Chemical isotopes are radioactive. Medical search. Frequent questions

Stable isotopes of carbon (δ13C), sulfur (δ34S), oxygen (δ18O), hydrogen (δ2H), nitrogen (δ15N), and radioactive isotope of hydrogen (tritium) have been applied in combination with conventional techniques (chemical) to investigate Karachi coastal water pollution due to Layari and Malir rivers, which mainly carry the domestic and industrial wastewater of Karachi Metropolitan. (intechopen.com)
The book I selected was Geochemistry of Non-traditional Stable Isotopes , a fascinating little volume that I imagine I'll read cover-to-cover before the year's end. (skepchick.org)
I started reading Geochemistry of Non-Traditional Stable Isotopes for my research paper on lithium isotopes, but I've found myself reading bits and pieces of the other sections of the book as well. (skepchick.org)
This little book on stable isotopes is opening my eyes to how recent developments mass spectrometry are revolutionizing isotope geochemistry. (skepchick.org)
There are two stable isotopes of chlorine: Chlorine-35 (which weighs 34.97 amu) and Chlorine-37 (which weighs 36.97 amu). (onlinemathlearning.com)

Radioactive decay is the process in which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state. (cdc.gov)
Half-life is the length of time it takes for half of the radioactive atoms of a specific radionuclide to decay. (cdc.gov)
This process is called radioactive decay. (cdc.gov)
The discovery of the natural radioactive decay of uranium in 1896 by Henry Becquerel, the French physicist, opened new vistas in science. (usgs.gov)
If there is no stable isotope, choose the one with the longest decay time. (oeis.org)
Isotope notation is particularly important in nuclear chemistry, because if you're doing fission, fusion, alpha decay, beta decay, positron emission, or electron capture, you want to be able to tell how many neutrons and protons are in the nucleus. (onlinemathlearning.com)
Some of this residual energy after radioactive decay can be emitted in the form of high-frequency electromagnetic radiation, called gamma rays. (ieer.org)
[1] It should be noted that the emission of gamma rays does not change the mass number or atomic number of the nucleus - that is, unlike radioactive decay by emission of particles, spontaneous fission, or electron capture, it does not cause the transmutation of the nucleus into another element. (ieer.org)

Radioactive atoms give off one or more of these types of radiation to reach a more stable state. (cdc.gov)
These atoms can become radioactive. (cdc.gov)
If you start with 100 atoms, after one half-life you'll have 50 radioactive atoms. (cdc.gov)
After two half-lives, you'll have 25 radioactive atoms. (cdc.gov)
And after a third half-life, you'll have 12 radioactive atoms. (cdc.gov)
Then 6, then 3, then 1, until eventually, all of the radioactive atoms in that population will reach their more stable state. (cdc.gov)
But in the process, several types of radioactive atoms are generated. (cdc.gov)
Although the atomic theory of matter, in its various forms, existed a good two thousand years before the time of John Dalton (1766 - 1844), he was the first to propose, in his 1808 book A New System of Chemical Philosophy , that atoms had weight. (encyclopedia.com)
A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound . (wikidoc.org)
For molecular compounds , it identifies each constituent element by its chemical symbol and indicates the number of atoms of each element found in each discrete molecule of that compound. (wikidoc.org)
If there were a double bond between the carbon atoms (and thus each carbon only had two hydrogens), the chemical formula may be written: CH 2 CH 2 , and the fact that there is a double bond between the carbons is assumed. (wikidoc.org)
Isotopes are atoms of the same element that have different number of neutrons. (onlinemathlearning.com)
Some of the atoms of certain isotopes are unstable because of the extra number of neutrons, and they are said to be radioactive. (onlinemathlearning.com)
Learn how to write atoms in isotope notation! (onlinemathlearning.com)
The term derives from the tendency to periodicity of chemical properties deriving from arrangements of electrons in atoms. (ieer.org)

