HQ Team
November 22, 2024: Air pollution is a human carcinogenic and is associated with lung, breast and gastric cancers. Long-term exposure to Particulate matter 2.5 m (≤ 2.5 µm) is a strong risk factor for cancer.
A new study highlights a specific link between PM2.5 air pollution and a heightened risk of head and neck cancer (HNC). Inhaling pollutants leads to the deposit of these particles in the upper respiratory airway, which then settles in the lungs.
Cells in the head and neck are especially vulnerable to air pollution. This exposure increases the risk of malignancies like squamous cell carcinoma.
The study was conducted by researchers utilizing data from the Surveillance, Epidemiology, and End Results (SEER) national cancer database, (2002–2012) and county-level PM2.5 exposure data (1981–2016). Researchers adjusted for demographic and lifestyle factors like smoking and alcohol consumption to isolate the impact of PM2.5.
Key findings
The strongest association was found at a five-year lag period, suggesting that the effects of air pollution on cancer development may not be immediate but can manifest years later. The strongest link was found at a 5-year lag, with a 24% higher risk. Zero and 20-year lag periods showed 16% and 15% higher risks, respectively.
The study found a significant association between higher levels of PM2.5 exposure and increased incidence rates of various types of head and neck cancers, particularly oral cavity and pharyngeal cancers. The incidence rate ratio (IRR) was reported as 1.04 per 1 µg/m³ increase in PM2.5, indicating a 4% increase in risk for each unit increase in particulate matter concentration.
Besides oral cavity and pharyngeal cancers, increased PM2.5 exposure was also linked to other specific HNC subtypes, including oesophagal, lip, and tonsil cancers.
“With increasing importance on environmental health and preventative medicine, this study adds to the expanding body of literature that supports improved air quality standards to mitigate the effects of air pollution on the development of cancer, including head and neck cancer,” the authors write.
Significance and further investigation
Air pollution is a significant modifiable risk factor for head and neck cancers, particularly in communities with high PM2.5 exposure. This reinforces the need for stricter air quality regulations and public health initiatives aimed at reducing pollution levels.
The authors want further studies to explore the mechanism and implications of pollutants for the spread of cancer. They also emphasize the importance of subgroup analyses to better understand how different demographics are affected by air quality.
