Fact Sheet - Cadmium
Population at risk: 5 million people
Estimated DALYs: 250,000
Cadmium is a bluish-white metal, rarely found in the earth’s crust. However, industrial activities such as mining, smelting and refining release large amounts of cadmium that is often found in lead and copper ores. It is mainly used in the production of nickel-cadmium batteries, fertilizers, coatings and plastic stabilizers.1 Worldwide use and disposal of electronic waste including televisions, computers and smart phones, greatly contributes to cadmium’s release into the environment. Its presence is of greatest concern in LMICs, where industrial activities continue to release cadmium into the environment.2
Ore mining and refining activities are the largest anthropogenic release of cadmium into the environment, caused by both emissions and the leakage of contaminated water.3 Combustion of fossil fuels and the incineration of waste, as well as the use of mineral fertilizers and sewage sludge as fertilizer also contribute greatly to anthropogenic cadmium sources.
Public awareness surrounding cadmium’s effects on health was first brought to attention during an exposure event in Fuchu Toyama Prefecture, Japan. Women living in regions with cadmium-polluted waters began to suffer from advanced renal and bone disease, now known collectively as Itai-Itai (Ouch-Ouch) disease, one of the Four Big Pollution Diseases of Japan. Regular mining for gold, silver, lead, copper and zinc beginning as early as the 1500s contributed to cadmium’s release into the environment. Mining production continued to increase during the Russo-Japanese War, as well as the World Wars that followed. As cadmium began to accumulate in nearby rivers and riverbeds, it found its way into rice fields as contaminated water was used for irrigation. Although it became clearer that the symptoms of Itai-Itai disease were not simply a regional anomaly deriving from natural sources, it was not until 1955 that scientists began to target cadmium as the potential cause of illness. Release of the cadmium into the environment had lessened by this time, but no formal public announcement was made regarding cadmium’s connection to the disease until the late 1960s.
In early 2012, Jinhe mining company released a large quantity of cadmium into the Guangxi Longiang River in the Guangxi Zhuang Autonomous Region of China. The cadmium spill caused massive fish deaths and threatened the water supply of the water of the greater area. While remediation efforts still continue, environmental releases of cadmium such as that seen in Guangxi continue to place a large burden on the public.
Pure Earth estimates that 5 million people are at risk for exposure to cadmium globally, with an estimated burden of disease of 250,000 DALYs. As of 2015, the Toxic Sites Identification Program has identified over 150 sites around the world where exposure to cadmium threatens the health of the population.
Pathways & Route of Exposures
Cadmium has been shown to have a marked route dependency, with only 5% of an oral dose being absorbed by the gastrointestinal tract. However, cadmium absorption through the lungs is markedly high, with up to 90% of a given dose being absorbed. Cadmium has a unique toxicological profile, with extremely low concentrations capable of causing significant toxicity. As the metal may not undergo metabolic degradation, the human body is ill equipped to rid itself of cadmium.4
The contamination of farmland with cadmium via industrial processes is thought to be the main source of exposure for the non-smoking population. The main contributors to dietary cadmium exposure include bread, potatoes, cereal grains and vegetables. Leafy vegetables and other agricultural products may bioconcentrate cadmium from the soil, and serve as an exposure pathway through the diet, finding its way into the body through both the digestive and respiratory tracts.
Air-borne cadmium particles produced during industrial activities may serve as another exposure pathway through the inhalation of contaminated dust. Electroplating workers, particularly in the aircraft industry, are often at risk of cadmium exposure through the inhalation of airborne cadmium, and this body burden may be further exacerbated in those workers who smoke tobacco.5
Health Effects
Detrimental health effects resulting from exposure to cadmium first came to light in the mid 19th century, as studies acknowledged respiratory and gastrointestinal symptoms resulting from the use of a cadmium containing polishing agent. Symptoms of acute cadmium exposure via inhalation include dizziness, nausea, vomiting, choking, headache and pulmonary irritation. Exposure through inhalation may also result in chronic bronchitis, with heavier exposures causing fibrosis and emphysema. Severe intoxication via inhalation may also result in respiratory distress syndrome due to acute pneumonitis and pulmonary edema, or cardiopulmonary obstructive disease. Following acute cadmium ingestion, health effects include hepatotoxicity with additional symptoms including vomiting, diarrhea and abdominal pain. In cases of severe intoxication via ingestion, death may result due to fluid loss, renal failure, cardiopulmonary depression or liver damage.
