Some people have allergies to very normal chemicals, or even peanuts, dairy or water. But is this maybe more a matter of reverse placebo effect? Thinking it might harm you might in fact be enough to actually hurt you.
It's the same with electromagnetic vibrations: some people are utterly convinced that EM radiation is bad, while others are thriving in the same environment. Like recently someone told me that the exposure limits for employees of a local radar manufacturer are apparently much higher than those for the general population. Go figure!
