Ecofriendly or Ecofiction: Reviewing Environmental Hazards of Plastic-Modified Asphalt Pavements

Global plastic production currently exceeds 350 million tonnes annually and is projected to surpass 1,100 million tonnes by 2050. This presents a major obstacle to waste management and sustainable construction practices. To address this issue, the incorporation of plastics into asphalt pavements has gained attention as a strategy to both divert waste from landfills and enhance pavement performance. However, plastic-modified asphalt pavement also raises environmental and occupational health concerns, including fume emissions, microplastic (MP) release, chemical leaching, and exposure risks for workers. Most studies focus on these impacts individually, and few investigations systematically assess them across different plastic types, mixing methods, and operational conditions. This review addresses this gap by providing a comprehensive and broad-spectrum assessment of five major plastics (low-density polyethylene, high-density polyethylene, polypropylene, polyethylene terephthalate, and polyvinyl chloride) used in asphalt modification. Laboratory and field studies are integrated to assess fume emissions, MP generation, leaching of contaminants, and occupational health risks. Findings indicate that plastic modification can enhance pavement stability, while emissions and leaching depend strongly on plastic type, mixing method, and processing temperature. The release of MP is influenced by both the plastic type and the incorporation approach, with wet mixing generally producing fewer fragments than dry mixing. Worker exposure to high temperatures and repeated contact presents potential genotoxic and carcinogenic risks. Overall, optimizing mixing practices, assessing long-term environmental impacts, and adopting a holistic sustainability perspective are essential for an ecofriendly and effective implementation.