Four-Year Population Exposure Study: Implications for Priority-Controlled E-Waste Pollutants and Characteristic Biomarkers of E-Waste Pollution

E-waste pollution has emerged as a significant environmental concern, necessitating the establishment of priority-controlled e-waste pollutants and useful biomarkers that facilitate the rapid assessment of the impact of e-waste pollution on human exposure risks. Therefore, we performed a longitudinal population exposure monitoring research in an e-waste recycling area of China after e-waste control. The urinary levels of oxidative stress damage and typical pollutants emitted during e-waste recycling, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and polychlorinated diphenyl ethers (PCDE), were continuously monitored in populations (including 275 children and 485 adults) from 2016 to 2019 using high-performance liquid chromatography-tandem mass spectrometry. After e-waste control, oxidative DNA damage levels in children decreased significantly, suggesting that scientific recycling of e-waste significantly reduced the human health burden. Although the decline of pollutants exposure level was more obvious in children than in adults, children still had higher burdens of heavy metals, VOCs and PCDE 28 exposure and oxidative stress damage than adults. Urinary tin, 1-hydroxypyrene, s -phenylmercapturic acid, and 2′-hydroxy-2,4,4′-trichlorodiphenyl ether decreased significantly and monotonically over the years were identified as the potential biomarkers of e-waste pollution. Based on the associations between pollutant exposure and oxidative stress damage levels, the top six harmful pollutants were identified as toluene, molybdenum, copper, pyrene, naphthalene, and nickel, which should be listed as the priority-controlled e-waste pollutants. Most noteworthy, toluene and naphthalene induced oxidative lipid and DNA damage without threshold, respectively. Despite the implementation of four-year e-waste management, the levels of priority-controlled pollutants in 5.26% to 92.9% of local populations were still higher than the cut-points, suggesting the long-lasting and profound impacts of e-waste pollution on human health. This work has tremendous economic and social value as it provides a reference for formulating environmental management and public health protection policies in e-waste recycling sites.