Krypton is present in the air at about 1 ppm. The atmosphere of Mars contains a little (about 0.3 ppm) of krypton. It is characterised by its brilliant green and orange spectral lines. The spectral lines of krypton are easily produced and some are very sharp. In 1960 it was internationally agreed that the fundamental unit of length, the metre, should be defined as 1 m = 1,650,763.73 wavelengths (in vacuo) of the orange-red line of Kr-33.
Under normal conditions krypton is colourless, odourless, fairly expensive gas. Solid krypton is a white crystalline substance with a face-centered cubic structure which is common to all the “rare gases”. Krypton difluoride, KrF2, has been prepared in gram quantities and can be made by several methods. Other compounds are unstable, unless isolated in a matrix at very low temperatures.
Applications
Krypton is used to fill electric lamp bulbs which are filled with a mixture of krypton and argon, and for various electronic devices. Krypton is also used in photographic projection lamps, in very high-powered electric arc lights used at airports and in some strobo-lamps, because it has an extremely fast respons to an electric current.
A mixture of stable and unstable isotopes of krypton is produced by slow neutron fission of uranium in nuclear reactors as Kripron-85, its most stable isotope. It is used to detect leaks in sealed containers, to excite phosphors in light sources with no external source of energy, and in medicine to detect abnormal heart openings.
Krypton in the environment
Krypton might be one of the rarest gases in the atmosphere, but in total there are more than 15 billion tonnes of this metal circulating in the planet, of which only about 8 tonnes a year are extracted, via liquid air.
Health effects of krypton
Inhalation: This gas is inert and is classified as a simple asphyxiant. Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. Death may result from errors in judgment, confusion, or loss of consciousness which prevent self-rescue. At low oxygen concentrations, unconsciousness and death may occur in seconds without warning.
The effect of simple asphyxiant gases is proportional to the extent to which they diminish the amount (partial pressure) of oxygen in the air that is breathed. The oxygen may be diminished to 75% of it’s normal percentage in air before appreciable symptoms develop. This in turn requires the presence of a simple asphyxiant in a concentration of 33% in the mixture of air and gas. When the simple asphyxiant reaches a concentration of 50%, marked symptoms can be produced. A concentration of 75% is fatal in a matter of minutes.
Symptoms: The first symptoms produced by a simple asphyxiant are rapid respirations and air hunger. Mental alertness is diminished and muscular coordination is impaired. Later judgment becomes faulty and all sensations are depressed. Emotional instability often results and fatigue occurs rapidly. As the asphyxia progresses, there may be nausea and vomiting, prostration and loss of consciousness, and finally convulsions, deep coma and death.
Environmental effects of krypton
Krypton is a rare atmospheric gas and as such is non-toxic and chemically inert. The extreme cold temperature (-244oC) will freeze organisms on contact, but no long term ecological effects are anticipated.
Molybdenum
Molybdenum is classified as a metallic element and found widely in nature in nitrogen-fixing bacteria. Molybdenum is essential in trace amounts for human, animal and plant health. In humans and animals, molybdenum serves mainly as an essential cofactor of enzymes and aids in the metabolism of fats and carbohydrates. Humans need only very small amounts of molybdenum, which are easily attained through a healthy diet. Deficiency is very rare in humans, so molybdenum supplements are rarely needed.
Why is it necessary?
The main known function of molybdenum in humans is to act as a catalyst for enzymes and to help facilitate the breakdown of certain amino acids in the body. Molybdenum combines with sulfite oxidase to catalyze sulfur-containing amino acids that are crucial for human health. Although cases of molybdenum deficiency are rare, signs of deficiency include defects in uric acid production as well as decreased metabolism of sulfur-containing amino acids. Epidemiologic evidence also suggests that populations living in areas where the soil has little molybdenum are at a greater risk of esophageal cancers. The only confirmed, documented cases of molybdenum deficiency come from studies of people with inborn errors of metabolism involving sulfite oxidase. Two forms of sulfite oxidase deficiency are known: isolated sulfite oxidase deficiency and molybdenum cofactor deficiency. Both types result in neurologic damage and are extremely rare.
