Trace element imbalance and thyroid hormone alterations among Iraqi oil refinery workers: a comparative cross-sectional study

The present cross-sectional study aimed to evaluate the potential impact of chronic occupational exposure to petroleum pollutants on thyroid hormone and trace element levels in Iraqi refinery workers. This comparative cross-sectional study included 40 male oil refinery workers and 40 unexposed male controls recruited from the community surrounding the refinery. Levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were examined using an electrochemiluminescence immunoassay. Zinc (Zn), copper (Cu), lead (Pb), cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), and magnesium (Mg) were also examined using atomic absorption spectroscopy. The results showed that serum T3 levels were higher by 12.97%, T4 levels were slightly increase of about 2.67%, while TSH levels were lower by - 16.02% in oil refinery workers compared to the control group, suggesting a possible hypothalamic-pituitary-thyroid (HPT) axis disorder. Increased levels of Cu (17.07%), Pb (156.45%) and Cd (83.22%), and decreased levels of Zn (- 17.95%), Cr (- 13.64%) and Co (- 11.97%), were observed in the oil refinery workers group. Additionally, a positive correlation was observed between Cd and TSH levels (r = 0.451, p < 0.01). The findings suggest primary biochemical changes in the endocrine system and mineral metabolism, resulting from endocrine disruption and mineral imbalance following exposure to petroleum products. The current study highlights the need for periodic biomonitoring and preventive measures to reduce chronic health effects in workplaces constantly exposed to environmental toxins like oil refinery.