Safe Handling and Disposal of Nanostructured Materials
Nanostructured materials are substances that contain at least one dimension in the nanometer-size regime and can include nanoparticulate materials such as quantum dots, nanofibrous materials such as carbon nanotubes, and nanoporous material such as activated carbon. Potential applications of these novel materials in the oil and gas industry include wastewater treatment, antimicrobial additives, and multifunctional coatings. These applications cause concerns regarding safe handling and disposal of the materials. This paper provides a first-hand perspective on the appropriate handling of nanomaterials in a laboratory setting.
After several cycles of technological advances in fields such as polymers, electronics, and the energy sector, the world is currently undergoing a nano revolution, wherein materials with increasingly smaller dimensions are generating considerable interest in the interdisciplinary technology community. Such materials, known as nanomaterials or nanostructured materials, typically have at least one dimension in the nanometer range. These materials have been found to possess many useful properties, such as high strength, high surface area, abrasion resistance, and tunable chemical reactivity. They are currently being researched extensively or actively proposed for related applications in critical realms (e.g., aerospace, defense, medicine) such as aircraft composites, electronic devices, biomedical sensors, and coatings. This trend makes it evident that nanomaterials and nanotechnology, the science and application of such material or the manipulation of material at molecular or atomic scales, are here to stay and will grow in popularity. A wide range of economic institutions worldwide estimate the global market for nano-related products and technologies to be worth currently more than USD 1 trillion.
As with any new material or technology, there will be unknowns such as questions related to safety, economy of handling and processing, and effect on the environment. Therefore, the increasing use of nanomaterials in research laboratories and industries makes it essential to understand and address these questions better.
This paper focuses on prevention of possible safety issues related to nanomaterials through a review of current good practices and regulatory developments as applied to an industrial laboratory setting. As the saying goes, “Prevention is better than cure.” As with any material or activity associated with human endeavor, risks exist and can always be addressed by the judicious use of appropriate protective or preventive measures in the research-and-development phase and during manufacturing and commercialization.
Potential Risks of Occupational Exposure to Nanomaterials
Various types of nanomaterials have their own unique sets of physical, chemical, and biological properties. For example, nanoparticulate powders can be easy to aerosolize and disperse, even unintentionally. Because these particles are very small, even a small quantity of the material can be dispersed over a wide area. Liquids containing dispersed nanomaterials (nanofluids) can sometimes be less dispersible because, unless pressurized, they cannot be dispersed over large areas as easily as the dry particles. Pressurized aerosol containers of nanodispersions (in a liquid or gaseous carrier), on the other hand, are energized and potentially are even more dispersible than dry nanoparticles.
Given that nanomaterials are a new class of widely used materials, only sparse definitive data exist on their effects on human beings. A person can be exposed to these materials through several key routes: oral ingestion, inhalation, skin contact, and injection. Upon coming in contact with finely dispersed particulate material, literature suggests that a person can suffer from mild or chronic symptoms (depending on the mode and duration of exposure). These range from respiratory discomfort and dermatitis to lung or eye damage (especially for prolonged exposure or exposure to high doses of the material). Several of these symptoms have been recorded in the literature for various micrometer-sized particles. Asbestos is another material that has been studied extensively and can provide an analog for the potential risks of exposure to nanomaterials.
Some common exposure routes and resultant consequences exist if precautions such as the use of personal protective equipment (PPE) are not taken. Initial damage arising from external exposure to nanomaterials (in the form of dispersions, aerosols, or powders) can translate into more-complex and -unpredictable consequences within the body of a human being. Exposure to nanomaterials can be prevented easily with some commonly used PPE such as safety glasses, laboratory coats, face masks, and gloves.
What Is Nanosafety?
Given the development of several new types of nanomaterials, the lack of definitive data on their harmful effects, and the availability of a wide range of preventive safety measures, approaches need to be developed to promote better safety when working with these materials. Such an endeavor results in safe working conditions for personnel, which can be termed “nanosafety.” Among the most common ways to promote nanosafety is prevention by the use of widely available and commonly used PPE and suitable engineering controls. A hazard-risk assessment usually helps identify opportunities for designing such controls. The use of PPE along with engineering controls effectively reduces external exposure and subsequent internalization of nanomaterials by personnel. One cannot emphasize enough the importance of these simple measures.
