mercredi 30 juillet 2014

210Pb: friend or foe? - The case of the undercover isotope

Part I

mardi 3 juillet 2012

Les cancers du fumeur sont-ils radio-induits ?

http://perline.org/nucleaire-6/le-nucleaire-dans-tous-ses-etats/article/les-cancers-du-fumeur-sont-ils

Les cancers du fumeur sont-ils radio-induits ?

Paru dans Silence, n° 161, en janvier 1993, puis dans le hors série - faibles doses de radiations

Août 2008 2008

par Perline

Tous les ans, en France le tabac cause 70 000 décès (Pr Tubiana 24-26/01/1980). C’est l’un des arguments utilisés par les nucléocrates pour montrer l’innocuité du nucléaire.

Officiellement les grands accusés du cancer du poumon, très rarement guérissable, dû au tabac, sont le goudron et la nicotine. Pourtant on a très tôt constaté [1] que le nombre de cancers du poumon était bien supérieur chez les fumeurs de plus d’un paquet de cigarettes faiblement dosées en ces deux composants que chez ceux fumant moins d’un paquet de cigarettes normales. On s’est donc demandé si le cancer du poumon ne serait pas plutôt dû aux radiations alpha de ses composants radioactifs, le plomb 210 (²¹⁰Pb) et le polonium 210 (²¹⁰Po), présents dans tous les types de tabac [2].
On sait que le ²¹⁰Pb se transforme en émettant des radiations bêta, en ²¹⁰Po, émetteur de radiations alpha, extrêmement destructrices à très courte distance. Chez les fumeurs l’action ciliaire de nettoyage des bronches est ralentie, provoquant une accumulation des particules radioactives aux bifurcations des segments bronchiaux [3] [2]. Des études en laboratoire sur une race de hamsters qui n’a jamais de cancer du poumon naturellement [4], ont montré l’évidence du lien entre l’inhalation du ²¹⁰Po et ce cancer.
Pour le fumeur d’1 paquet 1/2 par jour, les « points chauds » que sont les bifurcations des bronches reçoivent 8 rem par an, l’équivalent de ce que recevrait la peau avec 300 radios du torse durant cette période [3]. Des autopsies de morts de cancer du poumon [5] ont montré que ces points chauds avaient accumulé, pendant la quarantaine d’années de leur vie de fumeur, une dose de 1600 rem. Même si la dose totale reçue par les poumons est faible, certains points sont donc victimes de très fortes doses provoquant des dégâts considérables dans les cellules.
Les radiations alpha que le fumeur reçoit aux bifurcations des bronches non seulement proviennent du ²¹⁰Po contenu dans la fumée de cigarette qu’il aspire et du ²¹⁰Po qui naît du ²¹⁰Pb déposé aux bifurcations, mais encore des descendants du radon, inhalés entre les cigarettes [5].
De plus, la circulation de ces produits, que l’on retrouve dans le sang et l’urine des fumeurs, provoque un vieillissement et une mort précoce dus non seulement à d’autres cancers, mais également à de nombreuses maladies aussi diverses que l’emphysème ou la cirrhose du foie [6].

Les fumeurs passifs

50 à 75% du polonium et du plomb radioactifs de la cigarette, volatiles, restent dans la volute de fumée, et peuvent être réabsorbés par les poumons des personnes présentes [3] [7] [8]. De plus, les descendants du radon, présents dans les maisons, s’accrochent aux particules de fumée, augmentant ainsi la dose inhalée [8], tant pour les fumeurs actifs que passifs. Des chercheurs ont estimé que l’exposition aux descendants du radon intervient pour 20 à 100% des cancers du poumon des non-fumeurs [2]. Une étude japonaise qui a duré 14 ans [9] a démontré que les fumeurs passifs ont un risque doublé d’avoir un cancer du poumon par rapport aux non-fumeurs. D’autres chercheurs ont trouvé de très hautes concentrations de ces produits dans les poumons de non-fumeurs morts de cancer du poumon [10]. Ils soupçonnent très fortement ces « non-fumeurs » d’avoir été, en réalité, des fumeurs passifs.

