Urban Air Pollution Associated with the Incidence of Autoimmune Thyroid Diseases

Endocrine disrupting air pollutants such as sulphur dioxide (SO₂), carbon monoxide (CO), nitrogen dioxide (NO₂), fine particle matter (PM_2.5), and ozone (O₃) can affect thyroid gland function on the level of synthesis, metabolism, and the action of its hormones.

The aim of this study was to establish whether increased air pollution could contribute to an increased incidence of autoimmune thyroid diseases (AITD).

A retrospective analysis was conducted of the medical records of 82000 patients at the University Clinical Centre in Tuzla, Bosnia and Herzegovina. The target group of this study comprised a total of 174 patients from the Lukavac area. Daily data on concentrations of air pollutants were collected from the air quality monitoring station located in Lukavac. The study covered the period from 2015 to 2020.

The results of the monitoring confirmed the presence of air pollutants in concentrations above the permitted limits throughout the entire observed period. Concentrations of PM_2.5, SO₂, NO₂, CO, and O₃ were in the range of 1.90-431.40 μg/m³, 3.60-620.50 μg/m³, 3.40-66.20 μg/m³, 48.00-7002.00 μg/m³, and 0.70-89.40 μg/m³, with means of 64.08 μg/m³, 77.48 μg/m³, 22.57 μg/m³, 1657.15 μg/m³, and 31.49 μg/m³, respectively. During the six-year period, 174 cases of AITD were registered, of which 150 (86.21%) were women and 24 (13.79%) men. Hashimoto's thyroiditis was found in 33 patients (18.97%), whilst 141 patients (81.03%) were diagnosed with atrophic thyroiditis. The highest total incidence of autoimmune thyroiditis was recorded in 2017, when it reached 99.49, 95% CI.

The effects of chronic exposure to a mixture of air pollutants on the function of the thyroid gland are still not sufficiently well-known, but the numerical tendency towards a higher incidence of AITD in this study, albeit without statistical significance (p>0.05), still underlines the need for additional research.