Currently, risk assessment for workers in nanotechnology is still in its infancy because occupational exposure assessment strategies and physiologic and health outcomes of occupational exposure to engineered nanomaterials (ENMs) have not yet been well characterized or established. Due to their size and the novel physical and chemical properties that emerge at the nanoscale, some ENMs may be more toxic than their bulk counterparts, particularly when considering inhaled aerosolized nanoparticles potential pulmonary toxicity) or nanoparticle penetration of skin (dermal translocation and biodistribution to other organs).
The NIOSH Respiratory Disease Research Program has conducted lab-based studies that already indicate that engineered nanoparticulate exposures represent potentially preventable occupational health hazards. Similarly, NIOSH recently published several guidance documents to address occupational exposure to ENMs, specifically regarding exposure to titanium dioxide (TiO2) and carbon-based ENMs, such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs). These guidance documents recommend controlling worker exposure to CNTs and CNFs below 1μg/m3 for an 8-hour time-weighted average during a 40-hour workweek. The recommended exposure limit for ultrafine and engineered nanoscale TiO2 is 0.3mg/m3 for up to 10 hours per day during a 40-hour workweek. The rapid growth and projected acceleration of nanotechnology creates urgency in understanding, predicting, and managing the health risks associated with occupational exposure to nanomaterials.
NIOSH’s Nanotechnology Research Center (NTRC) has developed a strategic plan for nanotechnology research and guidance for fiscal years 2013-2016 which includes five strategic goals and expansion of research activities in ten critical areas: toxicity and internal dose; measurement methods; exposure assessment; epidemiology and surveillance; risk assessment; engineering controls and personal protective equipment; fire and explosion safety; recommendations and guidance; global collaborations; and applications.
Current methods used for direct visualization of ENMs, based on those developed two decades ago for micron-sized asbestos, may not be appropriate for the real-world nanomaterial exposures encountered today. Additionally, the associated costs, time, and lack of standardization and validation of methods make it difficult for industries to implement an occupational exposure assessment program for workers who handle ENMs, or attempt to comply with NIOSH’s newly recommended occupational exposure limits (ROELs) for ENMs. One fundamental hurdle where research is critically needed in the development of validated analytical techniques which consistently, reliably, and accurately identify and characterize ENMs captured in the occupational settings. Significant progress must be made in regarding measurement methods for ENMs and specifically in “developing and field-testing practical methods to accurately measure airborne nanomaterials in the workplace” as well as in “developing testing and evaluation systems to compare and validate sampling instruments.”
Knowledge gained by setting an innovative paradigm in one industry can be extrapolated to improve the health and safety environment for workers in a variety of industries, academic settings, and research laboratories that use or manufacture ENMs. Where there are currently dozens of different protocols, determination of a best known methods will enable investigators to standardize and track exposures across multiple platforms and facilities.
This cleanroom tip was taken from “Advancing Health and Safety for the 21st Century Nanotechnology Workforce” by Sara A. Brenner, MD, MPH; and Michael Liehr, PhD. The article originally appeared in the November/December 2014 issue of Controlled Environments.