home Fairy tales The biological role of polonium. The structure of the polonium atom

The biological role of polonium. The structure of the polonium atom

Polonium-210 has a very clear association with radiation. And this is not in vain, because it is extremely dangerous.

Discovery history

Its existence was predicted back in 1889 by Mendeleev, when he created his famous periodic table. In practice, this element, number 84, was obtained nine years later by the efforts of the Curies, who studied the phenomenon of radiation. tried to find out the reason for the strong radiation emanating from certain minerals, and therefore began to work with several rock samples, processing them in all ways available to her, dividing into fractions and discarding the unnecessary. As a result, she received a new substance, which became an analogue of bismuth and the third discovered radioactive element after uranium and thorium.

Despite the successful results of the experiment, Maria was in no hurry to talk about her find. conducted by a colleague of the Curie spouses, also did not give grounds to talk about the discovery of a new element. Nevertheless, in a report at a meeting of the Paris Academy of Sciences in July 1898, the couple reported on the alleged receipt of a substance that exhibits the properties of a metal and proposed to name it polonium in honor of Poland, Mary's homeland. This was the first and only case in history when an element that has not yet been reliably identified has already received a name. Well, the first sample appeared only in 1910.

Physical and chemical properties

Polonium is a relatively soft, silvery-white metal. It is so radioactive that it glows in the dark and heats up constantly. At the same time, its melting point is slightly higher than that of tin - only 254 degrees Celsius. The metal oxidizes very quickly in air. At low temperatures forms a monatomic simple cubic crystal lattice.

By their own chemical properties Polonium is very close to its counterpart - tellurium. In addition, the nature of its compounds is greatly influenced by high level radiation. So reactions involving polonium can be quite spectacular and interesting, albeit quite dangerous in terms of health benefits.

isotopes

Total science on this moment 27 (according to other sources - 33) forms of polonium are known. None of them is stable and they are all radioactive. The heaviest of the isotopes (with ordinal numbers from 210 to 218) are found in nature in small quantities, the rest can only be obtained artificially.

Radioactive polonium-210 is the longest-lived form in nature. It is found in small amounts in radium-uranium ores and is formed by a chain of reactions starting with U-238 and lasting about 4.5 billion years in terms of half-life.

Receipt

1 ton contains the isotope polonium-210 in an amount equal to approximately 100 micrograms. They can be isolated during the processing of production waste, however, to obtain a more or less significant volume of the element, it would be necessary to process great amount material. Much simpler and effective ways is the synthesis by neutron irradiation of natural bismuth in nuclear reactors.

As a result, after some more procedures, polonium-210 is obtained. Isotopes 208 and 209 can also be obtained by irradiating bismuth or lead with accelerated beams of alpha particles, protons, or deuterons.

Radioactivity

Polonium-210, like other isotopes, is an alpha emitter. The heavier group also emits gamma rays. Despite the fact that the 210 isotope is a source of only alpha particles, it is quite dangerous, it cannot be taken by hand and even approached near distance, because, warming up, it passes into an aerosol state. It is also extremely dangerous to get polonium inside with breath or food. That is why work with this substance takes place in special sealed boxes. It is curious that this element was found in tobacco leaves about half a century ago. The decay period of polonium-210 compared to other isotopes is quite large, and therefore it can accumulate in the plant and subsequently harm the health of the smoker even more. However, any attempts to extract this substance from tobacco have been unsuccessful.

Danger

Since polonium-210 emits only alpha particles, taking certain precautions, you should not be afraid to work with it. These waves rarely travel more than a dozen centimeters, and they usually cannot penetrate the skin.

However, once inside the body, they cause him great harm. When it enters the blood, it quickly spreads to all tissues - after a few minutes, its presence can be seen in all organs. It is primarily present in the kidneys and liver, but in general it is distributed fairly evenly, which can explain its high overall damaging effect.

