HSL has wide-ranging teams of experts with capabilities that are being applied to  nanoresearch.  These include exposure assessment, measurement and characterisation of nanomaterials, fire and explosion , toxicology and protective equipment , as well as biological monitoring, risk assessment and physiologically based pharmacokinetic modelling.

Exposure Assessment

Scientists in HSL have considerable experience in the measurement of ultrafine and nanoparticles in the workplace and outdoor environments. During the late 1990s HSL carried out a survey of the potential for the release of airborne ultrafine particles in the workplaces of UK industry. Particle number concentrations and size distributions were assessed in most workplaces and the findings were reported at Inhaled Particles IX in September 2001.

Since then we have carried out laboratory studies on the relationships between the various measurement metrics for airborne nanoparticles. During the course of this work we have accumulated and/or developed a wide range of instrumentation for the measurement and collection of nanoparticles in workplace atmospheres, including those for measuring mass, number and surface area concentrations. These are currently being used in a major study of potential nanoparticle exposures in the nanotechnology laboratories in UK universities.

This capability is founded on 35 years of experience at HSL in the development, testing and use in workplaces of instruments for the measurement of worker exposure to aerosols in all sectors of UK industry. For this purpose, we have an extensive range of experimental facilitieis including wind tunnels, calm air chambers and particle generating equipment for all sizes of particle (including nanoparticles) both solid and liquid.

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Fire and Explosion

HSL's Explosion Safety specialists are concerned with safety engineering and science relating to the control of explosion hazards in industry and domestic situations. The section has a range of capabilities to study the explosion characteristics and behaviour of flammable dusts, at both small laboratory scale and at large scale. Specialist facilities are being developed to study the behaviour of nanopowders.

HSL has extensive experience in the testing of the explosion characteristics of gases, dusts and vapours to international standards. Our facilities include apparatus for the following tests:

• Standard 20 litre sphere test and 2 litre sphere dedicated to nanopowder explosibility testing and characterization;
• Minimum ignition energy (MIE) with modifications to enable MIE measurements of nanopowders;
• Dust layer and dust cloud minimum ignition temperature;
• Electrostatic ignition assessment (resistivity/conductivity measurements, charge transfer measurements) and dedicated equipment for characterizing nanopowder;
• Self heating tests for CHIP and ADR;
• Rate of fire spread;
• Pyrophoricity and water reactivity tests.

HSL frequently constructs unique experimental apparatus used for the study of explosion characteristics of special materials. Expert consultancy is available on explosion protection/prevention systems and ignition related problems using a range of large and small-scale explosion research and testing facilities.

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Measurement and Characterisation

A critical and challenging issue when measuring exposure to airborne nanoparticles in workplaces is the discrimination between engineered nanoparticles and ultrafine particles generated from other sources such as combustion or vehicle emissions. Static measuring instruments and 'off-line' analysis of air samples can be powerful tools to assess occupational exposures. "Off-line" single particle analysis such as electron microscopy analysis can provide information on size, shape, structure and elemental composition.  Adopting this approach may enable us to discriminate between engineered nanoparticles and other ultrafines.

Scientists at HSL have extensive experience in the measurement and analysis of toxic particles and fibres in the workplace. HSL is currently developing sampling and characterisation methods to evaluate exposure to process-related nanoparticles. For this purpose, the laboratory has instruments for sampling (electrostatic and thermal precipitators allowing direct sampling onto coated electron microscopy grid; electrical low pressure impactor (ELPI)) and for analysis (Scanning transmission electron microscope coupled with Energy Dispersive X-Ray analyser (EDAX)). It also has a range of instruments for bulk materials characterisation such as X-Ray diffraction, Inductively Coupled Plasma Mass Spectrometry, Infrared and Raman spectroscopy.

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Toxicology

HSL's Toxicologists are keenly interested in the potential toxicity to humans of manufactured nanoparticles, but information on the toxicity and exposure levels is only just starting to emerge.

There is considerable concern that the unique properties of nanoparticles (e.g. their large surface area and reactivity) may lead to human health problems following exposure, based on studies that have examined either the toxicity in humans of ambient ultrafine particles (e.g. generated by motor vehicles), or the effects of inhaled particles in experimental animal models.  However there are insufficient data on the toxicity of manufactured nanomaterials to which people might be exposed in the workplace.  In particular, it has not been established whether these nanomaterials are toxic at doses that are realistic for human exposure.

HSL has a wealth of expertise in studies of human exposure to chemicals and biological hazards, specifically in analytical measurement of airborne exposure and in the use of biochemical, immunological and cell culture-based toxicity assays together with computational modelling for assessment of the potential health effects of exposure.  Based on this expertise, HSL is developing novel in vitro assays to investigate the toxicity of manufactured nanomaterials, building on our existing capabilities.  We are working closely with several nanomaterials manufacturers, testing products that they have either in development or production for potential toxicity.

We are also reviewing the emerging literature in this area through the NanoAlert bulletins.

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Protective Equipment Performance

Control of exposure to nanoparticles under all circumstances is unlikely to be achievable using only containment and ventilation. There will always be a need for effective personal protective equipment (PPE). However, existing forms of PPE have not been designed with exposure to nanoparticles in mind, and current testing regimes do not directly assess performance against this form of challenge. Therefore, for performance testing of PPE (e.g. gloves, garments) and respiratory protective equipment (RPE, e.g respirators and breathing apparatus), there is a fundamental need to develop practical, appropriate and representative nanoparticle test methods.

HSL have decades of experience in the development and use of RPE and PPE testing methods. Methods required for nanoparticle tests on the full range of equipment and filters are under development at HSL in association with other European laboratories (under NANOSH and PEROSH collaborations). These methods will require a stable and repeatable means of generating a high concentration of a non-toxic "worst case" (unagglomerated) nano-sized airborne challenge. The test substance generated must be readily detectable, preferably in real time, using methods which can discriminate between these nanoparticles and any other airborne materials which may be present. Finally, suitable facilities are required for testing RPE/PPE against these challenge aerosols, such as those already in existence at HSL (see attached photograph of protective performace assessment being carried out in our test chamber).