Routes of Exposure
There are three main routes by which workers can be exposed to nanoparticles a) inhalation, b) ingestion and c) dermal penetration.10 Figure 1 Predicted total and regional deposition of particles in the human respiratory tract related to particle size using ICRP 66 model. Deposition fraction includes the probability of particles being inhaled (inhalability). The subject is considered to be a nose breather, performing standard work. Figure 1 Predicted total and regional deposition of particles...
Effects of Environmental Particles
The adverse health effects of air pollution have been recognised throughout much of recorded time (Table 1). Burning of fossil fuels in towns and cities, where there is little mixing of air, during periods of cold weather has been associated with the generation of smogs consisting mainly of sulfur dioxide and particles. Particles or particulate matter (PM) represent a part of the air pollution cocktail present in ambient air, which also comprises gases such as ozone, nitrogen dioxide, etc....
Forbes Wolfe Nanotech Reports
Forbes Wolfe produce a monthly newsletter on nanotechnology called Nanotech Report and at the end of each year report on the top 10 nanotech products of the year. In 2004, the products included a nanotechnology-based footwarmer containing a nanoporous aerogel, golf clubs using titanium fullerene materials'' in the head of their new driver, nanosilver-containing wound dressings with improved antibacterial effectiveness, an additive from BASF that improves the hydrophobicity of building materials...
Toxicology of Nanoparticles
Nanoparticles may be derived from three distinct sources accidental release (generally combustion), manufactured bulk and manufactured engineered (see Table 1). The toxicological data available vary greatly between these sources, as shown in Table 1. One challenge for toxicologists is to determine whether the substantial knowledge derived from studies of the accidentally produced and bulk manufactured NPs can be generalised to engineered NPs. Traditionally, with respect to the human hazard...
Epidemiology
Because engineering of NPs is relatively new, and long-term exposure may be needed before any adverse effects can be identified and attributed, there is little epidemiological evidence. On the other hand, there is extensive epidemiology on long-term and short-term exposure to dusts in many industries. The main problem is relevance, i.e. that these results do not necessarily generalise to the new nano-materials that are currently being developed precisely because...
References
Archambault, Canadian stewardship practices for environmental nanotechnology. Prepared for Environment Canada, 2005. 2. Small sizes that matter Opportunities and risks of Nanotechnologies. Munich Allianz, 2005. 3. The Royal Society and Royal Academy of Engineering, Nanoscience and nanotechnologies opportunities and uncertainties, RS Policy document 19 04, UK, 2004. 4. A.H. Arnall, Future technologies, today's choices. Nanotechnology, artificial intelligence and robotics a...
Sampling Strategy Issues
Until it has been agreed which is (are) the most appropriate metric(s) for assessing exposure to nanoparticles in relation to potential adverse effects, it is recommended that a range of instrumentation be used to provide full characterisation of the aerosols in workplaces where nanoparticles are being produced, handled or used to make new materials. This results in large numbers of instruments that are not conducive to the normal personal sampling procedures that are required to assess...
Metric to be used for Assessing Exposure to Airborne Nanoparticles
The current method of assessing worker exposure to airborne particles in workplaces involves the measurement of the mass concentration of health-related fractions of particles in the worker's breathing zone13 and their chemical composition. The health-related aerosol fractions defined relate to the probability of penetration of airborne particles to the various anatomical regions of the respiratory system and provide a specification for the performance of Figure 2 Health-related sampling...
Nanoparticle Size Distribution Measurement
3.5.1 Measuring Size Distribution using Particle Mobility Analysis. The most common instrument used for measuring size distributions of aerosols of nano-particles is the Scanning Mobility Particle Sizer (SMPS). The SMPS is capable of measuring aerosol size distribution in terms of particle mobility diameter from approximately 3 nm up to around 800 nm, although multiple instruments typically need to be operated in parallel to span this range. A schematic diagram is given in Figure 6. It...
Surface Area Concentrations
Measurements of particle surface area have been possible for some time using the BET method.30 However, it requires the collection of relatively large amounts of particles, and measurements are influenced by particle porosity which may or may not be important and collection support substrate -particularly where the quantity of material analysed is small. The first instrument designed specifically to measure aerosol surface area was the epiphaniometer.31 This device measures the Fuchs or active...
Particle Size Distributions
If one considers a single particle of the size of a football and then imagines that particle broken down into many smaller particles, each the size of a pea, it can be readily appreciated that the same mass of material can comprise one very large particle or many thousands of much smaller particles. When the surface area of the smaller particles is summed, it is much greater than that of the original football-sized particle. This is expressed numerically in Table 1, in which the start point is...
Metal Oxides
The largest group of inorganic nanomaterials comprises metal oxides with titanium dioxide, zinc oxide and silicon dioxide as the largest volume materials. Copper oxide, cerium oxide, zirconium oxide, aluminium oxide and nickel oxide have also been produced commercially and are available in bulk. This category comprises the largest number of different types of nanomate-rials. Conducting an internet search for nanomaterial manufacturers generates many hits, with most of the companies identified...