The toxicity of polonium is so great that even small doses cause chronic radiation sickness and death after 6-11 months. The main routes of excretion from the body are through the kidneys and gastrointestinal tract. There is a dependence on the method of entry. The half-life is 30 to 50 days.

Accidental poisoning with polonium is completely impossible. To obtain a sufficient amount of the substance, it is necessary to have access to a nuclear reactor and deliberately put an isotope on the victim. The complexity of diagnosis also lies in the fact that only a few cases are known throughout history. The first victim is the daughter of the discoverers of polonium, Irene Joliot-Curie, who, during research, broke the capsule with the substance in the laboratory and died 10 years later. Two more cases occur in the 21st century. The first of them is the sensational case of Litvinenko, who died in 2006, and the second is the death of Yasser Arafat, in whose things traces of a radioactive isotope were found. However final diagnosis never been confirmed.

Decay

One of the longest-lived isotopes, along with 208 and 209, is polonium-210. (that is, the time during which the number of radioactive particles is halved) for the first two is 2.9 and 102 years, respectively, and for the last 138 days and 9 hours. As for the rest of the isotopes, their lifetime is calculated mainly in minutes and hours.

The combination of various properties of polonium-210 makes it the most convenient of the range for use in various areas of life. Being in a special metal shell, he can no longer harm his health, but is able to give his energy for the benefit of mankind. So what is polonium-210 used for today?

Modern application

According to some reports, about 95% of polonium production is concentrated in Russia, and about 100 grams of the substance is synthesized per year, and almost all of it is exported to the United States.

There are several areas where polonium-210 is used. First of all, these are spacecraft. With its compact size, it is indispensable as an excellent source of energy and heat. Although its effectiveness is halved about every 5 months, heavier isotopes are much more expensive to produce.

In addition, polonium is absolutely indispensable in nuclear physics. It is widely used in the study of the effect of alpha radiation on other substances.

Finally, another area of application is the production of devices for removing static electricity for both industry and home use. It is even surprising how such a dangerous element can become almost a kitchen utensil, being enclosed in a reliable shell.

Alexander Litvinenko, a former Russian FSB officer, has died in London. Presumably, the cause of his death was poisoning with a radioactive substance polonium-210.

Polonium is the first element inscribed in the periodic table after the discovery of radioactivity. Polonium was discovered by famous chemists Pierre and Maria Sklodowska-Curie in 1898 (according to other sources - in 1897). The element got its name from Poland - the birthplace of Mary (from the Latin Polonia - Poland). Maria Skłodowska-Curie received the Nobel Prize for this discovery.

According to Argonne National Laboratory\Argonne National Laboratory, polonium-210 can only be obtained by a person with access to nuclear research facilities. Polonium is usually obtained by irradiating bismuth-209 with neutron beams (this technology was developed in 1934). Every year, the nuclear reactors of the world produce approximately 100 g of polonium-210. In total, 27 isotopes of polonium with mass numbers from 192 to 218. The half-life of the longest-lived isotope (polonium - 209) is 103 years. The half-life of the polonium-210 with which Litvinenko was poisoned is 138 days, during which a large amount of heat is produced. A gram of polonium can heat up to 500 degrees Celsius, so it was used in space as an energy source, for example, it was the basis of the power plants of many satellites and even on the famous Soviet research probe Lunokhod-2, where polonium made it possible to maintain an acceptable for scientific instrument temperature. In addition, polonium is used in the manufacture of nuclear weapons.

The safe dose of polonium-210 for humans is 7 picograms (1 picogram is one trillion gram). Thus, literally a speck of polonium can become fatal to humans. Polonium-210 is one of the most toxic chemical substances. It cannot be taken with bare hands - otherwise it is possible to get a radiation burn, however, observing the simplest safety methods allows you to work calmly with this element. In particular, polonium can be transported in glass test tubes with ground-in lids.

