250
Trace Elements in Abiotic and Biotic Environments
34.3 WATERS
The median Po concentration in ocean waters is roughly estimated to be 1  fg/L
(Reimann and Caritat 1988). It may be accumulated by some aquatic biota, as well
as in phytobenthos.
The mean concentration of 210 Po in drinking water in Poland, in 1998, was
0.48 mBq/L, and its annual intake per person was calculated as 0.24 Bq (Skwarzec
et al. 2001). Guidance level of 210 Po in drinking water is 0.1 Bq/L (WHO 2011a).
34.4 PLANTS
The radioactivity of 210 Po in terrestrial plants is within the range of 8–12  Bq/kg.
However, 210 Po activity in plants from the area of U deposits in India is relatively low and varies from 0.02 to 6.69 Bq/kg (Marbaniang et al. vide KabataPendias 2011).
Radioactive 210 Po contained in phosphate fertilizers is absorbed by the roots of
plants and stored in its tissues. Phosphate fertilizers are considered to be the main
source of this radionuclide. However, 210 Po, as a very volatile element, is emitted from the soil surface and absorbed by broad leaves of plants. Increased 210 Po
levels in large leaves of tobacco suggest that its source is also the atmospheric
deposition. Its maximum allowable concentration in air is estimated to be about
10 11 μCi/cm 3 .
Polonium has been found in tobacco leaves, especially from plants grown on
soils with phosphate fertilizers. The presence of radioactive Po in tobacco smoke
has been known since the early 1960s, but this information was not spread. Tobacco
plants fertilized by phosphates contain 210 Po, which emits alpha radiation, which is
estimated to cause about 11,700 lung cancer deaths annually worldwide. Its mean
activity in cigarette tobacco of various countries is estimated to be 15.1  mBq per
cigarette. Cigarettes produced in Poland have 210 Po radiation within the range of
4.23–24.12 mBq per cigarette (Skwarzec et al. vide Kabata-Pendias 2011).
The range of 210 Po radioactivity in mushrooms varies from 20.1 to 76.5 in caps
and from 9.9 to 47.9 Bq/kg in stipes. It is higher in Boletus edulis than in other wild
mushrooms (Skwarzec and Jakusik vide Kabata-Pendias 2011).
34.5 HUMANS
Polonium can enter the human body via two principle ways: ingestion and inhalation
of radon gas originated from 238 U. The main route of 210 Po intake in the human body
is ingestion with foodstuffs. The absorption coefficient of 210 Po into the blood from
the digestive tract was estimated to be 35%. The highest concentration of 210 Po in the
body was observed in the skeleton and hair. The body burden of humans is 513 pCi
of 210 Po. Excretion of these radionuclides from the body in urine is 14–15 times less
than in feces. The calculated annual radiation doses of 710 Po in the bones, liver, and
kidneys were 2.1–5.0 mrad/yr, and in other soft tissues, 0.3–0.9 mrad/yr (Ladinskaya
et al. 1973).