UOIT researchers: KI pills not the only consideration for nuclear radiation protection

Potassium iodide (chemical symbol KI) is a familiar term to many of the hundreds of thousands of Ontarians who live near nuclear power plants. In the unlikely event of a radiation leak from a nuclear facility, KI is a salt pill that, when ingested, inhibits the thyroid gland from absorbing radiation.

For decades, stocks of KI pills have been given to pharmacies and institutions like schools, daycares, and police and fire departments. And now, the Canadian Nuclear Safety Commission (CNSC) has mandated KI pills be delivered to all homes and workplaces near nuclear plants by the end of 2015.

But two University of Ontario Institute of Technology (UOIT) researchers in the Faculty of Energy Systems and Nuclear Science are concerned there may be public misconception about KI pills. Dr. Ed Waller and Dr. Anthony Waker say distribution of KI pills is just one small part of a larger emergency response and public protection plan.

“KI pills only block one element (iodine) from being absorbed in the thyroid, but some interpret them as being magical anti-radiation pills,” said Professor Waller, NSERC/UNENE Industrial Research Chair in Health Physics and Environmental Safety. “They do not block or absorb radiation. They saturate the thyroid gland with non-radioactive iodine, so that when radioactive iodine is present, it does not readily get absorbed. In a hypothetical release, there will be many more radionuclides in the atmosphere that KI pills will do nothing for.” 

In addition to radioactive iodine (predominantly isotope Iodine-131, with a half-life of about eight days), there would also potentially be quantities of Strontium-90, Cesium-134 and Cesium-137, which were widely detected sources of radiation following the 1986 Chernobyl nuclear accident in Ukraine.

“People need to understand the exact purpose for using KI pills, because they may otherwise be overconfident that they do more than their purpose,” said Professor Waker. “Children are most vulnerable to thyroid cancer. Schools and daycares already have stockpiles of KI pills and parents can preauthorize its administration in the event of an accident. I am skeptical about the need for an even wider distribution of KI pills. There would be many logistics involved, and a financial cost passed on to utilities.”

KI pills also only have a shelf-life of about seven years. Dr. Waller says educating people on protective actions (such as sheltering in a place), might be a better preventive strategy versus the cost of stockpiling and maintaining KI inventory.

“The timing of KI administration is quite critical in its effectiveness,” said Dr. Waker. “The isotope Iodine-131 decays very rapidly, so proper sheltering techniques would be hugely important in reducing the public dose. Weather conditions, especially wind, wind speed and wind direction would also be enormous factors affecting the path and potential impact of a released radioactive plume. Rain could precipitate particulates to the ground faster. In some scenarios, staying sheltered may be a far safer choice than evacuating.”

“The impact of the radiological accident in Fukushima, Japan was less than it could have been because the prevailing wind was from land toward the ocean,” said Dr. Waker. “With Canadian house construction standards, there would not even be much need for plastic sheeting: the main strategy would be to get indoors with doors and windows closed. Sheltering and having bottled water and canned food sufficient for a few days is a good idea, and already recommended by Public Safety Canada.”

“The most important thing to remember is that you first need a release to be worried about a release, and while this is possible, it is highly improbable in a CANDU reactor,” said Dr. Waller. “There are many reactor design aspects to safely keep CANDU fuel bundles cool. The lesson here for residents is they should review all available preparedness literature. They should talk about protection strategies together as a family and have a plan. But they should not be relying solely on the availability of a pill which they might believe fully protects them from any possible radiation.”

Helpful links:

• OPG’s Nuclear Safety Guide
• Emergency Preparedness Canada Guidelines

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