Policy No: 2050 Responsible Office: Laboratory Safety Committee Last Review Date: 04/03/2023 Next Required Review: 04/03/2028
This policy describes recommended procedures for the proper generation, handling, and disposal of nanoparticles and other nano-objects. Nanoparticles are not necessarily novel materials. Some have been well-known and used for many years, e.g. ultrafine TiO2 and “carbon black”. Even these “legacy” nanoparticles can pose dangers, e.g. respiratory hazards. More recently produced nanoparticles such as aerosols have respiratory and cardiovascular effects, and welding and diesel fumes can be carcinogenic.
These procedures shall be followed by Academic Affairs, USA Health and Medical Affairs Divisions as well as any person who works with nanoparticles.
Nano-object: The ISO definition of a nano-object is any material with one, two, or three external dimensions in the range 1nm to 100nm. Nano-objects are frequently incorporated into a larger matrix.
Nanoparticle: A specific type of nano-object, with all three external dimensions at the nanoscale.
Ultrafine particles: Nanometer-diameter particles that have not been intentionally produced but are the incidental products of processes. Incidental or ultrafine particles exist naturally and although they are often produced only in small quantities they may also pose a significant risk.
4. Policy Guidelines
4.1 Typical hazards
The underlying hazard is determined by the chemical properties of the material(s) concerned, including any impurities. However, generally, nanoparticles can be more hazardous than the same material in larger particulate form because of the significantly increased reaction surface area. E.g., a flammable material (or even a material such as aluminum normally regarded as non-flammable) can be explosive in nanoparticle form. In addition, even if the basic material is inert or benign, there can be human irritation problems. Dry powders usually pose more threat (and require greater attention and controls, such as enclosure) than liquid suspensions, though sonication outside of containment equipment can increase airborne nanoparticle dispersion. Nanoparticles embedded into solids often pose little threat unless they are cut or machined to release some nanoparticles. Waste containers may pose unexpected threats as previously wet wipes can dry out and release captured nanoparticles. Exposure can potentially occur through inhalation, skin contact, ingestion, or combinations thereof, though inhalation may be the primary risk in many cases. Properties such as size, shape, functionalization, surface charge, solubility, agglomeration, and aggregation state can have profound effects on a particle’s toxicological properties and interactions with biological systems. In some cases, careful choice of materials may reduce the hazard of a particular process while maintaining the desired properties and functionality of the nanoparticles.
5.1 Mandatory procedures
The Principal Investigator (PI) is responsible for ensuring that all lab workers are aware of the hazards associated with nanoparticles and are trained in proper handling and disposal methods. The following work practices should be regarded as mandatory:
- The PI should review the appropriate Safety Data Sheet (SDS) and conduct a Risk Assessment before handling nanomaterials; more information on best practices appropriate for specific classes of materials is included in Section 5.2 below;
- SDS(s) of the nanoparticles in use must be readily available (e.g., paper copies kept in a file in the lab);
- If possible for the process concerned, use nanomaterials having the least risk (e.g., use liquid suspensions rather than dry nanoparticles);
- Ensure that all safeguards indicated in the SDS are in place;
- Evaluate all possible incidences, from receiving to disposal, including equipment maintenance (such as regular replacement of any exhaust filter) and reasonably foreseeable emergencies;
- If working with explosive or potentially explosive nanoparticles, eliminate ignition sources;
- All workers should wash their hands after any nano-object handling, or before eating, drinking, smoking, or leaving the workplace;
- Appropriate PPE, as identified in Risk Assessment (e.g., long lab coat with long sleeves and wrist covers of non-woven material; nitrile gloves; closed-toe shoes or slip-on overshoe booties) should be worn as a precaution unless installed containment measures have been proven sufficient; this may require use of a change room to prevent further contamination;
- Safety glasses and/or face shield may be needed when handling liquids.
