Through the back door, in the shadow of lithium whose mining is announced in the Jadra valley in western Serbia, pine has crept into everyday vocabulary, on banners during anti-mining protests and in the statements of officials.
Compounds of this chemical element are found in the mineral jadarite, which is also confirmed in the documentation of the "Jadar" project of the Australian-British company Rio Tinto.
According to the plans published on the company's website, in addition to the basic product of lithium carbonate, Rio Tinto's goal is to produce 160.000 tons of boric acid annually.
People ingest boron every day through food and water, it can be bought as a dietary supplement and "is not particularly dangerous for humans" in small quantities, says Michael Ingleson, professor of inorganic chemistry at the University of Edinburgh, for the BBC in Serbian.
"With each chemical element, the harmfulness depends on the boron compound we come into contact with, the amount and the way we are exposed to it," he adds.
It's also used for medicine, and Ingleson says scientists are testing a new therapy to fight resistance to boron-based antibiotics.
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Boron is used to make glass and ceramics, in alloys with other metals, in the pharmaceutical industry and in the production of nuclear energy.
The world's largest producers of pine and its compounds are Turkey, the United States of America and Chile, while the largest reserves, along with Turkey and the USA, are also found in Russia, it is stated on the website of the British Royal Society of Chemistry.
Its abundance in the earth's crust is about 0,0008 percent, and Ingleson says it is "neither a common nor a rare" element.
"At one point, American scientists even considered boron compounds as a replacement for car engine fuel, and through analysis they determined that we have enough boron on the planet to completely replace fossil fuel with boron-based fuels," explains the professor of inorganic chemistry.
"They never managed to solve some of the problems and there was no transition to boron fuels, but the key conclusion was that there would be enough boron in the earth's crust for such an undertaking," he emphasizes in a written answer for the BBC in Serbian.
In the documents of the American Central Intelligence Agency (CIA) as far back as 1955, there are claims that the Soviets were researching pine with the intention of using it as fuel for fighter planes and missiles.
"The most common misconception" that accompanies boron in Serbia, but also in other countries, is the claim that it is a heavy metal, says Dušan Veljković, associate professor at the Faculty of Chemistry in Belgrade, for the BBC in Serbian.
"Although you hear it in the media, even from some experts, boron is not a metal at all, but belongs to a small group of chemical elements that we call metalloids.
"They have properties between metals and non-metals," says Veljković.
Metalloids or semimetals, such as boron, have a shiny surface and high melting points like metals, but they are worse conductors than them, and they are connected with nonmetals by the tendency to form strong inorganic acids.
This group also includes silicon, germanium, arsenic, antimony, tellurium and astat.
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What is pine?
This metalloid is marked with the symbol "B" and is fifth in the periodic table of elements, which means that it is the fifth lightest chemical element.
Boron was discovered and isolated for the first time by the French chemists Joseph-Louis Guy-Lussac and Louis-Jacques Thenard in 1808, and a little later by Humphrey Davy in Great Britain, according to Encyclopaedia Britannica.
Pure boron has the form of a dark powder, but in nature it can most often be found in compounds with oxygen, i.e. boron oxides.
Boron is "fairly inert", which means that it does not react violently with other elements, says Professor Dušan Veljković.
But the compounds it builds and in whose composition it is most often found in nature are far more reactive, he adds.
"Those compounds dissolve well in water and can be accumulated and exploited locally, which is also the case in Serbia, primarily in the form of ores with silicon, lithium or sodium," adds this expert.
In rare cases, scientists isolate pure pine.
"It is difficult to obtain by mining and it is possible through very complex chemical procedures, where boron oxides are used at a very high temperature in contact with magnesium," says Veljković.
What is pine used for?
While the production of fuel from pine has not taken off yet, it is massively used in the glass industry, household chemicals and agriculture.
"The largest part of boron compounds is used for the production of special types of glass and ceramics, which are highly resistant to high temperatures and mechanical impacts, as well as detergents and powders and insecticides, because these compounds are very toxic to insects, but not so toxic to humans." says Veljkovic.
Some boron compounds, such as boron carbide (B4C), are also used in nuclear research.
"They can absorb neutrons, which is very convenient for controlling, or slowing down, nuclear reactions in reactors," Veljković explains.
In limited quantities, boron is also used in the metalworking industry to increase the strength of metals, as well as in the production of microchips and magnets, according to Encyclopaedia Britannica.
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Is it harmful to humans?
Due to concentration in soil and water, through plants and animals, certain amounts of boron end up in the human body every day.
"It is optimal to have 1,5 to two milligrams of boron in a kilogram of soil, and if these limits are exceeded, big problems can arise, primarily the drying of plants," says Veljković.
Such a case was recorded in the vicinity of Loznica, where as a result of investigative work by Rio Tinto as part of the "Jadar" project, groundwater with an excessive concentration of boron was spilled onto crops, which in 2021 reported Balkan Research Network of Serbia (BIRN).
But pine in small quantities can have a positive effect on people, and medicines and nutritional supplements with pine compounds can be bought in pharmacies and sports supplement stores in Serbia.
Supplements are often used to prevent the development of osteoporosis, a bone loss disease, says Dušan Veljković.
It is "necessary" for humans, and "more and more evidence" indicates that animals and some plants also need it, adds Michael Ingleson.
Taniborbactam, an innovative drug with wrinkles, "is currently scientists' best hope in the fight against antibiotic resistance," says Ingleson.
But, "it is difficult to give a complete answer" about whether exposure to boron has negative effects on the human body.
Boric acid (H3BO3), one of the most common compounds of this metalloid, is a real example of this, because it is as harmful to humans as table salt, i.e. sodium chloride, says a British scientist.
"Pine, as well as salt, can make us seriously ill if we take huge amounts into the body.
"There are other esoteric boron compounds that are more toxic, but they are obtained by processing in laboratories and are not similar to the minerals from the Earth's crust, from which boron is most often obtained," says the inorganic chemistry expert.
Scientific research also showed that excessive intake of boron can lead to disruption of the endocrine system and a negative effect on fertility in rodents and dogs.
"This has not been proven in humans, but it has been in warm-blooded animals, which is a pretty good indicator that the same would probably happen in humans," says Veljković.
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Bor in the legislation of Serbia
The maximum allowed concentration of boron is not defined by the Regulation on limit values of polluting, harmful and dangerous substances in the soil from 2018, i.e. the amendments to this document from 2019.
This was pointed out by a group of Serbian scientists in the paper "Impact of exploitation activities of a potential lithium mine on the environment of Western Serbia". published in Sajentifik reports, a newspaper under the aegis of Nejčr magazine.
Since 2019, when the Rulebook on the hygienic suitability of drinking water was amended, the maximum concentration of boron in drinking water is one milligram per liter.
Before the change, in the rulebook from 1999, it was three times lower - 0,3 milligrams per liter.
By raising the maximum allowed limit, this act is "aligned with the recommendations of the World Health Organization, which were also introduced in the directives of the European Union," says Veljković.
"It is absolutely certain that the amount of one milligram per liter, which is the maximum allowed and will not be present in all sources of drinking water, cannot cause any serious health problems in the human body.
"I assume that the main reason for changing the WHO and EU directives is to increase the availability of drinking water to as many people as possible, because you would not be able to meet the requirements for that with overly restrictive rules," adds the professor of the Faculty of Chemistry.
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