It is important to distinguish between radioactive material and the radiation it gives off. (cdc.gov)
However Geiger counters cannot differentiate between different types of ionizing radiation or identify the isotope producing the radiation1. (academicediting.org)
Naturally occurring sources of radiation are cosmic radiation from space or radioactive materials in soil or building materials. (cdc.gov)
Each radioactive element, including strontium, constantly gives off radiation, and this process changes it into an isotope of another element or a different isotope of the same element. (cdc.gov)
What we do know is experiments involved electro-shock treatment, sensory deprivation, sleep deprivation, administration of psychoactive drugs, psychosurgery, the effects of radiation, the testing of chemicals and biological weapons on American city, streets, "brainwashing" and "mind control", interrogation and torture techniques. (opednews.com)
External Radiation hazard) of by breathing in the radioactive material ( Internal Radiation hazard). (ionactive.co.uk)
NDT is a process where an article is "tested", and in the case of industrial radiography uses ionising radiation (via a radioactive source, x-ray tube or accelerator) to form an image on radiation sensitive film or real time imaging systems, to detect potential or actual defects. (ionactive.co.uk)
With respect to Radiation Protection , ingestion describes one possible mode by which Radioactive materials may enter the body and therefore present an Internal Radiation protection hazard. (ionactive.co.uk)
With respect to Radiation Protection , injection describes a route by which Radioactive materials may enter the body - thus presenting an Internal Radiation hazard. (ionactive.co.uk)
The internal radiation (hazard) exists where radioactive materials enter the body. (ionactive.co.uk)
The actual radiation dose delivered will depend on the radioactive nature of the material (its half-life and principal emitters) and its physical and chemical properties (its particle size and the biological half-life ). (ionactive.co.uk)
If radioactive isotopes are left inside the person they will of course continue to emit radiation. (healthengine.com.au)
Radiotherapy is delivered either by external beam radiation, which is similar to the way an x-ray is taken (however in much stronger doses) by the insertion of radioactive implants ( brachytherapy ) or via isotope therapy . (healthengine.com.au)
These nuclei are radioactive, in that they emit energy and particles, collectively called "radiation. (ieer.org)
Depleted uranium has several peaceful applications: as counterweights or ballast in aircraft, radiation shields in medical equipment used for radiation therapy and containers for the transport of radioactive materials. (who.int)
Ionizing radiation is emitted by radioactive elements and by equipment such as x-ray and radiation therapy machines. (msdmanuals.com)
The Monographs programme has since been expanded to include consideration of exposures to complex mixtures of chemicals (which occur, for example, in some occupations and as a result of human habits) and to environmental agents of other kinds, such as infectious agents and various forms of radiation. (who.int)

Uranium is a naturally occurring radioactive element, which has the atomic number of 92 and corresponds to the chemical symbol U in the periodic table. (iaea.org)
Like all other actinides, uranium is "radioactive" - it decays over time and releases energy in the process. (iaea.org)
Just like any other element, uranium comes in several variations that differ in mass and physical properties but share the same chemical properties. (iaea.org)
What are the different isotopes of uranium? (iaea.org)
U-238 makes up over 99% of the 3 naturally occurring isotopes of uranium on Earth. (iaea.org)
There are three natural isotopes of uranium - uranium-234 (U-234), uranium-235 (U-235) and uranium-238 (U-238). (iaea.org)
Most nuclear reactors use fuels containing U-235, however, natural uranium typically contains only 0.72 per cent of U-235 and, most reactors need a higher concentration of this isotope in their fuel. (iaea.org)
The study of radioactive isotope systems, such as potassium-argon and uranium-thorium, can also be used in the dating of rocks and archaeological samples. (skepchick.org)
This scientific review on depleted uranium is part of WHO's continuing process of assessment of possible health effects of exposure to chemical, physical and biological agents. (who.int)
Information is given on sources of depleted uranium exposure, the likely routes of acute and chronic intake, the potential health risks from both the radiological and chemical toxicity standpoints and future research needs. (who.int)
Uranium is a naturally occurring, ubiquitous, heavy metal found in various chemical forms in all soils, rocks, seas and oceans. (who.int)
In these conditions another uranium isotope, 236U, may be present together with very small amounts of the transuranic elements plutonium, americium and neptunium and the fission product technetium-99. (who.int)

Basically, a mass spectrometer uses electric and magnetic fields to separate isotopes and measure their ratios and concentrations. (skepchick.org)
Among those physical agents considered suitable for evaluation by the Monographs, and assigned high priority at that time, were electric and magnetic fields, the radioactive isotope iodine-131, and radioactive wastes. (who.int)

