The other two forms you hear the most about are the Cesium and Strontium forms.
Cesium is closely related to potassium and gets absorbed by the cells very easily. CS-137 is radioactive, and has a half life of about 30 years. That makes it, in a sense, less radioactive than radioactive iodine, that has a half life of only about 8 days.
Strontium 90 can replace Calcium in your bones, etc, but also has a longer half life.
Some good mineral supplements or even drinking hard water can help protect against these. But Iodine deficiency was a killer, that’s why they started to put Iodine in salt, then they started to tell people not to eat salt... there is alot of Iodine in the sea and seafood and kelp, but not much on the land, the body uses it in literally microgram amounts, so if even the smallest amount is radioactive, it can kill or disable you.
Radioactive iodine, in the form of 131-I, is a standard treatment in thyroid cancer, following thyroidectomy, extending lives, not killing or disabling them. 123-I, another iodine isotope, is used to image the thyroid gland, helping patients, not killing or disabling them. Sheesh.