Hi folks,
I'll throw my sixpence worth in here as I have had this discussion may times with people of different beliefs. My wife is vegetarian and doesn't get bitten much at all. Me, well I 'some' vegies and I get bitten badly. That is why my wife likes having me around - the mozzies bite me and not her. It's nice to know you are needed. The theory is the amount of vitamin B in your system and then you perspire the vit B out through your skin keeping the bugs away. Thus the connection to some alcohol (Guiness is apparently very good) and vegemite. Two weeks before camping I start taking Vit B Complex and get very few bites.
The problem is that taking Vit B in high doses for long periods can affect some organs.
I argued with a doctor once who told me I was a fool and was doing myself damage. When I got home I looked up long term effects of insect repellent (The doctor swore by Bushmans). See following extract: "The active ingredient in many insect repellents, deet, has been found to be toxic to the central nervous system. Researchers writing in the open access journal BMC Biology say that more investigations are urgently needed to confirm or dismiss any potential neurotoxicity to humans, especially when deet-based repellents are used in combination with other neurotoxic insecticides." http://www.medicalnewstoday.com/articles/159880.php I can't vouch for the website but this content is the same I have read on other sites. DEET is dangerous as well. I am assuming that DEET or something similar is used in the portable repellent devices.
So what can you do? Mix and match your poisons to restrict your exposure to any particular one. I still take Vit B, but also carry one of those citronella candles in a bucket and if that doesn't work I pull out the Bushmans.
Mind you, just living in a city and breathing the air is possibly more dangerous than any insect repellent.
Cheers
Murray