Study reveals potential link between air pollution and non-lung cancer risk in older adults

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A comprehensive study conducted on millions of Medicare beneficiaries in the US suggests that long-term exposure to fine particle air pollutants (PM2.5) and nitrogen dioxide (NO2) might elevate the risk of non-lung cancers among older adults.

Led by researchers from Harvard T.H. Chan School of Public Health, the study underscores that over a span of 10 years, prolonged exposure to PM2.5 and NO2 could heighten the likelihood of developing colorectal and prostate cancers.

The research, recently featured in the journal Environmental Epidemiology, further suggests that even low levels of air pollution exposure could render individuals more susceptible to the onset of these cancers, as well as breast and endometrial cancers.

Yaguang Wei, a research fellow in the Department of Environmental Health at Harvard, commented, "Our findings uncover the biological plausibility of air pollution as a crucial risk factor in the development of specific cancers, bringing us one step closer to understanding the impact of air pollution on human health."

Wei emphasized the importance of addressing this issue for the sake of equitable access to clean air and advocated for a concerted effort in understanding and mitigating the effects of air pollution.

Though air pollution's association with lung cancer is well-established, its connection to breast cancer risk has been emerging. However, few studies have delved into its influence on the risk of prostate, colorectal, and endometrial cancers.

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The research team analyzed data from the national Medicare beneficiaries aged 65 or older, spanning from 2000 to 2016. All participants were cancer-free for a minimum of 10 years during the study's commencement.

Distinct cohorts were formed for each cancer type - breast, colorectal, endometrial, and prostate - encompassing between 2.2 million and 6.5 million subjects in each group.

Employing diverse air pollution data sources, the researchers constructed a predictive map depicting PM2.5 and NO2 concentrations throughout the US. This map was then matched with beneficiaries' residential ZIP codes to calculate individual exposures over a decade.

The analysis revealed that chronic PM2.5 and NO2 exposures amplified the risk of colorectal and prostate cancers, while no correlation was observed with endometrial cancer risk.

Regarding breast cancer, NO2 exposure correlated with an escalated risk, whereas the association with PM2.5 was less conclusive, the study noted.

The research team posited that the varying associations could be attributed to the intricate composition of PM2.5, comprising a complex mix of solid and liquid particles.

Notably, when the analysis focused on regions where air pollution levels significantly adhered to national standards and PM2.5 composition remained stable, the impact on breast cancer risk became more prominent.

Moreover, stronger connections between both pollutants and endometrial cancer risk were discovered in areas with lower pollution levels.

Professor Joel Schwartz, a senior author of the study and an environmental epidemiology expert at Harvard, conveyed a critical message: "The key message here is that US air pollution standards are inadequate in protecting public health. Unless all of these standards become much, much stricter, air pollution will continue to result in thousands of unnecessary cases of multiple cancers each year." (Agencies)