 Previously, risk-bites covered the basics of dose-response and how this helps translate what we know about the potential for something to cause harm to the probability of harm occurring. In a couple of weeks we'll be looking more closely at dose-response relationships, but in between we need to say a few things about models. Talking about models can get tricky. Ask 10 people what a model is and you'll likely get 10 different answers. To some, it's something they'd make out of Lego or modelling clay. Or it could be a scale model of a planned new building. To others it's a naked dude posing in front of an art class, or a slightly less naked dude posing in a fashion magazine. It could even be a stick figure drawn to illustrate some point. Although what that point is might not always be obvious. And then you've got us scientists. We use the word model in so many different ways that we occasionally get ourselves tied up in linguistic knots. To some scientists a model is a Heath Robinson lash-up that demonstrates some process, the mechanics of walking perhaps. Or it could be a conceptual idea that sheds light on reality. To others a model is a complex mathematical expression that describes something or a computer model that's designed to predict behaviour, such as the weather, or what you're most likely to buy at the grocery store. In some cases even animals are described as models, especially when those animals are used to investigate how the stuff we're exposed to might affect our health. In other words, the word model can mean very different things to different people, and this can lead to some awkward misunderstandings. The good news is that models typically have a couple of basic things in common. Whether you're talking haute couture or climate change, models usually represent something else in a way that offers insight into that something, and allows predictions to be made about how that something will behave under different conditions. Fashion models, for instance, offer insight into designer clothes, and allow predictions on fashion trends. And climate change models provide insight into what influences the climate, and predictions on how it will change in the future. As a result, models are very powerful tools. This is especially so in dose response, where they're used to connect what we are exposed to to how this might affect our health. But models have their limitations. And without understanding these limitations, they can be rather dangerous. Next week's Risk Bites will look more at understanding and working within the limitations of models before diving further into dose response relationships. Until then, stay safe.