« September 11th - 2,996 Project | Main | Friday Miscellania - Tennis, Dr. Seuss, Pope, Global Warming »

September 01, 2006



Actually, it would take a lot of heavy water to have any toxic effects. You'd need to replace 25% to 50% of your body water with it. Because it would take a very great deal of heavy water to replace 25% to 50% of a human being's body water (which in turn is 70% of body weight) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. For a poisoning, large amounts of heavy water would need to be ingested without significant normal water intake for many days to produce any noticeable toxic effects (although in a few tests, volunteers drinking large amounts of heavy water have reported dizziness, a possible effect of density changes in the fluid in the inner ear). For example, a 70 kg human containing 50 kg of water and drinking 3 liters of pure heavy water per day, would need to do this for almost 5 days to reach 25% deuteration, and for about 11 days to approach 50% deuteration. Thus, it would take a week of drinking nothing but pure heavy water for a human to begin to feel ill, and 10 days to 2 weeks (depending on water intake) for severe poisoning and death.

So, maybe it could have therapeutic benefits if it isn't overused. There are many drugs that will kill you if overused, but can be medically beneficial when used in controlled amounts.


There is some history about discovery of heavy water and effects of heavy water on organism.
Deuterium (2H), the hydrogen isotope with nuclear mass 2, was discovered by Urey. In the years immediately following this discovery, there developed a keen interest in development of methods for uniform biological enrichment of a cell with deuterium, that may be best achived via growing of an organism on medium with high content of heavy water (99% of deuterum), which since yet resulted in a miscellany of rather confusing data (see as an example Katz J., Crespy H. L. 1972).
The main resolute conclusion that can be derived from the most competent and comprehensive of the early studies is that high concentrationsof heavy water are incompatible with life and reproduction and furthemore could even causing even lethal effects on a cell. However, today many cells could be adapted to heavy water either via employing a special methods of adaptation or using selected (or/and resistent to heavy water) strains of bacterial and other origin (O.V.Mosin, 1998).
It is seems very likely, that during adaptation to heavy water the structure and conformation of [U -2H]labeled macromolecules undergoing some modifications that are more useful for the working in heavy water-conditions. There have to be distingueshed three aspects of biological enrichment with deuterium: chemical, biological and biophysical aspects, all of them are connected in some way with the structure of [U -2H]labeled macromolecules. The presence of deuterium in biological systems certainly could be manifested in more or less degree by changes in the structure and the conformation of macromolecules. It is important what precise position in macromolecule deuterium ocupied and dipending from that the primary and secondary isotopic effects are distingueshied. The most important for the structure of macromolecule the hydrogen (deuterium) bonds form between different parts of the macromolecule and play a major part in determining the structure of macromolecular chains and how these structures interact with the others and also with heavy water environment. Another important weak force is created by the three-dimentional structure of water (heavy water), which tends to force hydrophobic groups of macromolecule together in order to minimize their disruptive effect on the hydrogen (deuterium)-bonded network of water (heavy water ) molecules.
But not only these functions but also the lipid composition of cell membrane are drastically changed during deuteration. The lipid composition of deuteriated tissue culture cells has been most complitely investigated by a certain scientists (Rothblat et all., 1963, 1964). As it is reported in these articles mammalian cells grown in 30% (v/v) heavy water contain more lipid than do control cells. The increase in the lipids of heavy water grown cells is due primarily to increased amounts of triglycerids and sterol esters. Radioisotope experiments indicate that the differens are due to an enhanced synthesis of lipid. Monkey kidney cells grown in 25% (v/v) heavy water and or irradiated with X-rays likewise showed increases of lipid. The heavy water grown cells contained more squalene, sterol esters, sterols, and neutral fat than did either the control of X-irradiated cells. Phospholipid levels were equal for all groups of cells. Thus the effects of heavy water on lipid synthesis are qualitatively quite similar to those of radiation damade. An interisting observation that deserves further scrutiny relates to the radiation sensitivity of deuterated cells. Usually, cells grown and irradiated in heavy water shown much less sensivity to radiation than ordinary cells suspended in water. Suspension of ordinary cells in heavy water did not have any effect on the reduced sensitivety became apparent.
A serious alteration in cell chemistry must be reflected in the ability of the cells to divide in the presence of heavy water and in the manner of its division. However, a many statements suggesting that heavy water has a specific action on cell division are common since today. Probably it may be true that rapidly proliferating cells are highly sensitive to heavy water , but that deuterium acts only to prevent cell division is unlikely. The rabbit cells grown on medium containing the various concentrations of heavy water shown, that heavy water caused a reduction in cell division rate, and this effect increased as the concentration of heavy water or duration of exposure, or both, were increased (Lavillaureix et all., 1962). With increasing concentration of heavy water the frequency of early metaphases increased, accompanied by proportional decreases in the other phases.