It must be noted that merely using PPE and engineering controls would not be sufficient to promote nanosafety. The authors of this paper consider nanosafety to be a philosophy and a responsibility to work with nanomaterials in a careful manner, guided by sound scientific principles and common sense.
Regulatory Activity: Emerging Trends and Challenges
Although general guidelines and regulations pertaining to the safe handling and disposal of chemical or hazardous wastes exist, the initiatives addressing the unique requirements related to nanomaterials are still in their infancy. Several regulatory organizations are looking into addressing these initiatives. In late 2014 and early 2015, some basic information regarding nanomaterials came to be required from manufacturers by the US Environmental Protective Agency (EPA) as part of the Toxic Substances Control Act (TSCA) under the auspices of the Significant New Use Rule. Moreover, in the US, the Nanoscale Materials Stewardship Program introduced by the EPA under the auspices of the TSCA still regards nanomaterials as conventional chemicals, despite differences in their properties. The Registration, Evaluation, Authorization, and Restriction of Chemicals program rolled out in the EU tends to focus on bulk chemicals. Consequently, the smaller quantities of nanomaterials and their related wastes tend to “fall through the cracks.” While it is likely that not all nanomaterials are harmful, several categories of these materials will be capable of having a negative effect on human health and the environment, either in isolation or in a mixture with more-conventional materials and chemicals (e.g., polymer nanocomposites). Challenges regarding the effective evaluation of hazards pertaining to nanomaterials could contribute to these inadequacies, where the issues could be addressed potentially through a combination of improved toxicology-test protocols and computational methods. Any improvements to the current regulatory stipulations may take some time to be formulated and implemented. Meanwhile, one way to handle this challenge is to voluntarily adopt suitable good practices, coupled with existing regulations and intracompany policies. The key will be to err on the side of caution wherever possible.
Good Practices in Action
Until nanosafety regulations are in place, some voluntary good practices should be adopted, based on currently used laboratory and industrial safety protocols. On the basis of literature published by the National Institute for Occupational Safety and Health, some suggested universal guidelines pertaining to nanosafety can include
- By default, treat nanomaterials as hazardous chemicals, and learn about related technical literature before working with them.
- When new to the field, employees should be provided with adequate training.
- Employers should work toward identifying tasks, processes, and equipment involved in handling nanomaterials, especially in their native forms (e.g., bulk powders). Workplace profiles of exposure to nanomaterials should be conducted regularly.
- Ongoing education programs pertaining to nanosafety should be in place and inform employees periodically about the latest developments in this field.
- Plan the experiment or process beforehand, and obtain the required amounts of nanomaterial; this reduces subsequent waste and disposal problems.
- Be aware of neighboring personnel when working with nanomaterials, and always confine or restrict the workspace where nanomaterials are handled.
- Use suitable engineering controls and proper PPE specific to the materials and processes in question.
- Properly dispose of any waste.
- Wash hands (even after removing gloves) with soap and water before handling food or working outside the laboratory.
- Regularly monitor changes in the organization’s policies, industry practices, and emerging regulatory activity, and comply as required.
In Fig. 1, we can see that the type and quantity of nanomaterial, the processes employed, the existing infrastructure, and (above all) the human factor all play a big role. The flow chart must be customized for specific nanomaterial-related activities.
This paper attempts to present a detailed overview of safe handling of nanomaterials in an industry setting, from a laboratory practitioner’s viewpoint. Increased usage of nanomaterials leads to increasing amounts of related waste, also termed “nanowaste,” with as-yet-unknown ramifications.
Nanowaste is currently treated as a conventional hazardous chemical in academic and industrial entities working with these new materials, though not all nanomaterials are toxic or harmful. However, owing to size-dependent differentiation of the properties of materials, nanomaterials and related waste require certain unique additional safety measures. Moreover, nanomaterials can consist of various compositions and chemistries that must be addressed separately. Many good practices are based on current precautions used when handling hazardous chemicals and involve general common sense.
This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 25975, “Safe Handling and Disposal of Nanostructured Materials,” by Pavan M.V. Raja, SPE, Monica Huynh, and Valery N. Khabashesku, SPE, Baker Hughes, prepared for the 2015 Offshore Technology Conference, Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2015 Offshore Technology Conference. Reproduced by permission.