Fallout of U.S. nuclear tests between 1945 and 1962 wider than so far believed

By Mayank Chhaya-

On the day Christopher Nolan’s epic ‘Oppenheimer’ releases, a remarkable new study finds that the radioactive fallout of the July 16, 1945, Trinity nuclear test, which is the focus of the film, spread wider than what was expected.

It practically affected the whole of the contiguous United States. The finding has several significant implications.

“Our results show the significant contribution of the Trinity fallout to the total deposition density across the contiguous U.S. (reaching 46 states within 10 days),” the study by Sébastien Philippe, Susan Alzner, Gilbert P. Compo, Mason Grimshaw and Megan Smith. The scientists are attached to Science and Global Security, Princeton University, Princeton, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Physical Sciences Laboratory, National Oceanic and Atmospheric Administration (NOAA), Boulder, and The Earth Genome, Los Altos.

The study also shows that the fallout from all 101 atmospheric nuclear weapon tests were conducted between 1945 and 1962 in the United States was far more widespread than expected.

“Finally, our deposition estimates also indicate that direct fallout from the Trinity test arrived at Crawford Lake in Ontario, Canada, on July 20, 1945 with a peak deposition on July 22, 1945. This would mark the first-time plutonium-249 and 240 deposited in the lake that is now proposed as the Global boundary Stratotype Section and Point to define the Anthropocene as a geological epoch – five years before the proposed base dated at 1950 CE.”

The reference to the Anthropocene as a new geological epoch caused by human activity. There is growing consensus among geologists that Earth has already entered the Anthropocene Age, or the age of humans.

It is more than likely that it has, and it has done so faster than any geological age so far. At the heart of this global transformation is human activity since the mid-20th century.

For geologists to declare a new epoch takes a great deal of time because geological epochs take thousands of years or even millions of years to make in order for them to identifiably alter Earth’s surface.

However, the Anthropocene seems to have unfolded disturbingly fast and propelling its advent goes to the very heart of the raging climate crisis debate. That is because several markers which are considered evidence in the way Earth’s surface has changed since the mid-20th century are direct consequences of human activity. One of those likely markers is the aftereffects of the Trinity test. The fact that the new study makes a pointed reference to the Anthropocene is important.

“Our findings also speak to debates about marking the beginning of the Anthropocene with nuclear weapons fallout. 10,11Our deposition estimates indicate that direct fallout from Trinity, a plutonium device, reached Crawford Lake in Canada, the proposed “golden spike” site marking the beginning of the Anthropocene epoch, 12,13 starting on July 20, 1945,” it says.

The study’s findings have important public health implications. “Our total deposition density estimates across the contiguous United States have implications for public health and discussions about the 1990 Radiation Exposure and Compensation Act (RECA). Aggregated by counties and federally recognized tribal lands, our total deposition density estimates show that there are locations in New Mexico, and in other parts of the United States, including Utah, Nevada, Wyoming, Colorado, Arizona, and Idaho, where radionuclide deposition reached levels larger than those we estimate in some counties covered by RECA. Total deposition density is a metric that reflects external exposure to radiation without accounting for internal contamination via the ingestion of contaminated water, fresh milk, and other foodstuffs,” it says.

What that could mean is that the question of compensation for those who were affected by the Trinity and subsequent radiation may have to be revisited. If radionuclide deposition reached levels larger than those estimated in some counties covered by RECA coupled with the wider spread of the radiation, it may require government agencies to reexamine the larger impact of the 101 tests.

“These findings include deposition in all 48 contiguous U.S. states. They provide an opportunity for re-evaluating the public health and environmental implications from atmospheric nuclear testing,” the study says.


[Photo courtesy: https://www.osti.gov/]