Occupational Safety

NIOSH Offers Guidance for Handling Nanomaterials

Vladimir V. Murashov, Ph.D., Special Assistant to the Director

Nanotechnology has the potential to dramatically improve the effectiveness of a number of existing consumer and industrial products and could have a substantial impact on the development of new applications ranging from disease diagnosis and treatment to environmental remediation. Because of the broad range of possible nanotechnology applications, continued evaluation of the potential health risks associated with exposure to nanomaterials is essential to ensure their safe handling.

Nanomaterials are engineered materials having at least one dimension between 1 and 100 nanometers. Nanomaterials often exhibit unique physical and chemical properties with specific characteristics that enable their use in products, but little is known about what effect these properties may have on human health should exposure occur. Research has shown that the physicochemical characteristics of particles can influence their effects in biological systems. These characteristics include: particle size, shape, surface area charge, chemical properties, solubility, and degree of agglomeration. Given the limited amount of information about the health risks and until the results from research studies can fully elucidate the pertinent characteristics of nanoparticles , it is prudent to take measures to minimize worker exposures (see National Institute for Occupational Safety and Health (NIOSH), Approaches to Safe Nanotechnology: An Information Exchange with NIOSH).

Exposure during handling and use to nanomaterial-enabled products, such as nanocomposites and surface coatings and materials comprised of nanostructures such as integrated circuits, is unlikely. But the potential for workplace release exists for nanoscale powders and suspensions of nanoscale particles in liquids. For example, liquids containing suspended nanomaterials can be spilled on the skin if it is not adequately protected (e.g. using gloves). Agitating liquids during mixing and pouring could also generate respirable particles containing nanomaterials, which could deposit in the lung or on the skin, unless adequate protection with personal protective equipment and respirators is applied.

The implementation of a risk management program in workplaces where nanomaterials are handled can help to minimize the potential for exposure to nanoaerosols. Elements of such a program should include:

• Evaluating the hazard posed by the nanomaterial based on available physical and chemical property data and toxicology or health effects data.
• Assessing potential worker exposure to determine the degree of risk.

• Education and training of workers in the proper handling of nanomaterials.
• Establishment of criteria and procedures for installing and evaluating engineering controls at locations where exposure to nanoparticles might occur.
• Development of procedures for determining the need and selection of personal protective equipment (such as clothing, gloves, respirators).

For most processes and job tasks, exposure to nanoaerosols can be controlled using a wide variety of engineering techniques similar to those used in reducing exposure to general aerosols (such as exhaust ventilation and enclosures) . While enclosed environments employed for manufacturing and handling nanomaterials can virtually eliminate potential for exposure during normal operations, potential for exposure still exists during maintenance on equipment used to produce or fabricate nanomaterials, during the cleaning of dust collection systems used to capture nanoparticles in ventilation systems, and the clean-up of spills or waste material.

Effectiveness of engineering controls to reduce concentration of nanoscale particles in the workplace can be evaluated using a three-step process. The first step involves identifying the source of nanoparticle emissions using, for example, a Condensation Particle Counter. Due to the presence of incidental and natural nanoscale particles in the ambient air, it is critical that background nanoaerosol measurements be conducted before the production, processing or handling of the nanomaterial.

Once the source of emissions is identified, aerosol surface area measurements could be conducted with a portable diffusion charger, and aerosol size distributions could be determined with a Scanning Mobility Particle Sizer or Electrical Low Pressure Impactor using area monitoring.

Lastly, sampling using filters or grids suitable for analysis by electron microscopy or chemical identification could be employed. High resolution electron microscopy combined with x-ray microanalysis and electron diffraction can be used to characterize size distribution, structure and chemistry of nanoscale particles. In addition, standard analytical chemical methodologies can provide information about chemical composition of the nanoscale particles.

The decision to institute respiratory protection should be based on a combination of professional judgment and the results of the hazard assessment and risk management practices recommended in NIOSH Approaches to Safe Nanotechnology. If worker exposure to nanoparticles remains a concern after instituting measures to control exposure, the use of respirators and other Personal Protective Equipment can further reduce worker exposures. Based on available scientific data, NIOSH-certified respirators should provide the expected levels of protection down to lower nanoscale-particle size range. Currently, no guidelines are available on the selection of clothing or other apparel for the prevention of dermal exposure to nanoparticles. NIOSH plans to conduct laboratory research on test methods to determine particle penetration through fabrics used into protective clothing and ensembles.

The NIOSH goal is to provide national and world leadership for incorporating research findings about the implications and applications of nanotechnology into good occupational safety and health practice for the benefit of all nanotechnology workers. NIOSH is working in parallel with the development and implementation of commercial nanotechnology by (1) conducting strategic planning and research; (2) partnering with public- and private-sector colleagues from the United States and abroad; and (3) making information widely available.

NIOSH coordinates its Nanotechnology Program with other US government agencies through the inter-agency Nanotechnology Environment and Health Implications (NEHI) working group that is a part of the National Nanotechnology Initiative. NIOSH has been also actively involved in developing a coordinated, government-wide strategic plan (PDF) to address environment, health and safety implications of nanotechnology.

Vladimir Murashov, Ph.D., is a Special Assistant for Nanotechnology to the Director of the National Institute for Occupational Safety and Health (NIOSH). He represents NIOSH in inter-agency subcommittee and working groups of the National Nanotechnology Initiative. He also actively participates in ISO TC 229 Nanotechnologies and leads the development of the ISO Technical Report “Health and Safety Practices in Occupational Settings Relevant to Nanotechnologies.” For further information on NIOSH Nanotechnology Program, please contact him by email. NIOSH is the federal agency responsible for conducting research and making recommendations to prevent work-related injury, illness, and death.

Disclaimer: The findings and conclusions in this report are those of the author and do not necessarily represent the views of the National Institute for Occupational Safety and Health.