Cadmium increases urinary stone risk.
Swaddiwudhipong, W, P Mahasakpan, P Limpatanachote and S Krintraun. 2011. An association between urinary cadmium and urinary stone disease in persons living in cadmium-contaminated villages in northwestern Thailand: A population study. Environmental Research http://dx.doi.org/10.1016/j.envres.2011.01.007.
Exposure to higher levels of the element cadmium increases the risk of stone formation in the urinary system and accelerates calcium loss, suggest results from a recent study in Thailand.
Cadmium affects calcium levels to lower bone density, leading to osteoporosis and a higher risk of fractures. Cadmium exposure also can increase the risk of kidney dysfunction, but little is known about its risk to form kidney and other urinary system stones. Left untreated, urinary stones can grow, cause pain and damage the kidneys and urinary tract.
This large study in cadmium-contaminated areas in Thailand is the first one to suggest a trend of increasing urinary stone diseases with increasing cadmium exposure. This adds additional evidence of cadmium-related damage to the urinary system in humans.
The element is found naturally in soil, rocks, coal and other deposits. It is released from the ground during mining operations where it can pollute water, soil, air and food. Cadmium is used in industrial processes and consumer products, including batteries, pigments and metal coatings. People are often exposed through work, using tobacco products and eating foods such as rice and leafy vegetables.
In this study, Witaya Swaddiwuhipong and colleagues examined 6,748 persons in 12 villages close to zinc mines in the Mae Sot District, Tak Province, Thailand. The cadmium exposure was determined by the levels of cadmium in urine samples, which are often considered an indicator of long-term exposure. The urinary stone disease was defined as a reported history of urinary stone disease or a screening of red blood cells in urine followed by x-ray or ultrasound exams. The researchers adjusted for age, medical conditions (diabetes, high blood pressure) and weight.
The results revealed significant differences in urinary stone disease risk by cadmium exposure: 11 percent in the highest exposure group versus 4 percent in the lowest exposure group. A total of four groups from high to low exposure were defined and each accounted for 25 percent of the study participants. As the cadmium exposure increased, the risk of urinary stone disease increased steadily.
People should reduce exposure to cadmium as much as possible to prevent future risk of bone and kidney diseases, the authors suggest. This is especially important in areas near mines and in the workplace where cadmium exposure is high.
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