The human body can usually repair almost all radiation damage if the daily doses are not large.
The first symptoms of radiation sickness are vomiting, headache, dizziness, and a general feeling of illness. This usually starts several hours after exposure, or if it is a larger dose, symptoms will start in 30 minutes, and prove to be fatal.
Even with a shelter, there is a chance of exposure to radiation. There is no medicine to prevent radiation from damaging the human body cells. The thyroid gland is especially susceptible to radiation. Normally, your thyroid absorbs iodine, but it has a set level of iodine that it can store. Certain forms of iodine help your thyroid work right. Most people can get enough iodide from iodized salt or fish in their regular diet.
During exposure to nuclear fallout, radioactive iodine can also be absorbed into the thyroid. Small amounts of radiation in the thyroid will eventually give a large radiation dose to other cells. This can result in loss of the thyroid functions, and even thyroid cancer. The effects of this exposure may not show up for many years.
Eating and drinking fallout contaminated water and food increases the retention of radioactive iodine in the thyroid. Even air that you breathe can add to your indirect exposure.
A way to prevent this absorption of radiation is to fill your thyroid with healthy iodine before radioactive material can get in. A small dose (130 mg) of potassium iodide will provide the thyroid with a daily supply of iodine. If it is taken before exposure to radiation, it will reduce later absorption by the thyroid to only about 1% of what it would have been without the potassium iodide.
Adults and children one year of age or older should take one tablet a day at the direction of state or local public health authorities. Babies under one year of age can take one-half tablet, crushed, once a day. You should take it for 10 days unless otherwise directed. The only people who should not take potassium iodide are those who know they are allergic to iodide.
Nuclear War Survival Skills, written by Cresson H. Kearny