In the highly unlikely event of a nuclear accident, a potassium iodide (KI) pill is a key component to keeping you and your family safe. All homes and businesses within 10 km of nuclear facilities are encouraged to have on hand potassium iodide (KI) pills. Anyone within 50 km of nuclear facilities is welcome to order KI for delivery.
KI (the chemical name for potassium iodide) is a salt of stable (not radioactive) iodine. It is an essential nutrient needed in small quantities for the thyroid gland to function properly. KI comes in tablet form and can be easily swallowed.
The effectiveness of KI as a specific blocker of thyroid radioiodine uptake is well established. When taken in the recommended dose and at the right time, KI is effective in reducing the risk of thyroid cancer in individuals or populations at risk of inhalation or ingestion of radioiodines. KI fills up the thyroid with non-radioactive iodine and prevents the uptake of the radioactive molecules. KI does not protect against other types of radiation.
The Canadian Nuclear Safety Commission (CNSC) is the federal agency that monitors safe operation of nuclear stations. It now requires all homes and businesses within 10 km of a nuclear station to receive a supply of the pills. Until now, the pills have been available at pharmacies. The CNSC now requires these be sent to every home and business due to increased safety standards.
In the very unlikely event of an emergency that results in a release of radiation to the public, the Chief Medical Officer of Health for Ontario will provide instructions through radio, TV, Internet and other available channels on where, when, how, and by whom KI should be taken.
It is important to wait for this notification. Do not take the pills unless instructed to do so. You would only need to take the pills for a short period of time, likely 1 – 2 days.
|Pregnant or breastfeeding women||2 tablets (1 single dose only)|
|Adults 18+||2 tablets every 24 hours|
|Children 3 – 18||1 tablet every 24 hours|
|Children 1 month – 3 years||½ tablet daily crushed in food or fluids|
|Children under 1 month||¼ tablet dissolved in fluids (1 single dose only)|
If necessary, and for younger children, tablets can be crushed in food or dissolved in fluids.
In case of overdose, get medical help or call the Ontario Poison Centre immediately at 1‑800‑268‑9017 or 416‑813‑5900.
The risk of side effects from taking a dose of KI is extremely low for all age groups who have normal thyroid function. The overall benefit during a nuclear emergency outweighs the risks of side effects.
There is an increased risk of side effects for people with thyroid disorders i.e., auto-immune thyroiditis, Graves’ disease, iodine deficiency and nodular goiter. These disorders are more common in adults and the elderly, and are rare in children.
Rare side effects in other parts of the body, such as gastrointestinal effects or hypersensitivity reaction, may occur but are generally mild.
People who are sensitive to iodine, who have an existing or previous thyroid disorder, or have any other concerns, should consult their doctor or nurse practitioner prior to taking KI.
When stored in a dry location between 15 and 30 degrees Celsius, the KI pills are effective for up to 12 years.
To order more KI pills please use our online order form.
Each adult in the household should have 4 pills available, and each child should have two pills available. This is enough for 2 days supply.
KI pills are available to children at schools in the 10 km zone, and select institutions in the 10 km zone such as health care facilities. KI tablets will also be available to the public at evacuation reception centres, and other locations designated by emergency officials.
No. In the very unlikely event of a radioactive release, it would take many hours and days to unfold. There would be time to respond to emergency instructions.
There is no requirement to give pets KI pills.
If you want to know more about the KI distribution program in Durham Region, please call 1‑800‑841‑2729; in Toronto you may call 311.
If you have any health questions related to KI pills, please discuss it with your health provider or you can contact Telehealth Ontario at 1‑866‑797‑0000.
For more information, please visit:
The letters and pills were mailed by postal code and in some cases by road boundaries, which means some homes beyond 10 km received the KI pill package.
The Canadian Nuclear Safety Commission (CNSC) — the federal agency that monitors the safe operation of nuclear stations — now requires that all homes and businesses within 10 km of a nuclear power station receive a supply of potassium iodide (KI) pills. The pills have been available free of charge at select pharmacies, but will now be sent by mail due to increased safety standards.
In the very unlikely event of a nuclear emergency and a release of radioactive iodine to the public, KI pills will help prevent the development of thyroid cancer, and are especially effective at safeguarding children's thyroid glands. It is important for each household to have a supply of these pills because they are most effective if taken just before or soon after exposure to radioactive iodine.
The distribution of KI pills is not due to any change in the risk of a nuclear emergency and is not meant to cause alarm. We believe that staying safe means being prepared, even for the most unlikely of events.
In the highly unlikely event of a nuclear emergency you will be promptly notified a number of ways including sirens, radio, television, Internet, automated telephone call and social media.
Follow instructions for evacuation, sheltering in place, taking KI pills, and reporting to a reception centre for monitoring.
And stay calm. Don’t evacuate unless advised to do so.
Enter your postal code to see if you’re within the eligible zone of a nuclear generating station.