D’où viennent les produits radioactifs du tabac ?

Les phosphates, utilisés pour la fabrication d’engrais, sont très concentrés en uranium. Parmi les descendants de celui-ci, le radon, gazeux, est libéré. Plus généralement, les produits radioactifs sont absorbés par les plantes. Si des produits phosphatés sont donnés aux animaux, ce qui est très courant, les vaches laitières, par exemple, pourront fournir du lait au radium (UNSCEAR 88).
Même s’il est vrai que tous les sols contiennent du radium et ses descendants, on trouve surtout le ²¹⁰Pb et le ²¹⁰Po dans les fertilisants utilisés dans la culture du tabac [3] [2]. Bien sûr, ces produits sont absorbés par les racines.
Mais le principal mode d’absorption du ²¹⁰Pb par le tabac est différent. Les feuilles possèdent de très fins petits poils appelés trichomes. Les descendants du radium chargés électriquement s’accrochent aux particules de poussières de moins de 0,1 millionnième de millimètre, se déposent sur les feuilles et restent accrochées aux trichomes où ils se concentrent [2]. Aucun des procédés actuellement utilisés dans le traitement du tabac ne les élimine. Pourtant, le ²¹⁰Po et le ²¹⁰Pb ne contribuent en rien au goût et ne seraient pas difficiles à éliminer [4]. Des solutions, autres que de ne pas promouvoir la cigarette : faire du tabac biologique (!) et rechercher des espèces ayant moins tendance à concentrer le ²¹⁰Po.
Les informations sur les effets liés à la radioactivité du tabac sont largement inconnues. En France les études n’existent pas et jamais rien n’est paru malgré quelques publications aux Etats-Unis, où il est également très difficile de faire connaître la composante radioactive du tabac et ses ravages, sans doute parce que les intérêts économiques priment. A côté de battages médiatiques contre la cigarette, prétendûment pour la santé, on peut voir la Communauté Economique Européenne subventionner les planteurs de tabac à hauteur de 10 milliards de francs (Verts Europe N°49).
Pourtant, aux Etats-Unis, de nombreuses personnes se sont arrêtées de fumer lorsqu’elles ont appris la composante radioactive de la cigarette, alors que goudron et nicotine ne les avaient jamais convaincues [8].
Mais en France nous avons en plus le poids des nucléocrates qui n’aimeraient pas qu’un quelconque rapport soit fait entre les poussières radioactives, d’où qu’elles proviennent, et les cancers. C’est la radiation alpha qui est responsable des cancers du poumon. La même que celle du plutonium, qu’on retrouve dans des déchets de décharges du CEA à la Hague ou bien encore à Moruroa, pour ne citer que quelques exemple.
Tout reviendrait à faire des études sur les faibles doses. Et là, il est urgent d’attendre...

Voir en ligne : La revue Silence

P.-S.

Note de l’auteure : 29 août 2008 : les journaux font mine de découvrir tous ces faits, alors qu’ils ont tout simplement couvert l’information.

Notes

[1] Hammond, E.C. & al. Some recent findings concerning cigarette smoking. In Origins of human cancer. New York : Cold Spring Harbor Laboratory, 1977 (102-12).
[2] Harley, N.H. & al. A model for predicting lung cancer risks induced by environmental levels of radon daughters. Health Physics. 1981 ; 40 : 307-316.
[3] Winters, T.H .& al. Radioactivity in cigarette smoke. New England Journal of Medicine. 1982 ; 306 : 364-365.
[4] Little, J.B. & al. Lung cancer induced in hamsters by low doses of alpha radiation from polonium 210. Science. 1975 ; 188 : 737-8.
[5] Martell, E.A. Radioactivity in cigarette smoke. The New England Journal of Medicine. 1982 ; 307 : 309-310.
[6] Ravenholt, R.T.Radioactivity in cigarette smoke. The New England Journal of Medicine. 1982 ; 307(5) : 312.
[7] Spencer, H. & al. Metabolic balances of ²¹⁰Pb and ²¹⁰Po at natural levels. Radiation research. 1977 ; 69 : 166-184.
[8] Winters, T.H. Radioactivity and lung cancer in active and passive smokers. Chest. 1983 ; 84 : 653-654.
[9] Hirayama, T. Non-smoking wives of heavy smokers have a higher risk of lung cancer : a study from Japan. Br. Medicine Journal. 1981 ; 282 : 183-5.
[10] Winters, T.H. & al. Radioactivity and cigarette smoke. Verlag Cherrie international inc.1984 ; 263-271.

