 Are engineered nanoparticles dangerous? Unfortunately there's no easy answer here because it depends on the type of particles and how they are used. But here are 5 things that you probably want to ask when thinking about how safe any type of particle is, nano or not. 1. What are the particles like? Are they large or are they small? What shape are they? Are they loners or do they clump together and are they intimately attached to something else? What are they made of both inside and outside and do they dissolve easily? 2. Can the particles get into your body and if so how? Once there where do they go? Do they concentrate for instance in specific organs, can they get into cells or even penetrate all the way to your DNA? And once there how long do they stick around? 3. Can the particles cause harm once they're inside your body and if so how do they do this? How many of them are needed before they cause serious harm? 4. Can our bodies handle small quantities of the particles? We did have to all evolve in a world chock full of small particles. And 5. How do any health benefits associated with the particles compare to the potential risks? Just like people, nanoparticles are complex which unfortunately means there's never an easy answer to the question are they dangerous? But by knowing what affects their behaviour it becomes easier to work out how risky a particular type of nanoparticle might be and how to use them safely. To find out more about the risks of particles nano or otherwise do check out the blog below and don't forget to subscribe for more videos on the science of risk.