The instructions for working with polonium-210, which are published by the American scientific organization Health Physics Society, indicate that in a laboratory where polonium is used, you cannot store food, water, cosmetics, etc., as well as use these products for their intended purpose (i.e. such as drinking or painting lips). It is also forbidden to put food and drinks in the refrigerator or on shelves where polonium-210 or devices (test tubes, etc.) that were in contact with it were once stored.

When ingested (for example, as a result of injection or inhalation), polonium-210 affects absolutely all organs. 50-90% of polonium-210 is excreted naturally. The remaining 10-50% penetrate the blood and are carried throughout the body, mostly settling in the spleen, kidneys and liver.

Humans are constantly exposed to polonium (produced by the decay of widespread radon gas or by smoking tobacco grown in a field treated with phosphate fertilizers), but under natural conditions these doses are negligible.

It is not known if polonium was previously used as a poison. However, ironically, the first known victim of polonium was Irene Julio-Curie, the daughter of the discoverers of polonium. The cause of her death was a broken capsule of polonium-210. It happened in the laboratory where Irene worked all the time. Her death from cancer occurred in 1956 - a decade after the pod incident occurred.

In 1991, the International Agency for Cancer Research\The International Agency for Research on Cancer has published the results of the first major study of human exposure to polonium-210. As part of this study, surveys were conducted of employees of one of the US nuclear facilities, who worked there from 1944 to 1972. Polonium-210 was noted to be the cause of many cases of lung cancer and kidney cancer, even though the plant was extremely strict about safety. The study, in particular, cited the following statistics: about 22.5 thousand people worked at nuclear facilities, approximately 9.4 thousand of them were exposed to radiation, of which 638 people were exposed to polonium-210.

The fruit of Marie Curie's efforts

Polonium was discovered by Marie Curie in 1897 by chemical extraction from the mineral uranium oxide. The researcher gave the element its name in honor of her homeland - Poland.

According to physicist Nick Priest, this method is not able to produce enough of the isotope needed to kill an adult human.

To obtain the required amount requires the use of a nuclear reactor, he said.

According to him, the most realistic way to obtain polonium-210 is to irradiate the element bismuth with neutrons in such a reactor, resulting in the isotope bismuth-210.

This isotope has a short half-life, after which it decays into polonium-210 and thallium-206.

As Nick Priest points out, there were reports of small amounts of radioactive thallium in Litvinenko's body, which could be an indirect sign of polonium production in the reactor.

Thallium-206 has a very short half-life, so there should be traces of bismuth-210 in polonium, which in turn gives us thallium.

This can occur in the case of incomplete separation of bismuth from polonium at the final stage of the process.

Obtaining polonium from the radium-226 isotope is considered a difficult process because this radium isotope produces hard penetrating radiation.

Lunar rovers walked on it

According to experts, there are only 40-50 reactors in the world capable of producing polonium-210. All available data points to sources outside the UK.

Among them are several nuclear facilities on the territory of the former Soviet Union as well as in Australia and Germany.

"There is only one reactor in Britain that could produce this isotope, and I'm sure the physicists working on it didn't do that sort of thing," says Nick Priest.

Polonium is used in various measuring devices, but it is not easy to extract it from them.

In the past, polonium, like beryllium, was used as an initiator nuclear reaction v atomic bombs produced in the USA, Great Britain and the USSR. In addition, Soviet lunar rovers in the 70s were equipped with isotope batteries based on polonium-210.

The culprits are harder to find

The Litvinenko case brings us back to the topic of illegal trade in Russian radioactive substances. Since 1995, the IAEA has maintained a database of recorded episodes of the spread of nuclear waste and radioactive materials. According to data for last year, a total of 827 such episodes were recorded.

The IAEA has no data on the presence of the isotope polonium-210 on the black market, but there have been unconfirmed reports in this regard.

