A new Canadian case-control study has reported that living up to two miles from a petroleum refinery, power plant, or steel or pulp mill could increase breast cancer risk. The study was designed to investigate the relationships between living near a paper mill, pulp mill, steel mill, petroleum refinery, thermal power plant, alum smelter, nickel smelter, lead smelter, copper smelter, or zinc smelter and risk of breast cancer. Most power plants are thermal (as opposed to hydroelectric), using steam to spin a turbine to drive an electrical generator. Thermal power plants include fossil fuel (coal, oil or gas), nuclear, and geothermal plants, among others.

The study included 2,343 breast cancer cases and 2,467 cancer-free controls. A questionnaire was used to determine residential proximity at any time between 1960 and five years before the data was collected.

Risk of breast cancer was found to be elevated for (1) premenopausal women who lived within two miles of a steel mill or within half a mile of a thermal power plant; and (2) postmenopausal women who lived within two miles of a petroleum refinery or pulp mill or within half a mile of a thermal power plant for at least 10 years. The authors conclude that their preliminary results suggest possible weak associations between breast cancer and proximity to steel mills, pulp mills, petroleum refineries, and thermal power plants.