Introduction
Environmental health and safety (EHS) in nanomanufacturing encompasses the work environment (occupational safety), as well as potential air, water, and waste impacts of nanomanufacturing processes. More broadly, EHS issues can include potential impacts on the consumer, including safe use and disposal of consumer products containing nanomaterials.
Any manufacturer will consider EHS impacts of their processes, and this is no different in the context of nanomanufacturing, except for the fact that much of nanomanufactuing is currently occurring in settings that may not be considered traditional “workplaces” (e.g., universities, research and development (R&D) labs). As the “front line” of nanomanufacturing, universities have become central to new developments, frequently with commercial industry partners. In traditional manufacturing, there is generally a substantial scientific basis behind regulatory guidance for EHS decisions.
Part of the current challenge in nanomanufacturing is that the preliminary scientific evidence regarding the safety of some nanoparticles is unclear – findings to date show that some nano-scale materials have greater toxicity than their macro-scale counterparts (Oberdorster, Ferin et al. 1992; Donaldson, Beswick et al. 1996; Oberdorster 1996; Brown, Wilson et al. 2001; Renwick, Donaldson et al. 2001; Hohr, Steinfartz et al. 2002; Gurr, Wang et al. 2005; Chen et al. 2006). Other studies have reported no difference or greater toxicity with larger size (Chen and Gerion 2004; Warheit, Webb et al. 2006). Additionally, as more toxicological research is conducted on engineered materials, it appears that concerns regarding some of these particles may be warranted as well. At present, in the US, nanoparticles are not regulated separately, and because of this, environmental health and safety aspects of nanomanufacturing, including implementation of safe work practices, falls to the individual nanomanufacturer, laboratory, university, or other developer.
Context
Traditionally, US regulations set by the Occupational Health and Safety Administration (OSHA) or the Environmental Protection Agency (EPA) serve as guidance to the manufacturer in providing a safe workplace for employees, a safe environment for the surrounding community, and guidance on disposal of waste materials in the manufacturing process. Sound scientific research provides the basis for these regulations – whether for human, animal, or environmental effects. Toxicological findings, which include studies in cell cultures (in vitro tests) in the laboratory and studies in animals (in vivo) provide the first line of evidence of possible hazards. Epidemiological studies, which are conducted in human populations, provide further evidence of whether certain chemicals or substances are harmful to humans.
OSHA sets standards for exposure limits to potentially hazardous chemicals and substances, as well as guidance for the use of personal protective equipment, based on such scientific findings. Similarly, EPA provides guidance for what levels are permissible and safe, for certain toxic air emissions and water discharges – based additionally on findings from ecotoxicological studies. In nanomanufacturing, the toxicology and identification of possible hazards of exposure to nanomaterials lags far behind the explosive development of the nanoparticles and associated uses. Approaches to measuring nanoparticles in the workplace are rapidly being developed, which will be important to understanding whether various setting pose any risk.
In traditional manufacturing settings, large companies have EHS officials to monitor the workplace, including industrial hygienists who can oversee, if necessary, guidance for handling materials, exposure measurements in the workplace, fitting of respirators, and other protective equipment, and general “best practices” for workers. Others, such as engineers, may be responsible for implementing adequate exhaust systems, filtration, etc., to prevent environmental exposures to byproducts of the manufacturing process, and safety officers to ensure proper disposal of any hazardous materials or other waste materials. These professionals are likely to extend their EHS efforts to any nano-developments within their companies. However, because nanomanufacturing developments are rapidly occurring in the “non-traditional” workplace settings, such as universities, traditional EHS professionals may or may not be consulted by universities or small nanomanufacturers.
Issues
“At the moment, nobody has died from engineered nanomaterials. To our knowledge nobody has even gotten sick…” (Dr. Andrew Maynard, Woodrow Wilson Project on Emerging Nanotecnologies ). Exposure to nanoscale materials is not new – automotive exhaust, volcanic ash, cooking gas – all contain materials considered to be “ultrafine” or in the nano-range. However, due to the unique physicochemical properties of engineered nanomaterials and findings from toxicological evaluations to date (both in vitro and in vivo), there are scientifically sound reasons to believe that exposure to some nanomaterials may have potentially serious implications for environment, health, and safety.
