1. Introduction

All people contain natural potassium of which a small fraction (0.012%) consists of the radioactive gamma emitting isotope 40K with the half-life of 1,258,300,000 years. A 70 kg adult human contains about 140 g of potassium in the whole body, of which 252,929,911,920,000,000,000 atoms are 40K. Every second a number of 4453 40K atoms decay in the human body, whereby emitting gamma radiation with the energy 1.46 MeV. Half of the gamma radiation is absorbed in the body while about 200 gamma ray photons per second are leaving the body. By recording these gamma rays in whole-body gamma-ray counting laboratories, the potassium content in the human body can be estimated and used in medical research.

In 1960 when people were measured for potassium at the whole body gammaray counting laboratory in Lund, the presence of another gamma-ray emitting

radionuclide, Caesium-137, appeared as well. This 137Cs-activity originates from nuclear weapons test performed in the atmosphere. Whole-body measurements of the Swedish Sami population, who consume products from reindeer that bite lichens in the Swedish mountains showed substantial content of 137Cs.

gamma-ray laboratory regularly measuring their potassium content. One collaborator was from Norway, and in 1960, when he returned from his vacation in Norway, a broad peak indicating gamma radiation from 137Cs appeared in the whole-body spectrum. He told that he had been eating cheese produced from sheep's baiting in the Norwegian mountains. The cheese contained high levels of radioactive caesium-137 released to the atmosphere by the United States nuclear weapons testing

Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions

A similar relationship would exist in the reindeer raising Sami people who live in

Northern Sweden. The transfer of atmospheric fallout through the food-chain Lichen-reindeer-man shown in Figure 2. Another collaborator Calle Carlsson (whom later on became a professor in Radiation Physics at Linköping University) was sent to Northern Sweden to collect samples. The piece of reindeer meat he brought from Northern Sweden to Lund was found to contain just over 1000 Bq of 137Cs per kg. That was quite a high level compared to the 137Cs levels in ordinary beef from Southern Sweden which contained about 4 Bq per kg. It became apparent that the Sami people should have high levels of caesium-137 due to the food chain

At the beginning of May 1961 encouraged by the results of Calle Carlsson's exploration, Kurt Lidén invited two Sami people from Lapland (67°N) to Lund. They measured at the gamma-ray laboratory, and it discovered that they had a caesium-137 content which was much higher than earlier was found in the

A research program was arranged to study the Caesium-137 activity in the Swedish Sami population, and in products from reindeer that bite lichens in the Swedish mountains. I participated in the annual expeditions to the Sami villages from Funäsdalen up to Karesuando at the Northern Swedish border to Finland. A mobile whole body counter laboratory was built on a military bus, lent by the National Defence Research department in Stockholm (FOA). In the middle of the bus was placed a lead-protected whole body gauge with a large NaI(Tl) crystal

Yngve Naversten was responsible for the design of the semi-portable wholebody counter [4]. The 42 cm wide chair arrangement was similar to the stationary whole-body counter at Lund and shielded was lead bricks. Since the 137Cs body

A sketch illustrating the food chain lichen-reindeer-man drawn by the author's colleague and friend MD

in the Pacific.

lichen-reindeer-man as shown in Figure 2.

DOI: http://dx.doi.org/10.5772/intechopen.83031

which was 5 inch in diameter and 4 inches thick.

Torsten Landberg (d. 2015) as a dedication to my thesis 1970 [3].

Norwegian collaborator.

Figure 2.

51

This chapter tells the story of how everything began and finally contributed to the termination of the extensive nuclear weapons testing in the atmosphere.

### 2. The low-level gamma ray laboratory

The research took place at the low-level gamma-ray laboratory located in the culverts of the children's hospital in Lund. There, a room was fitted with thick walls of iron plates to screen a sensitive Sodium iodide detector from ambient background radiation.

In the room, a crystal of sodium iodide, doped with thallium, was recording gamma radiation from radioactive substances in the human body. When the gamma rays hit the crystal, light flashes appear, which are captured by a photosensitive photo-anode in a photomultiplier tube which, in turn, generate electrical impulses whose magnitude are due to the energy of the gamma-rays. One of the inventors of the NaI (Tl) scintillation crystal was professor Sven Johansson at the Department of Nuclear Physics at Lund University. Recently the first small crystals he produced was found when tidying up at the Physics department in Lund.

Figure 1 shows the principle of how the sodium-iodine (Tl) detector record gamma-rays.

