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

Abstract

The National Cancer Institute study of projected health risks to New Mexico residents from the 1945 Trinity nuclear test provides best estimates of organ radiation absorbed doses received by representative persons according to ethnicity, age, and county. Doses to five organs/tissues at significant risk from exposure to radioactive fallout (i.e., active bone marrow, thyroid gland, lungs, stomach, and colon) from the 63 most important radionuclides in fresh fallout from external and internal irradiation were estimated. The organ doses were estimated for four resident ethnic groups in New Mexico (Whites, Hispanics, Native Americans, and African Americans) in seven age groups using: (1) assessment models described in a companion paper, (2) data on the spatial distribution and magnitude of radioactive fallout derived from historical documents, and (3) data collected on diets and lifestyles in 1945 from interviews and focus groups conducted in 2015-2017 (described in a companion paper). The organ doses were found to vary widely across the state with the highest doses directly to the northeast of the detonation site and at locations close to the center of the Trinity fallout plume. Spatial heterogeneity of fallout deposition was the largest cause of variation of doses across the state with lesser differences due to age and ethnicity, the latter because of differences in diets and lifestyles. The exposure pathways considered included both external irradiation from deposited fallout and internal irradiation via inhalation of airborne radionuclides in the debris cloud as well as resuspended ground activity and ingestion of contaminated drinking water (derived both from rivers and rainwater cisterns) and foodstuffs including milk products, beef, mutton, and pork, human-consumed plant products including leafy vegetables, fruit vegetables, fruits, and berries. Tables of best estimates of county population-weighted average organ doses by ethnicity and age are presented. A discussion of our estimates of uncertainty is also provided to illustrate a lower and upper credible range on our best estimates of doses. Our findings indicate that only small geographic areas immediately downwind to the northeast received exposures of any significance as judged by their magnitude relative to natural radiation. The findings presented are the most comprehensive and well-described estimates of doses received by populations of New Mexico from the Trinity nuclear test.

Fig. 1

One-year integral air kerma (outdoor) from fallout deposited by the Trinity detonation (July 16, 1945 to July 15, 1946) at centroid locations of 721 voting precincts and interpolated. Top panel: Air kerma estimates at precinct centroids. Bottom panel: Interpolation map of air kerma. Star on each panel represents approximate location of Trinity detonation. Gray rectangular area directly south of Trinity detonation site is the present-day White Sands Missile Range (in 1945 known as White Sands Proving Ground).

Fig. 2

Comparison of pathway and food type contributions to thyroid dose of adults by ethnicity: Whites (panel A), Native Americans (panel B), Hispanics (panel C), African Americans (panel D).

Fig. 3

Comparison of total organ doses to adults by ethnicity: Whites (panel A), Native Americans (panel B), Hispanics (panel C), African Americans (panel D). Total organ dose is a sum over all exposure sources shown in Fig. 2. Note different y-axis scaling for each panel.

Fig. 4

Comparison of total organ doses to adults by age and ethnicity: Whites (panel A), Native Americans (panel B), Hispanics (panel C), African Americans (panel D). Thyroid dose is a sum over all exposure sources shown in Fig. 2. Note that age groups are not equal sizes.

Fig. 5

Ordering (left to right) of counties by magnitude of population-weighted average doses to the thryoid gland of adults. Top panels (left to right): Whites, Hispanic. Bottom panels (left to right): Native Americans, African Americans. For discussion on Native Amerian doses in Torrance County, see section on “Comparison of county average doses.” Four counties with asterisks (*) are those identified as “high risk” (and presumably, “high dose” counties) by TBDC (2017).

Fig. 6

Results of exposure measurements from Los Alamos Scientific Laboratory (Hoffman 1945) using x-ray film badges deployed in communities across the state before the Trinity detonation.

Fig. 7

Cumulative distributions of lower credible doses, best estimates of dose, and upper credible doses for adults at each of the 721 precincts.