Iodine-131 and/or worsen hyperthyroidism and hypothyroidism respectively, and ultimately cause temporary or even permanent thyroid conditions. It can also cause sialadenitis (an inflammation of the salivary gland), gastrointestinal disturbances, allergic reactions and rashes. Potassium iodide is also not recommended for those who have had an allergic reaction to iodine, and people with dermatitis herpetiformis and hypocomplementemic vasculitis, conditions that are linked to a risk of iodine sensitivity. The use of a particular "iodine tablet" used in portable water purification has also been determined as somewhat effective at reducing radioiodine uptake. In a small study on human subjects who, for each of
Isotopes of iodine iodine-135 can temporarily preclude a shut-down reactor from restarting. This is known as xenon-poisoning or "falling into an iodine pit". Iodine fission-produced isotopes not discussed above (iodine-128, iodine-130, iodine-132, and iodine-133) have a half lives of a couple of hours or minutes, rendering them almost useless in other applicable areas. Those mentioned are neutron-rich and so go through beta decay to their xenon counterparts. Iodine-128 (25 min half-life) can decay to either tellurium-128 by electron capture, or to xenon-128 by beta decay. It has a specific radioactivity of 2.177 x 10 TBq/g. Colloquially, radioactive materials can be described as "hot,"