Metal concentrations in fingernails of male smokers and non-smokers: Analysis using total reflection X-ray fluorescence

Abstract

Cigarette smoking is a major source of exposure to toxic trace elements. Among common sources of exposure, cigarette smoking is one of the leading causes of the accumulation of metals such as cadmium (Cd), lead (Pb), nickel (Ni), arsenic (As), and chromium (Cr) in the human body. In this study, fingernails were used as a biomarker to assess metal accumulation in male smokers and non-smokers. The fingernail samples were analysed using total reflection X-ray fluorescence (TXRF). Compared with non-smokers, smokers had significantly higher levels of Cr, Ni, As, Cd, and Pb (p<0.05), while Zn and Se levels were substantially lower. In smokers, age was positively associated with toxic elements (Cr, Ni, As, Cd, and Pb) and negatively correlated to essential elements (Cu, Zn, and Se). Spearman correlation analysis showed antagonistic interactions between heavy metals and essential elements. These findings confirm that fingernails are an effective tool for monitoring long-term metal exposure and provide clear biological evidence of the adverse effects of cigarette smoking on trace element balance.