The original idea for the gamma-ray laboratory was to use the equipment to record the most common natural radioactive substance in the human body, potassium-40, for medical research [2]. As a quality control, the collaborators at the

#### Figure 1. The principle of how a sodium-iodine (Tl) detector record gamma-rays [1].

#### Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions DOI: http://dx.doi.org/10.5772/intechopen.83031

gamma-ray laboratory regularly measuring their potassium content. One collaborator was from Norway, and in 1960, when he returned from his vacation in Norway, a broad peak indicating gamma radiation from 137Cs appeared in the whole-body spectrum. He told that he had been eating cheese produced from sheep's baiting in the Norwegian mountains. The cheese contained high levels of radioactive caesium-137 released to the atmosphere by the United States nuclear weapons testing in the Pacific.

A similar relationship would exist in the reindeer raising Sami people who live in Northern Sweden. The transfer of atmospheric fallout through the food-chain Lichen-reindeer-man shown in Figure 2. Another collaborator Calle Carlsson (whom later on became a professor in Radiation Physics at Linköping University) was sent to Northern Sweden to collect samples. The piece of reindeer meat he brought from Northern Sweden to Lund was found to contain just over 1000 Bq of 137Cs per kg. That was quite a high level compared to the 137Cs levels in ordinary beef from Southern Sweden which contained about 4 Bq per kg. It became apparent that the Sami people should have high levels of caesium-137 due to the food chain lichen-reindeer-man as shown in Figure 2.

At the beginning of May 1961 encouraged by the results of Calle Carlsson's exploration, Kurt Lidén invited two Sami people from Lapland (67°N) to Lund. They measured at the gamma-ray laboratory, and it discovered that they had a caesium-137 content which was much higher than earlier was found in the Norwegian collaborator.

A research program was arranged to study the Caesium-137 activity in the Swedish Sami population, and in products from reindeer that bite lichens in the Swedish mountains. I participated in the annual expeditions to the Sami villages from Funäsdalen up to Karesuando at the Northern Swedish border to Finland. A mobile whole body counter laboratory was built on a military bus, lent by the National Defence Research department in Stockholm (FOA). In the middle of the bus was placed a lead-protected whole body gauge with a large NaI(Tl) crystal which was 5 inch in diameter and 4 inches thick.

Yngve Naversten was responsible for the design of the semi-portable wholebody counter [4]. The 42 cm wide chair arrangement was similar to the stationary whole-body counter at Lund and shielded was lead bricks. Since the 137Cs body

#### Figure 2.

A sketch illustrating the food chain lichen-reindeer-man drawn by the author's colleague and friend MD Torsten Landberg (d. 2015) as a dedication to my thesis 1970 [3].

radionuclide, Caesium-137, appeared as well. This 137Cs-activity originates from nuclear weapons test performed in the atmosphere. Whole-body measurements of the Swedish Sami population, who consume products from reindeer that bite lichens in the Swedish mountains showed substantial content of 137Cs.

the termination of the extensive nuclear weapons testing in the atmosphere.

2. The low-level gamma ray laboratory

Use of Gamma Radiation Techniques in Peaceful Applications

ground radiation.

gamma-rays.

Figure 1.

50

This chapter tells the story of how everything began and finally contributed to

The research took place at the low-level gamma-ray laboratory located in the culverts of the children's hospital in Lund. There, a room was fitted with thick walls of iron plates to screen a sensitive Sodium iodide detector from ambient back-

In the room, a crystal of sodium iodide, doped with thallium, was recording gamma radiation from radioactive substances in the human body. When the gamma rays hit the crystal, light flashes appear, which are captured by a photosensitive photo-anode in a photomultiplier tube which, in turn, generate electrical impulses whose magnitude are due to the energy of the gamma-rays. One of the inventors of the NaI (Tl) scintillation crystal was professor Sven Johansson at the Department of Nuclear Physics at Lund University. Recently the first small crystals he produced

Figure 1 shows the principle of how the sodium-iodine (Tl) detector record

The original idea for the gamma-ray laboratory was to use the equipment to record the most common natural radioactive substance in the human body, potassium-40, for medical research [2]. As a quality control, the collaborators at the

was found when tidying up at the Physics department in Lund.

The principle of how a sodium-iodine (Tl) detector record gamma-rays [1].

burdens in the Sami population was in the order of 4 kBq the background shielding was not critical.

Calle Carlsson declared in his death row over Kurt Lidén:

atmosphere" [7].

