Iodine-131 (also I-131) has a half-life of approximately 8 days, which means that after 8 days, the quantity of I-131 will have halved due to radioactive decay. The absorption of iodine-131 by the body can be significantly reduced by saturating the thyroid gland with stable (not radioactive) iodine by the taking of potassium iodide tablets. Due to its relatively short half-life, iodine is primarily relevant at the start of a nuclear accident.