Original article http://www.irmi.com
By John Matosky
As nanomaterials make their way from the laboratory to the store shelf in the form of consumer products, efforts to identify and manage risks associated with the materials have intensified. In particular, we have seen concerns for the health and safety of consumers manifested in the development and anticipated promulgation of labeling standards to alert consumers of the potential hazards of products that incorporate nanomaterials. But what attention is being given to those involved in the manufacturing of products incorporating nanomaterials given that this is the stage where exposure to component nanomaterials is most likely to occur? Recently, government agencies charged with ensuring occupational health and safety standards have begun providing guidance to employers on the need to assess and control nanomaterial hazards in the workplace.
On February 6, 2013, the US Department of Labor’s Occupational Safety and Health Administration (OSHA) published a fact sheet titled “Working Safely with Nanomaterials,” which the agency says provides “basic information to workers and employers on the most current understanding of potential hazards associated with this rapidly developing technology and highlights measures to control exposure to nanomaterials in the workplace.”1
In the document, OSHA advises that an effective risk management plan begins with identifying potential nanomaterials used in the workplace. It encourages concerned employees to ask their employers, who, in turn, should consult the manufacturers of the chemicals and materials used in their processes to determine the presence and identification of nanomaterials. The agency recommendations, however, place the onus on the employer to identify the risks, assess exposure to workers, develop controls to manage the risks, and provide training to employees.
With regard to identifying risks, OSHA counsels caution because the potential hazards associated with nanomaterials largely remain unknown, but it also describes currently recognized or suspected hazards. As an example from the current state of understanding, it advises that nano-sized titanium dioxide particles should be considered a carcinogen, as determined by the National Institute of Occupational Safety and Health (NIOSH), and protection should be provided against inhalation. Another example relates to carbon nanotubes and nano-fibers, which OSHA warns may cause pulmonary inflammation and fibrosis if inhaled.2 The agency also warns generally of the risk that certain nanomaterials have the ability to penetrate cell membranes and may damage cell structure and function.
In addition to personal health risks, OSHA warns employers about potential environmental hazards associated with nanoparticles in the workplace. Specifically, it cites the risk of fire or explosion resulting from either the catalytic chemical properties of some nanomaterials or simply the presence of airborne particulates in combustible concentrations (similar to the phenomenon of grain or coal dust explosions). The agency instructs employers to take these risks into account when developing appropriate control measures.
OSHA acknowledges that specific occupational exposure limits exist only for certain nanomaterials (e.g., carbon nanotubes and titanium dioxide) and notes that exposure limits for larger particles may not necessarily apply to nanoparticles, even of the same substance, because the latter may be more hazardous depending on their particular physicochemical properties. Employers can minimize the risks posed by these uncertainties, OSHA advises, by adopting certain best practices and hazard control measures.
According to OSHA, those measures should begin with the employer’s assessment of worker exposure. In making the assessment, the employer should (1) identify the processes that may expose workers to nanomaterials, (2) determine the physical state of the nanomaterials (e.g., dust, powder, spray, or droplets), (3) determine the likely paths of exposure (e.g., inhalation, ingestion, or skin contact), and (4) identify appropriate sampling methods for determining concentrations, durations, and frequencies of exposure. Based on all of these factors, OSHA recommends, the employer should evaluate current control measures and then determine whether additional controls are necessary. Again, the agency endorses utmost caution and the implementation of “the most effective controls available” to limit exposure.
Adopting Control Measures
In terms of practical measures and best practices, OSHA suggests that all employers in workplaces where nanomaterials are present consult NIOSH guidelines and adopt a combination of the following types of control measures:
- The agency recommends engineering controls such as the provision of adequate ventilation, including ventilated enclosures (e.g., glove boxes and process chambers) where possible, and high-efficiency particulate air filtering.
- Under the heading “Administrative Controls,” it encourages employers to provide basic hygiene facilities such as hand-washing stations. Employers also should establish procedures for decontamination and cleanup following spills.
- Employers should provide workers with proper personal protective equipment (PPE), including protective clothing and respirators, but also should train employees regarding the use and, critically, the limitations of PPE.
- Employers should make medical screening and surveillance available to workers exposed to nanomaterials.
On March 21, 2013, OSHA’s counterpart in the United Kingdom, the Health and Safety Executive (HSE), released its own guidance paper, titled “Using Nanomaterials at Work.”3 The HSE guidance places special focus on carbon nanotubes and “other biopersistent high aspect ratio nanomaterials”—for which it finds a heightened level of control is warranted—but offers general hazard control principles that apply to all types of nanomaterials presently used in the workplace. The HSE publication provides more detail than the OSHA document, but, like the OSHA guide, it emphasizes the emerging nature of the field and the as yet undeveloped understanding of the potential risks. It also largely mirrors the OSHA recommendations concerning exposure analysis, risk assessment, engineering controls, PPE, and medical monitoring. As an overriding theme, the HSE recommends “sensible and proportionate measures,” reminding employers: “You don’t have to remove all this risks, but the law requires you to do everything ‘reasonably practicable’ to protect people from harm.”
The OSHA and HSE guidelines are admirable, if tentative, first steps in setting standards for workplace safety in the manufacturing, handling, and processing of nanomaterials. Both agencies readily admit that their recommendations are constrained by the limitations of current knowledge in the field and acknowledge the challenges faced by employers and regulators in developing reliable and reasonable controls in the face of uncertain hazards. The clearest takeaway, perhaps, is that employers and others responsible for managing risks and ensuring safety should make immediate assessments based on the agency recommendations but must also constantly monitor the developing body of research and knowledge concerning the potential hazards.
2Indeed, at the annual meeting of the Society of Toxicology in March 2013, NIOSH added detail to the picture when it reported its preliminary findings from a laboratory study suggesting that multi-walled carbon nanotubes (MWCNT) are a cancer promoter when inhaled by mice. Significantly, NIOSH notes that the study indicates that MWCNT can increase the risk of cancer in mice exposed to a known carcinogen but does not demonstrate that MWCNT alone causes cancer in mice. V. Castranova, C.L. Geraci & P. Schulte, “New Findings on Lung Tumor Formation in Laboratory Mice Exposed to Multi-Walled Carbon Nanotubes,” NIOSH Science Blog,http://blogs.cdc.gov/niosh-science-blog/2013/03/mwcnt.