DOI: http://dx.doi.org/10.5772/intechopen.83031

as follow.

in Lycksele.

53

plants, animals, and man all over the world.

4. Reference groups for whole-body measurements

"I am convinced that the high radioactivity of reindeer raising people in The Northern Sub Arctic regions accelerated and actually forced the Test Prohibition Agreement pledging to refrain from testing nuclear weapons in the

Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions

until 1992 (its last nuclear test), and so did the Soviet Union until 1990.

After the Treaty in 1963 to refrain from testing nuclear weapons in the atmosphere, United States continued to perform underground nuclear weapons testing

In the explosion of a nuclear weapon, its load of uranium or plutonium splits into two lighter nuclei and release an enormous amount of energy, a process called fission. The most long-lived gamma-ray emitting lighter element released is 137Cs with a half-life of about 30.2 years. During the period of atmospheric testing, 137Cs was spread in the atmosphere and deposited as nuclear fallout and transferred to

In January 1960 a reference group for whole-body measurements which comprised of people of different age and both sexes was established in Lund. Since 1964 everyone in this group could not regularly participate in the whole-body measurements, and two utterly new reference groups started—one with 33 school-children aged between 14 and 15 years, from a school in Lund. The other group included 14 women and 20 men who worked nearby in a local factory. Three times a year, these groups experienced whole-body measurements of 137Cs originated from the fallout of atmospheric nuclear weapons tests and natural 40K for estimation of the total potassium content in the body. Since both the element Caesium (Cs) and potassium (K) belong to alkali metals, the first group in the periodic system, their physiological behaviour was believed to be highly correlated. Thus the 137Cs-body content, is sometimes indicated as the 137Cs/K ratio in Bq/gK. Figure 4 displays the time variation of the 137Cs/K ratio Bq/gK in the control groups at Lund, with the total yields of atmospheric nuclear weapons testing derived from Figure 3 at the bottom. In 1964, a comprehensive survey of school children aged 14–15 conducted at five different places, in different parts of Sweden. The selection criteria were

• That the students should have lived in the resort for at least 1 year.

The results given in Table 1 are 137Cs levels in March 1964 of non-Sami school-

The activity concentration of 137Cs in the Nässjö group was slightly higher than

A partial least square modelling of the activity concentration of 137Cs given in Table 1, with position(°N,°E), age (a), body-weight (kgBW) and potassium concentration (gK/kgBW) as dependent variables was performed for females (FM) and

the Lund group, which may be due to higher concentrations of 137Cs in locally produced foods. The high levels in Jokkmokk and Funäsdalen are probably due to consumption of reindeer products. While the unexpectedly low values in Lycksele may be that reindeer products are easier available in Jokkmokk and Funäsdalen than

• That they did not belong to any Same families.

children at the age of 14–15 years.

The sensitivity of the NaI(Tl) detector for 137Cs and potassium (40K) in a subject of 70 kg body weight, is 0.048 counts per minute per Becquerel (Bq) 137Cs, and 0.18 counts per minute per gram potassium.

The detection limit for 137Cs in people at the high radiation background level at Jokkmokk, corresponded to about 14 Bq 137Cs/kg, which is good enough for their people, with average body concentration of about 55 Bq 137Cs/kg. In Lund, however, the detection limit corresponded to about 10 Bq/kg which is too low for people in the control group with body concentration of about 12 Bq/kg. They measured in the iron shielded room with detection limit corresponding to about 3 Bq/kg.

### 3. Atmospheric nuclear weapons testing

The origin of 137Cs in the environment was the atmospheric nuclear weapons tests started by the development of the atomic bombs, which in 1945 felt over Hiroshima and Nagasaki. After World War 2 the developing and testing of nuclear weapons continued by both the USA and the Soviet Union. A summary of the annual Nuclear weapon explosion yield by the USA and the USSR up to 1990 given in Figure 3 in units of an equivalent amount (kilotons, kt) of the conventional explosive tri-nitro-toluene (TNT) [5, 6].

A Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space, was signed by the three (UK, US, Soviet Union) of the four nations developing nuclear weapons in 1963. The fourth nation France continued atmospheric nuclear weapon testing until 1974. Later China started to develop their nuclear weapons and continued with atmospheric testing until 1980.

#### Figure 3.

Annual nuclear weapon explosion yield by the USA and the USSR up to 1990, expressed in an equivalent amount (kilotons, kt) of the conventional explosive tri-nitro-toluene (TNT) [5, 6].

Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions DOI: http://dx.doi.org/10.5772/intechopen.83031

Calle Carlsson declared in his death row over Kurt Lidén:

"I am convinced that the high radioactivity of reindeer raising people in The Northern Sub Arctic regions accelerated and actually forced the Test Prohibition Agreement pledging to refrain from testing nuclear weapons in the atmosphere" [7].

After the Treaty in 1963 to refrain from testing nuclear weapons in the atmosphere, United States continued to perform underground nuclear weapons testing until 1992 (its last nuclear test), and so did the Soviet Union until 1990.

In the explosion of a nuclear weapon, its load of uranium or plutonium splits into two lighter nuclei and release an enormous amount of energy, a process called fission. The most long-lived gamma-ray emitting lighter element released is 137Cs with a half-life of about 30.2 years. During the period of atmospheric testing, 137Cs was spread in the atmosphere and deposited as nuclear fallout and transferred to plants, animals, and man all over the world.

#### 4. Reference groups for whole-body measurements

In January 1960 a reference group for whole-body measurements which comprised of people of different age and both sexes was established in Lund. Since 1964 everyone in this group could not regularly participate in the whole-body measurements, and two utterly new reference groups started—one with 33 school-children aged between 14 and 15 years, from a school in Lund. The other group included 14 women and 20 men who worked nearby in a local factory. Three times a year, these groups experienced whole-body measurements of 137Cs originated from the fallout of atmospheric nuclear weapons tests and natural 40K for estimation of the total potassium content in the body. Since both the element Caesium (Cs) and potassium (K) belong to alkali metals, the first group in the periodic system, their physiological behaviour was believed to be highly correlated. Thus the 137Cs-body content, is sometimes indicated as the 137Cs/K ratio in Bq/gK. Figure 4 displays the time variation of the 137Cs/K ratio Bq/gK in the control groups at Lund, with the total yields of atmospheric nuclear weapons testing derived from Figure 3 at the bottom.

In 1964, a comprehensive survey of school children aged 14–15 conducted at five different places, in different parts of Sweden. The selection criteria were as follow.


The results given in Table 1 are 137Cs levels in March 1964 of non-Sami schoolchildren at the age of 14–15 years.

The activity concentration of 137Cs in the Nässjö group was slightly higher than the Lund group, which may be due to higher concentrations of 137Cs in locally produced foods. The high levels in Jokkmokk and Funäsdalen are probably due to consumption of reindeer products. While the unexpectedly low values in Lycksele may be that reindeer products are easier available in Jokkmokk and Funäsdalen than in Lycksele.

A partial least square modelling of the activity concentration of 137Cs given in Table 1, with position(°N,°E), age (a), body-weight (kgBW) and potassium concentration (gK/kgBW) as dependent variables was performed for females (FM) and

burdens in the Sami population was in the order of 4 kBq the background shielding

The sensitivity of the NaI(Tl) detector for 137Cs and potassium (40K) in a subject of 70 kg body weight, is 0.048 counts per minute per Becquerel (Bq) 137Cs, and 0.18

The detection limit for 137Cs in people at the high radiation background level at Jokkmokk, corresponded to about 14 Bq 137Cs/kg, which is good enough for their people, with average body concentration of about 55 Bq 137Cs/kg. In Lund, however, the detection limit corresponded to about 10 Bq/kg which is too low for people in the control group with body concentration of about 12 Bq/kg. They measured in the

The origin of 137Cs in the environment was the atmospheric nuclear weapons tests started by the development of the atomic bombs, which in 1945 felt over Hiroshima and Nagasaki. After World War 2 the developing and testing of nuclear weapons continued by both the USA and the Soviet Union. A summary of the annual Nuclear weapon explosion yield by the USA and the USSR up to 1990 given in Figure 3 in units of an equivalent amount (kilotons, kt) of the conventional

A Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space, was signed by the three (UK, US, Soviet Union) of the four nations developing nuclear weapons in 1963. The fourth nation France continued atmospheric nuclear weapon testing until 1974. Later China started to develop their nuclear weapons and continued with atmospheric

Annual nuclear weapon explosion yield by the USA and the USSR up to 1990, expressed in an equivalent

amount (kilotons, kt) of the conventional explosive tri-nitro-toluene (TNT) [5, 6].

iron shielded room with detection limit corresponding to about 3 Bq/kg.

was not critical.

counts per minute per gram potassium.