On Tuesday, Sergei Kiriyenko, head of Rosatom, dismissed suggestions that the polonium-210 that caused Litvinenko's death could have been smuggled out of Russia. According to him, Russia exports only 8 grams of polonium-210 per month, and all this amount is sent to the United States. Exports to the UK were discontinued five years ago.

Theoretically, Litvinenko's investigators could trace the origin of polonium-210, but to do so, traces of other isotopes would have to be found first.

But even if such data were obtained, it would not necessarily lead to the discovery of the culprit, especially in the case of theft of such materials. According to many physicists, polonium-210 was chosen as the murder weapon precisely because of its high toxicity and difficulty in detecting.

London- Polonium first received widespread publicity in 2006, when it was used to assassinate Kremlin critic and former KGB agent Alexander Litvinenko in London.

This week, Yasser Arafat's widow demanded the exhumation of the Palestinian leader's body after Swiss scientists found traces of radioactive polonium-210 on clothing he was believed to have worn before his death in 2004.

So what is polonium, and how dangerous is it?

What is polonium?

Polonium-210 is one of the rarest elements, and it was discovered in 1898 by spouses Pierre Curie and Maria Skłodowska-Curie and named after Maria's homeland, Poland. The element accumulates in a natural way in extremely small quantities in earth's crust, and is also produced artificially in nuclear reactors. It is used in small quantities for legitimate industrial purposes, mainly to discharge static electricity.

Is he dangerous?

Very. If it enters the body, it is fatal even in negligible doses. Less than one gram of silver powder is enough to kill someone. In a 2007 study, scientists from the UK Department of Health showed that once polonium enters the bloodstream, its powerful action is almost impossible to stop. The poisoned victim experiences gradual organ failure as the alpha particles attack the liver, kidneys, and bone marrow. Litvinenko's symptoms are also typical - nausea, hair loss, throat swelling and pallor.

Who can get polonium?

The good news is few. The element can be a by-product of the chemical processing of uranium, but it is most commonly produced by nuclear reactors or particle accelerators. These nuclear facilities are tightly controlled and operate under strict international agreements.

John Croft, a retired British radiation expert who worked with Litvinenko, believes that enough polonium to kill would likely come from a government with civilian or military nuclear capability. That description fits Russia, which produces polonium and is suspected of killing Litvinenko, as well as Arafat's enemy Israel. But there are a dozen other countries, including the US.

Why would he be interested in assassins?

Polonium is a good weapon. Its large radioactive alpha particles do not penetrate the skin and are not picked up by radiation detectors, making it relatively easy to smuggle across the border. Polonium can enter the body through a wound or inhalation, but the most reliable way is to consume polonium through food or drink. Litvinenko drank tea with polonium during a meeting at a luxury hotel in London.

Who did they kill?

Poisoning with polonium is such a rarity that it took doctors several weeks to determine Litvinenko's illness, and security experts struggled to remember a previous case of poisoning. Five years have passed since the murder of Litvinenko, but no one has been detained. British investigators have named former KGB agent Andrei Lugovoi as their prime suspect, but Russia refuses to extradite him.

Some believe that Curie's daughter Irene, who died of leukemia, became ill after accidentally receiving a dose of polonium in the laboratory.

Israeli author Michal Karpin claimed that the death of several Israeli scientists due to cancer was the result of a leak in scientific institute Weismann (Weizmann Institute of Science) in 1957. The Israeli authorities have never acknowledged the connection.

Can scientists prove that Arafat was poisoned with polonium?

Scientists have warned that traces of polonium on Arafat's clothes are not enough to prove the poisoning. Exhuming the body for analysis is a much more reliable way. Radiology specialist from University College Derek Hill of London said that eight years after Arafat's death, polonium should have already decayed and is much less radioactive than it was in 2004. But the level would still be many times higher than normal, he said, and an autopsy should show "with a fairly high degree of certainty" whether Arafat's body had polonium at the time of death.

