Harm from radiation is disproportionate across the life cycle. We know that primary germ cells and the embryo are far more vulnerable. The cells of fetuses and children divide more rapidly than those of adults. Dr. Alice Stewart found that the vulnerability of elderly people also increases; their repair mechanisms may not function as well as those of younger people. Some genotypes are more likely to contract radiological cancers. To this list we must now add gender: females, both juvenile and adult, are less resistant to ionizing radiation exposure. In addition to the type, amount, and duration of exposure, it matters crucially who is exposed to the radiation.
Radiation is invisible, but you can see the harm that radiation causes; indeed, we can see radiation burns to the body. We can, with a microscope, see radiation-induced chromosomal aberrations and we can also see tissue damage from plutonium. An artist’s concept shows us the damage radiation can cause to DNA, reconstructed from chemical assay.
There is no safe dose of atomic radiation. It takes only a single, infinitesimal radioactive emission hitting a single cell to cause a fatal cancer. This does not happen every time—our bodies have incredible repair mechanisms—but the loss of an embryo or fetus, or even the death of an adult, are all possible outcomes from so small an event that it cannot be measured as a “dose.”
The U.S. Environmental Protection Agency (EPA) safe drinking water standards say that there is no safe dose of radiation, and the U.S. Nuclear Regulatory Commission (NRC) regulations in chapter 10, part 20 of the Code of Federal Regulations, and its ALARA (As Low As Reasonably Achievable) policy, reflect this fact. This is also the conclusion of the seven BEIR reports from the National Academy of Sciences. As Dr. Bertell once said, “There is no such thing as a radiation exposure that will not do damage. There is a hundred percent possibility that there will be damage to cells. The next question is: which damage do you care about?”
When radiation impact is considered, generalizations about radiation are based on males. The first standards were established by the medical community for doctors. Later, “health physics” was created to supervise paramilitary and military personnel sent into radiation areas in the Manhattan Project. Those standards were for young, healthy males to be sent into restricted zones that were, at that time, very rare. The radiation exposure standards were not created with the view of being applied to anyone, anytime, anywhere, and since the standards do not factor in the disproportionate impact of radiation, they lead us to drastically underestimate the harm for women. Since women make up about half the population, this means an overall underestimation of radiation harm for the general populace.
Radiation exposure standards have been generalized as radioactive industries have spread. A widely used image to illustrate the breakout of radiation exposure shows the startling fact that one-fifth of an average total radiation exposure is from man-made sources. This represents a relatively large percentage that is actually an increase in radiation exposure compared to natural levels prior to the discovery of radioactivity at the end of the nineteenth century. While the chart is often used to explain away concerns about radiation exposure from nuclear energy, one must not dismiss an overall increase in exposure to ionizing radiation over the last hundred years of 25 percent (on average) overall. If any other environmental factor such as heat or rainfall were to increase by this large amount, it too would have impacts on living organisms.
The World Health Organization was the first major agency to release information about the disproportionate harm of radiation on females. In spite of its flaws, the report, called “Health Risk Assessment from the Nuclear Accident After the 2011 Great East Japan Earthquake and Tsunami,” does acknowledge that radiation has different effects on males and females. They mention that for little girls exposed below the age of five, there is a 70 percent higher risk of cancer.
No research has yet determined why gender is a factor in radiation harm. Dr. Bertell hypothesized that it may be the higher percentage of reproductive tissue in the female body, since the gonads and mammary tissues are known to be radiosensitive.
Other factors like lifestyle and occupation are less likely to be operative in the 0–5 age group, where exposure to ionizing radiation produces the largest gender-based difference in outcome.
Not all radioactivity results in radiation exposure or dose, but at the moment official estimates of harm from radioactivity assume that when radioactivity impacts living tissues it is an external dose. It is important to keep in mind that internal exposure is not analogous to external exposure. Eating, drinking, and breathing in radioactivity are very different from getting an X-ray. External beta particles penetrate only about one centimeter, whereas external alpha particles bounce off the skin. If the alpha-emitting element is inhaled or ingested, so the alpha particles are hitting tissue from inside the body, estimates indicate that internal alpha particle damage is anywhere from seven to one thousand times more damaging to cell structures than is X-ray (external) exposure. Another way of saying this is that when there is no distance from the source of the alpha or beta particle to its target, the doses to the target are very much higher. The BEIR VII report only looks at A-bomb survivors’ exposure to external ionizing radiation. There is no consideration of contaminated areas: food, water, and air deliver cumulative, ongoing radiological exposure that is internal as well as external. We do not yet know the implications of internal versus external exposure in gender-based radiation harm. This is important because although there are a limited number of catastrophically contaminated zones like Chornobyl and Fukushima, every industrial site and mining site in the nuclear fuel chain produces wastes and contamination, impacting the local community.
Disproportionate harm from ionizing radiation to females raises many issues: medical, ethical, historical, occupational, political, legal, evolutionary, and policy or regulatory questions. All are worthy of engagement, but it is my belief that we need to protect first and study second.
17
Epidemiologic Studies of Radiation Releases from Nuclear Facilities
Steven Wing
There are two approaches to estimating the health impact of radiation releases from nuclear facilities. In risk assessment we begin by estimating the radiation doses for a population. Then we multiply the number of people at each dose level by a value that represents the estimated number of excess cases of disease that will develop over time for a population exposed to that amount of radiation. The numbers of excess cases at each dose level are summed to get a total, which is the estimated impact of radiation releases on that disease.
The other method is epidemiology, which involves monitoring the occurrence of disease in populations exposed to different levels of radiation. The amount of excess disease due to radiation is estimated by direct observation about the past rather than projection into the future based on assumptions. Epidemiology is modeled after experiments in which subjects are randomly assigned to be exposed to radiation and compared to unexposed subjects. However, human experiments on ionizing radiation are unethical, therefore radiation epidemiology has focused on disease rates among patients exposed to medical radiation, nuclear workers, people living in areas with different levels of environmental radiation, and people exposed to radiation from nuclear weapons.