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Source document:
SCENIHR (2006)

Summary & Details:
GreenFacts (2007)


8. Are current risk assessment methodologies for nanoparticles adequate?

Chemicals in their nanoparticle form have properties that are completely different from their larger physical forms and may therefore interact differently with and in biological systems. As a result, it is necessary to assess the risks arising from any nanoparticle that will potentially come in contact with humans, other species or the environment, even if the toxicology of the chemicals that make up the nanoparticle is well known.

Because of the restricted range of nanoparticle types whose biological properties have been studied to date, it is uncertain whether or not the current limited evidence on the behaviour in biological systems is representative of nanoparticles in general.

The traditional risk assessment methodology – which consists of exposure assessment, hazard identification, hazard characterization and finally risk characterization – has not yet been applied to nanoparticles. At the moment, there are no official guidelines on what is an appropriate testing procedure. The commercial manufacture of nanoparticles is relatively new and there is very little data available on their effects on human populations or on the environment.

More specifically, risk assessment of nanoparticles may need to address:

More safety requirements are expected for new or emerging technologies than for tried and tested technologies. If these expectations are not met, the public may come to fear or even reject products based in nanotechnology. More...


8.1 What considerations should the risk assessment take into account?

In terms of general exposure and health risks to humans, it is important for any risk assessment methodology to consider that:



8.2 What factors of exposure do risk assessment methodologies need to specify?

Risk assessment can be applied either to a chemical in nanoparticle form or to the product in which these nanoparticles are incorporated.

It is important for the purpose of assessing the risk of a chemical in nanoparticle form or of the product where such nanoparticles are incorporated to specify clearly the following factors:

If the above processes and characteristics of the nanoparticle are similar to those of the chemical at larger, conventional scale, the risk assessment could require fewer data. More...


8.3 How should risks and hazards related to nanoparticles be addressed?

The ability of nanoparticles to cause hazards can be mainly due to:

In the case of a), the nanoparticles are expected to have properties similar to those of the same chemicals in larger, conventional forms, unless the distribution of the nanoparticles in the body or in the environment is very different.

In the case of b) and c), nanoparticles will have toxic effects different from those of the same chemical in larger physical forms. In addition, in the case of c), the potential for the release of these adsorbed chemicals of concern will need to be addressed.

To identify the hazards related to nanoparticles made up of well known chemicals, a testing method to determine whether or not the nanoparticle form will cause significantly different adverse effects is needed.

No conclusions applicable to all nanoparticle-based products can be drawn at this stage regarding risks and hazards. Therefore, each product and process involving nanoparticles must be considered separately when assessing the safety of workers involved in its manufacture, the safety of consumers and of the public living near manufacturing or processing facilities, the environmental impact, and the human health and environmental risks involved in the disposal or recycling of the nanoparticle products.

When suitable hazard information is lacking, particular care is needed regarding nanoparticles which are likely to be highly persistent in humans and in environmental species.

At present there is no reliable information on the effect of the simultaneous exposure to multiple forms of nanoparticles, or on the interaction between nanoparticles and other agents. Therefore, risks should be assessed on a case-by-case basis. More...


8.4 What should be done to improve the risk assessment of nanoparticles?

In order to produce detailed guidelines for the risk assessment of nanoparticles, critical gaps in knowledge need to be filled. For instance, it would require:

The confidential nature of much of the research on nanoparticles calls for international cooperation on identifying and resolving gaps in knowledge. Cooperation with industry is also necessary.

Regulations for chemicals are currently based on tonnage, which may have to be reviewed as there are many more nanoparticles to the tonne than is the case for larger particles. Also, for the purpose of hazard warning labels, the nanoparticle form of each chemical should have its own identification. In addition, new workplace exposure standards need to be developed for nanoparticles that are different from those for dusts. Similarly, classification and labeling for human health and the environment may need to be reconsidered

Other needed developments include a harmonized terminology for the physical characteristics of nanoparticles and their general properties, standardized testing methodologies, available reference materials for the measuring of adverse effects, and a clear and widely acceptable framework to weight up the benefits and risks of nanotechnology. More...

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