How much, and what kind, does an adult need?
The Recommended Dietary Allowance (RDA) of molybdenum for men and women is 45 mcg (μg – micrograms) a day. On average, American adult males have a daily intake of about 109 mcg of molybdenum while women have a daily intake of about 76 mcg, well above the recommended amount. The RDA for pregnant women and breastfeeding women is 50 mcg. The risk of toxicity of molybdenum in humans from food sources is very low. The tolerable upper intake level (UL) for adults is 2 mg a day and occurs only through careless supplementation.
How much does a child need?
Infant adequate intake (AI) from birth to six months is 2 mcg and for infants seven to 12 months is 3 mcg, which the infant typically receives easily through the intake of human milk. The RDA for children from ages one to three is 17 mcg, children from four to eight is 22 mcg, children nine to 13 is 34 mcg, and children 14 to 18 years old is 43 mcg.
How do you get enough from foods?
The amount of molybdenum found in foods depends on both the food type and upon the soil in which the food (or fodder) grows. Legumes such as beans, lentils and peas as well cereals and leafy vegetables are considered good sources of molybdenum. Liver is also a good source of molybdenum, but animal products are generally poor sources of the element. In general, the typical America diet contains molybdenum levels well above the Recommended Daily Allowance (RDA).
Are there any risks associated with consuming too much?
Although molybdenum does not have a known toxicity level in humans, taking high concentrations of molybdenum supplements may have adverse effects on copper levels by interfering with its absorption. One study found that high levels of dietary molybdenum, up to 1,500 mcg, caused excessive excretion of copper. However, another study showed no negative effect of excess molybdenum intake via supplements (up to 1,500 mcg per day) on copper levels in humans.
Are there any other special considerations?
Niobium
Niobium is a rare, soft, malleable, ductile, gray-white metal. It has a body-centered cubic crystalline structure and in its physical and chemical properties it resembles tantalum. It must be placed in a protective atmosphere when processed at even moderate temperatures because it tends to react with oxygen, carbon, the halogens,nitrogen, and sulfur. The metal is inert to acids, even to aqua regia at room temperatures, but is attacked by hot, concentrated acids, and expecially by alkalis and oxidizing agents.
Applications
Niobium is used for the production of high-temperature-resistant alloys and special stainless steels. Small amounts of niobium impart greater strenght to other metals, especially those that are exposed to low temperatures. Niobium carbide is used in cutting tools. It is used in stainless steel alloys for nuclear reactors, jets, missiles, cutting tools, pipelines, super magnets and welding rods.
Niobium-tin and niobium-titanium alloys are used as wires for superconducting magnets capable of producing exceedingly strong magnetic fields. Niobium is also used its pure form to make superconducting accelerating structures for particle accelerators. Niobium alloys are used in surgical implants because they do not react with human tissue.
Niobium in the environment
Plants generally show only traces of niobium and many have none at all, although some mosses and lichens can contain 0.45 ppm. However, plant growing near niobium deposits can accumulate the metal to levels above 1 ppm.
Niobium was mined chifely as columbite, and is formerly known as colombium (Cb). Another mined metal is pyrochlore and this is now the most important. The main mining areas are Brazil, which produce more than 85% on the world’s niobium, Zaire, Russia, Nigeria and Canada. World production is around 25.000 tonnes per year. The amount of unmined reserves is not known, but there are extensive deposits of pytochlore.
Health effects of niobium
Niobium and its compounds may be toxic (niobium dust causes eye and skin irritation) , but there are no reports of human being poisoned by it. Apart from measuring its concentration, no research on niobium in humans has been undertaken.
