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Radiation 101: How Does Nuclear Radiation Affect The Body?

How does nuclear radiation affect the body?

The latest weather forecast reports that the winds over the nuclear power plant in Japan have switched directions, and instead of blowing radioactive particles out to sea, the nuclear plume is drifting over Japan. Which is tragic, really. Given that there's over 5000 miles of ocean between Japan and the United States for radioactive materials to disperse, I'd rather take the fallout this way than see Japan further under siege.

But winds are fickle, and the battle to contain the nuclear crisis at the earthquake-damaged Fukushima Daiichi nuclear power plant still rages.

You already know how I feel about stockpiling iodide pills (DON'T). And I gave you the 11 reasons why US left coasters shouldn't freak out about radiation in Japan (namely, we're safe right now). But I have yet to put on my white coat and fill you in on what you should know about nuclear radiation and how it affects our bodies.

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So here goes. Are you listening there in the back (Bueller...Bueller)? Where's my chalkboard? Now keep in mind that I nearly had a mental meltdown trying to keep my grades up in my pre-med physics classes at Duke. This is not your friendly neighborhood nuclear physicist's lecture. So we'll keep this real simple.

Radiation 101: The Facts, Just The Facts, Ma'am

Radiation surrounds us all the time. It's in the air, the ground, our homes, and our food (oddly enough, bananas and brazil nuts clock in as the most radioactive foods). The average human is exposed to about three millisieverts of radiation per year, mostly from cosmic radiation and medical procedures. At these levels, any damage done can be repaired by a healthy body. While this small dose of radiation has not been shown to have any adverse biological effects on humans, higher doses can definitely hurt us.

For example, the power plant in Japan has been recorded spewing out up to 800 millisieverts per hour.

So What Happens?

When cells -- and what lies within them -- get exposed to radiation, components of DNA and critical proteins within the cell get all jazzed up (ionized), meaning that the electrons with our atoms get kicked out, causing the DNA strands to break and the proteins to cramp up (denature).

Ionizing Radiation:

·      Leads to the production of free radicals

·      Breaks critical chemical bonds

·      Leads to changes in cellular structure within irradiated cells

·      Damages vital molecules, such as DNA, RNA, and other regulatory proteins

Because our cells are mostly water, this ionizing radiation breaking H20 down is harmful to free radicals (H+ and OH-). While cells are damaged by free radicals all the time, they normally repair themselves, keeping the body healthy. However, high doses of radiation can damage the cell's ability to repair itself, and then all hell breaks loose.

This shakes things up all over the body.

Let's do a head-to-toe walk-through to investigate how high doses of radiation can damage the human body.
  • BRAIN: Nerve cells (neurons) and brain blood vessels can die, leading to seizures.
  • EYES: Radiation exposure increases the risk of cataracts.
  • THYROID: When a nuclear reactor malfunctions, radioactive iodine (I-131) can be released into the atmosphere (this is one of the particles that hangs out in a "radioactive plume"). The thyroid is very sensitive to the effects of I-131 (in fact, I-131's affinity for the thyroid is used therapeutically to specifically attract radiation to the thyroid in order to treat thyroid cancer and overactive thyroid). When a healthy thyroid is exposed to I-131, it can lead to decreased thyroid function and, over time, thyroid cancer.
  • LUNGS: When you breathe in invisible nuclear fallout particles, it can lead to lung cancer down the road.
  • HEART: High doses of radiation can damage the cells in the blood vessels that feed the heart, reducing cardiac function.
  • GI TRACT: Sensitive cells in the intestinal lining can be damaged, leading to nausea, bloody vomiting, and bloody diarrhea.
  • REPRODUCTIVE ORGANS: Rapidly dividing cells (eggs and sperm) in the ovaries and testes can die, leading to sterility.
  • SKIN: Rapidly dividing skin cells can be damaged, leading to skin lesions and burn.
  • LYMPHATIC SYSTEM: Rapidly dividing lymphatic cells die and damaged bone marrow may have trouble replenishing these immune-boosting cells, increasing the risk of infection.
How Much Does Dose Matter?

