ABSTRACT
Background: Arsenic (As) is a toxic metalloid. The toxicity resulting from As exposure is linked to the generation of reactive oxygen intermediates, and various metabolic processes associated with the homeostasis of essential metals. Essential metals are coactivators of several important enzymes, including antioxidant enzymes and proteins necessary for health maintenance. Copper (Cu), manganese (Mn), zinc (Zn), cobalt (Co), chromium (Cr), molybdenum (Mo), and selenium (Se) are all essential metals, and any diet deficiency or excessive levels affect the integrity of various physiological and metabolic processes. Although As has no beneficial effects on the human body, it can affect multiple biological processes, including intracellular and intercellular signaling, cell adhesion, protein folding and maturation, apoptosis, ionic transportation, enzyme regulation, and release of neurotransmitters, by inhibiting or disturbing the homeostasis of essential metals.
Objective: To describe the effects of As exposure on Cu, Mn, and Zn concentrations in copper smelter workers and nearby residents.
Methods: In a cross-sectional study, we measured metals in the urine of 1 671 copper smelter workers and 187 community residents (unexposed reference group) using inductively coupled plasma mass spectrometry (ICP-MS). Correlations between the metalloid, As, and the three essential metals were assessed using Spearman’s correlation.
Results: Arsenic concentrations in copper smelter workers were more than three times higher than in the residents (99.3 µg/g and 28.9 µg/g, respectively). Significant differences in Cu, Mn, and Zn concentrations were observed in the two groups. There were significant correlations between urine As, and Zn and Cu in both smelter workers and residents. The strongest correlations were between As and Zn (R2 = 0.086, p = 0.0004), and As and Cu (R2 = 0.051, p = 0.033) for the copper smelter workers, and between As and Zn (R2 = 0.085, p = 0.0001), and As and Cu (R2 = 0.033, p = 0.012) for the residents.
Conclusion: Long-term exposure to As can disrupt the normal homeostasis of essential metals, which may adversely affect biological functions within tissues.