Thursday, August 4, 2011

Radioactive Idoine 131: What is it and Why Should You Care?

Iodine-131 is a radioactive particle that is produced by the fission of uranium atoms within nuclear reactors. It can also be produced by plutonium and/or uranium in the detonation of nuclear weapons. Iodine-131 takes the solid form of a purplish-blackish crystal. It can undergo sublimation, which means it can go from a solid to a gas without first becoming a liquid. Iodine-131 dissolves in water.

  • Iodine-131 can get into the environment through air or water.
  • Being that Iodine-131 is created through fission, the substance matures within rods, but if the rods are not carefully monitored then pressure within the rod can increase, leading to corrosion and eventually leakage.
  • Iodine-131 can get into water by a similar process; however it leaks into the liquid surrounding the cracked rod that is typically used to cool it. This liquid then circulates throughout the facility.
  • While Iodine-131 has the tendency to attach to organic particles, such as soil, it can be spread fairly quickly through water.
  • Iodine-131 can be ingested within water; since it dissolves in water it can easily move from the atmosphere to humans.
  • Some doctors actually use small amounts of ingested Iodine-131 to detect thyroid problems.
Health Effects:

  • Long term exposure to radioactive Idodine-131 can cause thyroid cancer.
  • Low doses of Iodine-131 can also lower the activity of the thyroid gland by lowering the production of hormones.
  • Doctors sometimes use small doses of Iodine-131 to treat an overactive thyroid, however the equilibrium must be perfect or the treatment will cause cancer in the area.
  • If large quantities of Iodine-131 are released via some sort of nuclear accident, government agencies can use stable, non radioactive iodine to ensure that people do not absorb too much Iodine-131.

In The News:

Following the collapse of the Fukushima nuclear plant in Japan due to the earthquakes that took place in early March 2011, Iodine-131 has been a large concern of the world media.
  • On March 23, 2011, the Los Angeles Times reported that tap water should not be consumed by infants in Japan due to the presence of Iodine-131 in the water.
  • In March 2011, the Philadelphia Inquirer reported that officials had discovered Iodine-131 in rain water wells in Philadelphia, which were inspected to ensure that the collapse of the plant in Japan didn’t affect water in the U.S. However, the amount found was not lethal, and officials declared the water safe to drink.


The U.S. Environmental Protection Agency (EPA) has applied both water-based and airborne regulations to Iodine-131.

The regulations limit the amount of Iodine-131 that can legally be released by nuclear plants and various industrial facilities.

Water Treatment:

  • EPA recommends that reverse osmosis be used to treat water containing Iodine-131.
  • EPA also recommends the use of ion exchange to remove Iodine-131.



Forbes, Los Angeles Times, Philadelphia Inquirer, U.S. Environmental Protection Agency.

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