Young girls could be up to 10 times more vulnerable to nuclear radiation than other members of society, with girls as young as five twice as likely to develop cancer as boys of the same age.
Understanding of the danger of radiation exposure has surged into the public consciousness since February, when Russia invaded Ukraine. Talk of nuclear war has simmered since then, with rhetoric intensifying on Oct. 6 when President Joe Biden warned of “Armageddon,” despite the U.S. having no new evidence that Russian President Vladimir Putin was planning a nuclear strike.
“In Hiroshima and Nagasaki, a lot of people were instantly vaporized,” said biologist Mary Olson, founder of the Gender and Radiation Impact Project. Newsweek, referring to the US dropping atomic bombs on Japanese cities in 1945.
“But there were places where people survived. Those are the people being studied now.”
Data gathered from the Hiroshima and Nagasaki Long-Term Study of Bombing Survivors is widely used by regulatory agencies and researchers around the world to assess the long-term effects of radiation exposure on the human body.
Today, the US Nuclear Regulatory Commission bases its assessments of the impact of ionizing radiation on the public, and thus its decisions on nuclear licensing and regulation, on a subset of data that describes the “Reference Man.”
The reference human, as defined by the International Commission on Radiological Protection, is 20 to 30 years old, weighs 154 kilograms, is 5 feet 6 inches tall, and is Caucasian with a Western European or North American lifestyle. This one-size-fits-all approach describes only a small subset of society.
In her research, Olson compared the effects of radiation on different demographic groups with the effect of that same level of radiation on reference humans.
“It seems natural to me to take those most affected in that data set and then compare that to where regulators are focusing their regulations,” he said. The most severely affected group in the data set was young girls aged 0 to five years at the time of exposure. “And what was the difference?” he said. “A factor of ten.”
The second most affected group were young men in the same age group. Even so, young girls were twice as likely to develop cancer during the study period as their male counterparts. In all age groups, women were more likely to develop cancer from radiation than men, although the gender difference became less pronounced in older age groups.
There is a clear explanation for why young people are more at risk from radiation: children’s bodies are constantly growing, which means that their cells divide faster. As a result, their DNA is more vulnerable to tumor-causing damage.
But why are young girls twice as vulnerable as young boys?
It’s possible that the young girls in the study simply received more radiation than their male counterparts, but the consistency and significance of the association suggests something else is at play.
More research is needed, but Olson believes this discrepancy may be due to physiological differences in the male and female bodies. “Female bodies have a higher relative concentration of stem cells [than males]”These stem cells are much more sensitive to being damaged by radiation.”
While this is still a theory, it would explain the pattern seen in Olson’s data: “The difference in stem cell concentration changes with puberty,” Olson said. “The onset of menstruation results in an actual reduction in stem cells in the female body compared to males.” As we age, the concentration of stem cells in our bodies declines, and this decline reflects the near-convergence of radiation risk for men and women in older age groups.
Assessing radiation risk with a one-size-fits-all approach is likely to open young women up to dangerous levels of radiation exposure, not only from nuclear warfare but also from more common radiation exposures such as CT scans, air travel and medical X-rays. As a result, the risk and harm of ionizing radiation to society is probably underestimated.