I'm both a flyfisherman and an environmental toxicologist, so I've spent a good bit of time looking into the efficacy of insect repellents and their potential toxicity. DEET is the only commonly available chemical that has been found to have significant insect "repellent" properties, anecdotal testimonials to the original Skin-so-Soft notwithstanding. There does appear to be some clinical evidence that S-s-S may have limited short-term effectiveness for certain insects (no-see-ums, for example) under certain conditions due to its oily coating action, and because of the repeated urban myths about its repellent action on mosquitos, Avon finally added a bit of mild insect repellent (oil of citronella, which is only marginally better in this regard than water) to it.
There are few chemicals that have been studied for their toxicological properties as extensively as DEET. DEET has never been shown to be carcinogenic and has repeatedly been proven safe when used as intended - this does not mean, of course, that it may not cause problems for some unusually sensitive individuals, who should obviously avoid using it. In addition, if I had small children I would not use excessive amounts of DEET (or any other chemical) on them. I don't hesitate to use 100% DEET on myself but I do try to use the minimum necessary to do the job. I got my supply from a chemical specialty company about 20 years ago at a fraction of the commercial retail price (minimum purchase was 1 gallon - so I have a several-lifetime supply).
Those interested in pursuing this question further may wish to start with the article "Mosquitos and mosquito repellents: a clinicians guide", which appeared in 1998 in the Annals of Internal Medicine 128:931-940 - it was available on-line at
www.acponline.org/journals/annals/01jun98/mosquito.htm for a number of years but I believe it is now expired (but still obtainable, I'm sure). Though much of this paper is very technical the pertinent points are easily understandable to the lay person. It also lists over 100 technical references for further reading.
ETA: Actually, I see that the article is still available on-line - just click on the link above.
There ain't much you can do down here when they are so thick you're chokin' on 'em if you breath through your mouth. Wear a net over your head, put on a gallon of deep woods off, and pray you have enough blood to get back to the truck. You KINDA get used to 'em after a while. Deet is the best, makes your skin feel funny, but it's better than getting eaten alive.
