Ten Groups Exposed to Radiation

In Medical Imaging Physics, William Hendee and E. Russell Ritenour list ten populations that have been exposed to high levels of ionizing radiation.

Atom Bomb Survivors

At the end of World War II, several hundred thousand Japanese were exposed to large doses of ionizing radiation caused by the dropping of atomic bombs. They have been studied carefully, and provide much of our data about the risk of radiation exposure.

Early Radiologists, Nurses, and Technologists

Medical personnel who worked with early and primitive radiation equipment were exposed to relatively large doses of radiation. They suffered from an increased risk for some cancers, such as leukemia. You can include in this category scientists like Marie Curie, who may have died from radiation encountered during her research.

Uranium and Other Miners

In Intermediate Physics for Medicine and Biology, Russ Hobbie and I discuss Bernard Cohen’s studies of lung cancer risk in uranium miners. They suffer from a toxic mix of radon gas, dust, and tobacco smoke.

Radium Dial Painters

These unfortunate workers (mostly women) applied radioactive paint to illuminate dials. Their sad story is told by Kate Moore in her book The Radium Girls. We could lump the kids exposed to shoe fitting fluoroscopy into this group.

Radiation Therapy Patients

When radiation is used to treat patients with cancer, some of their normal tissue is exposed to high doses. Getting good data about the risk of cancer for such patients is difficult; they already have cancer, which affects the chance of it reoccurring. Hendee and Ritenour point out that in the past some benign disorders have been treated with radiation (for example, ringworm). These patients tended to have an elevated incidence of cancer.

Diagnostic Radiology Patients

Today radiation exposure for most diagnostic imaging is very low, but it has not always been so. Fluoroscopy in the 1940s could give patients a dose of a few grays. These patients provide data about the risk of radiation, although confounding factors make it hard to interpret.

Nuclear Weapons Tests

In the 1950s, many nuclear bombs were tested in the atmosphere over the Pacific Ocean. In particular, Marshall Islanders were exposed to ¹³¹I in fallout, leading to thyroid cancer.

Regions with High Natural Background

Several locations have unusually high background radiation levels: Guarapari, Brazil; the Kerala Coast of India; and the Guangdong Province in China. Hendee and Ritenour tell a funny story about the Monazite sand formations in Guarapari. Local inhabitants, who were mostly Catholics, were given hollow medals of the Virgin Mary filled with thermoluminescent dosimetry powder. After three months the powder was analyzed to determine their dose. Hendee and Ritenour add helpfully “the subjects were allowed to keep the medals.”

Air and Space Travel

Cosmic ray exposure increases with altitude and latitude. Hendee and Ritenour state “a flight in a typical commercial airliner results in an equivalent dose rate of approximately 0.005 to 0.01 mSv/hr.” The risk is largest for those who spend a long time in the air (e.g., pilots). Astronauts in low-earth orbit typically receive about 1 mSv per day.  I fear the astronauts on a mission to Mars will provide too much data about the risk of radiation.

Nuclear Accidents

The Chernobyl nuclear accident “resulted in whole-body doses exceeding 1 Gy… to over 200 workers.” Millions of residents of Ukraine, Belarus, and Russia had elevated exposure. Since Medical Imaging Physics was written, the Fukushima disaster has provided additional data on the risk of radiation to humans.

These ten groups have one thing in common: they didn’t want to be subjects of an experiment. In many cases, the exposure was inadvertent or accidental. In other cases—such as for the radium girls—the exposure was criminal. Much of our knowledge about radiation hazards comes from these unwitting victims. It’s data we love to have, but hate to get.