5.2 Recommended procedures
DHHS (NIOSH) has published fact sheet 2018-103 (available at https://www.cdc.gov/niosh/docs/2018-103/default.html) summarizing best practices for work involving dry powder, nanoparticles suspended in liquid, and nanoparticles embedded in a solid. UNC-Chapel Hill has made available at https://ehs.unc.edu/lab/nano/ a matrix of best laboratory practices in handling the same categories of materials plus dry powders or aerosols of parent materials with known toxicity or hazards. Some specific work practices that should be considered, dependent upon recommendations in the nanoparticles’ SDS, include:
- If appropriate for the material(s) concerned, obtain a baseline medical evaluation by a qualified healthcare professional on each worker before handling nanoparticles and periodically thereafter;
- Review the NIOSH Risk Assessments and recommended exposure limits (RELs) for TiO2 (currently REL = 300µg/m³), and carbon nanotubes (CNTs)/carbon nanofibers (CNFs) (currently REL = 1µg/m³; previously a higher value was used), both for airborne exposure, and any other nanoparticles for which NIOSH has completed a Risk Assessment;
- General recommendations when the quantity of nanoparticles used is more than minimal include using flexible containment (plastic sleeves, continuous-feed bag liners), low flow containment hoods (exhausted through a HEPA filter), chemical fume hoods, Plexiglas gloveboxes (exhausted through a HEPA filter), glove box isolators and other types of isolation enclosures, and sticky mats (routinely replaced when showing signs of soiling) at laboratory exits;
- If airborne exposure is a potential problem, consider installing air sampling monitors;
- Consider working in an area under negative pressure, and exhausted through HEPA filters;
- Ensure that HVAC systems cannot transfer significant quantities of nanomaterials to another lab, by using appropriate containment and/or air ventilation routing;
- Remember that risk of faults such as leaks in containment equipment may increase the preventative measures routinely needed over what is minimally needed assuming equipment is operating correctly;
- When there is risk of inhalation, a respirator may be needed (i.e., a breathing filter or “gas mask”; full-face is preferred over half-mask; N95 or P100 filter cartridges are effective, but medical-type masks are generally ineffective against nanoparticles); this requires fit-testing and medical clearance to wear a respirator. Contact Safety and Environmental Compliance for guidance;
- Contaminated and potentially contaminated surfaces and clothing should be cleaned using HEPA vacuum and/or wet wipes (compressed air or dry wipes are not recommended); alternatively, protective/disposable coverings may be used;
- Maintain a spill kit on site containing at minimum: barricade tape, nitrile gloves, full-face respirator, spill mats, disposable wipes, sealable plastic bags, sticky mat, HEPA-filtered vacuum, and spray bottle with DI water, surfactant, or alcohol.
5.3 Action in the event of a spill or accidental exposure
Compressed air should never be used in case of a spill. A spill kit (see above) should be available at each location for use in case of an accidental spill. The effects of human exposure greater than the permitted respective RELs are currently not known in detail. In the case of major exposure it is therefore recommended to undergo medical evaluations to be compared against the baseline tests previously recorded.
5.4 Disposal procedures
Disposal of nano-objects into a sealed bag is typically recommended unless there are additional underlying hazards from the native material that require additional precautions.
This policy is enforced by the Safety and Environmental Compliance Department. Non-compliance may result in the suspension of associated activities and/or projects. University faculty and staff will be subject to disciplinary action per Faculty Handbook or Staff Employee Handbook, respectively.
7. Related Documents
This safety policy is summarized from and based upon the following reports from the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati:
- Beaucham C. & Hodson L.: “General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories”, Publication No. 2012-147, May 2012, available at http://www.cdc.gov/niosh/docs/2012-147/;
- Zumwalde R., Kuempel E., Birch E., Trout D., & Castranova V.: “Occupational Exposure to Carbon Nanotubes and Nanofibers”, Current Intelligence Bulletin 65, Publication No. 2013-145, April 2013, available at https://www.cdc.gov/niosh/docs/2013-145/pdfs/2013-145.pdf;
- Hodson L. & Hull M.: “Building a safety program to protect the nanotechnology workforce: a guide for small to medium-sized enterprises”, Publication No. 2016-102, March 2016, available at http://www.cdc.gov/niosh/docs/2016-102/default.html.
All these reports are in the public domain and permission is not needed to copy and distribute them. Further resources are:
“WHO guidelines on protecting workers from potential risks of manufactured nanomaterials”, Geneva: World Health Organization; 2017. Licence: CC BY-NC-SA 3.0 IGO, ISBN 978-92-4-155004-8 (particularly pp. 43-62), available at https://www.ncbi.nlm.nih.gov/books/NBK525054/
“Controlling health hazards when working with nanomaterials”, Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication Number 2018-103, available at https://www.cdc.gov/niosh/docs/2018-103/default.html
“Nanotechnology Safety”, UNC-Chapel Hill, available at https://ehs.unc.edu/lab/nano/