NIOSH Recommends New Exposure Levels for Nanomaterials to Reduce Worker’s Risk of Lung Damage

The CDC’s National Institute for Occupational Safety and Health (NIOSH) recommended that occupational exposures to carbon nanotubes and nanofibers be controlled to reduce worker’s potential risk for certain work-related lung effects. NIOSH is the first federal agency to issue recommended exposure levels for this growing industry.


The latest Current Intelligence Bulletin issued by NIOSH reports the results of research which showed various types of carbon nanotubes/carbon nanofibers can cause pulmonary fibrosis, inflammatory effects, and granulomas in laboratory animals exposed to them by inhalation. NIOSH considers these animal study findings to be relevant to human health risk because similar lung effects have been observed in workers exposed to respirable particulates of other materials in dusty jobs.


The number of workers that are potentially exposed to nanomaterials cannot be determined with certainty. However, the demand for nanomaterials is expected to grow over the next decade with increasing use in energy saving products, consumer goods and the structural material of medical devices. These nanomaterials are also incorporated into plastics, ceramics, paints, coatings, and electronics, among other everyday products.


Carbon nanotubes and carbon nanofibers are only two of many types of nanomaterials being incorporated into different products to increase strength, durability, versatility, heat resistance, and other useful properties. They are routinely used by workers in a variety of manufacturing industries including, automotive, aviation, construction manufacturers of structural materials, textiles, batteries, and consumer products such as sporting goods.


Results from recent animal studies indicate that carbon nanotubes (CNT) and carbon nanofibers (CNF) may pose a respiratory hazard. CNTs and CNFs are tiny, cylindrical, large aspect ratio, manufactured forms of carbon. There is no single type of carbon nanotube or nanofiber; one type can differ from another in shape, size, chemical composition (from residual metal catalysts or functionalization of the CNT and CNF) and other physical and chemical characteristics. Such variations in composition and size have added to the complexity of understanding their hazard potential.


Occupational exposure to CNTs and CNFs can occur not only in the process of manufacturing them, but also at the point of incorporating these materials into other products and applications. A number of research studies with rodents have shown adverse lung effects at relatively low-mass doses of CNT and CNF, including pulmonary inflammation and rapidly developing, persistent fibrosis. Although it is not known whether similar adverse health effects occur in humans after exposure to CNT and CNF, the results from animal research studies indicate the need to minimize worker exposure.


See the CDC Announcement


See the NIOSH Current Intelligence Bulletin