The content of the article

POLONIUM- radioactive chemical element Group VI periodic system, an analogue of tellurium. atomic number 84. Has no stable isotopes. Known 27 radioactive isotopes polonium with mass numbers from 192 to 218, of which seven (with mass numbers from 210 to 218) occur in nature in very small quantities as members of the radioactive series of uranium, thorium and actinium, the remaining isotopes are obtained artificially. The longest-lived isotopes of polonium are artificially produced 209 Rho ( t 1/2 = 102 years) and 208 Rho ( t 1/2 \u003d 2.9 years), as well as 210 Rho contained in radium-uranium ores ( t 1/2 = 138.4 days). The content of 210 Rho in the earth's crust is only 2 10 -14%; 1 ton of natural uranium contains 0.34 g of radium and fractions of a milligram of polonium-210. The shortest-lived known isotope of polonium is 213 Po ( t 1/2 = 3 10 -7 s). The lightest isotopes of polonium are pure alpha emitters, while the heavier isotopes simultaneously emit alpha and gamma rays. Some isotopes decay by electron capture, and the heaviest ones also exhibit very weak beta activity ( cm. RADIOACTIVITY). different isotopes polonium have historical names adopted as early as the beginning of the 20th century, when they were obtained as a result of a chain of decays from the “parent element”: RaF (210 Po), AcC "(211 Po), ThC" (212 Po), RaC "(214 Po), AcA (215 Po), ThA (216 Po), RaA (218 Po).

The discovery of polonium.

The existence of an element with serial number 84 was predicted by D.I. Mendeleev in 1889 - he called it ditellurium (in Sanskrit - the “second” tellurium) and suggested that it atomic mass will be close to 212. Of course, Mendeleev could not foresee that this element would turn out to be unstable. Polonium is the first radioactive element, discovered in 1898 by the Curies in search of a source of strong radioactivity in certain minerals ( cm. RADIUM). When it turned out that uranium resin ore radiates more strongly than pure uranium, Marie Curie decided to isolate from this compound chemically new radioactive chemical element. Before that, only two weakly radioactive chemical elements were known - uranium and thorium. Curie started with the traditional quality chemical analysis mineral according to the standard scheme, which was proposed by the German analytical chemist K. R. Fresenius (1818–1897) back in 1841 and according to which many generations of students for almost a century and a half determined cations by the so-called “hydrogen sulfide method”. At the beginning she had about 100 g of the mineral; then American geologists gave Pierre Curie another 500 g. Carrying out a systematic analysis, M. Curie each time checked individual fractions (precipitates and solutions) for radioactivity using a sensitive electrometer invented by her husband. Inactive fractions were discarded, active ones were analyzed further. She was assisted by one of the leaders of the chemical workshop at the School of Physics and Industrial Chemistry, Gustav Bemon.

First of all, Curie dissolved the mineral in nitric acid, evaporated the solution to dryness, dissolved the residue in water, and passed a stream of hydrogen sulfide through the solution. At the same time, a precipitate of metal sulfides precipitated; according to the Fresenius method, this precipitate could contain insoluble sulfides of lead, bismuth, copper, arsenic, antimony, and a number of other metals. The precipitate was radioactive, despite the fact that the uranium and thorium remained in solution. She treated the black precipitate with ammonium sulfide to separate arsenic and antimony - under these conditions they form soluble thiosalts, for example, (NH 4) 3 AsS 4 and (NH 4) 3 SbS 3 . The solution did not detect radioactivity and was discarded. Lead, bismuth and copper sulfides remained in the sediment.

