Pollution Raises Breast Cancer Risk

New research finds that even low levels of traffic-related air pollution can raise breast cancer risk, urging stronger clean air policies and early detection awareness.

Women living in areas with poor air quality—even those meeting current Environmental Protection Agency (EPA) standards—face a higher risk of developing breast cancer, according to new research from Oregon State University and collaborators across leading U.S. institutions (1^✔ ✔Trusted Source
Air Pollutants and Breast Cancer Risk: A Parallel Analysis of Five Large US Prospective Cohorts

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The study, published in the American Journal of Public Health, analyzed data from more than 400,000 women and 28,000 breast cancer cases, highlighting a concerning link between traffic-related air pollution and breast cancer incidence.

Invisible Pollutants, Visible Impact on Women’s Health

Researchers found that every 10-parts-per-billion increase in nitrogen dioxide (NO₂)—a pollutant emitted by car exhaust—was linked to a 3% rise in breast cancer cases. Nitrogen dioxide serves as a key marker of motor vehicle emissions.

Study co-author explained that even modest exposure below EPA limits could significantly affect population-level health. Based on current U.S. data, a mere 3% reduction in breast cancer cases could prevent approximately 9,500 new diagnoses annually.

Fine Particles, Deadlier Tumors

Beyond nitrogen dioxide, higher exposure to fine particulate matter (PM2.5)—tiny airborne particles from fuel combustion—was associated with a rise in hormone receptor-negative breast cancers. These tumors lack estrogen and progesterone receptors and are often more aggressive, harder to treat, and have poorer survival outcomes. In fact, a 5-microgram-per-cubic-meter rise in PM2.5 concentration was associated with a higher incidence of hormone receptor-negative breast cancer, underscoring the sensitivity of these tumor types to air quality changes.

Researchers combined findings from five major breast cancer cohorts that tracked participants for up to 10 years, adjusting for residential changes and overlaying data from 2,600 air quality monitoring stations across the U.S.

Why “Safe” Air May Not Be Safe Enough

Despite air quality improvements in many American cities, the study’s findings challenge current definitions of “acceptable” pollution levels. “It’s often not realistic for people to relocate to cleaner areas,” said the author.

“We need more effective clean air laws and policies that reduce car traffic and promote sustainable transportation.” Experts emphasize that the EPA guidelines may underestimate the health risks posed by long-term exposure to pollutants at low concentrations.

Breast Cancer and the Growing Environmental Burden

In the United States, breast cancer remains the second leading cause of cancer death among women, after lung cancer. Rates have risen steadily over the past four decades. Roughly one in eight women will develop breast cancer in her lifetime, and more than 4 million survivors live in the country today.

Lead author Dr. Alexandra White from the National Institutes of Health (NIH) collaborated with researchers from Harvard University, University of Washington, UC San Diego, Indiana University, The Ohio State University, and UNC Chapel Hill. Funding for the research came from the NIH, EPA, National Institute of Environmental Health Sciences, and other federal health agencies.

Protecting Women Through Policy and Prevention

Experts urge stronger public health responses, cleaner urban planning, and enhanced awareness of environmental carcinogens. Public health programs like Oregon State University’s upcoming panel, “Our Health & Breast Cancer”, aim to educate women about screening, early detection, and survivorship. Study concluded, “Clean air is not just about lungs—it’s about every cell in the body. Our findings remind us that environmental health is women’s health.”

Reference:

1. Air Pollutants and Breast Cancer Risk: A Parallel Analysis of Five Large US Prospective Cohorts – (https://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2025.308247?journalCode=ajph)

Source-Medindia