New internet of things devices and personal informatics sensors are creating a vast new archives of unstructured and messy but potentially valuable data about our lives and activities. In this talk Professor Barry Brown will discuss recent research which has looked at how data can be collected using IoT, what that data can be used for, but also the serious privacy and information control problems this can create. While big data is often presented as the “new oil”, storing, managing and securing data creates new liabilities and dangers for users and organisations. Data may not just enable new IoT systems and applications but also create new danger and burden for users and organisations. As with oil, data may sometimes be not just a resource but a toxic material.