jeudi 28 juin 2012

allvoices

http://www.allvoices.com/contributed-news/7848924/content/67809658-a-senior-us-diplomat-believed-russia-s-vladimir-putin-likely-knew-about-a-plot-to-kill

Polonium - 210 in cigarettes. Why? I have no idea?

La Crosse : KS : USA | Jan 10, 2011 at 4:25 PM PST

By RobertTilford01

3 0

2 of 2

A senior US diplomat believed Russia's Vladimir Putin likely knew about a plot to kill dissident Alexander Litvinenko

Many people may be surprised to know that the deadly poison Polonium 210 - the same stuff that killed former KGB operative Alexander Litvinenko, can be found in the cigarettes you smoke everyday.
In fact each and every time you "hit" that cigarette, you get a micro dose amount of Polonium 210.
It is contained within the very smoke you like so much to breath in to your lungs. Over time, of course that poison builds up to the equivalent radiation dosage of 300 chest X-rays a year for a person who smokes on average one and half packs a day.
And yes - the tobacco companies know it, so does the federal government.
In doing research on this subject I was able to find a reference to Polonium 210 study in cigarettes going back as far as the early 1960s at the main library (see: "Polonium-210: A Volatile Radioelement in Cigarettes" Edward P. Radford, Jr and Vilma R. Hunt in Science, Volume 143, pages 247-249, January 17, 1964).
Polonium-210 (Po-210) is a radioactive element that occurs naturally and is present in the environment at extremely low concentrations.
Polonium was discovered by Marie Sklodowska-Curie and Pierre Curie in 1898 and was named after Marie´s native land of Poland (Latin: Polonia). This element was the first one discovered by them while they were investigating the cause of pitchblende radioactivity.
It is a fairly volatile (50% is vaporized in air in 45 hours at 55°C) silvery-grey soft metal.
Po-210 has a half-life of 138 days. This is the time it takes for the activity to decrease by half due to a process of radioactive decay. Po-210 decays to stable lead-206 by emitting alpha particles, accompanied by very low intensity gamma rays. The majority of the time Po-210 decays by emission of alpha particles only, not by emission of an alpha particle and a gamma ray. Only about one in a 100,000 decays results in the emission of a gamma ray. Alpha spectroscopy is the best method of measuring this isotope.
In case your wondering there is no commerical advantage to having Polonium 210 in your cigarettes. At least none that I can find. I thought it might be an addictive property within it somehow, which would explain why the tobacco companies might want to lace it in your cigarettes but it isn't.
A scientist friend of mine, in Charlotte N.C., Dave Mathews said "if the federal government (FDA) ever decides to do the right thing and regulate this harmful product Polonium 210 would be excellent first "poison" to ban from cigarettes."
From what I understand that isn't that difficult to remove it from the cigarettes. Certainly the technology exists - so the question is why don't they do it? I don't have a good answer for you on that. Furthermore the FDA has not responded to my email asking them why they wouldn't regulate that substance out of something that people consume?
I heard someone say once "cigarettes can kill you in a thousand and one ways" - Polonium 210 is just one of those ways, I guess.
I've talked with others who say "smoking is a slow form of suicide".
I certainly agree with them on that.
In this respect I suppose you can literally measure your life in terms of the spent cigarette butts you flick out the window of your automobile or throw on the ground when you think nobody is watching.
Besides drinking alcohol, injecting heroin or shooting meth what could be worse than smoking cigarettes, especially when it is laced with polonium 210?
Robert Tilford
Charlotte, N.C.

