Worries outweigh radiation threats in U.S. Lo lắng nhiều hơn so với đe dọa phóng xạ ở Mỹ

All that worrying might cause more harm than the radiation from the Japan nuclear accident, experts say. A look at some common concerns.

In Japan, a baby is checked for radiation exposure before entering an evacuation center in Fukushima. Meanwhile, Californians are worrying that radiation plumes will find their way to American shores. (AP Photo / Kyodo News)

With reports that a radiation plume from the Fukushima Daiichi nuclear plant could reach Southern California as soon as Friday, worried citizens have been hoarding potassium iodide pills, wondering if it's OK to go outside and otherwise fretting over an invisible, and somewhat unpredictable, threat.

But all that worrying might cause more harm than the radiation itself, experts say. Here are some answers to common concerns.

How much radiation do scientists think will arrive here?
No one knows yet — but probably not a whole lot. It's unclear what's happening at the Japanese power plant, and whatever radiation escapes has to travel thousands of miles to reach U.S. shores. Over that distance, it will be greatly diluted, if it gets here at all.

Photos: In Japan, life amid crisis

In fact, the winds have been shifting, often blowing westward, back toward Japan, rather than toward the U.S., California officials said in a news conference Thursday. "We are not in Japan," said Dr. Jonathan Fielding, director of Public Health for Los Angeles County. "We are not within 10 miles of the reactor. We are 5,000 miles away — and we know a lot about dispersal patterns over that distance."

How much risk will any radiation that reaches here pose?

Not much. Gregory Jaczko, chairman of the Nuclear Regulatory Commission, an independent agency that regulates U.S. commercial nuclear power plants, told reporters Thursday that the basic science involved suggested that "there can't be any risk or harm to anyone here in the United States, or Hawaii, or any of the other [U.S.] territories."

Dr. Kei Iwamoto, of the faculty of the Division of Molecular and Cellular Oncology at UCLA, told The Times that he believed the amount of radiation from Japan that a person in California might be exposed to will be very low — perhaps around one microsievert.

To put that in perspective, people get some amount of radiation every day. Humans are exposed, on average, to 3,000 microsieverts of natural background radiation per year, according to the Centers for Disease Control and Prevention. One dental X-ray would add 40-150 µSv to that baseline. A CT scan of the abdomen, according to the Food and Drug Administration, would tack on another 8,000 µSv — more than 2 1/2 years of background radiation.

Did radiation reach here from Chernobyl? What happened then?

Yes, a tiny amount did reach the United States. But its health effects were miniscule, if they existed. "The radiation from the 1986 accident was negligible from a health standpoint. I know of no evidence that that accident caused any increase in cancer in this country," Iwamoto said.

What about kids? I've heard they're more sensitive to radiation.

That is true. "Kids are more vulnerable to radiation for a couple of reasons," said Dr. William Hendee, a radiation physicist with the Medical College of Wisconsin. "Their organs and tissues are growing and developing. Growing and developing cells are more susceptible to radiation. Kids also have a longer lifespan."

So should I keep them away from school?

No. Radiation levels are not likely to get very high. There is no reason to keep your kids out of school.

Should I take iodine tablets or eat iodized salt? It can't hurt, can it?

Well, yes, it can hurt. The tablets can be risky for some people — especially pregnant women. There is no reason to take iodine tablets at this point, said California officials at the news conference.

Indeed, potassium iodide is not recommended at all until radiation levels hit the tens of thousands of microsieverts. Levels won't reach anywhere approaching that level here.

In cases of true radiation exposure — for example, for people living close to the reactors in Japan — the benefits of potassium iodide outweigh the risks. The tablets can protect the thyroid from exposure to radioactive iodine-131 by "filling up" the gland and preventing it from taking up the radioactive iodine.

But potassium iodide can be harmful to people who are allergic to the substance or who have the skin disorders dermatitis herpetiformis or urticaria vasculitis, according to the Centers for Disease Control and Prevention. Pregnant women and infants should not be given potassium iodide because it could cause a serious thyroid disorder in infants. The supplements can cause some side effects including nausea, rashes and inflammation of the salivary glands.

As for eating iodized table salt to ward off the effects of radiation, that might work, but you'd have to gobble a great deal of the stuff — 3 1/2 pounds a day, according to the Salt Institute, an industry group — to reach the 130 milligrams of iodine you'd need. Even the institute said, in a statement, that this was not a good primary defense against radioactive fallout. That's saying something. Don't do it.

Would wearing a mask help me?

Sure, if it gives you peace of mind. "Masks would reduce a bit of the inhalation, but the amount of radioactive fallout is going to be so tiny," Hendee said. "For someone who is concerned or worried, if they felt better wearing a mask, they should wear a mask. I don't think it will reduce their risk, because the risk is already so low."

Should I stay indoors?

That's probably not necessary, unless local authorities alert you to do so. Currently, federal officials aren't recommending it.

What contingency plans do local and national health authorities have?

Although national health authorities defer to state governments, they will issue recommendations based on the severity of radiation levels, said Robert Taylor, a spokesman for the Nuclear Regulatory Commission. Possible recommendations include evacuating areas within 10 miles of a nuclear power plant, warning people to take shelter and close all doors and windows, and advising residents to consume potassium iodide tablets. "There's no need for U.S. citizens to take any protective measures at this time," he added.

What can I do to be safer?

Until more is known about the threat radiation from the nuclear plant might pose in California and beyond, your best bet is to get yourself prepared — for any expected emergency. Assemble your earthquake kit. Install gas shut-off valves, if your house doesn't already have them, "rather than going out and buying potassium iodide, I would encourage everyone to go out and buy three to five days of food and water, so that when we have our earthquake, you can be self-sufficient," said Howard Backer, interim director of the California Department of Public Health, at the news conference.

Most of all, address the health threats that you can control. According to the federal government, almost 1.5 million Americans die each year of heart disease or tobacco-related diseases. The best bang for your buck might be throwing away the cigarettes, exercising and improving your diet.

Photos: In Japan, life amid crisis

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eryn.brown@latimes.com