Air Pollution and Breast Cancer Risk – Home and Workplace Exposure
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Women living and working in areas with higher levels of fine-particle air pollution were found to have a higher risk of breast cancer than women in less polluted areas.
The European Society for Medical Oncology (ESMO) 2023 Congress featured a study by Dr. Béatrice Fervers and colleagues examining how air pollution exposure both at home and at work affected breast cancer risk.
The data showed a statistically significant association between long-term fine-particle exposure at home and work and breast cancer risk. This contrasts with earlier studies examining exposure at women's residences that found little or no effect on risk, making it an important new finding.
Study Details
The study compared home and workplace pollution exposure from 1990 to 2011 in 2419 women with breast cancer and 2984 women without it.
Breast cancer risk increased by 28% for each 10 µg/m³ increase in exposure to fine-particle (PM2.5, particulate matter measuring 2.5 µm in diameter) air pollution.
This is approximately equivalent to the typical difference in PM2.5 concentrations between rural and urban areas in Europe.
Smaller increases in breast cancer risk were also recorded in women highly exposed to larger-particle air pollution (PM10 and nitrogen dioxide). This indicates that particles of different sizes (PM2.5 and PM10) and gases such as nitrogen dioxide (NO2) have different effects on breast cancer risk. PM2.5 particles, measuring 2.5 micrometers or less, markedly increased risk, whereas PM10 particles, measuring 10 micrometers or less, and nitrogen dioxide gas were associated with smaller increases.
Dr. Fervers and colleagues now plan to study pollution exposure during commuting to obtain a fuller picture of its effects on breast cancer risk.
The Profound Effects of Air Pollution Particles on Breast Tissue
These tiny particles can penetrate deep into the lungs and enter the bloodstream, from which they are absorbed into breast and other tissues. Evidence already suggests that pollution may alter breast tissue architecture [papers by Niehoff and colleagues in Breast Cancer Research and Kotake and colleagues in Environmental Science and Pollution Research]. It will be important to test whether cells with pre-existing mutations drive tumor promotion, potentially through inflammatory processes, as in our observations of lung cancer in nonsmokers.
RELATED TOPICS
We do not yet fully understand how small air pollution particles, similar in size to microplastics, enter the environment. Their potential to trigger cancer is a major concern. Laboratory studies are urgently needed to investigate their effects on breast tumor aggressiveness and progression.
Strong epidemiological and biological evidence now links PM2.5 exposure to cancer, providing sound clinical and economic reasons to prevent cancers by reducing pollution.
How Is Air Pollution Measured?
Air pollution is assessed by measuring concentrations of various pollutants in the atmosphere. The study described here measured two main particle sizes: PM2.5 and PM10.
PM2.5 consists of fine particles measuring 2.5 micrometers (µm) or less in diameter; PM10 refers to larger particles measuring 10 micrometers or less. Nitrogen dioxide (NO2) levels were also considered as another pollution indicator.
Measurements are expressed as particle concentrations in micrograms per cubic meter (µg/m³).
PM2.5 particles are approximately 30 times finer than the diameter of a human hair. Main sources of PM2.5 pollution include:
Burning Fossil Fuels:
- Motor vehicles: Diesel- and gasoline-powered vehicles such as cars, trucks, and buses.
- Power generation: Burning fossil fuels such as coal or natural gas in power plants.
- Domestic heating: Heating homes using coal, wood, or natural gas.
Industrial Activities:
- Factories and manufacturing plants: Emissions from production processes.
- Construction sites: Dust from construction and demolition.
Agricultural Activities:
- Dust rising from farmland.
- Fertilizer and pesticide use.
Natural Sources:
- Natural events such as volcanic activity and forest fires.
- Windblown dust from deserts.
Indoor Sources:
- Activities such as smoking, cooking, and burning candles or wood.
PM2.5 particles can reach deep into the lungs through inhalation and enter the bloodstream. They can therefore have serious health effects, causing respiratory diseases, heart disease, and even cancer. Controlling emission sources and enforcing air-quality regulations are important for reducing them.
Pollution is generally measured by environmental monitoring stations, with data used in air-quality assessments and epidemiological studies.
Where Is the World's Air Most Polluted and Cleanest?
Pollution tends to be worse in industrialized, densely populated cities, high-traffic areas, and places with poorly organized urban planning.
The world's most polluted cities are generally in South and East Asia. Some cities in India, Pakistan, and China, for example, may have the highest air pollution levels.
Cities with the cleanest air generally have little industrial activity, comprehensive air-quality regulations, and extensive green spaces. Some cities in Scandinavia, New Zealand, and Canada are often cited as having low pollution levels.
Current air-quality indices and pollution measurements are available in reports regularly published by air-quality monitoring networks and environmental protection agencies worldwide.
Reducing airborne PM2.5 to World Health Organization recommended levels is vital, given its links to various tumors, including breast cancer. Researchers emphasize their responsibility to help achieve this important change not only in Europe but worldwide, where pollution levels vary greatly.
Conclusion
Clear scientific evidence now establishes the health harms of air pollution. Public health policy must take this into account. Producing evidence alone does not finish the task, and positive change will not happen overnight, but we must move in the right direction.
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