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NC3Rs | 20 Years: Pioneering Better Science
Office-led project

Opportunities to apply the 3Rs in the safety assessment of nanomaterials

At a glance

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  • Reduction
  • Refinement
  • Replacement


The unique properties of manufactured nanomaterials (e.g. increased electrical or thermal conductivity, strength/elasticity, absorbency) mean that there are many advantages to their use across a wide array of differing applications. As a result there has been a considerable rise in their development and production in the last decade. However, concerns over the health implications of human and environmental exposure to nanomaterials have been raised. Concerted, science-led efforts must therefore be made to understand the potential effects of exposure to nanomaterials, and ensure that health protection goals are met.

There is much ongoing discussion within the nanotoxicology field regarding how best to assess the safety of nanomaterials, particularly considering the large number of them that may need to be tested to meet regulatory requirements. Traditional animal toxicity tests continue to be relied upon to inform nanomaterial safety assessment outside the cosmetics sector, demanding large numbers of animals and resources. This approach is not practical, or evidence-based.  There are further scientific, business, ethical and legislative drivers to consider and re-evaluate the use of animal toxicity tests for nanomaterials, in particular due to recent geographical bans on the testing of cosmetics in animals and marketing of animal-tested products.

In 2016 we brought together an expert working group of European regulators, academics and industry scientists to discuss i) the opportunities being offered in the short, medium and long-term to advance the science underlying nanotoxicology and increase the uptake of alternatives to animal testing, ii) how to align these advances with the application of the 3Rs in safety testing of nanomaterials, and iii) shifting the focus of safety assessment towards a more balanced approach that considers the potential for exposure to nanomaterials as well as their hazardous properties. The discussions of the working group were published in the journal Nano Today. We followed up this publication with a paper in 2021 on the opportunities and challenges for integrating new in vitro methodologies in nanomaterial hazard testing and risk assessment.


  1. Burden N et al. (2017). The 3Rs as a framework to support a 21st century approach for nanosafety assessment. Nano Today 12:10-13. doi: 10.1016/j.nantod.2016.06.007 
  2. Burden N et al. (2017). Aligning nanotoxicology with the 3Rs: What is needed to realise the short, medium and long-term opportunities? Regulatory Toxicology and Pharmacology 91:257-266. doi: 10.1016/j.yrtph.2017.10.021
  3. Burden N et al. (2021). Opportunities and challenges for integrating new in vitro methodologies in hazard testing and risk assessment. Small 17(15):e2006298. doi: 10.1002/smll.202006298
  4. Poster presented at the NC3Rs Toxicology Showcase, September 2016: Aligning nanotoxicology with the 3Rs.