Correlation between urinary cadmium and thyroid hormones in outdoor workers exposed to urban stressors

Objectives: The aim of this study is to evaluate whether exposure to low concentrations of cadmium (Cd) can have effects on the thyroid hormone level of outdoor workers exposed to urban pollutants. Methods: The study was conducted on a final sample of 277 individuals (184 males and 93 females). The environmental monitoring of Cd was evaluated through the use of portable dosimeters, while the biological monitoring was achieved through the assessment of urinary Cd and thyroid hormones. The total sample was divided according to sex and task. The Pearson's correlation coefficient among the variables was calculated after subdivision on the basis of sex and task. The multiple linear regression was performed to take into account the major confounding factors. Results: Statistical tests showed a negative correlation between urinary Cd levels and free triiodothyronine and free thyroxine and a positive correlation between urinary Cd and thyroid-stimulating hormone levels. Conclusions: Our early results seem to point out that occupational exposure to low concentrations of Cd present in urban air affects the thyroid hormone levels in exposed workers.