HEALTH ALERT From the
Radioactive Polonium in Food and Water
Radon and radon decendants are naturally present in the earth and concentrated in fertilizer(1). This discussion focuses on Polonium 210 because it emits a particularly energetic(2) ionizing alpha radiation which is more hazardous when received internally(3). Although external exposure to alpha radiation is usually not dangerous, continuous external exposure to radiation from chemical fertilizer may cause skin cancer(4).
Research has shown that tobacco can absorb Po210. Similarly, many plants we commonly use for food can absorb polonium and other radon progeny(5). The widespread use of radioactive phosphate fertilizer may be increasing levels of radioactive polonium in animal feeds as well(6). In Europe, the majority of polonium in the average diet is sourced in grains, vegetables, and meat(7). In the United States, where chemical fertilizer use is more prevalent, the Florida Institute of Phosphate Research reports that polonium in American dairy and meat products expose human organs to radiation levels equivalent to tobacco use(8). Small amounts of polonium can even be found in fluoridated drinking water(9) which, in addition to normally present radionuclides, may be influenced by farm irrigation and run off(10).
Polonium from tobacco smoke is carried by the blood and accumulates in the liver, kidneys, bone marrow, and blood vessel walls(11). If fertilizer sourced polonium in food is distributed around the body in the same way, then much of the food we eat causes internal ionizing alpha radiation. In order to estimate the full measure of radiation in the diet, we must consider the radioactivity of all radon daughters(12) both naturally present and those added by fertilizer. There is a large variance in the estimates of polonium content in american polonium intake(13).
Food borne radon daughters may or may not be absorbed/distributed as efficiently as polonium in tobacco smoke. However, as seen in the above European diet example, food can deliver internal radiation exposure beyond the limits considered safe for external occupational exposure(14). It is not clear how much radioactive content fertilizer contributes to food and how much is naturally present.
Radon gas occurs naturally in most places on the planet. Exposure to naturally occuring radiation is unavoidable and relatively harmless(15). The needless additional radiation delivered via fertilizer can be reduced through the use of alternative phosphate sources or organic farming techniques.
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"Fertilizers made from phosphate rocks contain higher
amounts of uranium than natural soils..."
"Polonium-210, a decay product of bismuth-210, has a half-life of 138 days and gives off intense alpha radiation as it decays into regular lead and becomes stable. Any polonium-210 that might be present in the phosphate concentrate could pose a significant health threat. A very small amount of polonium-210 can be very dangerous, giving off 5,000 times more alpha radiation than the same amount of radium. As little as 0.03 microcuries (6.8 trillionths of a gram) of polonium-210 can be carcinogenic to humans.
"The three main types of radiation, alpha, beta, and gamma have different penetrating abilities. Alpha radiation to external skin is no hazard because it is likely that the outer (dead) layer of the skin stops all alpha radiation. But if alpha radiation is received internally than the damage to the surrounding tissue is expected to be 20 times more harmful than the expected damages from beta or gamma radiation."
4. Department of General Biology, Universidade Federal Fluminense, Niteroi, Brazil.
Human occupational radioactive contamination from the use of phosphated fertilizers.
Science of the Total Environment. 162(1):19-22, 1995 Jan 20.
210Po and 210Pb concentrations in urine, hair and skin smear samples from individuals using phosphated fertilizers have been compared with a control group of occupationally unexposed individuals. Urine and hair samples of the test group showed slightly higher concentrations of 210Po and 210Pb than those observed for the control group. These concentrations remained, however, lower than those for uranium mine workers. Skin smear values indicated contamination by direct contact with dust from fertilizers and this may contribute to skin cancer induction in this risk population.
"Many food products, especially nuts, fruits, and leafy plants (e.g. tobacco) concentrate these radionuclides by extracting them from the surrounding soil."
Watters RL. Hansen WR. The hazards implication of the transfer of unsupported 210 Po from alkaline soil to plants. [Journal Article] Health Physics. 18(4):409-13, 1970 Apr.
6. Radiation Safety Department, Soreq Nuclear Research Center, Yavne, Israel.
Concentrations of U and Po in animal feed supplements, in poultry meat and in eggs.
Health Physics. 56(3):315-9, 1989 Mar.
The present study was undertaken to assess the contribution of phosphate feed supplements to the radiation exposure of the population in Israel. The phosphates usually contain appreciable quantities of U and its daughters and the actual exposure of human consumers depends, to a very large extent, on the degree of equilibrium of the decay chain in the feed and through the metabolic process. The concentrations of 238U, 234U, 226Ra and 210Po (210Pb) in poultry feed supplements and in chicken meat (breasts, thighs) and organs (livers, spleens, gizzards) as well as in eggs were determined. From the results, the transfer coefficients of U and Po in chicken meat and in eggs were calculated. The effective dose equivalent to the Israeli population due to the consumption of poultry products which accounts for approximately 70% of all meat consumed in Israel is assessed to be 0.04 mSv y-1.
7. Measurement of natural radionuclides in U.K. diet.
Science of the Total Environment. 35(3):431-40, 1984 May 1.
The levels of radium-226, lead-210 and polonium-210 in the U.K. diet have been determined. The important food groups contributing to the intake of these radionuclides have been identified. Seventy-five percent of the daily intake of radium-226 is derived from beverages, cereals, other vegetables, bread, sugars and preserves. Seventy-five percent of the intake of lead-210 and polonium-210 is derived from bread, milk, cereals, beverages, other vegetables, sugars and preserves, and meat products. The average daily intakes of these radionuclides are tentatively calculated to be 30 mBq for radium-226 and 82 mBq for both lead-210 and polonium-210. These levels are compared with data from other countries. The annual effective dose equivalents resulting from the intakes are approximately 3 muSv for radium-226 and 54 muSv from lead-210 and polonium-210 together. The differences between these doses and other current estimates are discussed.