The part of the Curie precipitate that did not dissolve in ammonium sulfide was again dissolved in nitric acid, added to the solution sulfuric acid and evaporated it on a burner flame until thick white fumes of SO 3 appeared. Under these conditions, volatile nitric acid is completely removed, and metal nitrates are converted to sulfates. After cooling the mixture and adding cold water insoluble lead sulfate PbSO 4 turned out to be in the sediment - there was no activity in it. She discarded the precipitate, and added a strong solution of ammonia to the filtered solution. At the same time, a precipitate fell out again, this time - white color; it contained a mixture of basic bismuth sulfate (BiO) 2 SO 4 and bismuth hydroxide Bi(OH) 3 . The complex copper ammonia SO 4 of bright blue color remained in the solution. The white precipitate, unlike the solution, turned out to be highly radioactive. Since the lead and copper had already been separated, the white precipitate contained bismuth and an admixture of the new element.

Curie again converted the white precipitate into dark brown Bi 2 S 3 sulfide, dried it, and heated it in an evacuated ampoule. Bismuth sulfide did not change at the same time (it is resistant to heat and melts only at 685 ° C), however, some vapors were released from the precipitate, which settled in the form of a black film on the cold part of the ampoule. The film was radioactive and apparently contained a new chemical element - an analogue of bismuth in the periodic table. It was polonium - the first discovered radioactive element after uranium and thorium, inscribed in the periodic table (in the same 1898, radium was discovered, as well as a group of noble gases - neon, krypton and xenon). As it turned out later, polonium easily sublimates when heated - its volatility is about the same as that of zinc.

The Curies were in no hurry to call the black coating on the glass a new element. One radioactivity was not enough. A colleague and friend of Curie, French chemist Eugene Anatole Demarce (1852–1903), a specialist in the field of spectral analysis (he discovered europium in 1901), studied the emission spectrum of black plaque and found no new lines in it that could indicate the presence of a new element. Spectral analysis is one of the most sensitive methods, allowing the detection of many substances in microscopic quantities invisible to the eye. Nevertheless, in an article published on July 18, 1898, the Curies wrote: “We think that the substance we isolated from uranium resin contains a metal that is not yet known, which is analogous to bismuth in analytical properties. If the existence of a new metal is confirmed, we propose to call it polonium, after the birthplace of one of us” (Polonia in Latin - Poland). This is the only case when a new chemical element, not yet identified, has already received a name. However, it was not possible to obtain weight amounts of polonium - there was too little of it in uranium ore (later polonium was obtained artificially). And it was not this element that glorified the Curie spouses, but radium

properties of polonium.

Tellurium already partially exhibits metallic properties, while polonium is a soft silvery-white metal. Due to the strong radioactivity, it glows in the dark and gets very hot, so continuous heat removal is needed. The melting point of polonium is 254 ° C (slightly higher than that of tin), the boiling point is 962 ° C, therefore, even with a slight heating, polonium sublimates. The density of polonium is almost the same as that of copper - 9.4 g/cm 3 . In chemical research, only polonium-210 is used; longer-lived isotopes are practically not used due to the difficulty of obtaining them with the same chemical properties.

The chemical properties of metallic polonium are close to those of its closest analogue, tellurium; it exhibits oxidation states of –2, +2, +4, +6. In air, polonium slowly oxidizes (quickly when heated to 250 ° C) with the formation of red dioxide PoO 2 (when cooled, it becomes yellow as a result of rearrangement crystal lattice). Hydrogen sulfide from solutions of polonium salts precipitates black sulfide PoS.

The strong radioactivity of polonium is reflected in the properties of its compounds. So, in diluted hydrochloric acid polonium slowly dissolves with the formation of pink solutions (color of Po 2+ ions): Po + 2HCl ® PoCl 2 + H 2 , however, under the influence of its own radiation, the dichloride turns into yellow PoCl 4 . Dilute nitric acid passivates polonium, while concentrated nitric acid quickly dissolves it. With non-metals of group VI, polonium is related by the reaction with hydrogen to form the volatile hydride PoH 2 (m.p. -35 ° C, b.p. +35 ° C, easily decomposes), the reaction with metals (when heated) to form solid black polonides colors (Na 2 Po, MgPo, CaPo, ZnPo, HgPo, PtPo, etc.) and reaction with molten alkalis to form polonides: 3Po + 6NaOH ® 2Na 2 Po + Na 2 PoO 3 + H 2 O. Polonium reacts with chlorine at heated with the formation of bright yellow crystals of PoCl 4 , with bromine, red crystals of PoBr 4 are obtained, with iodine, already at 40 ° C, polonium reacts to form black volatile iodide PoI 4 . White polonium tetrafluoride PoF 4 is also known. When heated, the tetrahalides decompose to form more stable dihalides, for example, PoCl 4 ® PoCl 2 + Cl 2 . In solutions, polonium exists in the form of cations Po 2+ , Po 4+ , anions PoO 3 2– , PoO 4 2– , and various complex ions, for example, PoCl 6 2– .

