Air Pollution Determined to be Risk Factor for Thyroid Eye Disease

Thyroid eye disease, associated with Graves’ disease, can develop from other mechanisms, including oxidative stress and inflammation from air pollution. Photo: Getty Images. Click image to enlarge. Human health can be impacted by a multitude of factors, including the surrounding environment. Although imperceptible, particulate matter and harmful gasses are constantly circulating throughout the air, and these pollutants can be damaging to the eyes as well as the lungs.In a recent study, researchers from Taiwan investigated the influence long-term air pollution has on the risk of developing thyroid eye disease. Using the country’s National Health Insurance Research Database, they were able to gather data on newly diagnosed patients from 2003 to 2013. Then, they analyzed this data in conjunction with information from Taiwan’s Environmental Protection Administration. They chose 10 pollutants for their hypothesis that could potentially increase the risk of this inflammatory disorder: sulfur dioxide (SO2), carbon monoxide (CO), particles less than 10 μm in diameter (PM10), particles less than 2.5 μm in diameter (PM2.5), nitrogen oxides (NOX), nitric oxide (NO), nitrogen dioxide (NO2), total hydrocarbons (THC), nonmethane hydrocarbons (NMHC) and methane (CH4).The National Health Insurance Research Database outputted 7,340 cases; however, 218 patients developed thyroid eye disease within the 10-year time period. Researchers discovered that there was a significant association between the risk of developing this autoimmune disease and each of the 10 pollutants. Using a regression model, they discovered the percentage of each pollutant increased the risk of disease from a rise in pollution exposure rates over the 10-year time period. Disease risk rose 26% due to SO2, 62% due to CO, 74% due to PM10, 49% due to PM2.5, 47% due to NOX, 32% due to NO, 56% due to NO2, 27% due to THC, 20% due to NMHC and 24% due to CH4.“Air pollution elicits oxidative stress and inflammation, specifically enhancing the production of proinflammatory mediators and reactive oxygen species,” wrote the authors in their paper for Ophthalmic Plastic and Reconstructive Surgery on how air pollution influences thyroid eye disease. “The second possible mechanism is that air pollution exposure causes alterations in thyroid function, which in turn increases thyroid eye disease risk,” they noted. For their last hypothesis, they speculated that “pollution-induced stimulation of adipogenesis may be closely linked to thyroid eye disease onset and manifestations.”This study had several limitations that hindered the researchers’ results. For instance, they attempted to include smokers in their cohort, yet information from the database used possibly misclassified smokers. Additionally, the database restricted their ability to identify other key factors such as comorbidities, laboratory findings and lifestyle changes. Also, they attempted to account for residential changes for each patient, but patients could have inaccurately updated this information, which compromised the results. Other limitations included unmeasured data points, not accounting for mixed effects between pollutants, imminent exposure to all pollutants (regardless of the patient’s health) and deviation of pollution levels.“Our findings offer compelling evidence that authorities can utilize to formulate and implement air pollution prevention strategies, aiming to reduce the burden on the healthcare system,” concluded the authors. “Nevertheless, further studies incorporating well-adjusted confounders are essential to investigate the relationship between air pollution and thyroid eye disease, along with exploring the underlying pathophysiological mechanisms.”Click here for the journal source. Chuang SH, Chen YP, Wu CC, et al. The association between long-term air pollution exposure and risk of thyroid eye disease: A nationwide cohort study in Taiwan. Ophthalm Plast Recon Surg. May 7, 2025. [Epub ahead of print].