Summary
The Polonio 210 (Po-210), with half life of about 138,38 days, it is one of the most powerful carcinogenic agent among those presents in the smoke of tobacco. Various studies point out, as principal source of Po-210, the fertilizer used in the plant of tobacco, represented by the poliphsphatis rich in radio (Ra-226) from which emanates the radon (Rn-222) that in air it decays to lead-210 (Pb-210) and partly to Po-210.
Through the tricomis the Pb-210 is assembled in the leaf of tobacco where it turns it into Po-210 that, to the temperature of combustion of the cigarette (800°-900°C), it passes to the gaseous state, mainly absorbied on the micro particles freed by the combustion.
The smoke, so become radioactive, in its gaseous and particled component, it reaches the level of the respiratory apparatus, particularly on the spurs of the tracheo bronchial tree. In this center in way both as single as sinergistic with the other carcinogens, will expound, with the time and particularly in patient with very compromised mucous-ciliary clearance, its carcinogenic power. Various studies confirm that the biological risk of the Po-210 in a smoker of 20 sigarette/dies for one year is equal to that of 300 radiographies of the chest, with an autonomous oncogenic ability of 4 pulmonary tumors on 10.000 smokers. During the combustion parts of the Po-210 it disperses in the surrounding environment and so it also finds again it in the passive smoke.

 

 

Introduction
That the smoke of tobacco it is dangerous to the health it is an already documented fact since the years '50th.
Nevertheless they are still there in the world 1,2 billion smokers, with a tobacco epidemic, as the OMS calls /it, of 4,2 million deaths for smoke-correlated pathologies (1). A trend that if it will keep on persisting and it will bring to a smoke massacre of 10 million death in 2030(2). The pathologies smoke correlated are represented above all by cancer of the lung, esophagus and pancreas, cardiovascular pathologies, BPCO, pneumonias, sudden death in crib, premature delivery and death from smoke fire of tabacco.(3)
The cancer of the lung, kills alone more than 1 million people in the world ( 4) and the smoke of tobacco, is the most greater cause of cancer of the lung.
Nevertheless 1,200 million people in the world, 47 million U.S. citizens (25% )6 and 12,2 million Italians (24,3%) continue to smoke.(7,8)
If it is true that the carcinogeneticis mechanism of the smoke of tobacco are not still completely well understood (9) is indeed true that few smokers and not smokers know what, respectively inhale, and breathe.
The smoke of tobacco is a mixture composed by a phase of fine particles (5%) and a gaseous phase (95%). The petrol part constitutes the phase total particulated without water or nicotine.
There are 0,3-3,3 million particles for ml of smoke of cigarette and over 4.000 components,(10) inclusive 55 known carcinogens, with "sufficient evidence for carcinogenicity"according to the International Agency for Research on Cancer (IARC) .(11)
Not everybody perhaps knows that among the carcinogenic known as specific presents in the smoke of tobacco, besides the already known polociclic Aromatic Hydrocarbons to the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 2-naftilammina, 4-amminobifenile, arsenic and chrome, there is one of it that few know and that his despite it has recently had the honor of the chronicles with the spy story Litvinenko: the Polonio 210 (Po-210).
In effects up to few months ago, the Polonio was an unknown element to the more. Probably someone a character of the Amleto of Shakespeare thought only it.This unknown element to the more, discovered in 1898 from Marie and Pierre Curie and baptized Polonio as the earth native of the lady Curie-Sklodowska,is now object of curiosity of the media and of the physician-scientific comunity. For the discovery of radio and polonio Madams Curie it won the Nobel for the Chemistry in 1911.

 

 

Chemistry
The Polonio 210, called also "radio F", it was discovered from the consorts Curie while they looked for the source of the radioactivity of the pitchblende told, in in general sense, also uraninite, whose champions kept on also manifesting radioactivity after having been purified from the radio and from the uranium that they contained.(12).
To have an idea of the dimensions of the job that they performed at the end of 1800 to extract and to characterize this new element, is enough to think whether to get around 0,1 mgs of Polonio a ton of uraninite or pitchblende is needed. It is found in nature, in the rocks containing pitchblende.
The Polonio, under standard conditions, it is a radioactive metal of color silver. It is present in nature in the pitchblende, but in way so diluted that it is not convenient to try its extraction for which the most stable isotope, the Po-210, that has an halflife of 138,38 days, is produced in the laboratory for neutrin bombardment of Bi-209. Important layers of pitchblende are found in Canada, USA, Rep. Dem. of Congo (ex Zaire), Rep. Of South Africa. The Polonio is present in the periodic table of Mendeleev with atomic number 84 and molecular weight 210. Of Polonio exist - 25 isotopes are all radioactive and very dangerous ones, but the Po-210 is the most dangerous among the various existing types.