Obtaining polonium.

Polonium-210 is synthesized by neutron irradiation of natural bismuth (it contains only 208 Bi) in nuclear reactors (the beta-active isotope of bismuth-210 is formed intermediately): 208 Bi + n ® 210 Bi ® 210 Po + e. When bismuth is irradiated with accelerated protons, polonium-208 is formed, it is separated from bismuth by sublimation in a vacuum - as M. Curie did. In our country, the method for isolating polonium was developed by Zinaida Vasilievna Ershova (1905–1995). In 1937 she was sent to Paris to the Institute of Radium in the laboratory of M.Curie (headed at that time by Irene Joliot-Curie). As a result of this business trip, colleagues began to call her "Russian Madame Curie." Under the scientific guidance of Z.V. Ershova, a permanent, environmentally friendly production of polonium was created in the country, which made it possible to implement the national program for launching lunar rovers, in which polonium was used as a heat source.

Long-lived isotopes of polonium have not yet received a noticeable practical application due to the complexity of their synthesis. To obtain them, one can use the nuclear reactions 207 Pb + 4 He ® 208 Po + 3n, 208 Bi + 1 H ® 208 Po + 2n, 208 Bi + 2 D ® 208 Po + 3n, 208 Bi + 2 D ® 208 Po + 2n , where 4 He are alpha particles, 1 H are accelerated protons, 2 D are accelerated deuterons (deuterium nuclei).

The use of polonium

Polonium-210 emits alpha rays with an energy of 5.3 MeV, which are decelerated in solid matter, passing only thousandths of a millimeter and giving up their energy in the process. Its lifetime allows the use of polonium as an energy source in atomic batteries. spaceships: to obtain a power of 1 kW, only 7.5 g of polonium is enough. In this respect, it is superior to other compact "atomic" energy sources. Such an energy source worked, for example, on Lunokhod-2, heating the equipment during a long moonlit night. Of course, the power of polonium energy sources decreases over time - by half every 4.5 months, but longer-lived polonium isotopes are too expensive. Polonium is also conveniently used to study the effects of alpha radiation on various substances. As an alpha emitter, polonium mixed with beryllium is used to make compact neutron sources: 9 Be + 4 He ® 12 C + n. Boron can be used instead of beryllium in such sources. In 2004, inspectors from the International Atomic Energy Agency (IAEA) were reported to have discovered a polonium production program in Iran. This led to the suspicion that it could be used in a beryllium source to "start" with the help of neutrons a nuclear chain reaction in uranium, leading to a nuclear explosion.

Polonium, when it enters the body, can be considered one of the most toxic substances: for 210 Rho, the maximum permissible content in the air is only 40 billionths of a microgram per 1 m 3 of air, i.e. Polonium is 4 trillion times more toxic than hydrocyanic acid. The alpha particles emitted by the polonium (and to a lesser extent also the gamma rays) cause damage, which destroy tissues and cause malignant tumors. Polonium atoms can be formed in human lungs as a result of the decay of radon gas in them. In addition, metallic polonium is able to easily form the smallest aerosol particles. Therefore, all work with polonium is carried out remotely in sealed boxes.

Ilya Leenson