Media Fallout

The media are often accused of playing chicken little, shouting that
the sky is falling, but a new study purports to show that chicken little was
right. USA Today broke the story on February 28, with the front-page headline: “Fallout likely caused 15,000 deaths.” That night, it was covered by
CNN, PBS’ Newshour, and most local TV news stations. The next day, other
media followed with similarly scary headlines (“Almost all in U.S. have been
exposed, study finds,” The New York Times; “Nuke test fallout caused 15,000
deaths,” Reuters; “Most Americans were exposed to fallout,” Deseret News).
The study, from the Centers for Disease Control and Prevention (CDC)
estimated that at least 15,000 cancer deaths in Americans born since 1951
were likely to have been caused by breathing or ingesting radioactive
fallout from nuclear weapons testing.

According to the CDC study, it was “limited to rudimentary
evaluations of the average impact on limited health outcomes” for the U.S.
population. Unfortunately, while words like “limited,” “estimate” and
“uncertainty” were littered throughout the study, they rarely surfaced in
the media coverage.

The London Guardian claimed the study “measured radioactive isotopes
across the U.S.” On the contrary, all the CDC researchers did was model
the possible dispersal patterns of radioactive material from testing sites. From this model, they estimated the average dose of radiation each person
received based on the presumed collective national dose.

In calculating the average dose, the researchers took account of
domestic testing and above-ground tests conducted outside of the U.S. The
researchers cautioned that the “global doses have a larger degree of
uncertainty.” But considering that the estimate of domestic testing’s impact
on thyroid cancer cases in the U.S. population varied between 11,300 and
212,000, the addition of estimated fallout from foreign tests to the
equation would drive the margin of error into the stratosphere. In fact, the
study noted that “because the uncertainty in the preliminary doses estimated
for this feasibility study has not been quantified, uncertainty in the risk
of all cancers and leukemia cannot be fully evaluated.”

As a result, the researchers stressed that the estimates of cancers
linked to radioactive fallout were abstract and could in no way be
attributed to individuals. “The true risk to individuals in the United
States may vary substantially from the average for many reasons, e.g. a
difference in their dose from the predicted value, their lifestyle patterns,
other environmental exposures, their individual susceptibility to radiation
effects, and the random nature of the predicted risk. … accurately
determining the risk for specific individuals is not possible.”

Separating radioactive fallout from the many other sources of
background radiation would be difficult, and measuring its specific impact
would be even more so. Nonetheless, headlines were sensational, and notes of
caution only appeared deep inside the stories. Most media were at least
careful to note that the fallout may have led to “increased risk” for
certain cancers, not that it simply caused cancers. Some, like the New York
Times, even noted that “the average American had received almost 20 times as
much radiation from medical procedures like chest X-rays as from fallout of
all kinds over the same period.” Others, like the Salt Lake Tribune,
identified curious inconsistencies in the study’s data. The Tribune quoted
the director of the Utah Cancer Registry, who expressed surprise at the
estimated cancer figures for Weber and Salt Lake counties, which have “the
lowest overall cancer deaths among the 50 state and the District of
Columbia.”

Steve Tetreault and Keith Rogers of the Las Vegas Review-Journal
deserve special kudos for consulting a National Nuclear Safety
Administration health physicist. His comments emphasized the “significant
margin of error” in deriving expected deaths from the “scant” data available
and said that the study, which revealed no new knowledge, was “really a
guess about the effects of small doses from radioactivity factored into a
large number of people.”

Unfortunately, even presuming the models and estimates of the amount
of fallout were correct, the presumptions behind the estimated effects of
the radiation may not be. The CDC study relied upon the linear no-threshold
hypothesis (LNTH). LNTH presumes that with each incremental rise in
radiation exposure, the health effects will rise a proportionate amount in a
linear direction. It also assumes that any exposure to radiation is
deleterious to human health, even the smallest amount that can be measured
(hence the “no-threshold”). But many scientists question the veracity of the
theory. Much evidence now points to some possible positive health effects of
low-level radiation. In April 1999, the American Nuclear Society concluded
that “there is insufficient scientific evidence to support” the LNTH “in the
projection of the health effects of low-level radiation.” So, it seems, the study was based on unsteady theories as well as shaky estimates.

Because of all the uncertainties, there’s no way to know how many people
were exposed to how much radiation or what effects it might have caused. It
is a pity that the media’s knee-jerk reaction was to stir apocalyptic panic.