does exposure to cadmium increase the risk of cancer and other malignancies? Although the International Agency for Research on Cancer classifies cadmium as a carcinogen, there have been other population-based studies that have yielded inconsistent results. But now, a study by a group of Belgian scientists offers strong indication of a clear link between cadmium and cancer.

The scientists randomly chose 521 people living for 16-20 years near three zinc smelters (which use cadmium) in northeastern Belgium and 473 people residing in areas with lower cadmium exposure. It is important to track the exposure to cadmium and cancer incidence over a long time because it has a long elimination half-life of 10 to 30 years. The metal accumulates in the human body, especially the kidneys. Also, an extraordinarily long elimination half-life in the human body allows the lifetime exposure to the toxin to be measured in urine over 24 hours.

The scientists looked at the results of cadmium levels in the residents' urine and also in the soil from their gardens and subsequent occurrence of cancer till June 2004. They found that the environmental exposure to cadmium in the vicinity of zinc smelters was associated with about 30 per cent increase in urinary cadmium excretion, renal dysfunction, increased osteoporosis, a 30 per cent greater risk of all cancers and a 70 per cent increased risk of lung cancer. The study found that an average of 17.2 years of exposure had led to 50 fatal cancers (including 18 lung cancer cases) and 20 non-fatal cancers (including one lung cancer case). Cadmium concentration in the samples taken was found almost twice that for the control group.

The authors say the association between cadmium and cancer remained even after accounting for exposure to arsenic. The study was published online in the Lancet Oncology Journal on January 16, 2006. Says Jan Staessen, one of the authors, "Historical pollution from non-ferrous smelters continues to present a serious health hazard, necessitating targeted preventive measures.