So how small is "nano"? A nanometer is one billionth of a meter. A sheet of paper is about 100,000 nanometers thick. And there are 25,400,000 nanometers in one inch.
According to OSHA, nanomaterials can have unique physical, chemical, and biological properties that make them useful in innovative applications like stain-free textiles.
However, as nanotechnology moves from the lab to industrial and commercial settings, workers and employers should be aware of the hazards and measures to control exposure.
Exposure to NanomaterialsInformation from research and animal studies on nanomaterials has identified both potential safety hazards and health effects. But because nanotechnology is a rapidly emerging field, more information will likely become available about potential health and safety hazards associated with some nanomaterials.
One thing we do know for sure is that the hazard potential depends on the particular nanomaterial. For example:
- Certain inhaled nanoparticles may be deposited in the respiratory tract and may cause inflammation and damage to lung cells and tissues.
- NIOSH says that inhalation of titanium dioxide (TiO2) particles should be considered a cancer hazard.
- Some nanoparticles may penetrate cell membranes and may cause damage to intracellular structures and cellular functions.
- Some may act as chemical catalysts and produce unanticipated reactions, creating a risk of explosions and fires.
- Nanoparticle dusts maybe combustible in some cases, requiring less energy to ignite than larger dust particles (for instance, sugar or wood), creating a risk of explosions and fires.
OSHA RecommendationsIn workplaces where workers will be exposed to nanomaterials, OSHA says that employers should provide information and training to their workers. This information and training should include at least the following:
- Identification of nanomaterials in the workplace and the processes in which they are used
- Results from any exposure assessments conducted at the work site
- Identification of engineering and administrative controls and PPE to reduce exposure to nanomaterials
- The use and limitations of PPE
- Emergency measures to take in the event of a nanomaterial spill or release
Exposure LimitsFew occupational exposure limits exist specifically for nanomaterials. Certain nanoparticles may be more hazardous than larger particles of the same substance. Therefore, existing occupational exposure limits for a substance may not provide adequate protection from nanoparticles of that substance.
However, some specific exposure limits already exist. For example, OSHA recommends that:
- Worker exposure to respirable carbon nanotubes and carbon nanofibers not exceed 1.0 micrograms per cubic meter (μg/m3) as an 8-hour time-weighted average, based on the NIOSH proposed Recommended Exposure Limit (REL)
- Worker exposure to nanoscale particles of TiO2 not exceed NIOSH's 0.3 milligrams per cubic meter (mg/m3) REL. By contrast, NIOSH's REL for fine-sized TiO2 (particle size greater than 100 nm) is 2.4 mg/m3
Reducing Exposure To control potential exposures, OSHA recommends that employers use a combination of the engineering controls, administrative controls, PPE, and medical screening and surveillance.
Engineering Controls
- Work with nanomaterials in ventilated enclosures (e.g., glove box, laboratory hood, process chamber) equipped with high-efficiency particulate air (HEPA9) filters.
- Where operations cannot be enclosed, provide local exhaust ventilation (e.g., capture hood, enclosing hood) equipped with HEPA filters and designed to capture the contaminant at the point of generation or release.
Administrative Controls
- Provide handwashing facilities and information that encourages the use of good hygiene practices.
- Establish procedures to address cleanup of nanomaterial spills and decontamination of surfaces to minimize worker exposure. For example, prohibit dry sweeping or use of compressed air for cleanup of dusts containing nanomaterials, use wet wiping and vacuum cleaners equipped with HEPA filters.
PPE
- Provide workers with appropriate PPE such as respirators, gloves, and protective clothing.
Medical Screening and Surveillance
- Make medical screening and surveillance available for workers exposed to nanomaterials if appropriate.
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