According to Dr Peter Baratosy's book "It could still be your thyroid", "we are living in a sea of halogens", "halogens have an effect on the iodine metabolism", "it's been known for a long time that fluoride has a negative effect on the thyroid. It is best to avoid these halogens by using a water filter capable of filtering out fluoride. Berkey Water Purifiers with a fluoride & arsenic reduction filter remove 99.75%* of the fluoride from tap water. They also strip out viruse