Deuterium-depleted water
Encyclopedia
Deuterium-depleted water (DDW), or "light water", is water
which has a lower concentration than naturally occurs of deuterium
, a heavier isotope
of hydrogen
which has, in addition to its one proton, a neutron, roughly doubling its mass.
In Vienna Standard Mean Ocean Water, deuterium occurs at a rate of 155.76 ppm. The production of heavy water
involves isolating deuterium and produces light water as a by-product. Production of light water can result during electrolysis
, distillation
, and desalination
. It can also be produced directly using the Girdler sulfide process
.
Experiments have shown that consumption of light water may be beneficial as an adjunct to chemotherapy
. A 1999 Romanian study found that water with only 30ppm deuterium produced marked improvement in survival rates of mice bombarded with ionizing radiation. A study of four patients with brain metastases from lung cancer found a three-month regimen of light water "noticeably prolonged" their survival time. A 2010 Hungarian study found significant improvement in the survival times of prostate cancer patients treated with light water. Despite Gilbert Lewis' call in 1934 for such experiments, research on the effects of deuterium-depletion on living cells has been very limited with less than a dozen peer-reviewed research papers available via Pub Med in mid-2011. On the other hand, low doses of heavy water can slow the aging process by helping the body resist oxidative damage via the isotope effect
.
s, thermal reactors using normal water are known as light water reactors. Thus "light water" is sometimes used to describe standard water
.
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
which has a lower concentration than naturally occurs of deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
, a heavier isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
which has, in addition to its one proton, a neutron, roughly doubling its mass.
In Vienna Standard Mean Ocean Water, deuterium occurs at a rate of 155.76 ppm. The production of heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...
involves isolating deuterium and produces light water as a by-product. Production of light water can result during electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
, distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
, and desalination
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
. It can also be produced directly using the Girdler sulfide process
Girdler sulfide process
The Girdler sulfide process, also known as the Geib–Spevack process, is an industrial production method for making heavy water , an important component of many nuclear reactors because it acts as a neutron moderator. It takes its name from Karl-Hermann Geib and Jerome S...
.
Experiments have shown that consumption of light water may be beneficial as an adjunct to chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
. A 1999 Romanian study found that water with only 30ppm deuterium produced marked improvement in survival rates of mice bombarded with ionizing radiation. A study of four patients with brain metastases from lung cancer found a three-month regimen of light water "noticeably prolonged" their survival time. A 2010 Hungarian study found significant improvement in the survival times of prostate cancer patients treated with light water. Despite Gilbert Lewis' call in 1934 for such experiments, research on the effects of deuterium-depletion on living cells has been very limited with less than a dozen peer-reviewed research papers available via Pub Med in mid-2011. On the other hand, low doses of heavy water can slow the aging process by helping the body resist oxidative damage via the isotope effect
Isotope effect
Isotope effect can refer to:* Kinetic isotope effect* Magnetic isotope effect* Superconductive transition temperature varying by isotope atomic weight; See BCS theory#Successes of the BCS theory...
.
Other uses
In nuclear reactor technology, by comparison with heavy water reactorHeavy water reactor
A pressurised heavy water reactor is a nuclear power reactor, commonly using unenriched natural uranium as its fuel, that uses heavy water as its coolant and moderator. The heavy water coolant is kept under pressure in order to raise its boiling point, allowing it to be heated to higher...
s, thermal reactors using normal water are known as light water reactors. Thus "light water" is sometimes used to describe standard water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
.