When reactor 4 at the Chernobyl Nuclear Power Station in Ukraine exploded on April 26, 1986, a great plume of?

When reactor 4 at the Chernobyl Nuclear Power Station in Ukraine exploded on April 26, 1986, a great plume of radioactive isotopes erupted into the air and spread for thousands of miles. Most of the isotopes emitted after the blast were of the element iodine. Which of the glands of the endocrine system would be most seriously affected by the blast, and how do you think this would become evident in the nearby population?