Even before you look at the issues relating to technical security and the management of operational risk – imagine the braking system of your car being hacked or your insulin pump being recalibrated in error – a whole universe of cultural and ethical issues is exposed by the potential ubiquity of the systems. Who holds this mountain of aggregated data and who can access it? Where is it held, and for how long? Can I prevent it being sold and analysed further? What protection is there against precision location data, logs of activity and consumption, media viewing habits, heart rate traces and blood pressure recordings being intimately combined to make us all completely transparent to marketers, governments and insurers alike?