The National Institute for Occupational Safety and Health (NIOSH) continues to celebrate the 20th anniversary of its Nanotechnology Research Center (NTRC). NIOSH highlights NTRC activities in the risk assessment of engineered nanomaterials in a June 3, 2024, NIOSH Science log item entitled “NIOSH Risk Assessment of Engineered Nanomaterials.” The item notes that NTRC risk assessments were used in developing NIOSH recommended exposure limits (REL) for three different classes of nanomaterials — titanium dioxide, carbon nanotubes and nanofibers, and silver. Identifying relevant and reliable data, especially chronic exposure data of engineered nanomaterials, has been challenging. According to the item, dose estimation “is an important source of uncertainty for nanomaterials, where particle size may affect biological processes and internal dose.” NTRC collaborated with other researchers to develop and evaluate dosimetry and physiologically based pharmacokinetic (PBPK) models to estimate the internal dose of nanoparticles and supported some extensions of the Multiple-Path Particle Dosimetry model.

For nanomaterials that do not have enough data to develop occupational exposure limits (OEL), occupational exposure banding may be an option to determine provisionary guidance for risk management. NTRC researchers have derived occupational exposure bands for several engineered nanomaterials in an evaluation of available approaches.

According to the blog item, next steps include a multi-center program in the European Union (EU) to develop the NanoInformaTIX database and the U.S. Environmental Protection Agency’s (EPA) NaKnowBase database. The item notes that in addition, NTRC researchers “are developing a literature-based dataset as part of its evaluation of approaches to nanomaterials risk assessment.”