insidious.. a bit o/t

Insidious?
I live in balmy Brisbane, Australia, where the water is NOT fluoridated! My 3.5 y/o son has what appears to be mild dental fluorosis.
I feed him pretty well, on mainly unprocessed food. However, his mum doesn't exercise the same discipline, and feeds him anything at all.
He stays with me 2 nights of the week, and I try to compensate for her dietary indiscretions (I also paint Lugols spiders, butterflies and trucks on his legs, much to his delight - and in very small amounts).
There must be a lot of fluoride in today's food?
Or perhaps the food supply here is just terribly Iodine deficient?