Early Research on Polonium 210

http://www.motherearthnews.com/natural-health/polonium-210-zmaz82mazglo.aspx

Research in the 1970s and 1980s began to unveil a stronger link between cigarette smoke and lung cancer.

By Michael Castleman
March/April 1982

Image Gallery

Research in the 1970s and 1980s found a link between cigarettes and cancer.

PHOTO: FOTOLIA/IGOR KORIONOV

For decades, scientists researching the health effects of cigarette smoking have observed a correlation between that habit and such illnesses as heart disease, lung cancer and other tumors . . . but they've never been able to prove just how such a relationship might be brought about. Of course, it makes sense that cigarette smoke, which contains many proven carcinogens, could cause lung cancer from the simple accumulation of the harmful substances over a period of time. But — despite the fact that tens of millions of dollars have been spent on research — scientists still don't understand exactly why smokers face such a high risk of developing bladder and pancreatic cancers or atherosclerosis.
Now, however, a small group of medical experts — all of whom are highly respected specialists in the field of radiation hazard research — have proposed an unusual (and frightening) explanation of the devastating health consequences of cigarette smoking. For the past 16 years, this group has gathered evidence to support what they call the "warm particle theory." Their line of reasoning asserts that insoluble low-level alpha-emitting radioactive particles in cigarette smoke trigger the majority of diseases associated with smoking. Or, to phrase it more directly: These experts claim that cigarettes are actually radioactive!
Tobacco, like all other organic matter — including soil, food, water, and our bodies — contains trace amounts of radioactive isotopes, most of which are soluble in water. When those particles enter the human body (which is more than 90 percent water), they are suspended in solution and then quickly and safely excreted.
Most tobacco-related radioactivity, therefore, simply washes out of the lungs. But, some other radioactive particles are insoluble, so they accumulate in the lungs and bombard delicate tissue with low-level alpha radiation, which is the same kind of radiation emitted by plutonium! Now alpha particles aren't particularly dangerous outside the body, but inside — and particularly in the lungs — they pose a serious health hazard.

According to Dr. John Gofman (former director of biomedical research at Lawrence Livermore Lab and author of the recently published book Radiation and Human Health), the presence of even one one-millionth of a gram of plutonium in the lung virtually guarantees the development of cancer there within 20 years.

Radon's Dangerous Daughter

The specific alpha-emitter in tobacco smoke is polonium 210, a naturally occurring product — or "daughter" — of the decay of radium 226, which is, itself, a natural radioisotope. Polonium 210 was first isolated in cigarette smoke, in minute but significant amounts, by Dr. Edward P. Radford (professor of environmental epidemiology at the University of Pittsburgh and chairman of the prestigious Biological Effects of Ionizing Radiation — BEIR — Committee of the National Academy of Sciences) and Dr. Vilma Hunt (now a senior official in the Environmental Protection Agency).
In 1965, Radford and Hunt — along with several other researchers — published a report in the New England Journal of Medicine that related their findings of significant concentrations of polonium 210 in smokers' bronchial tissues. The article suggested that the cumulative dose of alpha radiation from years of smoking and inhaling polonium 210 might well be a key factor in the development of lung cancer.
Other scientists criticized the Radford-Hunt hypothesis, largely because they believed it unlikely that a relatively short-lived isotope such as polonium 210 (with a half-life of only 138 days) could expose lung tissue to enough radiation to cause cancer before its water-soluble particles were washed out of the lungs.
Further research was carried out in 1974 and 1975 by Dr. Edward Martell, a radiochemist with the National Center for Atmospheric Research in Boulder, Col., and the author of more than 75 scientific research papers. He discovered that the tiny leaf hairs on tobacco, called trichomes, attract high levels of lead 210 . . . another decay "daughter" of radium 226, which — unlike polonium 210 — is carried into the lungs in insoluble smoke particles, and remains there for a 22-year half-life. In related experiments, Martell also found a rather startling match between the areas in which polonium 210 accumulates in the body and the sites of the major illnesses most often linked to smoking.

