I’m not usually one to freak out about things, but I must admit my ears perked up when I read a recent study in the journal Cancer Research linking cadmium exposure to an increased risk of breast cancer.
Cadmium, a naturally occurring metal, is classified by the International Agency for Research on Cancer (IARC) as carcinogenic in humans, and by the U.S. National Toxicology Program as a known human carcinogen. Although cadmium is a known toxin of cigarettes, the recent study found a potential risk in food, and more specifically, food generally considered as healthy.
Researchers in Sweden observed nearly 56,000 postmenopausal women for more than 12 years and found those with the highest intake of cadmium in their diets – from foods like whole and refined grains, vegetables and potatoes – showed a 21 percent increased risk of developing breast cancer. Among women who were lean or normal weight, that risk increased to 27 percent.
Because cadmium is commonly used in farm fertilizer and has a tendency to accumulate on crops, scientists in Sweden worry the toxin may be leading to higher-than-normal human exposure.
As a woman who has maintained a plant-based diet for more than 15 years, I hoped more perspective would calm my worried mind. For insight, I turned to Kenneth Portier, Ph.D., managing director of the Statistics & Evaluation Center for the American Cancer Society. He also provides expert advice on issues related to the health risks of environmental toxins to the U.S. Environmental Protection Agency, the National Toxicology Program and the WHO/FAO.
What’s your overall take on this study?
“This is a very solid study that is likely to be influential in getting cadmium classified as either a breast carcinogen or a breast tumor promoter. The thing that’s different about this study is that it ties what we already know about the effects of cadmium exposures from research on cells and animals, to the increased risks of breast cancer in exposed women.”
Why the impact on postmenopausal women?
“Recent research has demonstrated that cadmium can operate like estrogen in the body, and we know from other data that estrogen promotes cancer growth. These effects are expected to be most evident in postmenopausal women who have less estrogen and hence are more sensitive to increases from external estrogens. In women who have gone through menopause, you have to be concerned about anything that may increase estrogen levels – including dietary sources.”
How concerned should women be about cadmium?
“The risk from cadmium in your diet has to be put in perspective with the risk from all of the other factors we know about; there are several risk factors for breast cancer: Do you have a family history of breast cancer? Do you drink too much alcohol? Are you obese? Do you get enough exercise? While many of these factors were accounted for in this study, there are many others that may not have been. Discussion of this study in the research and medical community will help sort out the level of risk.”
What would you anticipate next in cadmium research?
“Additional research is needed to tie together the chemistry of what happens to cadmium in the female body and to understand the mitigating factors on reducing risk. We have to have something concrete to offer women who want to reduce their risk, and determine how people can change behavior or diet in ways that would actually reduce their risk from cadmium exposure while not increasing other dangers or causing adverse health conditions. In this case, we are not sure of the next steps.”
Dr. Portier says now is the time to get answers to what appears to be a vexing question: how do we ensure people have access to healthy and affordable produce without facing potential risks from fertilizers? In the meantime, visit the American Cancer Society’s Staying Healthy website to find answers to common questions about healthy food choices.