Air pollution exposure and mammographic breast density in Tehran, Iran: a cross-sectional study

Abstract

Background: Air pollution is one of the major public health challenges in many parts of the world possibly has an association with breast cancer. However, the mechanism is still unclear. This study aimed to find an association between exposure to six criteria ambient air pollutants (PM 2.5 , PM 10 , SO 2 , NO 2 , O 3 , and CO) and mammographic breast density (MBD), as one of the strongest predictors for developing breast cancer, in women living in Tehran, Iran. Methods: Participants were selected from women attending two university hospitals for screening mammography from 2019 to 2021. Breast density was rated by two expert radiologists. Individual exposures to 3-year ambient air pollution levels at the residence were estimated.Results: The final analysis in 791 eligible women showed that low and high breast density was detected in 34.8 and 62.2 of participants, respectively. Logistic regression analysis after considering all possible confounding factors represented that an increase in each unit of NO 2 (ppb) exposure was associated with an increased risk of breast density with an OR equal to 1.04 (95CI: 1.01 to 1.07). Furthermore, CO level was associated with a decreasing breast density (OR = 0.40, 95CI = 0.19 to 0.86). None of the other pollutants were associated with breast density. Conclusion: Higher MBD was associated with an increased level of NO 2 , as a marker of traffic-related air pollution. Furthermore, CO concentration was associated with a lower MBD, while other criteria air pollutants were not related to MBD. Further studies are needed to evaluate the association between ambient air pollutants with MBD.

Pneumonia hospitalization risk attributable to ambient air pollution and temperature in a mid-temperate, industrial city: a time-series analysis

“…The findings of the Global Burden of Disease in 2019 showed that air pollution, as a major level 2 risk factor for the global burden of disease, has become the fourth leading cause of globally attributable mortality (5). Previous studies have shown that air pollution affects people's health (6,7). The World Health Organization estimates that 7 million deaths occur globally each year due to air pollution, with 7% of these deaths attributed to pneumonia (8).…”