Estimated Radiation Doses Received by New Mexico Residents from the 1945 Trinity Nuclear Test.

Reference:  Simon, S. L., Bouville, A., Beck, H. L., & Melo, D. R. (2020). Estimated Radiation Doses Received by New Mexico Residents from the 1945 Trinity Nuclear Test. Health Physics, 119(4), 428–477. https://doi.org/10.1097/HP.0000000000001328

What were the research questions?

The researchers aimed to provide estimations of radiation doses to specific body organs that people in New Mexico may have received from the Trinity test.

How was the scientific problem approached?

The researchers used methods developed by Bouville etal 2020 to make estimates of doses to the five organs or tissues at greatest risk of cancer from exposure to fallout (thyroid, active bone marrow for leukaemia, stomach, colon and lung). This was carried out for both men and women in the four ethnic groups, in all age groups, and all counties.

What did the research involve?

The research team used the fallout pattern, the data on diet and housing types, and the dose models developed to estimate exposure over the year following the Trinity test. They estimated the dose from external exposure, which is exposure received while the fallout is being deposited and, from the fallout deposited on the ground. They also estimated the dose from internal exposure, which is exposure due to consumption of contaminated foods, including mothers’ breast milk and drinking water, as well as from inhalation of contaminated air and dust.

What did they find?

The estimated organ doses varied considerably and reflected the geographical fallout pattern from Trinity. The researchers found most New Mexico counties had external doses of less than 1 mGy, the largest external doses in one or two counties were about 100 mGy. They compared this with the natural background external radiation dose in New Mexico of 2 and 3 mGy per year which leads to between 140 and 210 mGy over the lifetime of most adults.

Except for dose to the thyroid gland, external radiation from fallout on the ground was the greatest source of exposure. Drinking fresh cows’ milk contributed the greatest part of the internal dose to the thyroid gland, which is the organ that received the highest dose.

How did the researchers interpret their basic results?

The researchers report that the geographic areas where the exposures were substantially higher than naturally occurring background radiation, were limited and immediately downwind of the detonation site. They also report that the external doses received from Trinity were comparable with those received at the Nevada Test Site and due to global fallout (~1.6, 2.5 and 1.1 mGy from Trinity, Nevada tests, and global tests respectively). In highlighting the many uncertainties in such assessments so long in the past they emphasize that person-specific dose estimation is not possible because detailed information for this does not exist.

Who did this research?

This study was carried out by scientists at the US National Cancer Institute and US National Institutes of Health. The research was funded primarily by the US National Cancer Institute and US National Institutes of Health with additional support from the National Institute of Allergy and Infectious Diseases.