Summary
 
 

Novel Concepts, Methods, and Technologies for the Production of Portable,
Easy-to-Use Devices for the Measurement and
Analysis of Airborne Engineered Nanoparticles in Workplace Air

Engineered nanoparticles (ENP), defined as having at least one dimension ≤100 nm, have attracted a great deal of interest during recent years, due to their many technologically interesting properties. The unique properties of ENP and their applications have given birth to immense technological and economic expectations for industries using ENP. However, some of these properties have given rise to concern that they may be harmful to humans. This has prompted scientists, regulators, and the industrial representatives to investigate the features of ENP in order to be sure of their safe use in nanotechnologies (NT), i.e. technologies utilizing ENP. The European Commission has also explored in-depth the characteristics of ENP and issued a document on ways to assure the safety of ENP.

Overall objectives of the research: New and innovative concepts and methods for measuring and characterizing airborne ENP with novel portable and easy-to-use device(s) for workplaces; specific objectives of the research project:

Engineered nanoparticles

ENP cannot be considered as a uniform group of substances. They are produced from many substances, in many forms and sizes and with a variety of surface coatings. The health assessment of such diverse materials requires validated analytical methods both for their characterization in bulk samples, and for the detection and measurement of those ENP in workplace air since there they have the greatest potential for human exposure. ENP concentrations and size distributions by number, surface area, and mass, ENP composition and reactivity, ENP shape crystallinity, porosity, solubility, and ENP bio-persistence constitute the parameter set which must be assessed first in order to evaluate the exposure to, and the toxicological effects of these new materials.

ENP safety

Several types of ENP including titanium dioxide and carbon nanotubes (CNT) are known to produce pulmonary inflammation and fibrosis in animals. Oberdörster et al. have shown that manganese oxide ENP can reach the olfactory bulb in the forebrain of experimental animals via transport along the olfactory nerves which innervale the epithelium in the nose. In addition, recent observations indicate that CNT may gain access also to other organs via the airways, e.g. to induce inflammation of the vasculature. Unfortunately, there are no inexpensive, field-worthy ways to reliably assess the levels of biologically relevant exposure to ENP in workplaces.

One major uncertainty in the safety assessment of ENP arises from the lack of knowledge of their physico-chemical properties and behaviour in the airborne state. Nano-sized titanium dioxide particles form agglomerates, and CNT create bundles and ropes. The tendency of airborne particles to agglomerate is of special importance for ENP because they may very rapidly change their specific size-related properties or become attached to a background aerosol. Separation and identification of ENP against the ubiquitous background aerosol originating from different sources is another special and difficult challenge facing ENP monitoring in the workplace.

The thorough characterisation of airborne ENP is complicated by: the dynamic behaviour of ENP in workplace air, the large parameter set required for their complete characterization, the range of ENP materials already in use, and a the multitude of biological responses. At present, there is no appropriate set of devices which could be used for monitoring, measuring and characterizing ENP in workplace environments.

Measurement of ENPs

Measurement and monitoring of ENP which are present in the air in workers’ breathing zones in this proposal means capturing all relevant information about the amount (number, surface area or mass concentration) and size distribution, as well as shape, composition and chemical reactivity of airborne ENP in a given size class or a broad size range. Selection of the most relevant metric(s) for health-related sampling of ENP is an important component in the development of the concepts, methods and technology for ENP monitoring at workplaces. For this purpose, simultaneous toxicological characterization of ENP will also be carried out because this information is needed for the assessment of the many parameters which can be measured. In addition, there is a need to characterize the ENP emitted from processes and to obtain data on true exposure levels of ENP in workplaces in order to define the performance requirements of the exposure assessment means.

Approach

The real challenge ahead for ENP monitoring and health risk assessment is to:

  • redesign “ENP-capable” instruments already in laboratory use into portable and affordable devices, 
  • to expand the sensing technology available for ENP detection by adopting new options with realistic potential for real-time measurement and compact design;
  • and to extend the metrics into new areas such as CNT shape identification and catalytic properties.

Each of the above avenues addresses an important demand:

  • making current technology more compact, more affordable and more versatile will provide imminent short-term solutions required by toxicologists and the inhalation exposure community;
  • new sensing technology will have a mid-term effect by providing sophisticated measurement options for very small particles which can be adapted to the needs of aerosol monitoring technology. Finally,
  • the development of methods and pre-prototype devices capable of capturing entirely new metrics will provide new tools to characterize airborne ENP. In each category, the focus is on real-time, on-line methods and devices.

For more information visit the NANODEVICE consortium website (http://www.nano-device.eu/