Estimated Exposures and Thyroid Doses
Received by the American People from I-131
in Fallout Following Nevada Atmospheric
Nuclear Bomb Tests

Introduction for Annexes and Sub-Annexes
& Presentation of the Procedure to be Used to Estimate Individual Thyroid Doses for both Cow's and Goat's Milk Diets.

The purpose of the annexes and sub-annexes is to present information related specifically to each nuclear weapons test and test series.

The tests that are considered are listed in the attached table. Some of the tests have been combined because the detonations took place within a short time of each other and the wind patterns were similar, so that it was not possible to assign unambiguously the fallout at distant locations to a single test. The combined tests are:

• Bee (22 March 1955) and Ess (23 March 1955),
• Apple 1 and Wasp Prime (both detonated on 29 March 1955),
• Boltzmann (28 May 1957), Franklin (2 June 1957) and Lassen (6 June 1957),
• Kepler (24 July 1957) and Owens (25 July 1957), and
• Wheeler (6 September 1957), Coulomb B (6 September 1957) and Laplace (8 September 1957).

It should be noted that the scientific notation was used in most of the tables that are provided. This was done in order to minimize the number of pages in the report as the scientific notation allows results that differ by factors of billions or more to be written with the same format. For example, a value of "5.6E+2" may be found in a table. This means that "5.6", which is the number before "E+", should be multiplied "2" times (i.e., twice) by 10; in other words:

5.6E+2 = 5.6 x 10 x 10 = 560.

However, if the value found in the table were "5.6E-2", then "5.6", which is the number before "E-", should be divided "2" times by 10; in other words: 5.6E-2 = 5.6 / 10 / 10 = 0.056.

Finally, if the number after "E+" or "E-" is 0, as in "5.6E+0", then the number before "E+" or "E-" remains unchanged; in other words: 5.6E+0 = 5.6 and 5.6E-0 = 5.6. 

The attached sequence of numbers illustrates the range of values that can be found in the Tables and shows why the scientific notation is used to save space:

Four types of information are presented:

The information is indexed in two different manners:

1. by nuclear test
2. by state and county

In the version of the report that is available in hardcopy, annexes and subannexes are presented in different volumes. In this electronic version, all the information related to a given test has been assembled at the same location, for the convenience of the reader.

The basic information and the main results obtained for each nuclear test that is taken into consideration in the dose assessment are presented. This includes:

A description of the test along with a presentation of the environmental data, specific for that test, that have been used in the dose assessment. This includes systematically:

In addition, the following are included, when such type of information is available:

• a map of close-in exposure rates, denoted, for example, as Fig. UK/7/X, where UK/7 identifies the test and X represents the AExposure rates@,
• tables of available I-131 deposition data:
1. one table for the I-131 deposition data derived from the Town Data Base, which covers Clark, Esmeralda, Lincoln and Nye counties in Nevada, as well as Washington county in Utah; this table is denoted, for example for the test UK/7, as Tab. UK/7/TDB,
2. another table for the I-131 deposition data derived from the County Data Base, which covers all of Arizona, all of New Mexico, all of Nevada (with the exception of Clark, Esmeralda, Lincoln and Nye counties), all of Utah (with the exception of Washington county), large parts of Wyoming and Idaho, and small portions of California, Colorado, and Oregon; this table is denoted, for example for the test UK/7, as Tab. UK/7/CDB,
3. a third table for the I-131 deposition data derived from the gummed-film network for the 48 contiguous U.S.; this table is denoted, for example for the test UK/7, as Tab. UK/7/GF.
    
• maps of available I-131 deposition data:
1. two maps related to the I-131 deposition data derived from the Town Data Base, which covers Clark, Esmeralda, Lincoln and Nye counties in Nevada, as well as Washington county in Utah. One map, denoted, for example for the test UK/7, as Fig. UK/7/TDB/F, provides estimates of I-131 deposition, F, in each station of the Town Data Base, while the other map, denoted, for example for the test UK/7, as Fig. UK/7/TDB/TOA, provides estimates of initial times of arrival of fallout, TOA, in each station of the Town Data Base, and
2. one map for the county-averaged I-131 deposition data derived from the County Data Base and from the Town Data Base; this map is denoted, for example for the test UK/7, as Fig. UK/7/TCDB.
   
• Estimates of ¹³¹I depositions per unit area of ground for all counties of the contiguous United States: (1) a table providing daily values until the radioactive cloud had left the U.S. or until the gummed-film analysis showed negligible fallout levels; this table is denoted, for example for the test UK/7, as Tab. SA/UK/7/F; and (2) a color-coded map showing estimated ranges of deposition for all counties of the contiguous United States.; this map is denoted, for example for the test UK/7, as Fig. UK/7/F. The manner in which the estimates of ¹³¹I depositions per unit area of ground are obtained for all counties of the contiguous United States is explained in detail in Chapter 3 of the report. The I-131 deposition results are expressed in nanocurie per square meter of ground (nCi m^-2).
  
