Potential exposure to nano and microparticles during injection molding of glass fiber polymer composites

Assessing workers’ exposure during the molding of glass fiber-reinforced polymer composites is a complex task, influenced by both the materials used, and the manufacturing processes involved. Besides the possible presence of volatile organic compounds (VOCs), there is growing concern about the release of micro- and nanoparticles, which could lead to long-term exposure that should not be underestimated. In this pilot study, for the first time, the release of glass fibers and nano-microplastics was evaluated according to Tier 1 and Tier 2 of the multi-metric tiered approach proposed by the Organization for Economic Cooperation and Development (OECD). Multi-metric real-time instruments were used to determine particle number concentration (PNC), particle average diameter (Davg), and lung deposited surface area (LDSA), along with time-integrated instrumentation to collect airborne dust for off-line chemical and morphological characterization. The results of the workplace monitoring campaign showed a significantly higher level of airborne particles, particularly at the nanoscale, compared to the background levels. The sampling of airborne dust revealed the presence of ultrafine particles (UFPs), fiber-like structures mainly composed of carbon and oxygen, and aerodispersed SiO2 fibers. According to the OECD guidelines, since significant exposure can not be excluded, based on the results of Tier 2 measurements, an extensive monitoring campaign (Tier 3) has to be conducted with the aim of thoroughly defining the exposure scenario and, consequently, recommending appropriate protection and prevention measures to safeguard workers’ health and safety. Copyright © 2025 American Association for Aerosol Research