What are Nanotechnology and Nanomaterials?
Nanotechnology is “the understanding and control of matter at the nanoscale, at dimensions between approximately 1 and 100 nanometers (nm)” (www.nano.gov). A nanometer is one billionth of a meter, which is near-atomic scale. Engineered nanomaterials are assembled from nanoscale structures such as carbon nanotubes and filaments or from nanoparticles of materials such as titanium dioxide or cadmium selenide. Nanomaterials can have unique physical, chemical and biological properties that can enable their use in novel applications, such as making stain-free textiles using nanoscale additives or surface treatments or targeting drugs selectively to cancerous cells. The continued development of unique nanoscale structures has the potential to impact many industries, including electronics, healthcare, construction and consumer products.
Nanomaterials in the Workplace
Some examples of workplaces that may use nanomaterials include chemical or pharmaceutical laboratories or plants, manufacturing facilities, medical offices or hospitals, and construction sites. The potential for nanomaterials to pose health or safety hazards is greater if the nanomaterials are easily dispersed (such as in powders, sprays, or droplets) or are not isolated or contained.
Exposure to Nanomaterials
The health hazard potential depends on the particular nanomaterial and a person’s exposure level. For example:
- • Certain inhaled nanoparticles may be deposited in the respiratory tract and may cause inflammation and damage to lung cells and tissues; e.g., carbon nanotubes and nanofibers may be capable of causing pulmonary inflammation and fibrosis.
- • Titanium dioxide (TiO2 ), which has many commercial applications (e.g., paint, paper, cosmetics, food), can be produced and used in varying particle sizes, including the nanoscale particle sizes (< 100 nm). NIOSH has determined that nanoscale TiO2 particles have higher mass-based potency than larger particles, and that occupational exposure (by inhalation) to nanoscale TiO2 particles should be considered a potential occupational carcinogen.
- • Certain nanoparticles may penetrate cell membranes and may cause damage to intracellular structures and cellular functions.
- • Some nanomaterials may act as chemical catalysts and produce unanticipated reactions, creating a risk of explosions and fires.
- • Some types of nanoparticle dusts may be combustible and require less energy to ignite than larger dust particles (for instance, sugar or wood), creating a risk of explosions and fires.
Current Occupational Exposure Limits for Nanomaterials
Few 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 National Institute for Occupational Safety and Health (NIOSH) proposed Recommended Exposure Limit (REL).
- • OSHA recommends that 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.
Methods Employers Can Use to Reduce Worker Exposure to Nanomaterials
Because the research and use of nanomaterials continues to expand and information about potential health effects and exposure limits for these nanomaterials is still being developed, employers should use a combination of the following measures and best practices to control potential exposures:
- • Work with nanomaterials in ventilated enclosures (e.g., glove box, laboratory hood, process chamber) equipped with high-efficiency particulate air (HEPA ) 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
- • 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.
Personal Protective Equipment (PPE)
- • Provide workers with appropriate personal protective equipment such as respirators, gloves and protective clothing.
Medical Screening and Surveillance
- • Make available medical screening and surveillance for workers exposed to nanomaterials if appropriate
- • Review medical surveillance requirements under OSHA standards (e.g., Cadmium, Respiratory Protection).