People are still talking about taking iodized table salt as an effective anti-radiation antidote, but yesterday the World Health Organization specifically warned everyone outside of Japan against self-medicating at this time with any iodine-containing substance as protection from radiation exposure. As I was saying yesterday, people would need dozens of tablespoons of salt each day to reach the proper and proven dose of potassium iodide. And you absolutely can die from ingesting such large amounts of salt. First, let’s read some cut-and-paste highlights from the WHO’s press report (WHO | FAQs: Japan nuclear concerns):

17 March 2011 — WHO is cautioning people concerned about the radiation issues in Japan against self-medicating with potassium iodide or taking products containing iodine. The advice follows reports of people using these substances in response to radiation leaks from nuclear plants in Japan. Potassium iodide should only be taken when there is a clear public health recommendation to do so.

What are potassium iodide pills?

In the setting of a nuclear power plant accident, potassium iodide pills are given to saturate the thyroid gland and prevent the uptake of radioactive iodine. When given before or shortly after exposure, this step can reduce the risk of cancer in the long term.
Potassium iodide pills are not “radiation antidotes”. They do not protect against external radiation, or against any other radioactive substances besides radioactive iodine. They may also cause medical complications for some individuals such as persons with poorly functioning kidney and therefore taking potassium iodide should be started only when there is a clear public health recommendation to take this step.

Can pregnant women take potassium iodide pills?

Pregnant women should take potassium iodide pills only when instructed by the competent authorities because the thyroid of a pregnant woman accumulates radioactive iodine at a higher rate than other adults and because the thyroid of the fetus is also blocked by giving potassium iodide pills to the mother.

How can I protect myself?

Keep you and your family informed by obtaining accurate and authoritative information (for example, information from authorities delivered by radio, TV or the Internet) and following your government’s instructions.
The decision to stockpile or take potassium iodide tablets should be based on information provided by national health authorities who will be in the best position to determine if there is enough evidence to warrant these steps.

If I have been exposed to high levels of radiation, what should I do?

If you are coming indoors after radiation exposure, undress in the doorway to avoid further contamination in your home or shelter. Remove clothing and shoes and place them in a plastic bag. Seal the bag and place it in safe location, away from living areas, children, and pets.
Shower or bathe with warm, not scalding hot, water and soap.
Notify authorities that you may have contaminated clothing and personal belongings to be handled appropriately and disposed of according to accepted national procedures.

When people are advised to stay indoors, what does this mean?

When a radiological or nuclear event occurs, public health authorities may order residents in the affected areas to stay indoors rather than to evacuate. You may be advised to take shelter at home, at work, or in public shelters. The recommendation is usually issued to protect people from exposure to radiation.
If you are advised to stay indoors, you should find the safest room in your house or office building that has no windows or doors. Ventilation systems, such as heating and cooling systems, should be shut down.
Shelter provides protection from both external and internal irradiation, as well as from inhalation of radioactive material.
Taking shelter is a simple and protective action that can be implemented promptly during the early phase of an incident.

Is it safe to eat food imported from Japan?

Japan is not a major food exporter. Currently, there is no indication of transboundary food safety risks due to imports of foods from Japan. Domestically, food safety concerns are restricted to food from the affected zone around the Fukushima Daiichi nuclear power plant. Given the reported safety measures and the earthquake and resulting tsunami, it would be unlikely that food production or harvesting is taking place in the evacuated area.

How can food products become radioactive?

Foods can be contaminated with radioactive materials as the result of a nuclear or radiological emergency. The surface of foods like fruits and vegetables or animal feed can become radioactive by deposit of radioactive materials falling on it from the air or through rain water. Over time, radioactivity can also build up within food, as radionuclides are transferred through soil into crops or animals, or into rivers, lakes and the sea where fish and shellfish could take up the radionuclides. The severity of the risk depends on the radionuclide mix and the level of contaminant released.
Radioactivity cannot contaminate food that is packaged; for example, tinned or plastic-wrapped food is protected from radioactivity as long as the food is sealed.

Which public health actions are most important to take?

Health effects can only occur if someone is exposed to radiation, thus the main protective action someone can take is to prevent exposure. Those closest to the radiation are at greatest risk of exposure and the greater the distance away, the lower the risk. This is why when a nuclear accident occurs, the recommended public health actions involve evacuation and sheltering of those near the site.
These necessary actions depend on the estimated exposure (i.e. the amount of radioactivity released in the atmosphere and the prevailing meteorological conditions such as wind and rain). The actions include steps such as evacuation of people within a certain distance of the plant, providing shelter to reduce exposure and providing iodine pills for people to take to reduce the risk of thyroid cancer.
If warranted, steps such as restricting the consumption of vegetables and dairy products produced in the vicinity of the power plant can also reduce exposure.
Only competent authorities who have conducted a careful analysis of the emergency situation are in a position to recommend which of these public health measures should be taken.

So, that’s the latest from the WHO. As regards to dying from too much salt, this is a very real and not-rare problem. It’s called hypernatremia, and there are many causes of this but sodium overload is certainly one of them. Many people — from infants to the elderly — have inadvertently ingested too much salt, and yes, many have died. Here’s the abstract from one medical review (Fatal hypernatremia from exogenous salt intake: report of a case and review of the literature):

Mayo Clin Proc 1991 Apr;66(4):439.
Hypernatremia is a common electrolyte disturbance, most often caused by volume depletion. Hypernatremia due to sodium excess occurs less frequently, and fatal hypernatremia solely from ingestion of table salt is rare. We describe a 41-year-old man who had seizures and hypernatremia after ingestion of a supersaturated salt water solution intended for gargling. He had consumed approximately a third cup of table salt (approximately 70 to 90 g of salt or 1,200 to 1,500 meq of sodium). His initial serum sodium concentration was 209 meq/liter. Hypotonic fluid therapy was given to provide free water and to correct the hypernatremia gradually. Our patient, however, failed to recover from the initial insult and died 3 days later. Review of the literature revealed 10 adult and 20 pediatric cases of hypernatremia attributable to exogenous intake of salt. The type of therapy (fluid or peritoneal dialysis), the type of fluid used, and the rate of correction of hypernatremia did not influence survival. The age of the patient and the initial serum sodium concentration were the most important prognostic indicators. Both very young patients and those with lesser degrees of hypernatremia had a better rate of survival than did other patients. In addition, our review illustrates the surprisingly small amount of salt that can cause severe hypernatremia and the danger of using salt or saline as an emetic.

So please, everyone, let’s not fill up the world’s hospital beds with kidney failures, comas and heart failures from table salt overload. Let’s wait for our local public health bureaus to keep us posted — and let’s pray that none of us will ever need to take further steps…