For those of you who need a quick review, isotopes of an element are produced because of differences in the numbers of protons and neutrons in the nucleus. (skepchick.org)
is an isotope of chlorine that has 17 protons and 18 neutrons. (onlinemathlearning.com)
is an isotope of chlorine that has 17 protons and 20 neutrons. (onlinemathlearning.com)
Isotopes are versions of an atom or an element that have the same number of protons, but different numbers of neutrons. (onlinemathlearning.com)
In isotope notation, you can quickly show how many protons, neutrons, and electrons are in an atom. (onlinemathlearning.com)

Many physical, chemical, and biological processes can lead to isotopic fractionation. (skepchick.org)
Global and Local Silicon Cycling, Stable and Radioactive Si Isotopes, Natural Abundance and Isotopic Fractionation of Si, Production and Dissolution of Biogenic Silica, Reverse Weathering Processes, Silica Authigenesis, Pore Water Systems and Sediment Sorption Capacities. (lu.se)

A total of 500 different chemical constituents were identified, including metals, pesticides, fertilizers, and radionuclides (radioactive isotopes). (sciencealert.com)

However, it was suggested that a so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like ions of the same isotope can be used to cancel nuclear structure effects and provide an accurate test of QED [Shabaev et al. (fnal.gov)

Naturally occurring erbium is a mixture of six isotopes, all of whichare stable. (physlink.com)
NORM will always contain a mixture of different isotopes, each with varying degrees of intensity and composition. (unitednuclear.com)
Hydraulic fracturing involves the pressurized injection of a mixture of water, chemicals, and sand in underground formations to allow natural gas and oil to flow more freely from rock pores to the surface. (watershedcouncil.org)

Here, we evaluate the origin of plutonium using high-precision isotope measurements, investigate the impact of water column geochemistry on plutonium cycling during different stratification periods, and re-evaluate long-term mass balance of plutonium in the pond. (bvsalud.org)

Cox regression analyses were conducted to further evaluate the relation between chemical exposure and mortality risk due to selected cancers. (cdc.gov)
It was also under her personal direction that the world's first studies were conducted to treat neoplasms ("cancers") using radioactive isotopes. (listverse.com)
For example the implantable radioactive isotope wires Iridium-192 can be implanted into cancers of the tongue. (healthengine.com.au)
Caesium-137 is another example of an implantable radioactive isotope used in the treatment of uterine or vaginal cancers in conjunction with other therapies, i.e. chemotherapy . (healthengine.com.au)

The elements americium and curium, members of the radioactive actinides, are very similar to the lanthanides when it comes to key chemical properties such as size and charge. (sciencedaily.com)
The ability of the bacteria to incorporate radioactive actinides is also interesting with respect to potential applications: "Methylotrophic bacteria could potentially be used in bioremediation or in the separation and recycling of lanthanides and actinides. (sciencedaily.com)

All four isotopes behave the same chemically, so any combination of the four would have the same chemical effect on your body. (cdc.gov)
You are isotopes behave the same chemically, so any exposed to a substance only when you come in combination of the four would have the same contact with it. (cdc.gov)
Generally, isotopes behave the same way during chemical reactions. (onlinemathlearning.com)

In these lessons, we will learn about Isotopes, Isotope Notation, Atomic Mass Unit (amu), and how to calculate the Atomic Mass of an element. (onlinemathlearning.com)
The following diagrams show the isotopes of chlorine and how to calculate the relative atomic mass. (onlinemathlearning.com)
How do you determine and calculate isotope abundance when you know the relative atomic mass (also known as atomic weight), as measured in amu or atomic mass numbers? (onlinemathlearning.com)
If the relative atomic mass of chlorine is 35.45, what is the abundance of each isotope? (onlinemathlearning.com)

