IN 1969, as a sophomore at Northwestern University, I heard Barry Commoner speak at a campus rally. I was impressed by this founder of the nascent environmental movement in the United States, and that day significantly shaped my career. It was in part why, as a reporter for WCVB-TV (Channel 5) from 1978 to 2000, I eagerly grabbed every environmental story that came along, and why I helped found the Society of Environmental Journalists.

I look back on that reporting with pride, and shame. And I am reminded of that shame by an opinion essay in Commonwealth Beacon, “A warning about radioactive air pollution from Pilgrim,” by doctors representing the Greater Boston Physicians for Social Responsibility. They write with ominous alarmism about the threat from ionizing (nuclear) radiation associated with the decommissioning of the Pilgrim Nuclear power plant in Plymouth.

That’s the same alarmist “OMG! RADIATION!” tone that colored all my reporting about Pilgrim and Seabrook and Yankee Rowe and nuclear power in general. Shame on me, it turns out, and certainly shame on these physicians, people of science who should know better, given all that science has learned about the surprisingly minimal health impacts of nuclear radiation. It is not nearly the threat we have all been led to believe.

Radiation was the founding bogeyman of modern environmentalism. When Commoner was helping get the movement going in the late 1950s, he wrote “the greatest single cause of environmental contamination of this planet is radioactivity from test explosions of nuclear weapons in the atmosphere.”

It was fear of radiation that inspired Rachel Carson to expand things in Silent Spring in 1962: “Chemicals are the sinister and little recognized partners of radiation in changing the very nature of the world–the very nature of its life.” Back then, this fear made sense. All we knew about the health effects of nuclear radiation was what it did to people in Hiroshima and Nagasaki and to Godzilla.

But the Life Span Study, conducted by an international consortium of radiation biologists and epidemiologists under the Radiation Effects Research Foundation, has followed 86,000 survivors of the atomic bombings, and their offspring, for nearly 80 years. What we’ve learned from one of the longest epidemiological studies in history should have put our fears largely to rest.

Among 14,000 survivors who were within one kilometer of the explosions and who were exposed to extraordinarily high doses of various forms of radioactivity (including highly dangerous gamma rays released at the moment the bombs exploded), and who continued to be exposed to radioactive fallout for months, the lifetime cancer mortality rate rose by just two-thirds of 1 percent.

Among other survivors, exposed to moderate doses but still significantly higher than those released by the nuclear accidents at Chernobyl and Fukushima, no increase has been detected in the incidence of any illness associated with ionizing radiation exposure compared to normal rates for those diseases. In other words, even at doses orders of magnitude higher than we’re talking about at Pilgrim, if there was any health effect at all, those cases were too rare to be detected. And, Godzilla and all those sci-fil films notwithstanding, there have been no multi-generational effects either, although children born to pregnant women exposed to high doses did suffer terrible birth defects from fetal exposure.

(The Life Span Study findings are why the World Health Organization predicts the lifetime excess cancer death toll from radiation released by Fukushima will be zero.)

In short, careful thorough research has taught us that ionizing radiation is indeed a carcinogen, but a very weak one, even at massively high doses. At the tiny, tiny doses that may be released from the decommissioning of Pilgrim, the health risk is infinitesimal. Hardly worth OMG RADIATON! alarm. (Many experts believe there is a threshold dose below which ionizing radiation isn’t carcinogenic at all.)

Sadly, few people outside the radiation biology community know this. Few opponents of nuclear power do. I once had the opportunity to share this knowledge with US Sen. Ed Markey, who has fought long and hard against nuclear power based on safety concerns. He didn’t know. I sure wish I had known it when I was scaring the bejeezus out of New England with my radio-alarmism. Mea culpa.

But even when presented with this solid scientific evidence, those who see the facts through the bias of an old school environmentalism lens dismiss the reassuring findings and continue their radio-phobic alarmism. Which is then blared out to the public by a news media eager for the drama that draws clicks and likes and shares. All of which reinforces a fear that vastly exceeds the facts, and does great harm.

Fear of ionizing radiation has driven the cost of building nuclear power plants so high it can’t compete against other forms of non-greenhouse gas emitting power. Clean energy (as in zero GHG emissions) policy in many states supports renewables, but not nuclear. That has only recently just begun to change, in small ways, in Massachusetts. In states (and nations) that shut down their nuclear power programs after Fukushima, fossil fuel emissions rose.

It’s not radiation per se that we fear, of course. It’s the cancer we believe it causes, and cancer has been our most feared disease for 100 years, despite the quiet incremental progress that has made as many two-thirds of all cancers either treatable as chronic conditions or curable outright. A cancer diagnosis is not the automatic death sentence so many of us still assume.

We need to update our fear of cancer, and of radiation, if we want to make the healthiest choices for ourselves and society. And the experts and the news media that we rely on for accurate information about health issues have to be more responsible and avoid alarmism that simply does not match the facts. Otherwise they are complicit in the harm these fears can cause.

David Ropeik is a former reporter for WCVB-TV, a retired Harvard instructor in risk perception psychology and risk communication, and author of three books on risk, including the most recent, Curing Cancer-phobia How Risk, Fear, and Worry Mislead Us.