Duration-dependent Depletion of Micronutrients in Nigerian Male Workers Exposed to Lead

Abstract

Background: This study examined how the duration of occupational lead exposure affects haemoglobin levels and concentrations of key trace elements, zinc (Zn), selenium (Se), and iron (Fe) and non-enzymatic antioxidants (vitamin C and uric acid) in Nigerian male auto painters and battery chargers. Participants in both occupations were divided into two groups: those with less than 5 years of exposure (<5 years) and those with 5 years or more of exposure (>5 years). Methods: This six-month, cross-sectional study analyzed blood lead levels (BLL), haemoglobin (Hb), zinc, selenium, iron, vitamin C, and uric acid in 100 male Nigerian workers (50 battery chargers, 50 auto painters) aged 18-60 in Lagos. The subjects were categorized by duration of lead exposure (<5 years vs. >5 years). BLLs, Zn, Fe and Se were measured using Atomic Absorption Spectrophotometry (AAS), Haemoglobin (Hb), Vitamin C, and Uric Acid were analyzed using spectrophotometric methods. Data were processed with SPSS version 24. The Independent Student's t-test was used to compare the groups. The results are shown as mean ± standard deviation (SD), with statistical significance established at p < 0.05. The results showed a time-dependent increase in lead accumulation in both groups. For Auto Painters, Pb levels rose significantly from 24.02 µg/dL to 36.28 µg/dl. Battery Chargers displayed much higher lead levels, increasing significantly from 48.69 µg/dL to 67.74 µg/dL, indicating greater exposure severity in this occupation. Importantly, prolonged exposure resulted in a significant depletion of all measured micronutrients and antioxidants in both occupational groups, suggesting increased lead toxicity and chronic oxidative stress. In Auto Painters, the levels of Zn, Fe, Se, Vitamin C, and Uric Acid were all significantly lower in the >5 years group. This depletion was even more pronounced in Battery Chargers. Those exposed for over 5 years showed a highly significant reduction in Zn, Fe, Se, and Vitamin C, with Uric Acid also significantly decreased.  Conclusion: The duration of occupational lead exposure is directly and significantly correlated with increased lead body burden and a severe, progressive depletion of essential trace metals and antioxidant defences. These findings underscore the urgent need for targeted nutritional interventions, such as supplementation with Zinc, Iron, and Selenium, to mitigate the chronic health risks associated with prolonged lead exposure among these vulnerable Nigerian workers.