Working with nanowires and nanotubes

When considering the possible health implications of working with nanowires and nanotubes, two issues needs to be taken seriously into account: their chemical composition and their size.

For risk assessment in relation to the chemical composition please always consult the appropriate MSDS. This can be found at kemibrug.dk

The possible implications of inhaling nanowires (carbon, silicon, indium arsenide, etc) are not yet fully investigated nor understood. It is thus sensible to assume that there might be a potential health risk associated with the inhalation of nanowires. The reason for this assumption is that the dimensions of nanowires and asbestos are similar. This means that the risk is associated to the ratio of the length l of the wire divided by its diameter d being larger than 3 and smaller than 10. The dimensions that might potentially cause the highest health risk are:

8 μm < l < 100 μm
d < 250 nm
l/d > 3

As a consequence, certain precautions must be taken when working with nanowires in order to minimize the risk of inhaling them.

Guidelines

The health risks associated with nanowires and nanotubes are both based on airborne particles. Therefore reduction of the hazard associated with wires and dust is to minimize possibility of generating airborne particles.

Hazard reduction instructions are:

• Hygienic work conditions (no eating nor drinking in the lab, wet cleaning of surfaces after experiment and washing of hands after experiments).
• Personal protective equipment (gloves, face-mask, etc) must be worn. Note that the effectiveness of a face mask for very small particles is not proven.
• Process your sample in a fume hood or under local fume extraction
• Keep process wet as long as possible.
• Wear a class P3 particulate respiratory face mask or use fume exhaust during cleaving of nanowire samples. If you need a respiratory face mask please ask a clean room staff member for advice before purchasing.
• Clean surfaces with wet wipes to prevent nanowire or nanotubes from becoming airborne and dispose wipes as toxic waste.

It is important to note that PPE such as a face mask is only the last resort in order to keep you safe. It is much more important to prevent wires from escaping by good laboratory practice and working under the fume hood than it is to behave irresponsibly and wear a facemask. Also remember that the dimensions of the particles are small in one direction, so your mask should ensure that dimension cannot get through. This means that only class P3 particulate filter masks will suffice!

Remember, you are obliged to read the MSDS of all materials involved in your process before starting any work. If in doubt about anything please consult your supervisor, or a member of the NBI cleanroom staff.

More info on health and safety in nanotechnology can be found on here (Danish), or here (Danish)