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Worried about radiation danger?

Chat transcript: UCLA professor Keisuke Iwamoto answered reader questions about the dangers of radiation

March 17, 2011
  • A Radnet monitor on the roof of the Bay Area Air Quality Management building in San Francisco.
A Radnet monitor on the roof of the Bay Area Air Quality Management building… (Associated Press )

UCLA professor Keisuke Iwamoto answered reader questions about the dangers of radiation exposure in a live Web chat Thursday.

Iwamoto, a faculty member at UCLA's Division of Molecular and Cellular Oncology, studies radiation exposure and how it can lead to cancer. In his research, he also has analyzed donated tissue samples from Japanese atom bomb survivors.

Here's the transcript of the chat (moderated by L.A. Times staff writer Jeannine Stein with help from reader engagement editor Martin Beck):

Jeannine Stein: Welcome to our live Web chat on the health effects of radiation. Our guest is Keisuke Iwamoto, an adjunct associate professor of experimental radiation oncology. His research interests include how the body responds to radiation exposure and how it can lead to cancer. Welcome, Dr. Iwamoto, and thanks very much for being here today.

Kei Iwamoto: Hi everyone, thanks for being here. I hope I can answer some of your questions.

Jeannine Stein: I'll start off by asking something that's on a lot of people's minds: Radioactive isotopes are headed toward California after being released from the nuclear plant in Japan. We've been told that there's nothing to worry about, that the radiation levels are very low and not potentially harmful. Still, many people are worried. From what you know about this, is there any cause for alarm at this point?

Kei Iwamoto: There should be no alarm from the radiation because it will be so diluted and negligible by the time it gets here.

Comment From John: Should I buy Iodine tablets?

Kei Iwamoto: Hi John, there should be no need to buy the tablets except for nutritional purposes; i.e, you are deficient in iodine.

Jeannine Stein: Would there be side effects if people did take them without needing them?

Kei Iwamoto: There are studies that excessive iodine can be unhealthful; for example there can be allergic reactions, and in some cases it can actually cause goiter, which is ironic because deficiency is usually connected with goiter.

Comment from Joyful Diligence: What are 'harmful levels' of radiation in the short run and long-run? Cant even the slightest exposure to radiation require cancer in a person?

Kei Iwamoto: Hi Joyful, this is actually a complicated question. Defining a dose as high and low does not really describe the real situations. The range that we use in the radiation field generally runs from microsieverts to tens of sieverts; one sievert is a million microsieverts.

Background, from the rocks around us, the radiation from space, etc. give us about 3,000 microsieverts a year. Even pilots can get an extra 1,000 microsieverts a year from flying. The amount of radiation from Japan will be very much below the above doses I've just described, so the cancer risk will be negligible.

Jeannine Stein: How does the amount of radiation people may get from Japan compare to what people may be exposed to every day from flying in airplanes, getting an X-ray, etc.?

Kei Iwamoto: A medical X-ray like from a CAT scan is around 1,000 microsieverts, and the amount you might expect from Japan might be a thousand times less than that.

Comment From Concerned: I am in the very early stages of pregnancy -- 6 weeks -- living in Los Angeles. Do I need to take any precautions?

Comment From Nirav: Should pregnant woman and kids stay inside during the forecast weekend rain?. I am concerned that the radioactive materials will come down with rain.

Comment From elliot: My wife is 10 weeks pregnant. Any extra steps she should be taking?

Kei Iwamoto: The amount of radiation expected should be so negligible that there should be no effects on pregnant women and their children, in the womb or running around on the playground...

The risks from air pollution should be a greater one than that from any fallout from Japan.

Jeannine Stein: Dr. Iwamoto, is there a precedent for radiation arriving here from bombs or earlier accidents, such as Chernobyl? Do you know how much reached here? Did anything happen in terms of people's health?

Kei Iwamoto: I do not know the exact numbers but I do know that 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.

Comment From Dimitri: I have several retired Japanese business associates in Tokyo how hard should I encourage them to hop a plane and come stay in out guest room till all this problem is resolved one way or another.

Kei Iwamoto: The current reports for radiation levels in Tokyo suggest that they are still very low (in the microsieverts per hour range), so I doubt if there will be any health effects from the radiation...

They should be safe for the time being, staying put in familiar surroundings.

Comment From V. Swaminathan: When you say the radiaton will be diluted and negligible, can you be more specific? How solid is the science on this issue?

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