Niobium, when inhaled, is retained mainly in the lungs, and secondarily in bones. It interferes with calcium as an activator of enzyme systems. In laboratory animals, inhalation of niobium nitride and/or pentoxide leads to scarring of the lungs at exposure levels of 40 mg/m3.
Environmental effects of niobium
No negative environmental effects have been reported.
Zirconium
Zirconium is a very strong, malleable, ductile, lustrous silver-gray metal. Its chemical and physical properties are similar to those of titanium. Zirconium is extremely resistant to heat and corrosion. Zirconium is lighter than steel and its hardness is similar to copper. When it is finely divided, the metal can spontaneously ignite in air, especially at high temperatures. Zirconium powder is black and is regarded as very dangerous fire hazard. Zirconium does not dissolve in acids and alkalis.
Applications
Zirconium is used in alloys such as zircaloy, which is used in nuclear applications since it does not readily absorb neutrons. Also used in catalytic converters, percussion caps and furnace bricks. Baddeleyite and impure zirconium (zirconia) are used in lab crucibles.
The major end uses of zircon (ZrSiO4) are refractories, ceramic opacification and foundry sands. Zircon is also marketed as a natural gemstone used in jewelry. The metal also has many other uses, among them in photographic flashbulbs and surgical instruments, to make the glass for television, in the removal of residual gases from electronic vacuum tubes, and as a hardening agent in alloys, especially steel. The paper and packaging industries are finding that zirconium compounds make good surface coatings because they have excellent water resistance and strength.
Zirconium in the environment
Zirconium is not a particularly rare element but because its most common mineral, zircon, is highly resistant to weatering it is only slightly mobile in the environment. Zirconium is more than twice as abundant as copper and zinc and more than 10 times more abundant than lead.
The chief ores are zircon (ZrSiO4), which is mined in Australia, USA and Sri Lanka, and baddeleyite (Zirconium oxide ZrO2) which is mined in Brasil. World production is in excess of 900.000 tonnes per year of zircon, and 7000 tonnes of the metal are produced. The estimated reserves exceed a billion tonnes. Australia, South Africa, India, Sri Lanka and the USA have vast deposits of zircon and zirconia sands.
Health effects of zirconium
Zirconium and its salts generally have low systemic toxicity. The estimated dietary intake is about 50 microg. Most passes through the gut without being adsorbed, and that which is adsorbed tends to accumulate slightly more in the skeleton than in tissue.
Zirconium 95 is one of the radionuclides involved in atmospheric testing of nuclear weapons. It is among the long-lived radionuclides that have produced and will continue to produce increased cancers risk for decades and centuries to come.
Environmental effects of zirconium
Zirconium is unlikely to present a hazard to the environment.
While aquatic plants have a rapid uptake of soluble zirconium, land plants have little tendency to adsorb it, and indeed 70% of plants that have been tested showed no zirconium to be present at all.
Yttrium
Yttrium is a highly crystalline iron-gray, rare-earth metal. Yttrium is fairly stable in air, because it is proteced by the formation by the formation of a stable oxide film on its surface, but oxidizes readily when heated. It reacts with water decomposing it to release hydrogen gas, and it reacts with mineral acids. Shavings or turnings of the metal can ignite in air when they exceed 400 °C. When yttrium is finely divided it is very unstable in air.
Applications
The largest use of the element is as its oxide yttria, Y2O3, which is used in making red phosphors for color television picture tubes. Yttrium metal has found some use alloyed in small amounts with other metals and It is used to increase the strength of aluminium and magnesium alloys. When added to cast iron it make the metal more workable. Although metals are generally very good at conducting heat, there is an alloy of yttrium with chromium and aluminium which is heat resistant. Yttrium oxide in glass makes it heat- and shock-resistant, and is used for camera lenses. Yttrium oxide is suitable to making superconductors, which are metal oxides which conduct electricity without any loss of energy.