Department of Radiation Hygiene, Central Laboratory for Radiological Protection, Warsaw, Poland.
Intake of 226Ra, 210Pb and 210Po with food in Poland.
Science of the Total Environment. 203(2):157-65, 1997 Sep 6.
Intake with food and water of 226Ra, 210Pb and 210Po was determined for an adult population in regions of central, northern and northeastern Poland. The content of radionuclides was determined in the daily diet and, in the central region, also in foodstuffs and drinking water. The annual intake with foodstuffs was estimated on the basis of their average annual consumption. The 226Ra intake in northeastern Poland was approximately 17% higher than the overall average, correlating well with the higher concentration of this radionuclide in the soil. The 210Po/210Pb ratio was close to unity in the continental regions, whereas at the Baltic Sea coast it was approximately 1.5. The latter value can be ascribed to a larger consumption of fish for which the 210Po/210Pb ratio was found to be approximately 10. In central Poland the largest intake of 226Ra was with flour and vegetables (contribution approx. 60%), the largest intake of 210Pb was with flour and meat (approx. 50%) and the largest intake of 210Po was with fish (approx. 34%). From the intake and dose coefficient, annual effective doses were calculated. The dose from 210Pb and 210Po was approx. 54 mu Sv year-1, and the dose from 226Ra was approx. 4 mu Sv year-1.
The origin and magnitude of inhalation exposure and dose from tobacco products was also assessed. For the majority of internal organs evaluated, the dose resulting from smoking commercially available tobacco products is comparable to or greater than the dose estimates for ingestion of naturally occurring dietary Pb-210 and Po-210 (in meat and dairy products).
"The lead isotope behaves like calcium in the body. It may be stored in the bones for years before turning into polonium-210 and triggering a carcinogenic release of alpha radiation.
Drinking water fluoridated with fluorosilicic acid contains radon at every sequence of its decay to polonium. The fresher the pollution concentrate, the more polonium it will contain."
"Fertilizers made from phosphate rocks contain higher
amounts of uranium than natural soils, and highly
fertilized areas of the midwest (Mississippi River) tend
to contain more dissolved uranium (especially during
spring runoff) than other areas of the Missippi River
The levels of uranium in surface water and groundwater
have been measured more frequently than its
concentrations in drinking water. In general, the levels
of uranium in groundwater are higher than in surface
11. E. A. Martell, "Tobacco Radioactivity and Cancer in Smokers," 63 American Scientist 404-412 (July-August 1975).
"Because 210Pb has a radioactive half-life of 22 years, the body burden of the radioactive 210 Pb and its radioactive daughter products — 210Bi (bismuth-210) and 210Po — can continue to build up throughout the period of smoking . . . In addition, insoluble dust- particle accumulations in the lung and lymph nodes may ulcerate into adjoining blood vessels and be carried elsewhere in via the blood circulation. Thus long-term exposure to insoluble particles of respirable size leads to their accumulation in the lung. Lymph nodes, liver, bone marrow, and elsewhere," p 404.
"Alpha-emitting particles in bone marrow may destroy many of the rapidly multiplying cells that produce the blood platelets which assist in the control of blood clotting. . . . In addition, the gradual increase in alpha radiation-induced chromosomal structural changes may be expected to contribute to the whole pattern of degenerative diseases of the cardiovascular and renal system," p 408.
"Irradiation of endothelial cells of the artery wall has been shown to render them highly permeable to the passage of red cells, lymphocytes, small particles, lipids, cholesterol, etc., allowing their exchange between the blood and the intima of the artery wall. In addition, irradiation of arterial tissue results in morphologic changes, including radionecrosis and inflamation of the surrounding endothelial cells, radiation damage to red cells, and possible degeneration of lipids due to breakdown of red cells," p 410.
"Exposures to radionuclides may be internal
or external, and effects are caused by energetic particles or rays released as part of the decay of atoms. Decay
energies of particles or rays emitted by each radionuclide must be accounted for. Unlike chemical exposures
where effects of chemicals are generally evaluated individually, the internal and external doses from all
radionuclides present must be summed to arrive at the appropriate exposure dose for a given organism. In
addition, a number of radionuclides have daughter products that must also be included in the exposure
calculations. Internal exposures result from ingestion of contaminated food, soil, or water or inhalation of
contaminated soil or dust."
"For example, one extrapolated statistic about phosphoric acid production that perpetuates throughout the analysis is that about 80% of the Ra-226 in the original phosphate rock goes into the phosphogypsum wastes while about 86% of the uranium and 70% of the thorium remain in the phosphoric acid (and presumabley about 20% of the Ra-226)."
Table C-1 Comparison of food uptake factors (kg/yr) from various sources
Element NORM RESRAD* NCRP Miller*
Ac 0.18 0.61 0.20 0.49
K 113.00 --- 230.00 --
Pa 0.25 0.61 2.0 0.49
Pb 0.013 11.00 1.0 0.80
Po 0.013 1.5 0.99 0.059
Ra 0.013 0.27 9.2 2.7
Th 0.013 0.92 0.21 0.068
U 0.022 0.65 0.69 0.064
* Modified to include the effects of soil uptake from grazing cattle
"Any dose of radiation, no matter how small, is assumed to involve a possibility of risk to human health, but at doses below 50 millisieverts per year the risks are so small the effects are not measurable and may be negligible."
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