It wasn't long ago that smoking was a recommended treatment for asthma. Now we have conflicting opinions on whether mobile phones cause cancer. So what about future 'wearable tech' such as the Apple watch - the kind of technology that we will press against our skin, internal organs and blood vessels for hours at a time? Might they make us ill?
And whilst we're on the subject, what about all those medical apps available to anyone who wants to look? Are they helpful or do they actually damage our health?
1 - Some researchers believe that 3G raises the risk of radiation, so pressing a mobile against your ear is in fact pressing a tiny dose of radiation into your brain. Children in particular are at risk because they have thinner, more fragile skulls. Who knows what the Apple watch might do when it's constantly pressed against pulsating veins.
2 - Health apps cause paranoia and waste doctor's time. A single blip of raised blood pressure can send people running to the doctor whereas before they would not even have noticed. Our bodies change all the time and their processes are not supposed to be constantly measured and compared. We are all different.
3 - Some believe that medical apps are the work of the devil - even worse than Googling vague symptoms of ill health and self-diagnosing a life-threatening disease like Beriberi when all you have is a bit of thrush. They damage mental health, causing worry, anxiety, and an obsession with monitoring every breath.
4 - There is also the reality that these apps may be wrong or mismanaged so they provide inaccurate readings. Recently apps have been recalled because they miscalculated insulin doses, so what else are they getting wrong?
1 - Researchers point out there is no conclusive proof that mobiles cause radiation cancer, or any other illness. Stop being so paranoid, who's the hypochondriac now? You probably think your watch is trying to strangle you, or your rings are leaking poison into your fingers leaving you bereft at your inability to take selfies.
2 - No wearable tech includes 3G (not yet anyway) so it's not even an issue, for those who believe the signal can cause headaches and nausea.
3 - Statistics say you're more likely to get knocked over looking at your Apple watch or mobile than killed by any radiation from it.
4 - Health apps can be useful; they are self-monitoring tools that make us aware of our bodies, what we put into them, and what our outputs are. If a health app helps obese folk lose weight then that's a good thing, no?
5 - If you use them wisely health apps support your lifestyle. They are here to stay so learning how to use them is important.
So, either way we have no conclusive proof. Both sides have compelling arguments, but I think I'll stop leaving my mobile on the pillow… just to be sure.