Increased cadmium levels associated with cancer mortality
MedWire News: Cadmium exposure is associated with an increased risk for death from cancer, US research shows.
In men, cadmium exposure is linked with higher rates of death from lung cancer, non-Hodgkin lymphoma, and pancreatic cancer.
For women, however, the risk for death from specific cancers is less clear, report Scott Adams (Fred Hutchinson Cancer Research Center, Seattle, Washington) and colleagues in the journal Occupational and Environmental Medicine.
Cadmium is a heavy metal classified as a carcinogen. Humans are exposed to cadmium mainly through agricultural practices or industrial releases that result in contaminated soil. Leafy vegetables and grains can accumulate cadmium from the soil, and this leads to human exposure.
The carcinogenic data highlighting the risks associated with cadmium exposure are derived mainly from laboratory animal studies. The prospective, epidemiologic evidence in humans is limited, however, leading to some controversy about the risks associated with exposure to the heavy metal.
To investigate the relationship between cadmium exposure and cancer mortality, the researchers used data from the US National Health and Nutrition Examination Survey (NHANES) - a survey of a representative US sample taken between 1988 and 1994.
Cadmium concentrations of spot urine samples were measured and corrected for urine creatinine. The mean urinary cadmium concentration was 0.252 µg/g in men and 0.352 µg/g in women.
Each two-fold increase in urinary cadmium concentration was associated with a 26% increased risk for death from cancer in men and a 21% increased risk for death from cancer in women.
For men and women in the highest quartile of urinary cadmium concentration there was a 70% and 34% increased risk for death from cancer, respectively, compared with men and women in the lowest quartile.
In men, the risk for death from lung cancer increased by 81% with every two-fold increase in urinary cadmium, while the risk for dying from non-Hodgkin lymphoma more than doubled (hazard ratio=2.53).
There was a trend toward an increased risk for death from lung, uterine, and ovarian cancer in women with high concentrations of urinary cadmium, as well as a trend toward a higher risk for death from leukemia.
Restricting the analysis to individuals who never smoked attenuated the association between cadmium and cancer mortality.
"Overall, these results add evidence in support of the hypothesis that exposure to cadmium is a cause of excess cancer death in the US population," conclude Adams and colleagues.
The study also sheds light on some of the risks for specific cancers, but these findings should be considered cautiously and hypothesis-generating, they add.
By MedWire Reporters