Yttrium in the environment
Yttrium never occurs in nature as a free element. It is found in almost all rare earth minerals and in uranium ores. The yellow-brown ore xenotime can contain as much as 50% yttrium phophate (YPO4) and is mined in Malaysia. Yttrium is found in the rare-earth mineral monazite, of which it makes 2.5%, and in smaller quantities in other minerals such as barnasite, fergusonite and smarskite. The output of yttrium is about 600 tonnes per year, measured as yttrium oxide, and world reserves are estimated to be around 9 million tonnes.
Health effects of yttrium
Yttrium can rarely be found in nature, as it occurs in very small amounts. Yttrium is usually found only in two different kinds of ores. The use of yttrium is still growing, due to the fact that it is suited to produce catalysers and to polish glass.
Yttrium is mostly dangerous in the working environment, due to the fact that damps and gasses can be inhaled with air. This can cause lung embolisms, especially during long-term exposure. Yttrium can also cause cancer with humans, as it enlarges the chances of lung cancer when it is inhaled. Finally, it can be a threat to the liver when it accumulates in the human body.
Effects of yttrium on the Environment
Strontium
Strontium is a silvery metal found naturally as a non-radioactive element. About 99% of the strontium in the human body is concentrated in the bones.
Several different forms of strontium are used as medicine. Scientists are testing strontium ranelate to see if it can be taken by mouth to treat thinning bones (osteoporosis). Radioactive strontium-89 is given intravenously (by IV) for prostate cancer and advancedbone cancer. Strontium chloride hexahydrate is added to toothpaste to reduce pain in sensitive teeth.
Strontium chloride is the most common form of strontium found in dietary supplements. People use supplements for building bones. But there isn’t much scientific information about the safety or effectiveness of strontium chloride when taken by mouth.
How does it work?
A special form of strontium called strontium ranelate can increase bone formation and prevent bone loss when used in postmenopausal women with osteoporosis. It’s not known if strontium contained in dietary supplements has these effects.
A radioactive form of strontium may kill some cancer cells. This type of strontium is not available in dietary supplements.
There is some interest in using strontium for osteoarthritis because developing research suggests it might boost the formation of collagen and cartilage in joints.
There is also interest in studying strontium for preventing tooth decay because researchers have noticed fewer dental caries in some population groups who drink public water that contains relatively high levels of strontium.
Rubidium
Rubidium is present in the earth’s crust, in seawater, and in the human body. Our body contains about 350 mg. It has not yet been shown to be essential. Chemically, it is like potassium, and in some animals it can replace potassium in certain functions, though this does not seem to be the case in humans. Rubidium can possibly be a potassium antagonist in regard to absorption and utilization, though this needs further investigation.
Rubidium is absorbed easily from the gut, about 90 percent. It is found generally throughout the body, with the least in the bones and teeth; it is not known to concentrate in any particular tissue. Excess rubidium is eliminated mainly in the urine.
Sources: Food sources of rubidium have not been researched very well as yet. Some fruits and vegetables have been found to contain about 35 ppm. Rubidium may also be found in some water sources.
Functions: There are currently no known essential functions of rubidium. In studies with mice, rubidium has helped decrease tumor growth, possibly by replacing potassium in cell transport mechanisms or by rubidium ions attaching to the cancer cell membranes. Rubidium may have a tranquilizing or hypnotic effect in some animals, possibly including humans.
Uses: There are no clear uses for rubidium as yet. Because of its possible tranquilizing effect, it could help in the treatment of nervous disorders or epilepsy.
Deficiency and toxicity: There is no known deficiency or toxicity for rubidium.
Requirements: There is no RDA for rubidium. The average dietary intake may be about 1.5 mg. daily.
Krypton
Krypton is present in the air at about 1 ppm. The atmosphere of Mars contains a little (about 0.3 ppm) of krypton. It is characterised by its brilliant green and orange spectral lines. The spectral lines of krypton are easily produced and some are very sharp. In 1960 it was internationally agreed that the fundamental unit of length, the metre, should be defined as 1 m = 1,650,763.73 wavelengths (in vacuo) of the orange-red line of Kr-33.
