One Deadly Summer : Was Chernobyl the Cause of Higher U.S. Mortality?
Something strange happened to America in the summer of 1986: 35,000 to 40,000 more people than usual dropped dead. A statistical fluke? Dr. Jay Gould, a fellow of the Institute for Policy Studies in Washington and a distinguished statistician, thinks not.
The seasonal pattern of mortality in America is pretty stable. Over the 80 years before 1986, 31.7% of each year’s deaths occurred, on average, during the months of May to August. In 1986 that percentage rose to 33.1%--the highest this century--up from the 1983-85 average of 32%. Gould calculates that the odds against such an increase happening by chance are more than 1 million to one. So what happened?
The explosion of a nuclear reactor at Chernobyl in the Soviet Union on April 26, 1986--and, in particular, the ensuing radioactivity plume that reached America 11 days later--may offer a clue. As the radioactivity arrived, rainwater samples in America’s Northwest recorded 46 pico- curies (pc) of radioactivity per liter. By May 12, in Washington state, the level had risen to 6,620 pc per liter. In milk samples--a routine indicator of radioactivity--the concentration of radioactive iodine-131 peaked at about 130 pc per liter, compared with 1985’s average of below 7. Because the 130 peak was less than 1% of the U.S. government’s ceiling (15,000 pc per liter), no action was taken. The levels were, after all, between 100 and 1,000 times lower than those recorded across Europe after the disaster.
Gould’s analysis picks up a worrying correlation between regional American levels of radioactivity in milk and regional mortality in the summer of 1986. Gould calculated averages of the peak concentrations of iodine-131 in milk for nine regions during the four-month period. The highest concentrations were seen in Pacific states such as Washington and California, where the number of deaths in the four months was 5% higher than it had been in May-August, 1985. In areas recording the lowest concentrations--such as Texas and Arizona--the number of deaths was unchanged from the previous summer. That relationship between radioactivity and death held true across the country. Tests showed that for these correlations, sheer coincidence was hardly possible.
According to received wisdom, exposure to such low levels of fallout is harmless. Most of the debate on the medical consequences of Chernobyl has centered on the long-term danger of cancers and genetic defects that can be caused by higher doses. Any suggestion that the disaster had an immediate adverse effect on mortality rates is heresy. The Organization for Economic Cooperation and Development’s Nuclear Energy Agency recently restated its belief that the risk of “radiation-related harm” to the public in Western countries had “not been changed to any noticeable extent” by Chernobyl.
Such claims ignore research into the indirect effects of low-level radiation, according to Dr. Ernest Sternglass, emeritus professor of radiological physics at the Univer- sity of Pittsburgh. Bursts of high-level radiation--such as medical X-rays--are relatively harmless to normal adults. That is mainly because such “external” radiation does not concentrate itself in crucial organs. Ingested or inhaled fission products behave rather differently. Once inside the body, they seek out particular organs and sit there, emitting radiation.
Such low-level radiation promotes the slow release of molecules known as free radicals. Production of the most common, oxygen free radicals, is increased by protracted exposure to the radioactivity of ingested fission products. Oxygen free radicals (unstable oxygen molecules with an extra electron) are attracted to the membranes of cells, which they then disable. This process is efficient only when there is a low concentration of free radicals. At high radiation doses the free radicals deactivate each other. That is why America, despite its lower dose of radiation, may have suffered more from this problem than parts of Europe.
How could America’s increased mortality rate in the summer of 1986 be related to the damage caused by free radicals? Among the cell functions impaired or destroyed by prolonged exposure to free radicals is the production of hormones and white cells that provide the body’s immune defenses. Such an erosion of the immune system might be expected to hit two groups of people first: the old or weak, and those suffering from life-threatening diseases.
Of all those Americans over 65 who died in 1986, 32.7% did so in the four summer months. During the same months in 1985, the proportion was 30.6%. Compared with the 1983-85 summer average, about 30,000 more people in that age group died in summer, 1986.
The number of people dying from pneumonia in all age groups was 18.1% higher in May-August, 1986, than in the same months of 1985. Deaths from infectious diseases rose by 22.5% over the same period. And deaths caused by AIDS and its related infections increased by 60.3%. Changes were much smaller in the first and last four months of 1986.
Leaving out deaths caused by accidents, suicide, drug abuse and violence, Gould found that the “natural” death rate of all people between 25 and 34 was 5.3% higher in 1986 than in 1985. That age group was born in the 1950s, when atmospheric nuclear-bomb testing was at its peak. As they have aged, their mortality rate has increased much faster than the mortality rate of those born between 1935 and 1944--before bomb testing started. Gould and Sternglass believe that fallout from testing in the 1950s may have weakened the immune systems of the very young. In later life, that might make them more susceptible to the biological effects of additional fallout.
America’s seasonally adjusted fertility rate--measured by the number of live births per 1,000 women between 15 and 44--fell to a record low during July and August, 1986. In contrast, live births rose in the first four months of 1986. The fall is due, Sternglass believes, to an increase in miscarriages, fetal deaths and stillbirths. During the summer, infant mortality rates reflected the regional pattern of milk radioactivity.
Both Gould and Sternglass emphasize that their work is in its infancy. But their analysis already suggests that the change in the American way of death in summer 1986 was not a matter of chance. If Chernobyl was the cause, a complete review of “safe” radiation levels is needed. And if Chernobyl was not to blame, what was?
