New research finds that long-term exposure to fine particulate air pollution, whether at home or in the workplace, is linked to an increased risk of breast cancer. The findings add to growing evidence on the dangers of air pollution and underscore the need to reduce it.
Breast cancer has become the most common cancer worldwide. The risk factors are well known and include age, obesity, alcohol abuse, smoking and family history of breast cancer.
Now, a new study adds another risk factor: fine particle air pollution. At the upcoming European Society for Medical Oncology (ESMO) 2023 Congress in Madrid, Spain, researchers will present a paper exploring the link between long-term exposure to fine particulate air pollution and breast cancer risk.
"Our data show a statistically significant association between long-term exposure to fine particulate air pollution at home or in the workplace and breast cancer risk," said Béatrice Fervers, lead author of the study. "This is in stark contrast to previous studies, which looked only at fine particulate exposure where women lived and found little or no effect on breast cancer risk."
Fine particulate matter, or PM2.5, refers to tiny particles or droplets in the air with a diameter of 2.5 microns or less. Exhaust emissions from burning gasoline, oil, diesel or wood produce most of the PM2.5 in outdoor air. Indoor activities also produce PM2.5, including pets, mold, cleaning products, smoking, and burning wood and candles. Larger particles 10 microns or smaller are called PM10.
Researchers compared home and workplace pollution exposure in 2,419 women with breast cancer and 2,984 women without breast cancer between 1990 and 2011. They found that when exposure to PM2.5 increased by 10 micrograms per cubic meter, the risk of breast cancer increased by 28%, which is roughly equivalent to the typical difference in PM2.5 concentrations in rural and urban areas in Europe. Women exposed to high levels of PM10 or another air pollutant, nitrogen dioxide, had a smaller increase in breast cancer risk.
"These very small particles can penetrate deep into the lungs and into the bloodstream, where they are then absorbed by the breast and other tissues," said Charles Swanton of the Francis Crick Institute in London. "There is already evidence that air pollutants can change the structure of the breast. It will be important to examine whether pollutants can allow pre-existing mutated cells in breast tissue to expand and drive tumors, possibly through inflammatory processes similar to those we see in non-smokers with lung cancer."
The researchers say their findings add to growing evidence of the health risks of air pollutants and underscore the urgent need for further research.
"It is very concerning that small airborne pollutants and similarly sized microplastic particles have entered the environment when we do not yet understand their potential to induce cancer," Swanton said. "There is an urgent need to establish laboratory studies to investigate the impact of these small airborne pollutants on the latency, grade, aggressiveness and progression of breast tumors."