Under normal conditions krypton is colourless, odourless, fairly expensive gas. Solid krypton is a white crystalline substance with a face-centered cubic structure which is common to all the “rare gases”. Krypton difluoride, KrF2, has been prepared in gram quantities and can be made by several methods. Other compounds are unstable, unless isolated in a matrix at very low temperatures.
Applications
Krypton is used to fill electric lamp bulbs which are filled with a mixture of krypton and argon, and for various electronic devices. Krypton is also used in photographic projection lamps, in very high-powered electric arc lights used at airports and in some strobo-lamps, because it has an extremely fast respons to an electric current.
A mixture of stable and unstable isotopes of krypton is produced by slow neutron fission of uranium in nuclear reactors as Kripron-85, its most stable isotope. It is used to detect leaks in sealed containers, to excite phosphors in light sources with no external source of energy, and in medicine to detect abnormal heart openings.
Krypton in the environment
Krypton might be one of the rarest gases in the atmosphere, but in total there are more than 15 billion tonnes of this metal circulating in the planet, of which only about 8 tonnes a year are extracted, via liquid air.
Health effects of krypton
Inhalation: This gas is inert and is classified as a simple asphyxiant. Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. Death may result from errors in judgment, confusion, or loss of consciousness which prevent self-rescue. At low oxygen concentrations, unconsciousness and death may occur in seconds without warning.
The effect of simple asphyxiant gases is proportional to the extent to which they diminish the amount (partial pressure) of oxygen in the air that is breathed. The oxygen may be diminished to 75% of it’s normal percentage in air before appreciable symptoms develop. This in turn requires the presence of a simple asphyxiant in a concentration of 33% in the mixture of air and gas. When the simple asphyxiant reaches a concentration of 50%, marked symptoms can be produced. A concentration of 75% is fatal in a matter of minutes.
Symptoms: The first symptoms produced by a simple asphyxiant are rapid respirations and air hunger. Mental alertness is diminished and muscular coordination is impaired. Later judgment becomes faulty and all sensations are depressed. Emotional instability often results and fatigue occurs rapidly. As the asphyxia progresses, there may be nausea and vomiting, prostration and loss of consciousness, and finally convulsions, deep coma and death.
Environmental effects of krypton
Krypton is a rare atmospheric gas and as such is non-toxic and chemically inert. The extreme cold temperature (-244oC) will freeze organisms on contact, but no long term ecological effects are anticipated.
Bromine
Water Purification
One of the major uses of bromine is as a water purifier/disinfectant. Brominated compounds are used for water treatment in swimming pools and hot tubs. They are also used to control algae and bacterial growth in industrial processes.
Agriculture
Bromine compounds are effective pesticides, used both as soil fumigants in agriculture, particularly fruit-growing, and as a fumigant to prevent pests from attacking stored grain and other produce. Significant volumes of world trade in agriculture goods depend on the use of bromine compounds to ensure compliance with mandatory rules on quarantine.
Cars – past and future
In the past, bromine compounds were used in leaded fuel, as a constituent of “anti-knock fluid”. However, this use has declined as lead has gradually been removed from fuel. Bromine compounds are now being tested in batteries for electric cars, designed to produce zero emissions. Such batteries can also be used as electricity storage devices.
Healthcare
A key use of bromine compounds is in the manufacturing of pharmaceuticals. Brominated substances are important ingredients of many over-the-counter and prescription drugs, including analgesics, sedatives, and antihistamines. In fact, bromine compounds are active ingredients in several drugs that treat pneumonia and cocaine addiction. Currently, several drugs containing bromine compounds are undergoing trials for treatment of Alzheimer’s disease and new generations of anti-cancer and AIDS drugs.
Photography
Bromine compounds have a number of applications in photography. Several compounds are used to make the light-sensitive component of a photographic emulsion; without bromine compounds photographs would not capture sufficient light. Other bromine compounds are used as an ingredient in photo development.