• Tabulated estimates of ¹³¹I concentrations in fresh cows' milk resulting from the test for each county of the contiguous United States. The I-131 concentrations are integrated over time to assess the total impact of the test and estimated for both commercial milk and milk obtained from a backyard cow. The following categories of commercial milk are considered: (1) fresh from a cow, (2) consumed on the farm, (3) retailed from the farm, (4) originating from the same region, and (5) originating from another region. In addition, the average concentrations in the milk pooled from the latter 4 categories (called Avolume-weighted averages@) are presented as well as the maximum concentrations obtained for commercial milk. The table with all of those estimates is denoted, for example for the test UK/7, as Tab. UK/7/M. The time-integrated I-131 concentrations in milk are expressed in nanocurie days per liter (nCi d L^-1 ). The manner in which the estimates of time-integrated¹³¹I concentrations in milk are obtained for all counties of the contiguous United States is explained in detail in Chapters 4, 5, and 6 of the report.
  
• Tabulated estimates of ¹³¹I concentrations in ground-level air and in foodstuffs other than fresh cows' milk, resulting from the test, for each county of the contiguous U.S. The foodstuffs other than fresh cows= milk that are considered are: (1) mothers= milk (consumed by infants), (2) goats= milk, (3) cottage cheese, (4) eggs, and (5) leafy vegetables. The estimates of ¹³¹I concentrations in ground-level air and in foodstuffs other than fresh cows' milk are integrated over time to assess the total impact of the test. The table with these estimates is denoted, for example for the test UK/7, as Tab. UK/7/C. The time-integrated I-131 concentrations in ground-level air are expressed in nanocurie days per cubic meter of air (nCi d m^-3 ), while the time-integrated I-131 concentrations in foodstuffs other than fresh cows= milk are expressed in nanocurie days per kilogram of foodstuff (nCi d kg^-1 ). The manner in which the estimates of time-integrated¹³¹I concentrations in ground-level air and in foodstuffs other than fresh cows= milk are obtained for all counties of the contiguous United States is explained in detail in Chapter 7 of the report
  
• Estimates of ¹³¹I thyroid doses for all counties of the contiguous United States. The thyroid doses are estimated for 13 age categories (in utero: 0-10 wk, 11-20 wk, 21-30 wk, and 31-40 wk of pregnancy; infants: 0-2 mo, 3-5 mo, 6-8 mo, and 9-11 mo; children: 1-4 y, 5-9 y, 10-14 y, and 15-19 y; adults). For adults, the thyroid doses are estimated separately for males and females. These dose estimates, D in rad, are derived, for persons over one year of age, as:

D = [(IC(cows= milk) x CR(cows= milk)) + (IC(goats= milk) x CR(goats= milk))

+ (IC(cottage cheese) x CR(cottage cheese)) + (IC(eggs) x CR(eggs))

+ (IC(leafy vegetables) x CR(leafy vegetables)) + (IC(air) x BR(air))] x DCF x 10^-3 (1)

where:

IC represents the time-integrated concentrations in nCi d L^-1, nCi d kg^-1, or nCi d m^-3,

CR represents the consumption rates of the foodstuffs, in L d^-1 or kg d^-1, applicable to the age category considered,

BR represents the breathing rate, in m³ d^-1, applicable to the age category considered,

DCF is the dose conversion factor, in mrad per nCi, applicable to the age category considered, and

10^-3 rad per mrad is a unit conversion factor necessary to obtain the dose estimates in rad.

For infants, the consumption of mothers= milk had to be taken into account. The following equation has been used:

D = [(IC(mothers= milk) x CR(mothers= milk)) +(IC(cows= milk) x CR(cows= milk))

+ (IC(goats= milk) x CR(goats= milk))

+ (IC(cottage cheese) x CR(cottage cheese)) + (IC(eggs) x CR(eggs))

+ (IC(leafy vegetables) x CR(leafy vegetables)) + (IC(air) x BR(air))] x DCF x 10^-3 (2)

Finally, for the fetal ages, equation 1 has been used, but the parameter values for the consumption and breathing rates are those appropriate to the mother. Thyroid doses for the youngest fetal age (0-10 wk) have not been reportes, as they are very small because the thyroid does not start its development before week 12.

For each post-natal age and sex category, thyroid doses have been estimated for: (1) the population of persons drinking cows' milk, (2) a specified "high-exposure" group, with a high consumption rate of milk containing higher-than-average concentrations of ¹³¹I, (3) a specified "low-exposure" group, with no consumption of fresh cows' milk, and (4) a specified group with a high consumption rate of milk from backyard cows.

