What is nanotechnology?
Nanotechnology involves the manipulation of matter at the atomic, molecular, or macromolecular range of approximately 1-100 nanometers (nm) to produce new structures, devices, and systems that have novel properties because of their nanometer-scale dimensions.
Nanotechnology promises exciting advances in a many areas, such as energy, medicine, communications, and electronics. Although most work in the field of nanotechnology is in the research and development stage, commercially available nanotechnology-based products are becoming increasingly available. Nanoparticles of titanium dioxide are used in sunscreens, cosmetics, and self-cleaning windows. Other products that have benefited from the use of nanomaterials include paints and coatings, dental materials, burn and wound dressings, longer-lasting tennis balls, and improved stain and wrinkle-free fabrics.
What is a nanoparticle?
Nanoparticles are particles having a diameter between 1 and 100 nm. To put this in perspective, the diameter of a strand of DNA is about 2 nanometers, and the diameter of a strand of hair is about 80,000 nanometers. Nanoparticles may be suspended in a gas (as a nanoaerosol), suspended in a liquid (as a colloid or nanohydrosol), or embedded in a matrix (as a nanocomposite).
What is the difference between nanoparticles and ultrafine particles?
The term ultrafine has been in existence longer and has traditionally been used in the occupational and environmental health communities to describe airborne particles smaller than 100 nm in diameter. Ultrafine is frequently used in the context of nanometer-sized particles that have not been intentionally produced, but rather are the incidental product of processes involving combustion, welding, or diesel engines. The term nanoparticle is typically used to describe intentionally-produced or engineered nanoscale particles, though this is not always the case. The term engineered nanoparticles only refers to intentionally-produced nanoparticles.
Why are nanoparticles a health concern?
Little is known about the health effects of nanoparticles on workers. Because of their very small size, nanoparticles (and ultrafine particles) may present unique safety and health concerns which are not present in larger-sized particles. Upon inhalation, they are deposited in the lungs to a greater extent than larger respirable particles. In experimental studies, these small-sized particles were shown to pass through skin, enter the bloodstream from the lungs, cross cell membranes, and even travel through nerves directly into the brain. Some studies have also shown that, for a given mass dose, the toxicity increases as the particle size decreases due to increased surface area.
The size, shape, surface area, charge, chemical properties, solubility, and degree of agglomeration can all influence the effect that nanoparticles and ultrafine particles have on biological systems. However, more research is needed to fully understand the characteristics of nanoparticles that may potentially pose a health risk. Until more information is available, precautionary measures should be taken to minimize worker exposure.
How can workers minimize exposure to nanoparticles?
Research in this area is ongoing, but the information currently available indicates that airborne exposures to nanoparticles can be controlled using methods similar to those typically used with fine particles: engineering controls, good work practices, proper housekeeping, and respiratory protection. Enclosing the process can isolate the particles. Properly designed local exhaust ventilation (LEV) will capture the particles at the source, keeping them out of the general work environment and the worker’s breathing zone. Dust collection systems for LEV should be equipped with a high-efficiency particulate air (HEPA) filter. Work practices that minimize the amount of airborne dust produced should be adopted.
Work areas should be cleaned regularly using methods that do not reintroduce particles into the air. HEPA-filtered vacuum cleaners or wet methods can be used for cleaning up equipment or surfaces. The use of dry sweeping or compressed air for cleaning equipment, surfaces, and clothing should be prohibited. Handwashing facilities should be provided. Measures should be adopted to prevent employees from inadvertently contaminating other areas of the workplace or taking home contamination.
If appropriate, respiratory protection can supplement other control measures to further reduce worker exposure. At this point, the National Institute for Occupational Safety and Health (NIOSH) believes that NIOSH-certified respirators should provide the expected levels of protection if properly selected and fit tested. However, the agency will continue to evaluate the effectiveness of NIOSH-approved respirators against nanoparticles.
Although some studies suggest that nanoparticles could enter the body through the skin during occupational exposure, there is currently no evidence that this would result in disease. Gloves and personal protective clothing should be worn to minimize skin contact with solutions and powders of nanoparticles. However, even with powders of larger-sized particles, the effectiveness of protective clothing in reducing skin exposures can be limited. More research on the health effects of dermal exposure and the effectiveness of protective clothing is needed.
Are there any safety concerns associated with nanoparticles?
At this point, very little is known about the potential safety hazards of nanomaterials beyond those associated with traditional materials. Combustible nanoscale materials could present a higher risk of fire and explosion than a similar quantity of coarser material. Depending on their composition and structure, some nanomaterials may initiate catalytic reactions and increase their fire and explosion potential in a way that would not be anticipated from their chemical composition.
Where can more information be found?
NIOSH Nanotechnology Homepage: www.cdc.gov/niosh/topics/nanotech
National Nanotechnology Initiative: www.nano.gov/html/facts/appsprod.html
The above evaluations and/or recommendations are for general guidance only and should not be relied upon for legal compliance purposes. They are based solely on the information provided to us and relate only to those conditions specifically discussed. We do not make any warranty, expressed or implied, that your workplace is safe or healthful or that it complies with all laws, regulations or standards.
