Iodine-131 is a particuarly dangerous product from nuclear fission when it is set free in the atmosphere by atomic bombs or an accident like Chernobyl. The danger results of the fact that is it volatile and highly radiactive . Absorbed by respiration, it gets concentrated in the tyroid gland and causes cancer. The short contributes to the reduction of danger.
The activity of iodine-131 is reduced by a factor of 14 in one month, by a factor of 2700 in three months. That leads to a very specific prevention method.If we make absorb non-radioactive iodine pills by the patient, the tyroid gets saturated with iodine and absorbs no more radioactive iodine-131. So he can go to a less contaminated place and wait for the disappearance of iodine-131. Experts estimate that iodine-131 is responsibel for 46 % of the dispersed round by the accident of Chernobyl.
The russian authorities were not able to distribute iodine pills in the region of Chernobyl. The assimilation of iode-131 has generated cancers of the thyro´d gland, particularly in children who are more sensible. Fourteen year after the disaster, an excess of 1800 cancers of the thyro´d has been estimated. That was not expected by the experts who looked primarily for leucaemias. If the pills are taken in time, thyro´d cancer can be avoided.
As long as in 2006 an abnormal rate of tyroid cancers was found in Northern Great Britain probably due to the Chernobyl disaster.
During hours after liberation of radioactive iodine, inhalation is the major source of assimilation by the tyroid, later iodine enters the body mostly through food and especially milk. Inhalation risk is reduced by masks, by shutting the windows and staying indoors. Milk contamination is avoided by leading the cattle to the stables and providing uncontaminated food. Fresh milk must be avoided by children. Iodine pills are often given to late to prevent contamination by inhalation, but are useful to avoid further contamination. Children, teenagers and pregnant women must be provided primarily. Source G.Gerber Drawing by Martine Beugin