Collective doses to the population of each county have been obtained by summing, over all post-natal age and sex categories, the products of the arithmetic means of the thyroid doses estimated to have been received by the population of each category by the size of that population group. Per capita doses were computed by dividing the collective doses by the population sizes.

Values of the consumption rates of milk, CR(milk), that were used in the study are given in Tables 6.2, 6.3, and 6.4. Table 6.2 presents the median milk consumption rates of milk drinkers, appropriate for the 1950s and averaged over the U.S. 

Because the consumption of milk showed substantial variations in the 1950s from one region of the country to another, refined calculations used the consumption rates of milk shown in Table 6.3 for persons over one year of age according to the state of residence at the time of the nuclear test.

Finally, the estimates of average daily milk consumption by the Ahigh-exposure@ groups are presented in Table 6.4.

The values used in the report for the average consumption rates of foodstuffs other than cows milk and of breathing rates are given in Table 7.4.

Finally, the values used in the study for the dose conversion factor, DCF, are provided in Table 6.7.

Various estimates of thyroid doses are presented for each nuclear test and each county of the contiguous U.S.: (1) tables of estimates for each age group (and gender for the adult population) for each of the four milk consumption scenarios considered (denoted, for example for the test UK/7, as Tab. SA/UK7/D2 to SA/UK7/D14, where D stands for "thyroid dose" and "2" or "14" are values of the age group index, shown in Table 6.7 for all age groups), (2) a table of estimates of the collective dose and of the per capita thyroid dose to the county population (denoted, for example for the test UK/7, as Tab. SA/UK7/CD, where CD stands for both "collective dose" and "per capita dose"), and (3) a color-coded map showing estimated per capita thyroid-dose ranges (denoted, for example for the test UK/7, as Fig. UK7/CD, where CD stands for "per capita dose").

Results are also summarized for each test series for each county of the contiguous U.S.:

• tabulated estimates of I-131 concentrations in fresh cows' milk resulting from the test series, for all categories of milk considered in the study. For example, for the test series Upshot-Knothole, these estimates are provided in Tab. UK/S/M,
• tabulated estimates of I-131 concentrations in ground-level air and in foodstuffs other than fresh cows' milk (mothers' milk, goats' milk, cottage cheese, eggs, and leafy vegetables). For example, for the test series Upshot-Knothole, these estimates are provided in Tab. UK/S/C,
• tabulated estimates of thyroid doses for each age group (and gender for the adult population) for each of the four milk consumption scenarios considered (denoted, for example for the test series Upshot-Knothole, as Tab. SA/UK/D2 to SA/UK/D14, where D stands for "thyroid dose" and "2" or "14" are values of the age group index, shown in Table 6.7 for all age groups),
• maps presenting estimates of I-131 depositions per unit area of ground (denoted, for example for the test series Upshot-Knothole, as Fif. UK/S/F) and of per capita thyroid dose ranges (denoted, for example for the test series Upshot-Knothole, as Fig. UK/S/CD).

Individuals can readily obtain an estimate of the individual dose they received from each test by indicating their date of birth and their location at the time of the test. Results are provided for each of the four milk consumption scenarios considered.

For people wishing to obtain estimates of thyroid doses that correspond more closely to their dietary habits, equations 1 and 2 can be used. The estimation of the thyroid dose to a specified individual from a given test requires the knowledge of:

• The time-integrated concentrations, IC, of ¹³¹I in cows' milk, goats' milk, cottage cheese, eggs, leafy vegetables, mothers' milk (only for infants), and ground-level air in the county of residence of the individual considered at the time of the test. These time-integrated concentrations are found in the tables indexed by nuclear test.
• The consumption rates of cows' milk, goats' milk, and mothers' milk (only for infants), expressed in L d^-1, of cottage cheese, eggs, and leafy vegetables, expressed in kg d^-1, as well as the breathing rate, expressed in m³ d^-1, of the individual at the time of the test. This information is to be provided by the individual or by another knowledgeable person (e.g., relative or friend) who could supply estimates of those quantities. Average values for the 10 post-natal age and sex groups are given in this introduction.
• The appropriate thyroid dose conversion factor, expressed in mrad per nCi. It may be available for those individuals who underwent thyroid irradiation for medical reasons. In most cases, however, the value of the thyroid dose conversion factor appropriate for the individual is not available and use of the estimated average thyroid dose conversion factors, DCF, presented in this introduction for the 14 age and sex groups is recommended.

It should be noted that the results obtained using equations 1 and 2 are only an approximation of the results that would be obtained with the methodology used in the report. Because parameter values are assumed in the report to be log-normally distributed, more complex equations need to be used to obtain more accurate estimates of the thyroid doses. This more complex methodology is actually used in the estimation of the thyroid doses summed over test series and over all tests available on the State and County pages.