The most common observed health effect from chronic cadmium exposure in both the general population and in occupationally exposed individuals is kidney and renal damage. Tubular and glomerular damage resulting from cadmium’s affinity toward epithelial cells may result in nephritis and nephrosis. Additionally, cadmium exposure is also a risk factor for type II diabetes and diabetic complication.6
Cadmium is a known carcinogen, having been designated as such by the World Health Organization’s International Agency for Research on Cancer (IARC). Research studies have repeatedly found an association of cadmium exposure with pulmonary cancers, as well as cancers of the prostate and kidney, while others have found an association with cancer of the liver, hematopoietic system, urinary bladder, breast and stomach. Aside from cadmium’s known association with lung cancer, inhalation may also result in inflammation and fibrosis. Evidence continues to build for an association between exposure and pancreatic cancer.
Cadmium is also a known cardiovascular risk factor and has been shown to contribute to the onset of atherosclerosis, which may contribute to hypertension, stroke, cardiac arrest and heart failure.7 A correlation exists between osteoporosis and cadmium burden in some populations, namely for post-menopausal women, as exposure decreases bone mineral density and increases the chance for fracture. Such decreases in bone density are likely related to kidney malfunction and reduced reabsorption rates in the nephron.
Itai-Itai disease, resulting from cadmium poisoning, includes a number of health effects including the weakening and deformation of bones, gait abnormalities, bone pain, anemia, coughing, kidney failure and death. Recent research has also shown cadmium to have epigenetic effects; altering DNA that is passed from mother to offspring and leading to malignant transformations.8 Additional teratogenic effects due to cadmium ingestion include fetal malformation and restriction of growth.9
1 Tellez-Plaza M, Jones MR, Dominguez-Lucas A, Guallar E, Navas-Acien A. Cadmium exposure and clinical cardiovascular disease: A systematic review. Curr Atheroscler Rep. 2013;15(10):1-15
2 Anetor JI. Rising environmental cadmium levels in developing countries: Threat to genome stability and health. Nigerian Journal of Physiological Sciences. 2013;27(2):103-115
3 Sigel A, Sigel H, Sigel RK. Cadmium: From toxicity to essentiality. Springer; 2013
4 Waalkes MP. Cadmium carcinogenesis. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 2003;533(1):107-120
5 Julin B, Wolk A, Johansson J, Andersson S, Andréen O, Akesson A. Dietary cadmium exposure and prostate cancer incidence: A population-based prospective cohort study. Br J Cancer. 2012;107(5):895-900
6 Thénod F, Lee W. Toxicology of cadmium and its damage to mammalian organs. In: Cadmium: From toxicity to essentiality. Springer; 2013:415-490
7 Messner B, Knoflach M, Seubert A, et al. Cadmium is a novel and independent risk factor for early atherosclerosis mechanisms and in vivo relevance. Arterioscler Thromb Vasc Biol. 2009;29(9):1392-1398
8 Thénod F, Lee W. Toxicology of cadmium and its damage to mammalian organs. In: Cadmium: From toxicity to essentiality. Springer; 2013:415-490
9 Wang Z, Wang H, Xu ZM, et al. Cadmium-induced teratogenicity: Association with ROS-mediated endoplasmic reticulum stress in placenta. Toxicol Appl Pharmacol. 2012;259(2):236-247
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