- This report which essentially consists of abbreviated notes from a number
of sessions from the nanotechnology study workshop is welcome in concept particularly
as a multi-disciplinary approach was employed. However, the text reads simply
as a précis of the meeting with the assumption that the reader had
been involved in the original meeting – the provision of explanatory
footnotes would have helped enormously.
- This whole field is truly multi-disciplinary, but, and this comes through
occasionally in the odd comment in the report, each individual involved in
the meeting had their own particular area of expertise and a varying degree
of knowledge in the other areas. Consequently if the final report of this
workshop is to be used as a cross- disciplinary resource then the text needs
to be expanded to include context and explanations for those not familiar
with specific areas within this field.
- To that extent a preliminary preamble on the background of why the working
group was set up including some basic information such as definitions would
help the flow of the document.
- I come from a health-based background with a particular interest the health
effects of airborne particles in ambient air and the possibility that ultrafine
(sub 300 nanometre) particles when inhaled may be a route for therapeutic
intervention. I am not an engineer and therefore it is difficult if not impossible
for me to comment on some of the physico-chemical aspects of this report.
In addition, these comments are mine as an individual and
do not represent the thoughts of the Department of Health’s Committee
on Medical Effects of Air Pollution (COMEAP) which I chair.
Nano-Engineering and Measurement
- Although not my particular area, I would agree with the comment under “applications”
that networks are important in the context of the development of strategies
for the development of nano-technology. However it is important to stress,
as is mentioned later in the document, that such networks need to be truly
cross-disciplinary and perhaps incorporated within the strategy should be
some process either virtual or real, for being able to see what others are
doing in the diverse fields in this broad area.
- Section e ix
One existing technology is in the generation of therapeutic aerosols which,
while mostly concentrating on much larger particles do contain a very significant
ultrafine component (see below).
- Section d vi
I would agree that it is important to assess the properties of the individual
chemical components that make up nano materials as well as size, concentration
and surface area, but of particular importance may well prove to be the disposition
of the constituents of nano-particles on the surface of the particles. This
is particularly true in terms of health effects/toxicity where it is the surface
of the particle that first comes into contact with the biological surface.
The interaction of nano particles with fluid interfaces such as the epithelial
lining fluid in the respiratory tract and then again with cellular interfaces
is key in understanding the toxicity or toxic potential of nano particles.
In the same area it is important to flag up that novel imaging techniques
of the intact organism - not just at a cellular level - would be eminently
suitable for exploring the whole area of toxicity.
ELECTRONICS AND OPTO-ELECTRONICS
- I would fully endorse the comments on the development of good multi-disciplinary
teams (Section d) rather than developing inter-disciplinary people. While
training at a masters level is the logical way to take this forward it is
essential that this whole area is embraced at first degree level.
BIO NANO-TECHNOLOGY AND NANO-MEDICINE
- This is the only section of the report that made specific comments on addressing
definitions and was the only place in the report where I came across any idea
of what definitions were being offered in the first instance! I would agree
broadly with their definition of nano-technology but am a little less happy
with their definition of nano-science. Specifying that nano-science is “on
the scale of atoms and molecules” suggests that nano-science is limited
to atoms and molecules and not to structures developed from them. This may
seem pedantic but I would favour going to back to some broad assessment of
the upper limit in terms of length scale rather than a comparator.
- Section b ii
While there is some comment at various points about dermal application of,
for example, creams containing nano-particles, nowhere (apart from inferentially)
is there any mention of the inhaled route as probably the major way in which
nano-particles enter the body either deliberately – as in therapeutic
aerosols – or obligatorily such as inhaling ambient air. It is all very
well concentrating on cellular uptake of drugs but in order to be taken up
by specific target cells the vehicle has to get there and deposition within
the lung is key from that point of view particularly as this is majorly affected
by the presence of intrinsic lung disease.
