The Prof I watched said Deet was tested as safe in the sprays we buy. It has to be by law. If you look it up on the net it tells you this. Jungle Formula etc., all have Deet. I would image if you used all day every day for years and years it would not be good, but just for the holidays it is fine. In fact I read that it is safe enough to use on children.
I am chancing my luck here, but, I have to say that since I have used Off I have been fine. I did get some very bad bites a while ago and had to have antibiotics and cream. Also, we need to remember it is not just the mossies that bite, also sand flies black flies and jumping spiders to name but a few.
This was my infected leg in 2014 when I used Avon Skin So Soft, which was useless. Be brave and have a look.
Mozzies love me.