Using hair as a non-invasive matrix to assess the exposure of e-waste workers to selected heavy metals in Pakistan

Abstract

Pakistan has become a significant recipient of e-waste, largely due to lower labor costs, lack of local environmental regulations, and less stringent international controls. Limited research exists on e-waste generation, management, and pollution in Pakistan. This study aimed to analyze levels of selected heavy metals in human hair samples from workers at informal e-waste processing facilities in six major cities: Karachi, Lahore, Rawalpindi, Faisalabad, Gujranwala, and Peshawar. A total of 150 hair samples were collected from workers aged 15 to 60 years and compared with samples from a control group of individuals who had no exposure to e-waste processing for at least the previous five years. Results revealed higher average concentrations (mu g/kg) of Zn (577) in the hair of e-waste facility workers, followed by Fe (534), Al (265), and Cu (105). Significant age-related differences were observed for Zn, Fe, Cd, and Pb (p < 0.01), indicating these metals are prevalent during e-waste recycling. Notably, Fe, Zn, and Al concentrations were significantly higher in the 56 + age group, suggesting prolonged exposure. Strong correlations (p < 0.01) were found between pairs such as Al-Cu, Al-Fe, Zn-Cu, and Cd-Pb, which can serve as markers of high exposure due to prolonged e-waste recycling activities. In conclusion, hair analysis is a noninvasive, cost-effective method to provide preliminary information on heavy metal exposure in both control and exposed groups. Further studies are recommended to evaluate the correlation between heavy metals in hair, urine, and blood samples of informal e-waste recyclers to establish exposure routes and adverse health effects on metabolic activities.