Breast Cancer Risks Could Increase With Long-Term Air Pollution Exposure: Study

Women who live in close proximity to major roads and industrial areas face an increased risk of developing breast cancer, which could affect differences in breast cancer rates between white women and other ethnicities, according to the findings of new research.

Breast cancer is the most commonly diagnosed form of cancer among women worldwide. Although survival rates are often high, there can be a number of adverse side effects for women diagnosed with breast cancer, including physical, mental and financial distress.

In recent years, a number of factors have been discovered that could increase breast cancer risks for women, including alcohol use, smoking, obesity and reproductive histories. However, researchers have noted that the risk of breast cancer continues to be increasing for some groups of women, particularly along ethnic lines.

In a study published last month in the Journal of Clinical Oncology, researchers indicate that it may not be genetic predispositions that are leading to an increased number of Black and Latina women developing breast cancer. Rather, it appears that environmental factors are impacting the risk for these women, who often live in urban areas with high levels of air pollution.

In the report, a team of researchers led by Anna H. Wu of the Keck School of Medicine at the University of Southern California looked at breast cancer rates among a group of 58,538 female participants from California, in a multiethnic cohort study.

After following the women for an average of 19 years, and adjusting for sociodemographic and lifestyle factors, Wu’s team determined that air pollution is a primary risk factor for breast cancer. However, the researchers also determined that Black and Latina women accounted for 70% of the total number of breast cancer diagnoses.

Although the majority of women included in the study were from urban areas, Wu’s team indicates that the histories of those areas have placed Black and Latino populations in areas with more industrial facilities and highways, which release greater amounts of pollutants into the air, contributing to greater incidences of breast cancer in those ethnicities.

This information does not necessarily help prevent cases of breast cancer, but it could assist doctors in diagnosing and treating it.

“Increased awareness of the relationship between air pollution and breast cancer for both physicians and patients could facilitate more routine capturing of information related to a patient’s residential histories,” Dr. Alexandra J. White said in an article accompanying the study. “Although exposure to outdoor air pollution is largely not directly modifiable or treatable, patients’ comprehensive residence information can be used to estimate air pollutant exposure concentrations and other residence-based environmental exposures.”

Air Pollution Affects Millions of Americans

According to the American Lung Association, one-third of Americans live in areas with unhealthy levels of air pollution, leading to a number of serious health problems, including asthma, heart disease and different forms of cancer. Approximately 120 million people live in these highly polluted areas, and prior research has found that the vast majority are minorities.

To address the health risks in certain areas of the country, the U.S. Environmental Protection Agency (EPA) proposed a rule to reduce particulate matter in air pollution in January 2023. The EPA’s proposed addition to the national ambient air quality standards (NAAQS) was passed by Congress in April 2024.

This effort to reduce the negative impact of air pollution on human health in the U.S. was targeted specifically at disadvantaged communities. It included strengthening the primary standard for particulate matter released into the air from 12 micrograms per cubic meter to between nine and 10 mcg per cubic meter.

Researchers have indicated that strengthening these standards could prevent up to 4,200 premature deaths each year, from various different health problems linked to air pollution.