678e89c5___CTBTO_Preparatory_Commission__Health_hazards
[Radionuclide] Iodine-131 (131I) [Half-life*] 8 days [Health hazards] 
When present in high levels in the environment from radioactive fallout, I-131 can be absorbed through contaminated food. It also accumulates in the thyroid gland, where it can destroy all or part of the thyroid. May cause damage to the thyroid as it decays. Thyroid cancer may occur.
General overview of the effects of nuclear testing: CTBTO Preparatory Commission
Health hazards