BOHS Conference workshop on nanotechnology

Titanium dioxide nanoparticles

In her Keynote address to the 2011 BOHS Conference, the Chair of the HSE, Judith Hackitt, mentioned nanotechnology as one of the “emerging issues” that HSE will continue to give priority to despite the cutbacks in its budget. Nanotechnology has been a high profile issue for HSE for a number of years as the production of “engineered” nanoparticles has increased. Their toxicology isn’t fully understood and measurement presents a number of problems, so it is difficult to properly evaluate the risks to health.

At last year’s conference, a plenary session was devoted to nanotechnology and this year it was the theme for one of the workshops. It was a good session, with three speakers covering health effects, assessment and control. However, the content of their talks was very similar to those given during the plenary sessions last year, suggesting that there haven’t been any major advances in the science over the past 12 months.

Rosemary Gibson form HSL made a very good presentation summarising the health implications of engineered nanoparticles. The key points she made included

  • Nanoparticles have a very large surface area to volume ratio and this has implications for their effects on health. Some researchers have identified a relationship between surface area and inflammation and this suggests that surface area is the best metric to use to assess the risk, rather than mass concentration (which is normally used with particulates).
  • Research has mainly focused on their effects on the respiratory system with some work on skin effects. Less work has been carried out on systemic effects. However, the main concern identified from experience with ultrafine particulate air pollutants (from non-engineered sources such as diesel exhaust emissions) is effects on the cardiovascular system, and some research has suggested that this is also relevant with engineered particles, so more work is needed on this aspect.
  • There are continuing concerns about the effects of carbon nanotubes and whether these fine, fibre like particles may behave like asbestos. Work by Poland et al, the results of which were published n 2008, certainly suggest that this may be the case with long multiwalled carbon nanotubes, where there was evidence of inflammation and granulomas. However their research also suggested that short multiwalled carbon nanotubes were non-harmful. (For further details, see the commentary by Ken Donnaldson, here).

The other two speakers, James Wheeler of the HSE and John Hulme of Cambridge University (who gave a Keynote on Nanoparticles at last year’s conference) both concentrated on practical implications in the workplace.

James emphasised the need for a sensible approach to risk management. Precaution was needed, as nanotechnology was a “step into the unknown”, but he emphasised that the risks could be managed and controlled in the same way as high hazard materials, using the principles of good practice embodied in the COSHH Regulations. HSE has a website on nanotechnology and has also issued guidance on carbon nanotubes. Further guidance, produced in conjunction with relevant partners, should be available in March 2012

John, who has considerable experience of managing the risks from nanoparticles in research laboratories at Cambridge University, concentrated on the practical assessment and control of the risks. He pointed out that the hazard information provided by some suppliers of nano-materials was inadequate, treating them as if they were no different from macro forms of the substance when there were clear differences in toxicology. He re-emphasised one of the points Rosemary made about the importance of surface area and discussed the practical difficulties of measurement.  Methods are available to measure particles on the basis of their surface area, but as these techniques can’t identify what the particles are it isn’t possible to tell where they have originated. There can be high background levels of fine particles from natural and man-made sources, which confuse the results from any surveys. So the problem with nanoparticles is that we aren’t sure of the hazards and can’t properly quantify the risk!

John’s answer was that we need to take a precautionary approach and control all potential exposures to a high standard. He provided some good examples from his experience of controls that can be applied in practice including:

  • preventing particles becoming airborne by using slurries rather than powders
  • working in glove boxes and microbiological safety cabinets
  • applying well designed local exhaust ventilation, pointing out that nanoparticles behave like gases and so are easy to capture
  • using HEPA filters to minimise emissions to the environment and workplace

For further information on nanotechnology hazards and control see

HSE nanotechnology website

HSE guidance on carbon nanotubes

Safenano website

Image credit : http://newsroom.ucla.edu/portal/ucla/srp-view.aspx?id=85846

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