In large doses, cadmium is carcinogenic. A study now shows that even chronic exposure to the heavy metal in low doses causes breast cancer. Dinsa Sachan speaks to Maggie C Louie, associate professor of biochemistry at Dominican University of California in the US, about the study
What were your key findings?
We have found a link between chronic exposure to cadmium, a common environmental contaminant, at low level and rapid breast cancer growth. The longer the breast cancer cells are exposed to cadmium, the more aggressive they become. This is relevant as people are not exposed to high levels unless they work in manufacturing plants.
How does cadmium cause cancer?
Under acute exposure, cadmium acts as a metalloestrogen and mimics the female hormone. Higher levels of estrogen promote breast cancer growth. We don’t know exactly what happens when there is chronic exposure to low doses of the metal. To find this, we used breast cancer cell lines. We found upon exposure, the cancer cells invade through the extracellular matrix. The cells also produce higher level of a protein associated with tumor invasion and metastasis. We have evidence that a dose between seven and 10 mole/litre over six months promotes breast cancer, but we need more evidence.
Can we reduce cadmium exposure?
People are exposed to it via contaminated air, water and food. For example, nickel-cadmium batteries should be properly recycled so that the metals do not leach into the groundwater and soil. Smoking should be minimised because cigarettes contain lots of cadmium.