From what I understand of "Cold Light" or Cold Cathode Fluorescents is that they emit no IR and only really low levels of UV-A (no UV-B) which is how you can sit in front of them for hours on end day after day (well....I do and it doesn't seem to harm us squirrels) when they are used in TFT's.
In contrast the flash from most cheap cameras produce plenty of IR and UV-A, the lens absorbs most of the UV-B and -C, thankfully, otherwise we'd be blasting people to death with our snapshots
The other problem is wattage, and the associated heat absorption of materials. A typical scanner is in the order of 10-20 watt seconds where as flashes can be upwards of 10 times that number. As an example scan your hand, and then flash your hand from short range with a camera. I suspect the latter may well impart some warmth.