They do have specifications for such devices, the FDA monitors a lot more than just food. They monitor all sorts of electronic devices. I work around a lot of radiation and here we have a rule for safety (not sure if this is universal) called ALARA which stands for As Low As Reasonably Achievable. The "reasonably achievable" parts being key words, as exposure to radiation is literally unavoidable. I mean our fish are being exposed to radiation every second our tank lights are on, among thousands of other sources.