Occupational exposure to hazards and volatile organic compounds in small-scale plastic recycling plants in Thailand by integrating risk and life cycle assessment concepts

Plastic waste recycling is gaining momentum as a means to promote a sustainable measure and circular economy. Most developing countries are facing significant challenges associated with recycling practices. In Thailand, 90% of the plastic recycling businesses are categorized as small-scale enterprises. There is still a dearth of research on health risk assessments associated with indoor exposure in small-scale waste recycling. This research aims to apply a holistic approach of integrated health risk and life cycle assessment concepts in investigating occupational exposure to all potential hazards in small-scale polyethylene (PE) and polypropylene (PP) recycling plants in Thailand. The results indicated that all exposure levels of heat stress in wet bulb globe temperature in the melting/extrusion stage exceeded the Thai and global Occupational safety and health (OSH) threshold limits for workers with heavy workloads. For workers' exposure to volatile organic compounds (VOCs), the average total VOCs concentrations emitted from PP and PE recycling were 1625 mu g/m3 and 1190 mu g/m3, respectively. Hexane and toluene were remarkably found in the extrusion process. The non-cancer hazard quotients (HQs) and hazard indices (HIs) were higher in PP than in PE. The adverse non-cancer risks were concerned in plants that recycle only PP wastes at full capacity (100%) loaded operation (HQs and HIs >1). Recycling facility concentrating more on PE recycling tends to reduce risk to workers. By integrating the revised one box model into the life cycle impact assessment, the results demonstrate that the health impact from indoor VOCs exposure due to the production of 1 kg of recycled PP or PE resin was significantly greatest. Workers in the extrusion process were considered at higher risk of exposure to VOCs and heat. This research makes important contributions to the literature by providing insights into environmental health management and implications for cleaner production in plastic waste recycling. The promotion of effective engineering controls and development of collaborative circular business models in plastic waste recycling sector were highly recommended to increase resource efficiency and promote sustainable production patterns.