Obviously, how much radiation the body is exposed to matters a lot. We are all exposed to radiation every day. High doses of radiation tend to flat out kill cells, while lower doses tend to alter the genetic code (DNA) of cells. If enough cells in an organ are killed, organ failure can result.

Lower Doses of Radiation

It's hard to say exactly what radiation dosage is "safe," but certainly, any radiation floating across the sea from Japan to the US is currently deemed safe. While one station in Sacramento detected "minuscule quantities" of a radioactive isotope xenon-133, believed to have originated from Japan, the level detected would result in a "dose rate approximately one-millionth of the dose rate that a person normally receives from rocks, bricks, the sun and other natural sources," according to an EPA statement reported in this article.

While these levels do not put us at any known biological risk, higher doses -- such as those people exposed to ionizing radiation during cancer treatment undergo -- can increase the risk of cancers. Because radiation kills rapidly dividing cells (which is why we use it to treat fast-growing cancer cells), radiation exposure most increases the risk of cancers of rapidly dividing cells -- leading to leukemia, lymphoma, breast cancer, bladder cancer, colon cancer, liver cancer, lung cancer, esophageal cancer, ovarian cancer, multiple myeloma, and stomach cancers. Radiation may also lead to cancers of the prostate, nose/sinuses, throat/larynx, and pancreas. Many years can transpire between exposure and a cancer diagnosis.

So while we in the US do not appear to be at risk right now, the Japanese workers heroically battling against the possibility of nuclear meltdown certainly might be.

800-1600 Millisieverts (0.8-1.6 Sieverts)

Workers responding to the Chernobyl accident and some 1945 atomic bomb survivors were exposed to radiation doses at this level, which resulted in Acute Radiation Syndrome (radiation sickness). 134 plant workers at Chernobyl power plant exposed to these levels of radiation suffered from acute radiation sickness. Of these, 28 died within three months as the result of their exposure, and two died within the first few days.

3.5-5 Sieverts

It's nearly impossible to predict the threshold of exactly how much radiation you would need to be exposed to in order to die, but according to the US Nuclear Regulatory Commission, "It is believed that 50% of a population would die within 30 days after receiving a dose of between 3500-5000 mSv (3.5-5 Sieverts) to the whole body, over a period ranging from a few minutes to a few hours."

Everything In Between

For every Sievert past 1, the chance of dying within 30 days increases 15% above a base of 10% (meaning that someone exposed to two Sieverts of ionizing radiation has a 25% chance of dying within 30 days; someone exposed to three Sieverts has a 45% chance of dying within 30 days; at six Sieverts, the death rate is 90%). People lose their hair, become sterile, their bone marrow shuts down -- and at high doses, internal bleeding and complete immune system breakdown lead to overwhelming infection, hemorrhage, and death.

Perspective, People!

Most importantly, please keep things in perspective. The doses we're talking about here are the kinds of dosages we'll only see in nuclear disaster. No one except the workers at the nuclear power plant in Japan are at risk of any of these severe outcomes right now -- and because of their heroic actions, hopefully, we never will be.

May we all say a prayer for those we have lost to the earthquake and tsunami, as well as for all the power plant workers who are putting themselves at risk of cancer, radiation sickness, and death in order to protect the rest of the world. May God bring peace to the hearts of those who are mourning, and bring courage and serenity to those battling nuclear disaster, and may God watch over their families and keep them safe. And may the rest of us live in gratitude for our health, our safety, and the gift of living on this earth at this remarkable time in history.

For more information:

Does it help to talk about this? Or did this freak you out? Does this make you question your own mortality? What are you feeling right now? I'd love to hear...

 

Lissa Rankin, M.D., is an OB/GYN physician, author, and founder of Owning Pink Center, a women's health practice in Mill Valley, California.

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