Man-made sources of radioactive materials are found in consumer products, industrial equipment, atom bomb fallout, and to a smaller extent from hospital waste and nuclear reactors. (cdc.gov)
A becquerel is the amount strontium is extracted from strontium ore, it is of radioactive material in which 1 atom transforms concentrated into strontium carbonate or other every second. (cdc.gov)
If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol (although 19th-century books often used superscripts). (wikidoc.org)
In chemistry , the empirical formula of a chemical is a simple expression of the relative number of each type of atom or ratio of the elements in the compound. (wikidoc.org)

This book is basically about all the new types of stable isotope systems (lithium, magnesium, zinc, selenium, et cetera) that are now able to be studied because of recent advances in mass spectrometry. (skepchick.org)

Studying ratios of both stable and radioactive isotopes can provide important constraints on these processes. (skepchick.org)

organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or of isotopes. (wcoomd.org)

90 Sr, or strontium ninety, is the most hazardous of the radioactive isotopes of the chemical element strontium. (cdc.gov)
Mass number of the most abundant isotope of the element with atomic number Z = n. (oeis.org)
She named the first new chemical element that she discovered (1898) "polonium" for her native country, and in 1932 she founded a Radium Institute in her hometown Warsaw, headed by her physician-sister Bronisława Dłuska. (listverse.com)
The term empirical refers to the process of elemental analysis , a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element. (wikidoc.org)
The USGS team referred back to a 2021 study of an aquifer in southern New Jersey: it linked an increase in the carcinogenic chemical element radium with the growing use of road salts in the area. (sciencealert.com)
Thus, isotopes of an element have slightly different masses that can lead to small, but important, differences in the behavoir of an element. (skepchick.org)
You put the atomic number, mass number, and net charge around the chemical element symbol. (onlinemathlearning.com)
This quantity takes into account the percentage abundance of all the isotopes of an element which exist. (onlinemathlearning.com)
The neon element has three isotopes. (onlinemathlearning.com)
It is a weighed average of the different isotopes of an element. (onlinemathlearning.com)

Here we will go through the algebra and reasoning to figure out the amount of abundances of the isotopes, in percentages and in decimals. (onlinemathlearning.com)

Radioactive tracers. (umt.edu)
Tracers that may be labeled include chemical substances, cells, or microorganisms. (bvsalud.org)

However, beta particles carry enough energy to cause burns on exposed skin and present an internal hazard if we breathe or eat beta-emitting radioactive material or if the radioactive material is introduced through an open wound. (cdc.gov)
Gamma rays also can be an internal hazard if we breathe or eat gamma-emitting radioactive materials, or if the radioactive material is introduce through an open wound, but the damage they do to cells inside our bodies is not as severe as that done by alpha and beta particles. (cdc.gov)

Made from Naturally Occuring Radioactive Material (NORM) which features a wide range of isotopes. (unitednuclear.com)
A: Each test card is made from Naturally Occuring Radioactive Material (NORM). (unitednuclear.com)

Although isotopes are more relevant to nuclear chemistry or stable isotope chemistry than to conventional chemistry, different isotopes may be indicated with a left-hand superscript in a chemical formula. (wikidoc.org)
Isotopes and isotope notation are particularly important in nuclear chemistry. (onlinemathlearning.com)

You can also find customs duty rates applicable for importing of "radioactive chemical elements and radioactive isotopes" into the USA and the European Union Countries . (findhs.codes)
Her achievements include creating a theory of radioactivity (a term coined by her), techniques for isolating radioactive isotopes, and the discovery of two new elements: radium and polonium. (listverse.com)
Bacteria can use certain radioactive elements to sustain their metabolism. (sciencedaily.com)
A team led by LMU chemist Lena Daumann has demonstrated for the first time that bacteria can use certain radioactive elements to sustain their metabolism. (sciencedaily.com)
It turns out, however, that they are not as irreplaceable as previously thought, as an international and interdisciplinary team led by Professor Lena Daumann from the Department of Chemistry at LMU has demonstrated: Certain bacteria can use the radioactive elements americium and curium instead of the lanthanides -- and even prefer them sometimes. (sciencedaily.com)
We could thus show for the first time that organisms can use these radioactive elements for life processes," emphasizes Daumann. (sciencedaily.com)
All elements have at least some isotopes that are radioactive. (ieer.org)
All isotopes of heavy elements with mass numbers greater than 206 and atomic numbers greater than 83 are radioactive. (ieer.org)

