Exposure to Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 341

tially since that estimate. The authors suggested that it may double over the
fi ve years to 2009. The proportion of those involved in existing chemical and phar-
maceutical companies and in other powder handling activities exposed to nano-
particles is likely to increase substantially as the use of nanoparticle materials
increases.
It is reasonable to expect that the balance between numbers exposed in research
and production and applications will shift, with greater emphasis and exposures
being found during the secondary manufacturing of products. It is also clear that
potential occupational and public exposure to manufactured nanoparticles will
increase dramatically in the near future due to the ability of nanomaterial to
improve the quality and performance of many consumer products the public
employs daily, as well as the development of medical therapies and tests which will
use manufactured nanoparticles.

8.4 Control of Exposure

8.4.1 Introduction

Using chemicals or other hazardous substances at work can potentially put people' s
health at risk. In the United Kingdom, the law requires employers to control expo-
sure to hazardous substances to prevent ill health. The framework by which compli-
ance can be achieved and demonstrated is the Control of Substances Hazardous
to Health Regulations 2002 (COSHH) (HSE, 2002). This is a scheme of good health
and safety management involving eight basic measures that set out in a simple
step-by-step approach to help assess risks, implement any measures needed to
control exposure and establish good working practices. The major elements in this
approach are:

• Identify the hazard
• Assess the risk
• Prevent or control the risk
• Evaluate the effectiveness of control measures.

At the current time there are some major uncertainties that limit the extent to
which adequate assessment of the risks arising from exposure to nanoparticles can
be made. Risk assessment requires an understanding of the toxic potential of a
material and the levels of exposure that are likely to arise in various scenarios
where it is used. It is clear from the foregoing that nanoparticles are not a single
group of objects but a multiplicity of shapes, sizes and compounds. A unifying
feature of nanoparticles is that they will be smaller than the materials that they
replace and will have larger specifi c surface area per unit mass. These parameters
are known to increase the toxic potential of a material (Tran et al. , 2000 ).
It is clear from this review that little is known concerning the exposures of those
working with these materials. There is some reassurance that the limited studies
that have been carried out do not suggest that there are high airborne concentra-
tions of nanoparticles in workplaces where they are manufactured, although these