 

 

Toxicity
The polonio is a toxic element, highly radioactive and dangerous to manipulate, even in quantitative of the order of the milligram or less. The radiations alpha, constituted by nucleuses of helium-4 (He-4), have an elevated ionizing power and, accordingly they are particularly harmful, when they come into contact with the living tissue. The tolerable maximum limit of radioactivity from polonio is 1100 Bqs (0,03 µCis), a quantity corresponding to that produced by 6,8 miliardesimis of milligram of Polonio.(13)
0,1 mg of this metalloid sends forth the same number of particles alpha of 5 grams of radio. A powerful killer. The effect on the man is terrible therefore: he dies, obviously, consequently of the radioactivity, in how much a mechanism is baited for which the cells go in necrosis, "as you burn." It happens, , a massive effect that the organism is not able to face, because it is not able of "to replace" in brief times the great quantity of cells "burned" and gone to necrosis.( 13 )

Principal modalities of use
The uses of the Po-210 are extremely limited both for its elevated issue of radioactivity alpha both for the difficulties to extract it in nature and in the laboratory.
The main use are principally: to) as source of neutrons when it is mixed in league with berillium. b) as source of energy for satellites and in other spatial devices. c) in the anti-static devices of some tools of precision and in special brushes that eliminate the dust accumulated on the negative photographic.
The polonio in these brushes is sealed and screened so that to minimize the risks from radiations. d) In devices to eliminate the electrostatic position in the manufacture of cloths, but it has been replaced from rising of rays beta, more easily available and less dangerous.(13 )

 

From the earth to the tobacco
The Po-210 is also a present alpha-issuing radionuclide in traces in a lot of plants and foods - that then we find again in the human tissue(14).
The most greater source of support of natural Po-210 it is represented by the food. Data of Spencer et co. point out that the 77,3% of the daily suppor tof of Po-210 of an adult male originates from the foods, 4,7% from the water and 0,6% from the air.
The inhalation of smoke of cigarette brings more Po-210 (17,1%) of that present in the water is drunk and in the air toghether.(15)
The discovery of the presence of the Po-210 in the smoke of tobacco goes back to the first years '60 thanks to Turner and Radley in 1960, Marsden and Collins in 1963 and Radford and Hunt in 1964 (16), when the scientists individualized the presence of radioactivity alpha in the tobacco.
The Polonio (Po-210) and its precursor, the Lead (Pb-210), present in the plants of tobacco it can have origins (17). It is believed that the Po-210 can be absorbed from the plant of the tobacco, through way variedly combined between them:
1) directly from grounds containing Uranium through the roots(18, 19, 20 )
2) for deposition on the leaves, through meteorological events, of rain, snow and atmospheric dust. In fact the Radon-222, derived by the chain of decadence of the U-238, being a noble gas, it is volatile for which escapes, partly, from the ground and it passes in the atmosphere, where it decays in turn with formation of Lead-210 and, partly, of Polonio-210.
These absorbed by the atmospheric dust form the particles of Aitken that are deposited then on the leaves of the plants accumulating in the tricomis through a diffusive brownian deposition , with the consequent growth in the time of the consequential Polonio-210 from the decadence of the Lead-210.(21), (22) Skwarzecs et co. point out this way as the principal source of Po-210 in the plants of tabacco (19) in contrast with big part of the authors, and particularly Singh and Nilekani, that have underlined the importance of the used fertilizers. (24)
3) from fertilizers constituted by calcium poliphoshates coming from the ground with presence of Pitchblende and Apatite, that contain Uranium and its products of fell down,(18), (23) have enriched accordingly in radio, chemically similar to the calcium. Various studies have not by chance shown ,that the Indian cigarettes, done with tobacco poorly manured, as from poor agriculture, are approximately from 6 to 15 less radioactive times of those of USA (24), built with cultivated tobaccos as intensive agriculture and highly fertilized..
The plant of tobacco has the characteristic to be endowed with numerous tricomis, a kind of filamentous pore, that are big concentrators of Pb-210 and Po-210.
Fleisher and Parungo have experimentally confirmed that the products of decadence of the radon and the Pb210 are strongly assembled in the tricomis of the leaves (22).
The mechanisms of accumulation of the Pb-210 in the tricomis of the tobacco it has been discussed and studied by Martell and Poet.(25 26)