After the strontium is extracted from strontium ore, it is concentrated into strontium carbonate or other chemical forms by a series of chemical processes. (cdc.gov)
One curie is the amount of chemical forms by a series of chemical processes. (cdc.gov)
To single out an isotope would require extensive analysis and chemical processes that would drive the price of each card well above $100. (unitednuclear.com)

Laboratory tests conducted for EWG at one of the country's leading water quality laboratories found that 10 popular brands of bottled water, purchased from grocery stores and other retailers in 9 states and the District of Columbia, contained 38 chemical pollutants altogether, with an average of 8 contaminants in each brand. (ewg.org)

A dedicated material surface treatment procedure in combination with cleanroom facilities optimized for storage and detector assembly were developed in order to mitigate radioactive surface contamination. (springer.com)
Despite the oppressive weather, a small group of residents had gathered at the community center for a workshop on bioremediation, basically how to remove chemical contamination from their land and water. (motherjones.com)
Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. (who.int)

Terrorist use of radioactive nuclear materials via nuclear and/or radiological dispersion devices (dirty bombs) is a serious threat. (sbir.gov)
This is insignificant with respect to both chemical and radiological toxicity. (who.int)

Organic chemicals. (wcoomd.org)

Possible reasons will be discussed and ways to further investigate this puzzle by laser spectroscopy on radioactive species will be discussed. (fnal.gov)

The longest living isotope is is 257 Fm with a half-life of 80 days. (webelements.com)

The mass numbers (once also referred to as the isotope numbers) are always integer, and should not be confused with relative atomic masses (or isotope masses), nor with (mean) atomic weights, none of which are ever integer. (oeis.org)

Phosphorus and arsenic share many chemical properties. (citizendium.org)
Heredity, and the development, organization, and function of living cells, all depend on the physical and chemical properties of the molecules involved. (todayinsci.com)
Fermium's chemical properties are largely unknown. (webelements.com)

The program was developed for the covert use of biological and chemical materials" for the control of human behavior. (opednews.com)
Prior to that, he was at the Laboratory Response Network as a biological and chemical threat coordinator, biosafety officer, and select agent responsible official with the Oregon State Public Health Laboratory. (cdc.gov)

In 1969, the International Agency for Research on Cancer (IARC) initiated a programme to evaluate the carcinogenic risk of chemicals to humans and to produce monographs on individual chemicals. (who.int)
With Supplement 6 (IARC, 1987a), the title of the series was modified from IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans to IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, in order to reflect the widened scope of the programme. (who.int)

Long term we envision a collection of porphyrinoid nanoparticles each with a unique selectively for an isotope of interest as a means of detecting the presence of a specific radio-hazard. (academicediting.org)

The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. (cdc.gov)
tracer , detectable substance added to a chemical, biological, or physical system to follow its process or to study distribution of the substance in the system. (britannica.com)
Techniques for labeling a substance with a stable or radioactive isotope. (bvsalud.org)

Statements about hazardous substances and their or radioactive materials in soil or building materials. (cdc.gov)
Man-made sources of radioactive materials are also available. (cdc.gov)
Typical concentrations in how much a radioactive material decays every most materials are a few parts per million (ppm). (cdc.gov)
Injection routes can obviously occur where needles are used to handle or administer radioactive materials, but may also be present where any sharp object is contaminated with radioactive materials which then causes a wound. (ionactive.co.uk)
Produced in the decays of residual $^{226}$ Ra, which is present in nearly all materials, the radioactive noble gas $^{222}$ Rn might be released into the LXe target. (springer.com)
Grout materials are commonly used to immobilize low-level radioactive waste. (bvsalud.org)

carbon-12) isotope. (onlinemathlearning.com)

Twenty minutes later, you have constrained the chemical and isotopic composition of your sample. (skepchick.org)

Even if biomolecules self-assembled into cellular organization, that would not produce life because life requires non-equilibrium chemical reactions. (grisda.org)
They were indestructible and preserved their identities in all chemical reactions. (encyclopedia.com)

Natural strontium is not radioactive and exists in four stable types (or isotopes), each of which can be written as 84 Sr, 86 Sr, 87 Sr, and 88 Sr, and read as strontium eighty-four, strontium eighty-six, etc. (cdc.gov)

