[Illustration: _Long-lived radionuclides, particularly cesium-137,
accumulate on plants._]
[Illustration: _Reindeer herds graze on lichens and mosses._]
[Illustration: _A substantial portion of the Laplanders’ diet is
reindeer meat._]
[Illustration: _Here personal data and eating habits are recorded for
each person to be counted._]
[Illustration: _A Laplander in a whole body counter._]
[Illustration: _The University of Helsinki (Finland) study revealed a
close correlation between the consumption of reindeer meal and the
Lapps’ body burdens of cesium-137. However, these levels did not exceed
acceptable limits._]
[Illustration: Figure 12 _Using a whole body counter to determine
radioactivity in milk._]
The idea that this nuclide had entered the body with food later was
tested by placing various foods in the whole body counter. All foods
tested were found to contain some cesium-137, but beef and dairy
products had highest levels. The radiation spectra of persons of the
same age but different diet habits were compared, and correlation was
found between their cesium-137 content and the amount of dairy products
they ate.
In October 1960, Kurt Liden at the University of Lund in Sweden
encountered evidence of the source of cesium-137 in humans. While he was
using the whole body counter at the University’s Radiation Physics
Department, Liden found several Norwegians whose bodies contained
quantities of cesium-137 several times higher than previously recorded.
He substantiated these data by counting 15 additional Norwegians from
Oslo and 6 from Bergen. The Oslo residents averaged 21 nanocuries
(abbreviated nc) of cesium-137 and the Bergen group 60 nc. Swedes
averaged only 8 nc. (A nanocurie is one billionth of a curie, the
standard unit of radioactivity.)
Curiosity regarding these high values in the Norwegians led him to
investigate goat cheese, which Norwegians consume in larger quantities
than Swedes. Goat cheese at that time showed a high cesium-137 content
of 41 nc per kilogram. In northern Norway, near Bergen, another main
food is reindeer meat, which was found to contain 28 nc of cesium-137
per kilogram, compared to 0.1 nc per kilogram in beef. These factors
indicated that goat cheese and reindeer meat were responsible for the
high cesium-137 count in the Norwegians.
Investigation of the soil in northern Norway revealed that it averaged
20 nc of cesium-137 per square meter. Only thin covers of lichens grow
in this region, and reindeer must graze over large areas to obtain
sufficient food. It was obvious that cesium-137 from fallout was
collecting on lichens and then was being concentrated in the bodies of
the reindeer before they were killed for meat.
Similar studies have been conducted by scientists of the Pacific
Northwest Laboratory at Richland, Washington, who since 1959 have been
measuring radioactivity of plants and animals in Alaska. When they found
high levels of cesium-137 in lichens and caribou, they became interested
in the body burdens of fallout isotopes in the Eskimos.
A portable crystal type of whole body counter was used to measure the
cesium-137 content of Eskimos at five villages. The Eskimos cooperated
willingly; in some communities nearly everyone accepted the invitation
to be counted. This table presents the results:
Cesium-137 (in nanocuries)
Village Number of Minimum Maximum Average
subjects
Diomede 12 8 35 22
Barrow 259 8 166 51
Point Hope 107 3 119 17
Kotzebue 132 17 518 138
Anaktuvuk 52 83 719 421
(For comparison, the average body burden of cesium-137 of residents of
Richland, Washington, during this period was between 5 and 7
nanocuries.)
These data show that the Eskimos who lived inland at Anaktuvuk and ate
heavily of caribou meat carried cesium-137 burdens up to 20 times
greater than Eskimos who lived in the four villages along the coast and
had more variety in their food. (See pages 18 and 19 for photo story of
a similar project in Finland.)