Potassium iodide pills

Quick facts

• KI is a salt of non-radioactive iodine.
• KI only protects the thyroid gland from radioactive iodine; it is not effective against any other nuclear substance.
• Do not take KI pills unless you are instructed to do so by public health officials.
• The overall benefit of taking KI during an emergency outweighs the risk of side effects.
• KI pills are effective for up to 12 years if they are stored in a dry location between 15 and 30 °C.

What is KI?

KI can be used to protect the thyroid gland from radioactive iodine that may be released into the air in the unlikely event of a radiological emergency. In very small quantities, it is an essential nutrient for your thyroid gland to function properly. In the event of a nuclear emergency, KI is effective in reducing the threat of thyroid cancer to residents at risk of inhaling or ingesting radioactive iodine.

Depending on the nature of the emergency, KI is a protective measure that can be used in isolation or in combination with other protective measures (i.e., evacuation, shelter-in-place).

How does it work

The thyroid gland will absorb iodine that is in a person's bloodstream; it cannot tell the difference between radioactive iodine and non-radioactive (stable) iodine. The absorption of radioactive iodine can be prevented by taking KI before or soon after its release into the air.

When should it be taken?

Not all radiological emergencies involve radioactive iodine, and KI is only required when there are significant amounts of radioactive iodine present. KI should only be taken when directed by public health officials. It works best when taken immediately before or as soon as possible after exposure.

Where are KI pills pre-distributed in Canada?

In Canada, the CNSC established regulatory requirements for nuclear power plant licensees to ensure that KI pills are pre-distributed to everyone within 10 km of all power plants. This requirement was established in REGDOC-2.10.1, Nuclear Emergency Preparedness and Response, Version 2, and all nuclear power plant licensees are currently in compliance. Regional municipal and provincial authorities responsible for emergency management, including the Province of Ontario’s Office of the Fire Marshal & Emergency Management and the New Brunswick Emergency Management Organization, also facilitate the pre-distribution of KI pills.