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Radiation: Is the threat real?

How do risks from Fukushima compare to the radiation threats we face everyday at home?

The doses are higher if you live with a smoker. The lung cancer risk from cigarettes emerges not only from tar and nicotine but also from significant doses of radioactive lead and polonium that they emit. The housemates of a pack-and-a-half-per-day smoker receive the equivalent of 12 chest X-rays each year in extra radiation each year, by one estimate. (The EPA has a simple dose calculator you can use to calculate your exposure.)

Your radiation dose is also affected by where you live. In Ramsar, a village in northwestern Iran famous for its hot springs, the local bedrock emits doses as much as 100 times greater than normal — a fact that makes it of particular interest to scientists attempting to understand chronic low-level radiation exposure. Lying on some beaches in Brazil — where the sand includes radioactive mineral called monazite — can expose you to radiation up to 400 times the normal background levels in the United States.

But don’t let that reassure you. Currently, scientists presume that there is no safe dose of radiation — that any exposure, including what we get from the sun and earth, increases the likelihood of adverse impacts. Scientists have not yet mastered the art of teasing out exactly how many cases of cancer, birth defects and mental retardation emanate from radiation versus other toxins. While the health effects of chronic, low-level exposure remain poorly understood, there is a “convincing case” that such exposure is harmful, according to research led by the International Atomic Energy Agency.

“Just because it is natural doesn’t mean it is safe,” writes Makhijani. “Cobra venom is natural. Aflatoxins in peanuts are natural. Death is natural. Does that mean it’s OK for our neighbors to punch us? According to the National Academies and other detailed studies by official investigations, the best science is: low dose, low risk; high dose high risk. Zero risk is at zero dose,” he argues.

Of course, risk-free life doesn’t exist, so it’s essential to keep the danger in perspective. For now in North America, scientists say that the contamination that already exists in your home or doctor’s office is far more harmful than fallout from Fukushima.

A CT scan, for example, delivers a dose ranging from one year to 15 years worth of background radiation. Scientists recently estimated that the 70 million CT scans performed in 2007 would add 29,000 cancers, about half of which would be fatal. Two-thirds of them would afflict women. So while the benefits of medical imaging dramatically outweigh the drawbacks, the risk is by no means negligible.

Better yet, if you wish you could do something about the risk, consider radon gas, the second-biggest cause of lung cancer in America. It claims 21,000 lives each year according to EPA estimates. Radon emerges from naturally-occurring uranium in the soil and water in much of North America (particularly in the Rocky Mountain, Midwest and Appalachian states). It builds up in well-insulated homes. As usual for this sinister foe, radon is invisible and odorless, so there’s no way you’d know it’s there.

The good news: Unlike Fukushima, there’s something that you can do about radon. Get your home tested, and fix it if you have a problem. You may save a family member from a painful and premature death.

Follow David Case on Twitter: @DavidCaseReport