check out oneradionetwork and maybe send an email to Patrick Timpone on this topic. There are many podcasted shows on this topic and many... I have heard taking elevated vitamic C will help absorb the toxins.
Like Kai, I would avoid them and try and find a doctor who is aware and able to squirt them into an orange or something maybe... :)
If they are in already, I'd take the vit C and chorella if it was my child or me... OSR is worth trying to find... Oxidative Stress Relief.
First, I would like to say ayzik's advice should be definitely considered and used where you see fit, however, I would strongly recommend avoiding supplementing your child with Vitamin D3, which has been admitted by several prominent figures and documents as being a main ingredient in rat poison, designed to degenerate the overall rna/dna of the body. 15 minutes of decent sun exposure a day is sufficient for one's body to accumulate and assimilate natural Vitamin D, generally speaking. Most store bought milk has vitamin D3 added. I would also expound on his recommendation of coconut oil along with olive oil, if you can afford it, as an oil supplement. Coconut and olive oil contain different chains of omega oils, but in order for ones' body to properly digest and use the omega oils they should be taken together. Only taking one kind of oil with leave the full omega chain incomplete, thus an imbalance of omega oils (Decently priced coconut oil, here, and here). I'd also like to say that distilled water, while pure, will leech nutrients and minerals from the body, so it would be beneficial to take herbal and mineral supplements IN the water, before consumption of supplements, or much, much later in the day so one's body has had time to use the nutrients it needs for the day. As for an alternative water source, if the water in your area is treated with flouride and/or chlorine, I would suggest searching for a Kangen water machine distributor (they usually have a 30 day trial period where you can get clean, ionized water for free). There are knock-off brands of the Kangen machines on the internet, it just takes a little while to find one reliable and nearly identical in design to the Kangen line of water ionizing machines.. (And some other water information here)
I recommend acquiring some form of Gotu Kola (Desert Botanicals and Herbs) - loose leaves make a tea; I personally buy powdered gotu kola and take about 1 tsp - 1 tbsp in a glass of room temperature water, but this may not be palatable for a child. You can find vegetable based gel capsules for pretty cheap and capsulize your own powder, if your child would prefer this method. These are the two forms of gotu kola that I have found to be the most cost efficient for supplementation. Cat's claw would be good to use as a tea because it promotes T cell production, along with dandelion tincture or root. Dandelion contains trace gold mineral, and is a liver tonic, aiding in the removal of toxins from this organ especially during detoxification. Garlic is a blood cleaner and anti-fungal/viral, as well as many other things and you can find supplements in various places, if your children do not like the flavor of garlic, or you do not cook with it on an almost daily basis.
I think you should get a complete B Vitamin complex because this is something that our bodies are constantly in need of. B Vitamins are used up pretty fast, so need consistent replenishment. It will also help detoxify the body. Also, a Calcium-Magnesium-Zinc supplement would be good to help make the body alkaline and remove radioisotopes.
To chelate metals from the body system you'll want something called Lugol's Iodine. You can make your own (which is what I do) or buy it, but again, I've found it to be more cost efficient to make it myself. I've provided the video for the recipe I have used to make my own Lugol's Iodine below, as well as links to find potassium iodide and iodine crystals. This is something to be ingested, in SMALL amounts, and along with its chelation properties, heals and promotes healthy function of the thyroid glands, and pushes out flouride from the body. (More information about Iodine - here)
http://www.youtube.com/watch?v=Znqej6FBxTA - How to make Lugol's Iodine part 1
http://www.youtube.com/watch?v=HImgijfyjiQ - How to make Lugol's Iodine part 2
Try activated charcoal