Refinery Workers Show Thyroid and Trace Element Shifts

A comparative cross-sectional study published in Environmental Geochemistry and Health reports distinct alterations in thyroid hormone levels and trace element concentrations among male workers at an Iraqi oil refinery. The research, conducted by Mohammed Nameer, Falah S. Al-Fartusie, and Ammer Salih, aimed to evaluate the potential impact of chronic occupational exposure to petroleum pollutants on the endocrine system and mineral metabolism. The study specifically focused on a group of 40 male oil refinery workers who were compared against 40 unexposed male controls recruited from the community surrounding the refinery.

The investigators examined several key biological markers to assess the physiological impact of the exposure. Thyroid function was evaluated by measuring the levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) using an electrochemiluminescence immunoassay. In addition to thyroid markers, the study analyzed the concentrations of eight specific trace elements: zinc (Zn), copper (Cu), lead (Pb), cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), and magnesium (Mg).

The results indicated significant differences in thyroid hormone profiles between the refinery workers and the control group. Serum T3 levels were found to be higher by 12.97% in the workers compared to the controls. Similarly, T4 levels showed a slight increase of approximately 2.67% in the exposed group. In contrast, TSH levels were lower by 16.02% among the refinery workers. The combination of elevated T3 and T4 alongside suppressed TSH suggests a possible disorder in the hypothalamic-pituitary-thyroid axis.

Analysis of trace element levels revealed a complex pattern of imbalance in the exposed workers. The study observed increased levels of copper by 17.07%, lead by 156.45%, and cadmium by 83.22% in the refinery group relative to the controls. Zinc levels dropped by 17.95%, chromium by 13.64%, and cobalt by 11.97%.

The researchers also identified a statistical relationship between specific toxic elements and thyroid function. A positive correlation was observed between cadmium levels and TSH levels, with a correlation coefficient of r = 0.451 and a p-value of less than 0.01. This statistically significant association implies that higher cadmium exposure is linked to changes in thyroid-stimulating hormone levels. The study suggests that these biochemical changes are primary effects of endocrine disruption and mineral imbalance resulting from exposure to petroleum products.

The findings highlight the need for periodic biomonitoring and preventive measures in workplaces where workers are constantly exposed to environmental toxins like those found in oil refineries. The study underscores that chronic occupational exposure can lead to measurable changes in both endocrine function and mineral metabolism.

While it establishes clear differences between the exposed and control groups, it does not track changes over time or definitively prove that the exposure caused the observed alterations.

Subject of Research: Impact of occupational petroleum exposure on thyroid function and trace element balance in refinery workers

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

Article References: Nameer, M., Al-Fartusie, F. S., & Salih, A. (2026). Trace element imbalance and thyroid hormone alterations among Iraqi oil refinery workers: a comparative cross-sectional study. Environmental Geochemistry and Health, 48(17), Article 684. https://doi.org/10.1007/s10653-026-03593-y

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03593-y

Keywords: thyroid hormones, trace elements, oil refinery, occupational health, endocrine disruption, cadmium, lead, cross-sectional study, Iraq, petroleum pollutants, Trace, element