I-131 Quick Facts

	I-131 is radioactive, has an 8.03 day half-life, and emits beta and gamma radiation.  I-131 is normally present at low levels in hospital nuclear medicine departments, patients administered radioactive iodine in the last 3 months, and nuclear power plant releases.
	During 1945–1962 many persons, as young children, received radiation fallout exposure from I-131 from multiple sources in the United States. This exposure puts those persons at risk for thyroid and parathyroid disease and cancer of the thyroid.
	Health care providers should be prepared to medically evaluate the health effects from radiation exposures, including those related to past exposure from I-131. The public trusts health care providers to provide accurate and helpful health information.
	Radioiodine has a strong affinity for the thyroid gland, which is the critical organ for exposure. Exposure to I-131 increases the risk for hypothyroidism, thyroid nodules, and cancer, especially in childhood.
	I-131 can play a specific role in the health consequences of radioactivity released into the environment, primarily related to uptake in children’s thyroid from the ingestion of milk from goats or cows that grazed on contaminated pasture land.
	The concentration of I-131 in goat’s and sheep’s milk is 10 times higher than in cow’s milk. Inhalation is the major exposure pathway for persons who are exposed to a cloud of I-131 but do not eat contaminated food from the area.
	Risk communication is of critical importance in the evaluation and management of persons with concerns about exposure to I-131. Individuals and communities who might have been exposed should be involved with developing the information that is communicated to others. These individuals and communities are stakeholders in the risk communication process.