Scientists have known for some time about the increased risk of breast cancer from certain chemicals that mimic the natural hormone estrogen. Typically, these have been the complex molecules that are found in many plants and man-made products like detergents, pesticides and plastics. But now, scientists speculate that a variety of simple metals - such as aluminum and cadmium - can also bind to the body's estrogen-receptors, influence their action and thereby possibly increase a woman's risk of developing cancer. Researchers, writing in the Journal of Applied Toxicology, say they are most concerned about certain aluminum compounds, which often make up a quarter of the volume of antiperspirant deodorants. They hypothesize that the metallic compound can break through the skin and that once in the body, it could mimic the effects of estrogen.
The aluminum salts in antiperspirants are a major source of exposure to aluminum in humans, say the researchers, and because it is sprayed into armpits, exposure is concentrated near the breast. Worryingly, it is often applied immediately after shaving, when the skin is likely to be damaged and less able to keep the aluminum out.
"It is reasonable to question whether this aluminum could then influence breast cancer," said Philippa Darbre, at the University of Reading, in the UK. "Since estrogen is known to be involved in the development and progression of human breast cancer, any components of the environment that have estrogenic activity and which can enter the human breast could theoretically influence a woman's risk of breast cancer," she added.
Aluminum is not the only metal of concern to the researchers. Smoking introduces the metal cadmium into the body, and past studies have shown that it too can collect in breast tissue. And there are indications that this accumulation of cadmium may also be linked to an increased risk of breast cancer.
Darbre says that more research into the possible side-effects of exposure to metallic compounds is needed. "Each of these agents on their own may not have a powerful effect, but we need to see what happens when a number of them act together - it could be that this would have a significant effect on diseases like breast cancer," she said.
Source: The Journal of Applied Toxicology
