Nanomaterials are materials that have at least one external dimension less than 100 nm and properties that differ from the bulk material. The physical and chemical properties of materials can vary greatly from their bulk counterparts at this scale, and their use in research is increasing.
Materials with all three dimensions under 100 nm are referred to as nanoparticles. Materials with two dimension in the nanoscale are referred to as nanofibers. Materials with one dimension in the nanoscale are referred to as nanoplates. Below are three types of nanomaterials and their sources:
Volcanic ash, salt from ocean spray, materials in the Earth's crust
Vehicle engine exhaust, welding fumes, combustion of fuels, fires
Engineered Nanomaterials (ENM)
Engineered by humans to have specific chemical properties, unique from their bulk counterparts
The table below lists some common nanomaterials:
Buckyballs (C60), fullerenes (large spheroidal carbon structures), carbon nanoparticles and nanotubes, dendrimers (polymers with branched structure)
Metals and metal oxides
Titanium dioxide (titania), zinc oxide, cerium oxide (ceria), aluminum oxide, iron oxide, silver, gold, zero valent iron nanoparticles
Zinc Selinide (ZnSe), Zinc Sulfide (ZnS), Zinc Telluride (ZnTe), Cadmium Sulfide (CdS), Cadmium Telluride (CdTe), Cadmium Selenide (CdSe), Gallium Arsenide (GaAs), Aluminum Gallium Aresenide (AlGaAs), Lead Selenide (PbSe), Indium Phosphide (InP)
Biological materials such as protein, DNA, or RNA are NOT nanomaterials.
Because nanomaterial properties differ from those of the bulk material, their toxicity and health effects can be very different. Their small size allows them to enter the body easily, and the higher surface area can make them particularly reactive and/or toxic. In addition to the higher surface area, the number of particles per unit mass is far greater than the bulk counterparts.
The effects of exposure vary with the material as the composition of the nanomaterial affects how it enters the body. There is evidence that nanomaterials deposit in the lungs, penetrate intact skin, and enter the blood stream, through which they can translocate to any organ including the central nervous system.
Due to the increased reactivity, nanomaterials represent a greater fire and explosion risk than the bulk materials. Keep nanomaterials away from potential ignition sources to minimize the risk of fire or explosion.
The greatest risk of exposure is through inhalation of airborne nanomaterials. The amount of material released depends on the type of nanomaterial and how it is being manipulated. The following table lists three common preparation techniques for nanomaterials and their potential for release of nanoparticles into the air:
Risk for release into air
Potential routes for Inhalation Exposure
Nanomaterial embedded into a solid matrix or tightly bound to a surface
Mechanically working on the material such as cutting, sanding, drilling.
Formation of aerosols through agitation such as sonicating, stirring, centrifuging of open containers holding suspensions
Any open handling of powder
Once nanomaterials are released into the air, they can remain suspended for days or even weeks.
Exposure to nanomaterials can also occur through dermal contact, particularly damaged skin. There is evidence to support that nanomaterials can penetrate intact skin. Quantum dots in particular have been shown to penetrate intact skin. Follow the Safe Handling practices below to limit the risk of dermal exposure.
Exposure to nanomaterials through ingestion is unlikely, but is possible. Ingestion can occur after inhalation, or through poor laboratory hygiene practices. There is evidence to support that nanomaterials can translocate to organs throughout the body after ingestion.
Every effort should be made to avoid releasing nanomaterials into the air. Since they can remain suspended for an extended period of time, any release poses a hazard to anyone entering the laboratory.
Perform all work with nanomaterials inside an enclosure such as a glove box, glove bag, or an enclosure made especially for nanomaterial or dry powder use. These enclosures are designed to operate at a much lower airflow than conventional fume hoods. Some nanomaterials, carbon nanotubes in particular, are difficult to handle in a chemical fume hood because the air flow is often too high to contain the material inside its container, and can release back into the work area. Even fume hoods that are effective at containing bulk material may fail to contain nanomaterials, posing a risk to laboratory workers.
Any enclosure that vents into the room or through the ventilation system must be equipped with a HEPA or ULPA filter. Develop a procedure for changing the filter without releasing nanomaterials into the room air such as a bag-in/bag-out technique.
Enclosures specifically made to contain nanomaterials are ideal engineering controls. Those enclosures have a lower air flow and are equipped with a mechanism for safe filter change. If possible, dedicate an enclosure for nanomaterial use.
Every effort should be made to fully enclose processes involving nanomaterials with a suitable enclosure. If it is not possible to fully enclose a process (due to the scale for example), other local exhaust ventilation systems equipped with a HEPA filter may be adequate (e.g. welding fume extractors). Be aware of the limitations of local exhaust ventilation systems that do not fully enclose the process.
When working with dry powders, sticky floor mats can help reduce the levels of nanomaterials in the air.
Always wet-wipe areas where dry nanomaterials are used. If the wipes are contaminated, collect them in a sealed plastic bag and dispose of them as hazardous waste through DRS. A vacuum cleaner with HEPA filter can be used to clean areas that are difficult to clean.
Protect yourself from skin contact by wearing standard laboratory attire such as closed-toe shoes, long pants, a lab coat, safety glasses, and gloves when handling nanomaterials.
A respirator should not be necessary when working in a well-ventilated enclosure. If a respirator is required for certain procedures, remember that other people working in the laboratory who are not wearing respirators are at risk, and nanoparticles may remain in the air after the work is done. Wearing a respirator also requires a medical evaluation and fit-testing before use. Contact Safety and Compliance before purchasing a respirator.
If skin or the eyes are exposed to nanomaterial, rinse with plenty of water.
If nanomaterial is inhaled, move into fresh air. If respiratory irritation or breathing problems persist, seek medical attention as described in the Lab Safety Guide.
Powdered nanomaterial or debris from mechanically working on embedded nanomaterial should be wiped up with a wet paper towel or a wetted absorbent pad. Spilled suspensions should be wiped up with an absorbent pad compatible with the solvent. Collect contaminated wipes in a sealed plastic bag and dispose of them as hazardous waste. A vacuum cleaner with a HEPA filter can also be used to clean spills of dry nanomaterials.
Store all nanomaterial in well-sealed containers. Label the container with the chemical identity of the material and add the term “nano.”
Collect nanomaterial in a separate waste stream and dispose of through DRS.
OSHA Factsheet “Working Safely with Nanomaterials”:
Leo Old & Mark M. Methner (2008) Engineering Case Reports, Journal of Occupational and Environmental Hygiene, 5:6, D63-D69, DOI: 10.1080/15459620802059393