The possibility of radiation exposure from Japan’s nuclear accident is on the mind of every parent today, judging from the questions I’m fielding in my pediatric practice. Here are some of the most frequently asked questions, and some answers:
1) How much radiation will reach California from Japan?
A: No one knows for certain. The Centers for Disease Control predicts that there is little risk of significant radiation reaching California. This is based in part on the nature of radioactive fallout. Many of the particles are heavy and don’t travel very far. Others can be airborne for long distances, but wind dilution means the effect would be much weaker by the time it travels the 5,000 miles from Japan to California.
2) How does radioactive material get into the body?
A: Most people think the danger comes from inhaling fallout, but this isn’t the case. 98-99% of exposure comes from ingesting contaminated food. As Dr. David Brenner of Columbia University points out in a March 14 New York Times article, “[Fallout] falls to the ground, cows eat it and make milk with radioactive iodine, and you get it from drinking the milk. You get very little from inhaling it.”
3) Why is thyroid cancer in children such a concern?
A: The thyroid gland normally concentrates dietary iodine. Since radioactive iodine is a major component of fallout, it can concentrate in the thyroid gland, too, increasing the risk of cancer. Potassium iodide (KI) can prevent this, by flooding the gland with non-radioactive iodine and preventing uptake of radioactive iodine. The younger you are, the greater the risk of developing cancer.
4) How many children got thyroid cancer as a result of the 1986 Chernobyl nuclear disaster?
A: More than 6,000, and almost all lived within a 300 mile radius of the reactor. The tragedy is that the vast majority of these cases were completely preventable. If parents had been warned not to feed their children locally-produced milk (the main source of radioactive iodine) several thousand cases of cancer could have been avoided.
5) Should I give KI (Potassium iodide) to my children now?
A: No. Each dose of potassium iodide only protects you for a day, so taking it while there is no increase in radiation is a waste. The Environmental Protection Agency has radiation monitors in place on several Pacific islands, so we should have warning as to when (or if) significant radiation is headed our way. (A brief political comment: this is the same agency that Republican budget hawks want to eliminate.) Remember, all the children who got cancer from the Chernobyl disaster lived within a three hundred miles of the reactor, and we are 5,000 miles from Japan.
6) Can KI prevent other radiation-related health problems?
A: No. It only protects the thyroid gland.
7) What else can we do to prepare?
A: Follow the Red Cross guidelines for earthquake preparedness, which we should all be doing anyway. We’re much more at risk from a California quake than anything that’s going on in Japan. Have a few days’ supply of food and water stored up. Hopefully you won’t need it.
Anything else?
A: Yes – send money to organizations like the Red Cross to help the Japanese people in this time of crisis!
Bottom line:
At this point (March 17, 2011), we don’t know how much radiation will reach us from Japan. Using Chernobyl as an example—and it’s good to remember that the Chernobyl reactor was producing about 100 times more energy than the Japanese plant when it exploded in ‘86—it seems that the risks of thyroid cancer and other radiation-related illnesses in California children is quite low. We’ll know more as the coming days pass. In the meantime it’s best to stay calm and check the websites of the CDC, EPA, and the Sonoma County Public Health Department for updates.
CDC: http://emergency.cdc.gov/radiation/
EPA: http://www.epa.gov/radiation/
Sonoma County Public Health Department: http://www.sonoma-county.org/health/ph/news/20110315radiation.htm
© 2010 by Mark Sloan, MD
Mark Sloan, MD has been a pediatrician and a Fellow of the American Academy of Pediatrics for more than 25 years. His book, Birth Day was named a finalist for the 2010 Northern California Book Awards in Creative Non-Fiction, and named one of fifty notable Bay Area Books of 2009 by the San Francisco Chronicle. Read his complete biography here.
4 Comments
Thank you for this information! It is easy to let fear get the best of us. I feel for the moms in Japan…it is a terrible thing, worry about our children!
I feel for those moms, too. I got an email from a woman I know in Tokyo shortly after the earthquake – her daughter was on a school trip, her husband was someplace else, and they couldn’t reach each other. They’re all fine, but a lot of people obviously aren’t. It’s a terrible tragedy.
I’ve been curious about the half life and the crops. If the crops are polluted and contain too much radiation, why doesn’t it start to dissipate after 8 days, the so-called half life?
If I am growing crops, should I be concerned about the radioactive rainwater that has fallen on them?
Hi Dana,
Fallout contains radioactive material of several types, some of which lasts much longer in the environment than others. While radioactive iodine (the isotope that can cause thyroid cancer) decays in a relatively short period of time*, other elements, like cesium-137, can last much longer. For example, more than half of the cesium-137 that was released at Chernobyl in 1986 is still in the environment, cycling through plants and animals and making large areas of Belarus and Ukraine near the reactor uninhabitable for humans.
The Washington Post has an excellent graphic about Chernobyl’s radiation woes at:
http://www.washingtonpost.com/world/persistent-danger/2011/04/04/AF3wKrYC_graphic.html
(Notice that the “hot zones” taper off within a few hundred miles.)
I would not worry about planting or eating local crops. We are too far from Japan (and the radiation emitted is far lower than at Chernobyl) to have much effect in rain or groundwater here. The effect on fish remains to be seen, though. Radiation in contaminated water running into the ocean can be picked up by plankton and work its way up through the food chain. At this point it isn’t known how significant this will or won’t be for seafood consumers.
* A note about rate of decay. A half-life of 8 days means that half of the material (radioactive iodine in this case) will be gone in 8 days. Half of the remaining material will disappear in another 8 days, and so on. After 6 half-lives (48 days for radioactive iodine), 1/64 of the original material will still be present. Cesium-137 has a half life of 30 years, which explains why it’s still such a problem at Chernobyl.
Half-lives are explained well and in more detail at:
http://en.wikipedia.org/wiki/Half-life
Hope that’s helpful!
Mark Sloan
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