From the tobacco to the lung
The trip toward the respiratory apparatus of the Po-210 and the Pb-210 begins with the lighting of the cigarette, in the stove of combustion where, the tobacco, in phase of aspiration burns to around 800-900° C. it forms so the smoke of tobacco that is a melange composed by a phase of particles (5%) and a gaseous phase (95%) .10 Considering the different temperatures of ebullition for Po-210 (962° Cs) and Pb210 (1740° Cs), in the gaseous phase it is present, among the other substances, also the Po-210 that partly it is eliminated in the external environment and partly it comes "to make body" with the phase particled, that will contain, besides the Po-210, also an elevated presence of insoluble particles of Pb-210, weak issuing alpha (<1/100.000) range, beta and issuing X and precursor of the Po-210.
All these inhaled particles are deposited in the respiratory apparatus and particularly, because of the ciliary action, to level of the bifurcations of the segmental bronchi.
Measurements performed by Cohen et co. on the summary of cigarette, have also shown the presence of Radium and Torio, lock staying that the 99% of the radioactivity originate from the Po-21023 that, once inhaled it is held in the respiratory apparatus (27)
All these particles will have a different destiny according to the efficiency of the Clearance of the ciliary secretions This mechanical purification progressively is missed in the smokers with BPCO.
This involves a stasis of the radioactive load (28) that partly, through the pulmonary and systemic circle, it reaches various organs and tissue causing in the mutation of the genetic cellular structure, deviation of the cellular characteristics from the optimal standard, accelerated aging and died more rapid to work of a wide spectrum of pathologies (29, 30). The levels of Po-210 are in fact meaningfully superior, of 30% in the blood and of 6 times in the urines, in the smokers in comparison to the not smokers.(16, 31) The raise of the concentrations of Polonio in the lung of the strong smokers can be explained above all through the accumulation of insoluble particles of Lead-210 that then in the time it decays to Polonio-21021, because of a more and more progressive deceleration of the Clearance of the ciliary secretions.
More it increases the degree of BPCO, more it increases the risk of accumulation of the radioactive load (28).
The dose-radiations brought by the local concentrations of Polonio on the wall of the bronchial epithelium, depend on the fraction of particles accumulated in these areas and from their time of permanence.
Holzman (17) in his researches has shown that the concentrations of Pb-210 are greater in the skeleton and in the bellows of the smokers in comparison to that of the not smokers. Insofar considering that the Polonio has a T ½ of 138, 38 days and the Lead, than that in Polonio, of 22 years, it derives of it that a meaningful risk of cancer (49, 50) can be attributed to a chronic lower part exposure to the level of insoluble particles issuing alphas that are responsible of very elevated local doses in small areas of tissue, above all of the bifurcations (hot spots) .(21). all of this is often facilitated in presence of an alteration of the present Clearance in the smokers because of the chronic bronchitis, in which, as has shown Auerbach, they are present metaplasic lesions of the ciliary epithelium in the 100% of the strong smokers( 32). The Po-210, present in the insoluble particles, it becomes through the zones changed or poorly ciliate where mostly stagnates the secretions.(16, 33) are not a case the recent observation that the patients with severe BPCO, smokers and ex smokers, have a greater incidence of lung cancer.(28 )

Quantity of Po-210 in the smoke of tobacco
The degree of radioactivity alpha from Po-210 in the smoke of tobacco it is related to numerous variable: the geographical region where tobacco grows, times and ways of conservation of the tobacco, presence or absence of the one filter, greatness and composition of the filter and way of smoke.(50).
The risk to the smoke of cigarettes it is due not only to the quantity and quality of the carcinogenis, but also to the scarce efficiency of the filters used that it doesn't adequately reduce the quantity of the present carcinogenis in the smoke of tobacco.
The middle efficiency of the communes filters of cigarette used in commerce it reduces the activity of the Po-210 of around 4,6% of the Po-210 contained in the tobacco of cigarette.(52) The use of filters of resin minimizes even more the exposure of the bellows of the smokers to the alphas radiation.53 Radford and Hunt 16 in 1964,
Mussealo-Rauhammaa and Jaakkola 54 in 1985 have found 6.5-22% of Po-210 in the primary tide of the smoke of cigarette. Other Authors have brought different percentages appraised in a range of 3.7-58%.(55) In average, according to Parfenov, approximately the 50% of the Po-210 foresee in the tobacco of cigarette moves to the smoke, 35% remain in the stub and around 15% it finds again in the ash.(58)
From some years, together with the professor Enrico Gattavecchia of the Department of Chemical Sciences, Radiochimiche and Metallurgical science of the university in Bologna, in collaboration with the ENEA and with the Italian Society of Tabaccologia-SITAB, we are effecting some studies on the radioactivity alpha from Polonio 210 in the smoke of tobacco.
In our researches we have found that the smoke of a manufactured cigarette with western tobacco contains a radioactivity alpha from Po-210 of around 75 mBqs, variedly distributed among active smoke, passive smoke and ash: smoke active (mainstream) 5 mBqs (6,7%), passive smoke (sidestream) 1,2 mBqs (1,6%), (ash 68,8 mBqs (91,7%) .(43, 56, 57)

 

 

