Health impacts of asphalt emissions: Examining neurological risks and the need for long-term exposure mitigation

Abstract

Asphalt, widely used in infrastructure, emits complex chemical mixtures throughout its service life, posing significant risks to human health and the environment. This expanded understanding extends the concern from a construction-related hazard to a broader public health issue, especially affecting vulnerable populations like children who play on blacktop surfaces. Despite increased awareness, the specific mechanisms behind asphalt emissions, their impact on asphalt deterioration, and their effects on the human nervous system remain poorly understood. Our study addresses these knowledge gaps by examining the long-term health effects of asphalt emissions, focusing on neurological impacts. We investigate how environmental stressors and asphalt's chemical composition influence emission types and severity, using a combination of in vitro experiments, Drosophila melanogaster models, and advanced computational analyses. FTIR analysis reveals that as asphalt ages, emissions evolve from aliphatic to aromatic compounds, increasing toxicity. Our results demonstrate significant neurological damage from asphalt emissions, with effects worsening with age and being more pronounced in females, as shown in the Drosophila model, emphasizing the need for gender-specific health risk research. In vitro studies using 3T3L1 cells show that VOC exposure disrupts lipid droplet formation and metabolism, processes linked to neurodegenerative disorders. To mitigate emissions, our novel approach introduces wood-based biochar as a functional carbon to enhance intermolecular interactions within asphalt. GC-MS analysis indicates that biochar reduces VOC emissions by up to 76 %, while molecular dynamics (MD) simulations highlight biochar's effectiveness in hindering free-radical diffusion. Density functional theory (DFT) calculations confirm biochar's role, with adsorption energies of -20.4 kcal/mol, demonstrating strong and stable interactions that decelerate oxidative aging and mass loss. These findings offer a comprehensive understanding of emission mechanisms and propose a sustainable strategy to enhance asphalt durability while reducing environmental and health risks. This in turn provides evidence-based recommendations for the asphalt industry, emphasizing proactive measures toward long-term exposure mitigation. SYNOPSIS: Asphalt emits chemicals throughout its service life, posing neurological risks, especially to vulnerable groups, and needs emission mitigation.

Keywords: Adsorbents; Asphalt; Emission; Human health; Nervous systems; Volatile organic compounds.