The key issues surrounding EHS for nanomanufacturing are whether or not additional protections and cautions are needed, given the unique properties of nano-scale materials, and mixed findings from the toxicological literature regarding hazards from:
- inhalation (Nemmar, Hoet et al. 2002; Oberdorster, Sharp et al. 2002; Lam, James et al. 2004; Oberdorster, Sharp et al. 2004; Warheit, Laurence et al. 2004; Shvedova et al. 2005)
- dermal penetration (Monteiro-Riviere et al. 2005; Rouse et al. 2007; Ryan-Rasmussen et al. 2006, 2007; Zhang et al. 2007)
- and translocation (movement) of materials from entry into the body to other organs (Oberdorster, Sharp et al. 2002; Kreyling et al. 2002; Takenaka, Karg et al. 2004; Geys 2006; Long, Saleh et al. 2006).
Because nearly every nanomaterial is unique, and developed for very specific applications, specifying the particular physiochemical properties of each for appropriate toxicological testing is critical. Although some types of nanomanufacturing take place in a closed environment, reducing the likelihood of worker exposure to “free” or “unbound” nanoparticles, not all nanomanufacturing or manipulation of nanomaterials is contained. Studies have indicated that nanotubes can be released from solution form and measured in the workplace (Maynard, Baron et al. 2004). To address these concerns, implementing “best practices” through engineering and personal protection controls can minimize or eliminate possible exposures. Similar to approaches taken with potent drug compound manufacturing (Naumann, Sargent et al. 1996) or biohazard levels for handling of virulent strains of pathogens, levels of protections can be implemented depending on the perceived hazards.
Additionally, because EHS research is lagging behind development and manufacturing research, many unknowns exist pertaining to environmental impacts – both from industrial discharges, as well as from disposal of consumer products containing nanomaterials. Some companies with nanomanufacturing or R&D in nanotechnologies are treating industrial wasteproducts as “hazardous” under current regulations, until additional scientific information is available. Currently, there are over 500 consumer products that claim “nano,” and this number is growing rapidly. Although the likelihood of nanoscale materials being released from a discarded baseball bat made of a nanocomposite is unlikely, these concerns have yet to be systematically and scientifically addressed. Issues related to safety of nano-containing cosmetics have been raised by some non-governmental organizations such as Friends of the Earth, which has gained the attention of the US Food and Drug Administration.
Players
There are presently many players on the international scene in EHS of nanomanufacturing. International standards setting organizations such as ASTM Committee E56 and the ANSI-NSP and the ISO/TC229 committees are looking at a number of standards in nanomanufacturing, and specifically ESH. Additionally, governments across the globe are re-evaluating existing regulations, and making assessments as to whether additional protections to workers and the environment are necessary.
The US EPA has been developing a voluntary Nanoscale Materials Stewardship Program (NMSP) over the past 2 years, and the current documents are available for review and comment. One non-regulatory government agency that has been at the forefront of providing guidance to companies and facilities on ESH matters is the National Institute of Occupational Health and Safety (NIOSH). NIOSH has developed “best practices” guidelines for the workplace, a nanoparticle information library (including health and safety information if available), and has invited nanomanufacturers to work with them to conduct exposure monitoring (for free), in the workplace in order to begin to understand what the exposures might be in typical nanomanufacturing settings, and to understand what the measurements mean using a variety of instrumentation. The toxicological studies that are underway, which will provide the foundation for understanding potential hazards, are being conducted in university, government and industry settings, as well as by the NIOSH Nanotechnology Research center.
Conclusion
Even in the absence of specifically identified human hazards at this time, there is guidance readily available on health and safety actions that can be taken, and information is published and posted to the internet regularly. Although the scientific findings to date are mixed and limited pertaining to the environmental, health and safety hazards of nanomanufacturing, nanomanufacturers – including universities and R&D facilities – have the responsibility to ensure that individuals handling materials are safe, and that the environment is not adversely impacted by emissions or waste generated in the process.
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