Cancerogenity of the Po-210 in the smoke of tobacco
Martell esteems that the cumulative dose of radiations alpha to level of the bronchial bifurcations of the smoker that dies of pulmonary cancer is of around 80 rads (1.600 rems), that is the enough dose to induce malignant transformation from interactions alpha with the basalcells (34, 35).
Various experimental studies have shown the induction of tumors in experiment animals after inhalations of Po-21036.
According to clinical and experimental observations of Marmorstein,(37)the toning of istotyp of pulmonary tumor that is observed in the last 40 years is due to the radioactivity tobacco's smoke alpha sustained by the use and abuse of fertilizing poliphosphatic.
The useless one as harmful radioactive component communicated by the fertilizers could be reduced through an alternative use of the sources of poliphosphate as the animal fertilizing phosphaticis (38)or with a treatment of the same mineral poliphosphatis (ammonium phosphate to the place of calciophosphato) (38) and/or with different techniques of storing and/or passing to genetic modifications of the plants of tobacco with meaningful reduction of the concentration of tricomis on the leaves of tobacco .
A study has shown that the concentration of radioactivity from Po-210 in the tobacco increases with the time in phase of storing, after having been picked up (39).
A profit and opportune recommendation of the researchers it is that to still pick up the green tobacco and to avoid prolonged storing in the siloses to avoid the increase of the concentrations of Po-210 that happens for slow decadence of the Pb-210.
Applying to the values from us found the data 199040 ENEA around the real middle time of permanence in the bellows for the Po-210, that is of 53 days, the data of the Committee 198841 BEIR IV on the risk lung cancer subsequently to exposure to radom and its products of decadence (Pb-210 and Po-210), the correct data and esteemed by the ICRP42 in base to the survivors to the bomb Á., a risk results "pure" of tumor to the lung equal to 4 xes 10-4 year-1 (4 cases on 10.000 smokers a year equal to 4.480 on an Italian population of 12.200.000 smokers), without counting the role of promoter (co-carcinogen) in the bronchial and lung tumor for a general sinergic action with the other carcinogenic substances, around 55 notes, present in the smoke of tobacco. To understand the biological damage that can be caused by the Po-210 foresees in the smoke of tobacco, that has been compared to from X rays used in the common radiographies of the chest.
To have a relationship with this common source of radiations, is considered that a modern radiography to the chest involves an equal equivalent dose 0,034 mSv/radiography,48s for which, in practice, a smoker of 20 siggs. / die, in 1 year it receives a dose of equivalent radiations to around 300 radiographies to the torace.(43, 44)
However what determines the upsurge of the risk of cancer, it is not so much the single action and not even the summation of the radioactivity alpha to the policiclic hydrocarbons , to the other carcinogens and the free radicals (produced for pyrolysis and for damage by radiations alpha), how much the sinergic action and moltiplication of the single carcinogetic component and co-carcinogenetic cmponent(44, 45, 46, 47)
The presence of Po-210 in the smoke of tobacco doesn't obviously determine an acute contamination from radiations alpha on the contrary a contamination type chronic, slow and progressive that, in the smoker, it becomes more and more important and dangerous with the time. A contamination that is that it interests all the smokers , 1,3 Billion people.

Conclusions
About the presence of radioactive alpha in the smoke of tobacco the multinationals of the tobacco perfectly knew since the years '60, but have strategically maintained an iron mute to the whole problem.
Going to snoop among the over 37 million documents now available and made pubblic on the site public www.pmdocs.com, for a sentence of the State of the Minnesota against Phillip Morris (PM), 462 confidential document-memorandums are found on the radioactivity alpha from Po-210 of the smoke of tobacco (present documents to the whole 14 March 2007).
One of these, dated 1980, it reveals, for example, that the PM knew already that the cigarettes contained Lead and radioactive Polonio and that this was due to a large extent to the used fertilizers, in particular to the phosphates of calcium, in the cultivation of the tobacco.
The producers of cigarettes were besides, perfectly to knowledge of the studies of Martell et co. on the possibility to be able to reduce the levels of radioactivity of the tobacco and the smoke, reducing that some fertilizers through the transformation of the calcium phosphate in ammonium phosphate… "a procedure however too much expensive" (Newscript: Radioactive cigarettes, PM, Apr 2,1980, doc. 2012611337/1138).
Instead
The great majority of the public opinion still ignores the presence of radioactivity from Polonio 210 in the smoke of tobacco that represents a serious threat for the public health, but it can also represent a great opportunity from the communicative and motivational point of view.
It would be therefore opportune to add a new notice on the packets of cigarettes: "they represent a source of radiations exposure alpha". And seen the fear of the opinion public toward all of this it is obvious that a campaign of suitable information on radioactivity in the smoke it could contribute to accelerate the motivational run of the smoker and to meaningfully increase the effectiveness of the anti smoke programs .51