A chemical formula supplies information about the types and spatial arrangement of bonds in the chemical, though it does not necessarily specify the exact isomer . (wikidoc.org)

A NIOSH case-control study is underway to examine more closely the relation between multiple myeloma and a variety of chemical exposures among workers employed at the Oak Ridge K-25 facility. (cdc.gov)

More than one-third of the chemicals found are not regulated in bottled water. (ewg.org)
Also in Walmart's Sam's Choice brand, lab tests found a cancer-causing chemical called bromodichloromethane at levels that exceed safety standards for cancer-causing chemicals under California's Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65, OEHHA 2008). (ewg.org)
Ruthenium-106 is a radioactive isotope that is not found in nature. (kpbs.org)

Douglas Dean Osheroff is an American physicist who shared with David M. Lee and Robert Richardson ) was the corecipient of the 1996 Nobel Prize for Physics for their discovery of superfluidity in the isotope helium-3. (todayinsci.com)

These workshops are a regular occurrence here and broach topics like isotope analysis, well testing techniques, and the best ways to navigate the political machinations between oversight organizations. (motherjones.com)

OBJECTIVE: This study evaluates the mortality experience of 6,157 chemical laboratory workers employed at United States Department of Energy facilities. (cdc.gov)

However, they can be very damaging to cells inside our bodies if we breathe or eat alpha-emitting radioactive material or if the radioactive material is introduced through an open wound. (cdc.gov)
Inhalation can occur where the radioactive material is airborne, volatile or being processed in such a way as to make the inhalation route possible. (ionactive.co.uk)
European authorities are providing new details about a cloud of mysterious radioactive material that appeared over the continent last month. (kpbs.org)
Gariel says that while Mayak is a possible source of the cloud, there simply aren't enough data to conclusively link it to the release of radioactive material. (kpbs.org)

For example, technetium-99m, one of the most common medical isotopes used for imaging studies, has a half-life of 6 hours. (cdc.gov)
half-life of most stable known isotope, 223Fr, is 21.8 min. (theodora.com)

The studies were performed on behalf of Dow Chemical Company, the U.S. Army, and Johnson & Johnson. (opednews.com)
He said the Army wanted him to become a chemical weapons specialist, but he chose to join the infantry. (motherjones.com)

1987. pp. 59-61 Radioactive Waste Management Associates on behalf of Alliance for Nuclear Accountability. (wikipedia.org)

Detrimental sources of background are the primordial isotopes $^{232}$ Th, $^{238}$ U, $^{235}$ U, $^{40}$ K and their progeny, as well as $^{60}$ Co and $^{137}$ Cs. (springer.com)
Singular Isotope sources are also available if desired. (unitednuclear.com)

A cohort mortality study of chemical laboratory workers at Department of Energy Nuclear Plants. (cdc.gov)

Anatomy7

Organisms6

Diseases2

Chemicals and Drugs92

Analytical, Diagnostic and Therapeutic Techniques and Equipment47

Psychiatry and Psychology3

Phenomena and Processes65

Disciplines and Occupations14

Anthropology, Education, Sociology and Social Phenomena8

Technology, Industry, Agriculture4

Humanities1

Information Science6

Health Care18

Geographicals2

Stable isotopes5

Decay8

Atoms15

Radiation17

Uranium12

Electric and magnetic fields2

Neutrons5

Isotopic fractionation2

Radionuclides1

Hydrogen1

Mixture3

Geochemistry1

Cancers4

Actinides2

Behave3

Atomic mass4

Atom4

Advances1

Ratios1

Rare-earth1

Element10

Abundances1

Tracers2

Beta Particles2

Naturally2

Nuclear chemistry2

Elements8

Processes3

Contaminants1

Contamination3

Radiological2

Organic1

Investigate1

Longest1

Masses1

Properties3

Biological and chemical2

Carcinogenic2

Hazard1

Substance3

Materials6

Carbon1

Composition1

Reactions2

Natural1

Types1

Exposures1

Found3

Discovery1

Techniques1

United States1

Material4

Half-life2

Army2

Behalf1

Sources2

Study1