STOCKHOLM, Sweden, March 15 (UPI) -- Dietary cadmium, a toxic metal dispersed in the environment and found in fertilizers, might lead to an elevated breast cancer risk, Swedish researchers said.
Agneta Akesson, an associate professor at Karolinska Institutet in Sweden, and colleagues traced 55,987 women for more than 12 years. They estimated the dietary cadmium exposure using a food frequency questionnaire.
Cadmium occurs at low concentrations in nature but there is a concern because contamination of farmland mainly due to atmospheric deposition and use of fertilizers leads to higher uptake in plants, Akesson said.
"Because of a high accumulation in agricultural crops, the main sources of dietary cadmium are bread and other cereals, potatoes, root crops and vegetables," Akesson said in a statement. "In general, these foods are also considered healthy."
During the follow-up period, researchers observed 2,112 incidences of breast cancer -- including 1,626 estrogen receptor-positive and 290 estrogen receptor-negative cases.
The study, published in Cancer Research, found a higher exposure to cadmium from the diet was linked with a 21 percent increase in breast cancer, but among lean and normal weight women, the increased risk was 27 percent.
Both estrogen receptor-positive and negative tumors had the same risk increase, at roughly 23 percent.
Akesson said women who consumed higher amounts of whole grain and vegetables had a lower risk of breast cancer compared to women exposed to dietary cadmium through other foods.