Concern about radiation exposure has been rising in Japan as nuclear experts struggle to contain the cores of at least three nuclear reactors and a spent nuclear fuel facility at the Fukushima Daiichi nuclear plant.
Details of the Fukushima accidents remain sketchy, and it will likely be months before the true scope of radiation release will be known, both in terms of which isotopes have escaped containment and at what levels. According to the International Atomic Energy Agency, radiation levels following Monday’s reactor explosion reached 100,000 microsieverts per hour, four times the maximum allowed by the I.A.E.A., and more than 100 times the normal radiation exposure per person, per year. But even that worrying fact fails to offer guidance about human health impacts. Details regarding what types of isotopes, emitting which forms of radiation, are not yet available.
To date, authorities have listed 190 Fukushima workers as victims of radiation sickness — the most acute form of radiation exposure, which results in damage to multiple organ systems, skin burns, and usually a slow deterioration and death.
If the reactors fall like dominoes, however, and if fires remain uncontained, the danger of radiation could become much greater. But while the fallout levels so far have been well above normal background radiation for Japan, they have not yet come close to those produced by the April 25, 1986, Chernobyl catastrophe in Ukraine.
Much of the immediate data and analysis about Chernobyl were biased by Moscow’s need to downplay the incident, which occurred during the final years of Soviet power, and allay panic across the Soviet Union and Eastern Europe. Soviet authorities insisted that fewer than 10,000 people were dangerously exposed.
In contrast, authorities in post-Soviet Ukraine have claimed that more than 34 million people in Ukraine, Belarus, Russia and Moldova were exposed to radioactive fallout. In 2006, a multi-agency panel of United Nations experts estimated that 200,000 square miles of Eastern Europe were blanketed with fallout, 5 million residents of the area were exposed, and 100,000 people continue to receive radiation contamination from their food and environment.
Following the Chernobyl meltdown, the nearby town of Pripyat was evacuated, and it remains a ghost town inside a so-called Alienation Zone around the nuclear power plant. Though some Ukrainians stubbornly continue living in the zone, radiation levels detected in soil samples and local flora and fauna remain high, and food in the form of local animals or mushrooms is still considered dangerous for human consumption. Nearly 7,000 workers still make their way to the plant every day, maintaining safety operations.
Inside the Alienation Zone and another 70 kilometers into Russia, gamma radiation levels in soil samples exceed normal background levels by 14 to 46 times those found in the United States.
According to the Center for Russian Environmental Policy in Moscow and its 1996 publication, “Consequences of the Chernobyl Catastrophe: Environmental Health,” levels of plutonium-238 isotope radiation found years after the Ukrainian nuclear accident in the village of Starye Bobrovichi, in the Bryansk Oblast of southwestern Russia, were 89 times greater than the combined impact of all 1960 surface nuclear bomb tests (both Soviet and Western). Local fish and wildlife are heavily contaminated with radioactive cesium-137 and local biologists claim evidence of high levels of mutations in both flora and fauna.
Yet the cancer rates across the region, and in Western European countries that experienced spikes in radiation levels after Chernobyl, never reached the terrifying proportions predicted by scientists in 1986. Yes, cancer and disease rates rose, but not to levels that endangered or killed the million or more Europeans forecast to suffer.
When I visited the region and spent time in the Alienation Zone in 1997, I found the local Ukrainian and Russian populations in the grips of two extremes: “radiophobia” and denial.
“Radiophobia” was a term coined by the Russians for the syndrome in which people across the region feared every morsel they ate, every drop they drank, and the very air they breathed, regardless of how far away from Chernobyl they lived. The denialists were the opposite: They claimed all radiation concerns were mere hysteria, and continued living and working in or near the Alienation Zone, drinking the water and eating locally harvested (and highly radioactive) mushrooms.
Each successive administration in Kiev and Moscow has struggled to move these extremes toward a more scientifically supported middle ground.
Overall cancer rates did rise in Ukraine after 1986 — including in areas that never received Chernobyl fallout — from 300 diagnosed cases per 100,000 people in 1988 to 410 per 100,000 in 1994. But these numbers are hard to interpret, as all health indicators across the region deteriorated after the 1991 collapse of the Soviet Union for a host of reasons.
The clearest evidence of Chernobyl impact on human health was damage to the thyroid gland, which absorbs iodine. Radioactive iodine was a key component of Chernobyl fallout, and along the path of that grim extrusion there are today thousands of deaths as well as ailing adults who were children in 1986.
Distribution of prophylactic iodine — which saturates the organ’s receptors, blocking attachment by radioactive forms of the element — was slow after the Chernobyl incident. The 2006 I.A.E.A. analysis found this mistake fatal for many, because thyroid uptake of radioactive iodides was very rapid, saturating the organ within days.
Thirteen years after the Chernobyl disaster, the incidence of pediatric thyroid cancer was 52 times the region’s pre-1986 level. In Belarus, where the fallout blew, it was 113 times higher. In the immediate area surrounding Chernobyl, the incidence of pediatric and adult thyroid cancer remains the highest found anywhere in the world — more than 500 times the pre-1986 levels for the region.
The rate of thyroid diseases, including non-cancer conditions such as Graves and Hashimoto’s dysfunctions, is also extraordinary. Fourteen years after the accident, thyroid diseases of various kinds were diagnosed in Ukrainians at a rate of about one per 3,000 local residents annually.
Researchers at the Institute of Experimental Physiology in Kiev have diagnosed a range of immune system and blood disorders among most of the estimated 700,000 people who were children in 1986 and exposed to significant fallout. Harvard scientists estimate the leukemia rates in this population are about 50 percent higher than among Ukrainians not exposed to the fallout.
Unlike Soviet authorities in 1986, the Japanese government has responded swiftly to each stage of the Fukushima disaster. It has rapidly evacuated citizens from the area, and has been relatively transparent about radiation evidence as it has been collected. Aware of the dangers of both “radiophobia” and cavalier denial, the government has tried to convey information that directs the Japanese people to a rational response.
Still, health dangers remain, not only for the workers remaining inside the Fukushima plant, but all people remaining in a roughly 20 to 30 mile periphery of the area. Until details regarding the radionuclide types and doses that have already been emitted are known, most health claims regarding the general Japanese population are pure speculation. Certainly, further breaches, fires, explosions or meltdowns will increase the probability of health problems.
Chernobyl taught us that the thyroid gland is among the most vulnerable parts of the human body, but it can be protected with iodine pills. Chernobyl also illustrated the special vulnerabilities of children. And Chernobyl demonstrated the wisdom of evacuating people rapidly away from likely fallout zones. Finally, Chernobyl showed that the environmental absorption of fallout results in persistent radiation that will affect plants, wildlife, soils and water for thousands of years.
Laurie Garrett, a senior fellow for global health at the Council on Foreign Relations.