Yes, your child can drink the clay in water. Perry Aldridge has a yahoo support group on clay, she's written books on clay and sells it. She's a good resource for info. http://health.groups.yahoo.com/group/aboutclay/
Bromide is a halide with a lighter atomic weight than iodine. It is found in some prescription drugs, on fruits like strawberries as pesticide residue, it's used as a flame retardant in electronics, it's found in some baked goods (as a dough conditioner "bromated flour ") in beverages like orange gatorade (bromated vegetable oil). If your body is Iodine deficient, the bromide (and fluoride which is also lighter than iodine) will take up residence in you body's Iodine receptors (which are found ALL over the body, not just the fluoride). Unprocessed salt will help the body flush out the bromide. Lack of Iodine and bromide toxicity are being found in women with breast cancer.