Intrinsic safety (IS) is a protection technique for safe operation of electrical equipment in hazardous areas by limiting the energy, electrical and thermal, available for ignition.
In other words "explosion proof". Iphones are used by a lot of people in industry where the manufacturing area is a classified areas (classified as per section 500 of the NFPA 70 i.e. NEC). These classified areas are dangerous in that it is possible under normal or abnormal conditions (depending on the classification) that a spark could result in an explosion. I am just trying to find a document authored by Apple stating that the Iphone (or Ipad, Macbook, whatever) is not intrinsically safe or it is. So far, I have only found user responses stating such.
Just a point of clarification, this is a hardware based comment. IOS has nothing to do with Intrinsic safety.