Use of Gamma Radiation Techniques in Peaceful Applications

3. Atmospheric nuclear weapons testing

explosive tri-nitro-toluene (TNT) [5, 6].

testing until 1980.

Figure 3.

52

#### Figure 4.

Time variation of the 137Cs/K ratio Bq/gK in the control groups at Lund. The columns at the bottom represent the yields of atmospheric nuclear weapons testing.


#### Table 1.

The 137Cs-concentration, Bq per kg body weight (Bq/kg), the potassium concentration in g per kg body weight gK/kg measured 1964 in male (M) and female (FM) school children (age about 14) at the various locations in Sweden and who did not belong to any Sami families.

males (M) respectively. The equations for prediction of 137Cs activity concentration in Bq per kg body weight are given below for females and males respectively.

$$\begin{aligned} \text{^{137}Cs} \left( \text{Ag/kg}\_{\text{BW}} \text{FM} \right) &= -\mathbf{81.6} + \mathbf{1.366} \times \left( \text{^{\text{\textdegree C}}} \text{\textdegree 0.379} \times \left( \text{^{\textdegree C}} \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\text{\textdegree } \text{\textdegree } \text{\textdegree } \text{\text{\textdegree } \text{\texttop } \text{\text{\textdegree } \text{\textdegree } \text{\text{\texttop }} \text{\text{\text1}} \text{\text{\text1}} \end{aligned$$

R2 <sup>¼</sup> <sup>0</sup>:32,

$$\begin{aligned} \text{^{137}Cs}(\text{kg/kg}\_{\text{BW}}\text{M}) &= -\text{169.8} + \text{3.796} \times \text{(~N }) + \text{1.584} \times \text{(~E)} + \text{ 5.843} \times \text{(a)} - \text{7.623} \\ &\times \text{(kg}\_{\text{BW}}\text{)} - \text{113.0} \times \text{(gK/kg}\_{\text{BW}}) \end{aligned}$$

(2)

Variable importance in the projection (VIP) of the 137Cs prediction equations

Other whole-body measurement reference groups established at different places in Sweden with farmers, forest workers and other heavy working people with their family members. The aim was to compare the body activity of 137Cs in the Sami

As seen from Table 2 the activity concentration of 137Cs in females are about

A principal component analysis (PCA) was performed with the variables 137Csconcentration (Bq/kgBW), potassium concentration (gK/kgBW), and position (°N, °E). The results shown in Figure 6 are those labelled A from Table 1, and that

As seen in Figure 6 the reference groups are well separated, with Funäsdalen (62.50°N, 12.50°E) and Lycksele (64.6°N,18.7°E) as a subgroup in A and Övre Soppero (68.09°N, 21.70°E), Jokkmokk (66.60°N, 19.80°E) and Arvidsjaur

(65.66°N, 19.47°E) as a subgroup in B, and the two groups in Jokkmokk separated.

Location Male Female Male Female

Övre Soppero BOS 273.8 166.5 2.3 1.8 Jokkmokk BJ 188.7 103.2 2.4 1.8 Arvidsjaur BA 92.1 57.0 2.2 1.8 Funäsdalen BF 80.7 34.4 2.1 1.9

The 137Cs-concentration, Bq per kg body weight (Bq/kg), the potassium concentration in gK per kg body weight gK/kgBW in the reference groups from the rural population measured 1965 at various places in northern

137Cs Bq/kgBW 137Cs Bq/kgBW gK/kgBW gK/kgBW

(Eqs. (1) and (2)) are given in Figure 5a for female and Figure 5b for male respectively. The most important variables for female are latitude and potassium concentration, while for male, the body weight is of great importance as well.

Variable importance in the projection of the 137Cs prediction equations for (a) female and (b) male.

Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions

5. Whole-body measurement reference groups from the rural

population in northern Sweden

DOI: http://dx.doi.org/10.5772/intechopen.83031

half of the corresponding values in males.

people with other groups of people,

labelled B are from Table 2.

Table 2.

Sweden.

55

Figure 5.

R2 <sup>¼</sup> <sup>0</sup>:88.

Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions DOI: http://dx.doi.org/10.5772/intechopen.83031

Figure 5. Variable importance in the projection of the 137Cs prediction equations for (a) female and (b) male.

Variable importance in the projection (VIP) of the 137Cs prediction equations (Eqs. (1) and (2)) are given in Figure 5a for female and Figure 5b for male respectively. The most important variables for female are latitude and potassium concentration, while for male, the body weight is of great importance as well.
