A small but definite increase in thyroid and small bowel cancers was seen in individuals who received radioactive iodine to treat hyperthyroidism.

Lancet June 19, 1999 353:2111-5

Dr. Mercola's Comment: 

I believe that most people with elevated thyroid levels, which is typically found in Graves disease, hyperthyroidism or autoimmunue Hashimoto’s thyroiditis, have another option other than destroying their thyroid gland with radioactivity. I have learned from Dr. Jonathon Wright that using large amounts of iodine (about thirty drops daily of SSKI daily for three weeks) along with addressing the diet with my recommendations on the web site (www.mercola.com under Read This First) have been quite effective in controlling this problem without the use of radioactive iodine.