Selenium
Selenium is a mineral found in the soil. Selenium naturally appears in water and some foods. While people only need a very small amount, selenium plays a key role in the metabolism.
Why do people take selenium?
Selenium has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage. Evidence that selenium supplements may reduce the odds of prostate cancer has been mixed, but most studies suggest there is no real benefit. Selenium does not seem to affect the risk of colorectal or lung cancer. But beware: selenium also seems toincrease the risk of non- melanoma skin cancer.
Among healthy people in the U.S., selenium deficiencies are uncommon. But some health conditions — such as HIV, Crohn’s disease, and others — are associated with low selenium levels. People who are fed intravenously are also at risk for low selenium. Doctors sometimes suggest that people with these conditions use selenium supplements.
Selenium has also been studied for the treatment of dozens of conditions. They range fromasthma to arthritis to dandruff to infertility. However, the results have been inconclusive.
How much selenium should you take?
The recommended dietary allowance (RDA) includes the total amount of selenium you should get from foods and from any supplements you take. Most people can get their RDA of selenium from food.
In studies to determine if selenium could aid in prostate cancer prevention, men took 200 micrograms daily.
The safe upper limit for selenium is 400 micrograms a day in adults. Anything above that is considered an overdose.
Arsenic
Arsenic gets a bad rap. Sure, it’s a carcinogen, and long-term exposure to high concentrations is a death sentence. But the 2,400-year-old Chinese medicinecould be the key to treating breast cancer, according to a groundbreaking study by University of California, Berkeley researchers.
Scientists from the university’s Arsenic Research Program conducted a massive longitudinal study on women from a region in northern Chile that, for a time, had extraordinarily high levels of arsenic in its drinking water. They found rates of breast cancer dropped by up to 70 percent compared with another region whose water had normal arsenic concentrations. The results were “completely unexpected,” lead author Allan Smith, professor of epidemiology at UC Berkeley and director of the Arsenic Health Effects Research Program, wrote in an email.
Worldwide, breast cancer killed approximately 508,000 women in 2011, accordingto the World Health Organization. It’s the most common form of cancer among women and survival rates range from 90 percent in the United States to 40 percent in low-income countries.
Smith and his lab examined breast cancer data from 1950 to 2010 in the region, which is the world’s driest inhabited place. In 1958, a new piping system was built in its main city, Antofagasta, and as a result, the concentration of arsenic in the drinking water jumped — to more than 80 times the limit recommended by the World Health Organization. An arsenic treatment plant was installed in 1970. Over those 12 arsenic-laden years, breast cancer plummeted by 50 percent and bottomed out at 70 percent over the last five years. (Other studies found that lung, bladder and kidney cancer ran rampant among the same population.) Back at the lab, the team was able to replicate the arsenic effect, apoptosis (also known as cell suicide), in breast cancer cells.
It won’t be the first time arsenic has been deemed cancer-killing, not cancer-ous. After studies in the 1980s, a form of arsenic called arsenic trioxide has been used successfully to treat relapsed promyelocytic leukemia, a rare and often fatal disease. Recently, arsenic trioxide has also been deployed with promising results against basal cell carcinoma (a skin cancer) and medulloblastoma (a brain cancer), both in animals, according to Philip Beachy, a professor of developmental biology at Stanford, who conducted the experiments. Smith’s study goes against the establishment thinking (and dogma) that “a little is bad, so a lot must be worse,” but “based on what we’ve found, it’s not a stretch at all to say arsenic could treat breast cancer,” Beachy told OZY.
Still, further research is needed to know if what happened in Smith’s lab was the same as what happened in Antofagasta. “The connection is not clear, yet,” cautioned Beachy. And since no other major city on Earth has experienced such high levels of arsenic, the findings can’t be corroborated by other populations. “Plausible” and “potential” are the key words here, but they are said with gusto and optimism. Arsenic, anyone?