Manufacturers working with nanoscale materials will be pleased to know that the U.S. Occupational Safety and Health Administration (OSHA) recently published a fact sheet entitled "Working Safely with Nanomaterials". This document is a welcome addition to the widely available literature on managing prudently workplace exposures to nanomaterials.
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ARE NANOMATERIALS HAZARDOUS?
Nanotechnology promises scientific advancement for many sectors such as medicine, consumer products, energy, materials and manufacturing. While there's no one definition of nanotechnology, in general terms it covers engineered structures, devices and systems that have a length scale between 1 and 100 nanometers.
Nanoscale materials are today a routine part of the industrial workplace as nanotechnology is deeply and widely embedded in a range of manufacturing sectors. While nanomaterials have long been a part of the occupational work environment, engineered nanomaterials, tiny highly-engineered materials manufactured to specification to impart certain chemical, physical, electrical, or other properties, are becoming more common as their value and significance grows exponentially.
But like other workplace materials, nanomaterials must be managed carefully. Some studies have shown that low solubility nanoparticles can be more toxic than larger particles on a mass-for-mass basis. Some indicate nanoparticles can penetrate through the skin or move from the respiratory system to other organs. Ongoing research continues to determine whether and how these unique properties may lead to specific health effects. In this regard, OSHA notes that workers who use nanotechnology in the workplace may be exposed to nanomaterials through inhalation, skin contact or ingestion.
FACT SHEET
OSHA intends the fact sheet to provide "basic information to workers and employers on the most current understanding of potential hazards associated with this rapidly-developing technology and highlight measures to control exposure to nanomaterials in the workplace." OSHA offers a checklist of information and training elements that workers should get. These include:
• Identification of nanomaterials the employer uses 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 personal protective equipment (PPE) to reduce exposure to nanomaterials;
• The use and limitations of PPE; and
• Emergency measures to take in the event of a nanomaterial spill or release.
OSHA states that few occupational exposure limits exist specific to nanomaterials. Because certain nanoparticles may be more hazardous than larger-sized particles of the same substance, OSHA notes that existing occupational exposure limits for a substance may not provide adequate protection from nanoparticles of the same substance. OSHA notes the following specific exposure limits:
• OSHA recommends that worker exposure to respirable carbon nanotubes and carbon nanofibers not exceed 7.0 micrograms per cubic meter (μg/m3) as an 8-hr 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 titanium dioxide (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.
OSHA suggests that because exposure limits for other nanomaterials don't exist yet, employers should minimize worker exposure by using the hazard control measures and best practices identified in the fact sheet and in the references noted.
The suggestions in the fact sheet augment the many excellent publications prepared by NIOSH, including "Approaches to Safe Nanotechnology: Managing the Health and Safety Concerns Associated with Engineered Nanomaterials" (www.cdc.gov/niosh/docs/2009-125/). As noted above, while there are few occupational exposure limits specific to nanoscale materials, employers have an overarching duty to furnish their employees with a workplace that's free from recognized hazards under Section 5(a) of OSHA's General Duty Clause.
