On February 19, 2020, the National Institute for Occupational Safety and Health (NIOSH) posted a Science Blog item entitled “Are There Nano- and Microplastics in the Workplace?” that reviews workplace exposure to microplastics (defined by NIOSH as “plastic particles smaller than 5 mm”) and nanoplastics (the nanoscale fraction of plastic particles).  NIOSH states that nano- and microplastic particles (NMPP) “can be formed through environmental and mechanical degradation (the top-down mechanism).  They can be also generated through condensation of molecular species, for example, during heating or burning of plastics (the bottom-up mechanism).”  NIOSH provides the following examples of inhalation exposure in the workplace:

• Top-Down Mechanism:
  • During mechanical and environmental degradation of plastic goods, which can lead to potential exposures to nano- and microplastics among workers in the waste management and recycling operations;
  • Degradation of carpets and other synthetic fiber products that can produce airborne fibers considered NMPPs with potential for exposure among office/teleworkers and custodial staff;
  • Machining of polymer and plastic products generating dusts; and
• Bottom-Up Mechanism:
  • During high-energy or high-heat processes (such as laser cutting or high-speed drilling), treatment of polymer composites, and during 3D printing from melting or fusing of plastics; and
  • Facilities hosting plastic processers and printers could expose workers to airborne NMPPs.

According to NIOSH, its Nanotechnology Research Center (NTRC) has developed approaches for exposure measurement, assessment and mitigation, and hazard characterization for nanomaterials, and many of these approaches would also be applicable to characterize and minimize risk of nano- and microplastics in the workplace.  NIOSH notes that presently there are no occupational exposure limits for nano- and microplastics.  In the absence of occupational exposure limits for nano- and microplastics, NIOSH states that workplace safety efforts should focus on minimizing potential exposure through appropriate engineering controls such as isolation cabinets, exhaust ventilation, and utilizing good industrial hygiene practices.

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