Not sure if this classes as an EM inspired cock up, but is a good story anyway.
Remember those BT Trimphones from the 80's and 90's, that had the luminous dial thingee? The glow in the dark was created using Tritium, a radioactive element. When BT decided to retire them all, they gathered faasands of them together and then some bright spark realised that the one drop of Tritium per phone, added up to a lot of Tritium when you have over 2 million of them in one place.
I went down to AEA Winfrith on a number of occasions when they were building the recovery plant there and the standing joke was that had BT just told everyone to bin the phone, they would never have had enough Tritium in one place to make it a danger. Instead they spent millions having to safely break the glass dial and recover the Tritium from each one. Oops!