- Section c
It is intriguing that no mention is made of therapeutic aerosols. 3M have
produced over the past few years an inhaled corticosteroid drug (QVAR) which
has a spread of particle sizes which is much smaller than the conventional
metered dose aerosol. We have undertaken work which shows that all medical
aerosols in fact contain many particles below 100 nano-metres in size. What
is not known is how much of the therapeutic potential lies in the ultrafine
fraction compared to the larger fraction (say >1micron). The assumption
has always been that it is in the larger size particles but as no-one has
delivered ultrafine particles containing drugs as yet (we are in the process
of trying this) we do not yet know how useful ultrafine/nano-technology would
be in targeting the lung for drug delivery as opposed to getting the drug
into the lung for systemic use.
- Section e
I would fully agree that research councils need to have overlapping remits
and to be fair they are, in general, trying to do this. However, when trying
to apply for such overlap funding one often gets told by one of the funding
partners that the application is less suitable for them and more suitable
for the other partner and vice versa!
I am not sure what lies behind the statement that the RAE is hindering collaboration
specifically within nano-technology, I suspect this is partly because of the
stresses in encouraging individual departments to focus in an enormous blinkered
fashion of their own area of research as the units of assessment tend not
to be able to embrace the essential nature of nano-technology, ie. multi/disciplinary
In the fifth bullet point (funding) in this section I am not entirely sure
what the first sentence means (apart from being bad English!).
HEALTH, SAFETY ENVIRONMENTAL AND SOCIAL ISSUES
- I can see why these were pulled together as a joint heading but it would
reasonable to separate out health and safety from the environmental and social
issues in my view as there are different strands of argument for each.
- I fully agree with the concerns about carbon nano-tubes and their similarity
to asbestos. This is a good analogy but one must bear in mind that not all
fibrous type materials do have the same lethal implications as has asbestos.
For instance glass fibre is much less toxic (hardly at all) and on the spherical
particle side of things carbon black workers have only very minimal (entirely
non-dangerous) effects of persistent exposure to high levels of nano-particles.
However, I would agree with the participants that further study into the potential
durability and toxicity of nano-tubes is undertaken but non-tubular particles
need also to be addressed.
- It is quite true that the most likely agent for the adverse aspects of
air pollution are sub-100nm particles and the statement that “the background
concentration of many tens of thousand (of particles) in urban air”
should be corrected to: ..”..tens of thousands of particles in each
millilitre of urban air”.
- Section c
I would agree that mass per unit volume is probably not the most important
metric for assessing dose when considering toxicity. However, at this stage
it is difficult to know exactly what the best metric would be. Particle size,
particle surface area and fractal properties may all have their role as may
the concentration of specific components of the particles and/or their disposition
over the surface of a core particle.
This raises the whole issue of the importance on the negative side of inhaling
of ultrafine particles either of pure drug or of a carrier with a drug on
them for therapeutic purposes as the mere size of the particles in themselves
may be deleterious. This equation is I think extremely important and one that
is not easily addressed at the present stage until such products are available.
- Section d
Getting the messages that are required across to the public is clearly the
key. Much comment is made throughout the report on public perceptions implying
that again the public have got it wrong having been stirred up by the media!
The trouble is that quite often the public are right and I think it would
be wrong of us to sit and believe that nano-particles are inherently safe
and a splendid addition to our modern world. We need to be crucially careful
about the potential deleterious effects of nano-particles particularly where
they get into a situation where they could inadvertently enter the human body
in some form or have an adverse effect on the environment in general.
However the concern about the innate suspicion that the public has about industry
is undoubtedly true. While in the pharmaceutical industry the relationship
between public and the pharmaceutical industry seems to have improved somewhat
over the last decade or so, nevertheless there is still quite a substantial
issue of the relationship between the public and the pharmaceutical industry.
Indeed, some doctors also express concerns regularly on this area. In my view
a confrontational approach does not help and again this needs to be dealt
with I think by some form of approach where these worries could be allayed.
One possibility is that industry puts money into a central fund aimed at addressing
specific areas within the whole area of nano-technology with control over
that fund being through an independent group. Industry would then seem to
be contributing in an unselfish way in trying to address issues not only on
the basic science but also on applications, safety and public communication.
Professor of Environmental & Occupational Medicine
University of Aberdeen