As the latest news from Japan reaches our shores, informing us that more radiation from the Fukushima reactor is leaking into the sea, we can't help but wonder if this radiation could be on its way to the United States to harm us.

Radiation scares us. It is an invisible killer, linked in our collective unconscious to fears of a nuclear holocaust. Our reaction to the hypothetical risk of radiation is not rational, it is emotional.

We can only imagine how the Japanese people feel, many of whom already experienced a real nuclear holocaust in the 20th Century. 

On a rational level, people understand that the radiation that is emanating from the Fukushima reactors in Japan is not good for human health. Many even know the details of it: that iodine-131, which degrades in little more than a week, has nevertheless been linked to 6,000 thyroid cancer cases following Chernobyl. Also comprehensible is the fact that Cesium-137 and Plutonium-239, other components of the radiation, can stay in the environment for many years, and are proven carcinogens.

But what the American public is having trouble with, what we always have trouble with, is wading through the media hype and figuring out whether there is an actual risk to you and me. Knowing whether we actually have something to worry about is especially difficult when it comes to hypothetical long term health risks.

The answer in this case, despite all the hype, as it was with anthrax scare in 2001, smallpox in 2002, bird flu in 2006, is a resounding...NO.

The miniscule amounts of radioactive iodine (less than a picocurie, a trillionth of a curie) that have made it across the ocean and into our rainwater, cows, and their milk is far from a threat to us. It is 5,000 times less than the amount that would normally land it on the FDA or EPA radar screen. The same iodine 131 is routinely beamed into people's bodies at many thousands times this amount to treat the overactive thyroid of Graves Disease, and no one worries about it then.

Our scientists and public health officials are only on the alert now, testing every morsel of food in sight, because the frenzied news media is telling them to be vigilant. In our modern American world of "CYA," public accusations and frivolous lawsuits, if you aren't vigilant in the face of a public obsession, you simply aren't around very long.

In the past several days, I have spoken with public health officials and environmental scientists here in New York City who are all geared up for the testing, taking their jobs quite seriously, their collective noses to the grindstone. The FDA is testing our food, and the EPA is investigating our water and milk. We have better equipment than ever available to sense even the tiniest particle, and our scientists are ready to use it to protect us.

But I believe the American public is capable of understanding a complex message: Radiation is bad for you, but this amount of radiation just isn't; unless you happen to live in Japan and are exposed to much much more.

Marc Siegel M.D. is an associate professor of medicine and the medical director of Doctor Radio at NYU Langone Medical Center. He is a Fox News Medical Contributor and the author of "False Alarm; the Truth About the Epidemic of Fear."

Dr. Marc Siegel, a practicing internist, joined FOX News Channel (FNC) as a contributor in 2008..