Posted: June 22, 2009

Literature review - workplace exposure to nanoparticles

(Nanowerk News) The European Agency for Safety and Health at Work (OSHA) has published "Literature Review - Workplace exposure to nanoparticles" (pdf download, 1.6 MB) which reviews the most recent publications on nanoparticles and focuses on the possible adverse health effects of workplace exposure. The report presents the regulatory background and activities taken to manage this emerging risk.
Literature review - workplace exposure to nanoparticles
Aufnahme einer Küvette mit einem Rasterelektronenmikroskop (REM). (Bild: Kompetenzzentrum Nanochem)
From the report: The European Agency for Safety and Health at Work has published a series of expert forecasts providing an overview of the potential emerging risks in the world of work (physical, biological, psychosocial and chemical risks). Among the top ten emerging risks, three have in common their physico-chemical state as insoluble particles or fibres: nanoparticles and ultrafine particles, diesel exhaust, and man-made mineral fibres. The experts agreed that nanoparticles and ultrafine particles pose the strongest emerging risk.
Nanomaterials possess various new properties and their industrial use creates new opportunities, but they also present new risks and uncertainties. Growing production and use of nanomaterials result in an increasing number of workers and consumers exposed to nanomaterials. This leads to a greater need for information on possible health and environmental effects of nanomaterials. This report focuses on the possible adverse health effects of workplace exposure to engineered nanomaterials and possible subsequent activities taken to manage the risk. Nanomaterials originating from natural sources as well as non-intended nanoscale by-products, such as diesel engine exhaust and welding fumes, are not included in this review. In order to provide a broad overview, information from different sources such as scientific literature, policy documents, legislation and work programs were collected. Documents from the EU were given priority, although national and international activities have also been described. Studies published up to November 2008 have been considered in the report.
When particle size is decreased to the nanoscale range, physical and chemical properties often change with consequent new product opportunities. Thus a considerable future expansion of the nano-market is expected. Nevertheless it should be remembered that nanomaterials are not fully new: some established chemicals like amorphous silica or carbon black show a nanostructure. The knowledge about the occupational exposure to new nanomaterials is very limited. In addition, the measurement techniques to determine exposure are not fully developed. Various physical and chemical parameters have to be considered.
Different methods to investigate possible health effects of nanomaterials, such as in vivo- and in vitromethods and methods to determine physico-chemical properties, are currently under discussion. The standardised in vivo-studies represent at present the best standard to detect toxicity evoked by nanomaterials. Effects like inflammation, fibrosis and tumours were induced by several granular nanomaterials in the lungs after respiratory exposure. Currently the mechanism of tumour formation is not fully understood and scientific uncertainties remain. Thus, the evaluation of toxicity is not only influenced by results from toxicity studies but also by the policy decision to what extend the precautionary principle is applied in case of scientific uncertainties. Skin exposure is not yet investigated in detail. Generally, in case of insoluble substances skin exposure is not as relevant as respiratory exposure.
The current principles of risk assessment seem to be in general appropriate; however, the validation of in vitro methods and the development of a testing strategy remain future tasks. Classification and labelling as well as occupational exposure limits, which are derived from toxicological data, are appropriate instruments for management of risks resulting from exposure to nanomaterials, but critically depend on the availability of studies on toxicity.
Several handling guidelines describing possible risk management activities and best practice were published. These are mainly based on technical feasibility and some of them recommend, based on the precautionary principle, to minimise exposure as far as possible. The protective measures that are typically used to protect against insoluble materials, like dusts, are often recommended also for nanomaterials. Because of the particular smallness of nanomaterials, especially the filter materials/media used in general ventilation systems, personal respiratory protective devices and the materials of gloves have to be examined. Preliminary studies indicate a protective effect, but further research is needed. In relation to filtering half masks, the lack of tightness (inadequate sealing) between face and the mask seems to be the most important risk factor. Control banding methods are used to assess occupational exposure in the case of non-existent occupational exposure limits or exposure measurements. First initiatives to adapt this method to nanomaterials have been developed, but need further elaboration. An important instrument of risk management providing information about hazards and appropriate control measures is the Material Safety Data Sheet. To what extent this instrument considers nanospecific properties sufficiently is currently under discussion.
Several statutory instruments are in place to ensure an appropriate level of protection of workers. The general framework is provided by the regulation on occupational safety and health of workers (EU Directive 89/391/EEC) and specifically for chemical safety - the directive on the protection of the health and safety of workers from the risks related to chemical agents at work (Directive 98/24/EC). Substance-specific regulation is intended by the biocide Directive (Directive 98/8/EC) and the regulation No 1907/2006 (REACH – Registration, Evaluation, Authorisation and Restriction of Chemicals). Currently it is discussed how to consider appropriately the broad variety of nanomaterials in these regulations.
The Community strategy on health and safety at work for the period of 2007 – 2012 includes nanotechnology as an important topic to be worked on in the context of the identification of new, emerging risks. Furthermore a communication from the European Commission ‘Towards a European Strategy for Nanotechnology’ was published. The European Commission developed an “Action Plan” to implement a safe, integrated and responsible approach for nanosciences and nanotechnologies. To ensure a safe and ethical development and use of nanotechnologies, the European Commission issued a Code of Conduct. There are many ongoing initiatives/activities aiming at the development of a safe, sustainable, responsible research and development of this new technology. Large scale research and standardisation programmes have been started and partly finalised to establish standards, close data gaps and reduce uncertainties. European and global collaboration is recognized as an important aspect in achieving these goals. Activities have been initiated by organisations such as the International Organization for Standardization (ISO) and the Organization for Economic Cooperation and Development (OECD) to support a globally harmonised development. Collaboration between EU and US is also being developed to investigate the regulatory challenges posed by nanotechnologies and to assess the effectiveness of existing approaches on both sides of the Atlantic. The project takes a comparative perspective and contributes to the early identification of regulatory methodologies and best practices that promote regulatory convergence between the EU and US.
As the conclusion of this review of the most recent publications, the following topics are identified as priorities for future actions and activities:
  • identification of nanomaterials and description of exposure
  • measurement of exposures to nanomaterials and efficacy of protective measures
  • risk assessment of nanomaterials in line with the current statutory framework
  • in vivo studies for assessment of the health effects of nanomaterials
  • validation of the in vitro methods and methods of physico-chemical properties as methods to determine health effects
  • training of workers and practical handling guidelines for activities involving nanomaterials in the workplace.
  • Source: European Agency for Safety and Health at Work
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