex. This accumulation disrupts kidney function, causing tubular dysfunction and proteinuria (excess protein in urine), which are early signs of kidney damage. Over time, cadmium poisoning can cause chronic kidney disease due to this progressive impairment.
Cadmium also interferes with calcium metabolism in bones, leading to bone disorders such as osteomalacia (softening of bones) and osteoporosis. This effect was notably observed in the Itai-Itai disease outbreak in Japan, where cadmium-contaminated rice caused severe bone pain, fractures, and skeletal deformities.
At the cellular level, cadmium induces toxicity by generating oxidative stress and disrupting cellular homeostasis. It interferes with antioxidant defense systems, leading to damage of cellular components like membranes, proteins, and DNA. This oxidative stress can trigger inflammatory responses and cell death in various tissues, including bone-forming cells (osteoblasts), which contributes to bone weakening.
Cadmium exposure has also been linked to increased risks of certain cancers, including breast cancer. It can reduce DNA repair capacity and promote genomic instability, which facilitates the proliferation of abnormal cells. This carcinogenic potential adds to the health risks posed by cadmium.
In summary, cadmium poisoning is caused by inhaling cadmium fumes or dust in industrial environments, consuming cadmium-contaminated food or water, and living in polluted areas. The metal accumulates in the kidneys and bones, causing damage through oxidative stress, inflammation, and interference with essential metabolic processes. The long biological half-life of cadmium means it remains in the body for decades, making chronic exposure particularly dangerous and leading to serious health consequences such as kidney failure, bone disease, respiratory problems, and increased cancer risk.