Conclusions About the Dangers of Cigarette Smoke

The findings of Martell's study — and of some related research — were published in a 1975 American Scientist article entitled "Tobacco Radioactivity and Cancer in Smokers." The conclusions reached in that report included the following points...
[1] The unusually high levels of lead 210 found in tobacco trichomes (and in the smoke) result from heavy applications of phosphate fertilizers used in commercial tobacco farming. Those chemical preparations contain significant quantities of radium 226 and of its nine primary decay products.

[2] When tobacco is smoked, the insoluble lead 210 particles accumulate in the lungs and, as they decay into polonium 210, the small cell populations around the radioactive particles are subjected to "hits" of alpha radiation that are hundreds of times greater than naturally occurring background radiation levels.

[3] If the polonium 210 particles were highly radioactive — or "hot" — they'd kill lung cells immediately. But, because they're merely "warm" isotopes, they kill only a few healthy cells and damage others by altering their genetic coding (while still leaving them able to reproduce). Over succeeding cell generations, however, those that contain alpha-altered DNA material become cancerous as a result of receiving further alpha hits.
[4] Unexpectedly large amounts of 210 particles are found in smokers' lung tumors.

[5] Unexpectedly high levels of the 210's are also found in lymph nodes adjacent to the sites of smokers' secondary cancers, because some of the insoluble particles are picked up by the lymph system and circulated through the body collecting in lymph nodes and irradiating nearby organs.
[6] Finally, those fatty arterial deposits that characterize atherosclerosis show "anomalously high concentrations of alpha activity," which is a possible explanation for the high rate of early coronaries among cigarette smokers.

Mixed Reactions on Polonium 210 Research

Martell's groundbreaking research report was received — for the most part — with indifference, a reaction that he attributes to the unfamiliarity of the ideas contained in the study.
"You have to remember that the entire field of study concerned with the health effects of low-level radiation is considered new and controversial," said Martell. "Most cigarette and cancer researchers are still working on the chemistry of smoking, and as yet very little attention has been paid to its radiochemistry."

Ted Howard, a spokesman for the Tobacco Institute (the cigarette industry's lobbying organization in Washington), says that "several reputable scientific studies" have shown the warm particle theory to be "ludicrous." He cites, in particular, a 1980 Australian project that reported "no significant levels of alpha activity" in smokers' lungs. The catch, of course, is the word "significant." Although the Australian scientists found lower levels of alpha activity than those noted by advocates of the warm particle theory, the levels they reported were still 10 times greater than the alpha activity of lung cells not exposed to cigarette smoke.

Radford, the BEIR committee chairman, said, "Martell hasn't proved the warm particle theory . . . but no one has refuted it, either. It is controversial, but it must be taken seriously." Radford added that he does remain skeptical of Martell's ideas about the specific role of alpha radiation in causing atherosclerosis.

Also skeptical — but eager to see more information — is Dr. Samuel Epstein, author of The Politics of Cancer and one of the nation's leading authorities on carcinogenesis. Epstein says the warm particle theory is "interesting," but he also cautions that "the question of causality has not yet been resolved" . . . particularly in regard to the relation between the 210's and atherosclerotic fat deposits. For that reason, he urges more research, noting, "I'm surprised by the lack of experimentation in the area."

Ed Radford, however, is not so surprised. He maintains that the inertia surrounding the warm particle theory is largely due to the combined influence of two vested interests.

"The tobacco lobby and the nuclear energy lobby are two of the largest and most powerful in Washington," he says. "They don't control research funding, but I'd say they have a disproportionate influence over it. The nuclear industry doesn't want the warm particle theory to gain credibility because it would prove, once and for all, that low-level radiation is dangerous. That, in turn, would mean substantial downward revisions in radiation exposure limits . . . revisions the nuclear industry cannot afford. The tobacco industry, of course, doesn't want cigarettes labeled as radioactive, either. So it's a case where two major lobbies have parallel interests."
The BEIR Committee — which includes several pronuclear scientists — has yet to pass judgment on Dr. Martell's findings. But Radford, for one, firmly believes that the concept provides the most likely explanation offered thus far for the development of lung cancer in smokers. He predicts "growing interest in the warm particle theory" in the next few years.