A Blood‐Based Risk Assessment of Heavy Metal Exposure to Tannery Workers in Bangladesh

Leather tanning industry is a major economic contributor in Bangladesh; however, inadequate safety measures and unregulated exposure to pollutants pose substantial health risks to tannery workers. This study aimed at characterizing the exposure profile of selected heavy metals among tannery workers, considering demographic factors like age, gender, work experience, and smoking habit. Blood samples were collected from 50 workers in four tanneries of Savar, Bangladesh, during February 2023. After acid digestion, the samples were analyzed by ICP-MS to quantify 14 heavy metals. Results revealed that the average blood concentration of Cu was the highest (692 ± 158 μg/L), whereas that of Be was the lowest (0.10 ± 0.08 μg/L). Mean blood level of Cr (24.7 ± 13.9 μg/L) exceeded the international standards. Workers with > 20 years of experience exhibited 1.5 times higher blood Cr levels than those with < 10 years (32.3 vs. 21.2 μg/L), indicating the bioaccumulation of Cr from tannery exposure. Direct interaction with raw materials and heavy machinery probably caused elevated heavy metal levels in men, as compared to women. In addition, Cd, Cr, Hg, Ni, and V levels were higher in workers over 40 years of age, implying the bioaccumulation of metals over the years. Smokers recorded higher levels of Pb, Ni, Cr, Cd, As, and Co than nonsmokers; however, the difference was statistically insignificant (p > 0.05). Strong correlations were observed between metal pairs (Co-Mn, Co-Pb, As-V, Mn-Ni, Ni-Pb, Mn-Pb, and Hg-V), suggesting common sources. Three sources were resolved by positive matrix factorization (PMF)-industrial source, mixed source (industry and traffic), and crustal source, contributing 36.1%, 36.4%, and 27.5% to the total heavy metal levels in blood samples. These findings highlighted severe occupational risk among the tannery workers from uncontrolled heavy metal exposure, emphasizing the need for ensuring occupational safety in the tanneries of Bangladesh.