CLAIM: 100 million humans in the same place would emit enough radiation to be deadly.
AP’S ASSESSMENT: False. Radiation experts confirm the human body contains trace amounts of radiation, but the levels aren’t nearly enough to be lethal, even if 100 million people were somehow packed into a single place.
THE FACTS: Social media users are claiming that if you put enough people together in one place, they’d emit so much radiation that it would be deadly.
Many are sharing a post with the headline “Humans are Radioactive” along with the statement: “If 100 million average humans kept in an isolated place for eight hours, they will admit enough radiation to kill each one of them within 20 days.”
The post also includes a picture of actor Rosamund Pike holding up a glowing green vial from the 2019 film “Radioactive,” about famed Polish scientist Marie Curie who conducted pioneering research on radioactivity.
While it’s true that humans, like other living organisms, contain radioactive material, the levels are “extremely low” — thousands of times smaller than an x-ray, according to Melissa Sullivan, a spokesperson for the U.S. Environmental Protection Agency.
The radiation also can’t be easily transmitted to others, experts say. To reach a dangerous level, the radiation would somehow have to be gathered from millions of people and then distilled into an extremely confined space.
“The claim is indeed ridiculous,” Christopher Clement, CEO of the International Commission on Radiological Protection, a Canada-based group of scientists that advocates for radiation safety, wrote in an email.
“If you concentrated the radioactive material from many millions of people into a very small space, the result could be a radioactive source that would need to be handled with care to avoid being dangerous,” he wrote. “But not as harmful as squeezing a hundred million people into a phone booth.”
The social media claims also show a misunderstanding of the kind of radiation found in our bodies, said George Chabot, a physics professor at the University of Massachusetts, Lowell who delved into greater detail about the claim ina 2021 post for the Health Physics Society, another group of scientists that advocates for radiation safety.
Human radiation largely comes from eating foods that contain potassium — a tiny fraction of which is radioactive potassium-40, he explained in an email.
“What may confuse people is that most of the dose to an individual from eating potassium-40 comes from the beta radiation emitted during the decay of the radioactive atoms,” Chabot wrote. “This beta radiation is not very penetrating so that practically all of the energy emitted remains within the individual and cannot irradiate anyone else.”
Michael Short, a nuclear science professor at the Massachusetts Institute of Technology, agreed, arguing that the radiation produced by 100 million people still wouldn’t be deadly, despite what social media users claim.
Every few hours, a person emits roughly 0.00000001 Sieverts, which is a unit of measure for radiation that quantifies the risk of negative effects on the human body, he said.
If multiplied by 100 million people — as the social media posts appear to have done — that amount would produce a single Sievert of radiation, or enough to cause radiation sickness, but not likely fatal enough for an otherwise healthy person, Short said.
“All that radiation would have to be localized in one person-sized place, or smaller, to be that damaging,” he explained in an email. “100,000,000 people would take up a tremendous amount of space, spreading out their radiation dose over that space. The dose one gets from being near a source of radiation decreases quickly with distance away from that dose.”
What’s more, the human body acts as a sort of buffer, absorbing much of its own radiation and mitigating its wider impacts, added Christopher Baird, a physics professor at West Texas A&M University.
“If one human absorbs a bit of ionizing radiation, then this bit of radiation is no longer available to affect another human,” he wrote in an email. “A hundred million humans will be emitting a hundred-million worth of human background radiation, but there will be a hundred million people absorbing this radiation.”
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This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.