Heavy water blocks mitosis in the prophase and the early metaphase of many cells grown in heavy water . The blockage, however, was overcome if the initial concentration of heavy water was not too high and the exposure time not too long. In experiments with eggs of the fresh water cichlid fish Aequidens portalegrensis, they observed that in 30% heavy water only one-fifth of the eggs hathed and in 50% (v/v) heavy water none did so. Segmentation in fertilized frog eggs developed normally for 24 hours in 40% (v/v) heavy water , after which the embryos died. It was also found by that heavy water disturbed embryogenesis in Drosophila melanogaster eggs (Lavillaureix et all., 1962. Feeding female flies with 20% (v/v) heavy water caused a significant increase in the proportion of nondeveloped eggs, whether males were deuterated or not. The reason for the cessation of mitotic activity from exposure to heavy water is not clear. Certain microorganisms have been adapted to grow on fully deuterated media. However, higher plants and animals resist adaptation to heavy water. Even in microorganisms, however, cell division appears initially to be strongly inhibited upon transfer to highly deuterated media. After the adaptation, however, cellular proliferation proceeds more or less normally in heavy water, but this stage is not reached in higher organisms. No ready explanation in terms of the present understanding of mitosis suggests itself. In Arbacia eggs antimitotic action of heavy water is manifested almost immediately at all stages of the mitotic cycle and during cytokinesis (Gross P. R., et all., 1963, 1964).
A stabilizing action on the nuclear membrane and gel structures and peripheral plasmagel layer of the cytoplasm, was detected. Prophase and metaphase cells in 80% (v/v) heavy water remain frozen in the initial state for at least 30 minutes. Furrowing capacity probably is not abolished by heavy water. The heavy water -block is released on immersion in heavy water although cells kept in deuterium-rich media for long periods show multipolar and irregular divisions after removal to heavy water , and may subsequently cytolyze. The inhibition of mitosis in the fertilized egg is not the only interesting effect of deuterium. The unfertilized egg also responds. It was described that deuterium parthenogenesis in Arbacia in the following graphic terms: if an unfertilized egg is placed in heavy water, there appear in the cytoplasm, after half an hour, a number of cytasters. The number then increases with time. If, after an hours immersion in heavy water, eggs are transferred to normal sea water, a high proportion (80% of the population) raises a fertilization membrane, which gives evidence that activation has occurred.
It was reported in a series experiments designed to test the ability of deuterium to produce mutation and nondisjunction. Deuterium like tritium appear to increase nondisjunction, but either agent separately is less effective than the two acting together. Hughes and Hildreth exposed male flies which had been grown on a 20% (v/v) heavy water diet to an irradiation of 1000 r. of X-rays. It was found that there was not significant difference in the frequency of observed mutations between heavy water flies and normal flies subjected to the same radiation.
Tumanyan and Shnol also found no mutagenic effect of heavy water on recessive and dominant lethal marks in D. melanogaster, inbred line Domodedovo 18. Flaumenhaft and Katz grew fully deuteriated E. coli in 99,6% (v/v) heavy water with fully deuteriated substrates, and found that the mutation rate after ultraviolet irradiation was distinctly lower than that of nondeuteriated organisms. The simultaneous presence of both deuterium and protium in nearly equal proportions in the constituent molecule of an organism could conceivably create difficulties for the organism since the rate pattern would be seriously distorted. They further found that cells grown in heavy water and then transferred to heavy water showed an enhanced susceptibility to ultraviolet irradiation. This suggests that organisms containing both hydrogen or deuterium, but it leaves unanswered the question of why serial subculture in water- heavy water media is required for adaptation of many organisms.
Many researchers studied the growth of phage T4 in E. coli cells which were cultivated in media containing various concentrations of heavy water from zero to 95% (v/v). No significant increase in forward mutation in this phage could be observed, but the rate for reverse mutation was increased, and reached a maximum in phage grown in 50% (v/v) heavy water. Although it was reported that a further increase in heavy water concentration up to 90% (v/v) producers little augmentation of the reversion index, the actual data presented by Konrad indicates a decided increase in reverse mutation rate in phage exposed to more than 50% (v/v) heavy water.
There have been carried out a big deal of cytochemical study of fully deuteriated microorganisms grown autotrophically for very long periods in heavy water (Flaumenhaft E., Conrad S. M., and Katz J. J., 1960a, 1960b). The main conclusion that could be made from these studies is that the nucleus of deuterated cells was much larger than that of nondeuterated cells, and it contained greater amounts of DNA. Also present were much greater amounts of rather widely scattered cytoplasmic RNA within the cells. It was found also, that deuterated cells stained much more darkly for proteins, indicating higher concentrations of free basic groups. Both fluorescence and electron microscopy indicated that deuteration results in readily observable morphological changes. For example, the chloroplast structure of deuteriated plants organisms was more primitive in appearance, less well-differentiated, and distinctly less well-organized. The very interesting conclusion was made, then a low or/and high temperature grown organisms implied the morphological consequences of extensive isotopic replacement of hydrogen by deuterium so that in some respects resemble with the effects produced by reduction or/and increase in temperature of growth.
But, paradoxically, many cells of bacterial and algae origin could, nevertheless, well grown on absolute heavy water and, therefore, to stabilize their biological apparatus and the structure of macromolecules for working in the presence of heavy water (O.V.Mosin, 1998). The mechanism of this stabilization nor at a level of the structure of deuterated macromolecules or at a level of their functional properties is not yet complitely understood. Adaptapion to heavy water is a complex phenomenon resulting both from the changes in structural and the physiological level of a macrosystem. That is why there is every prospect that continued investigation of deuterium isotope effects in living organisms will yield results of both scientific and practical importance, for it is precisely. The studies of the structure and the functioning of biolodical important deuterated labeled macromolecules obtained via biological adaptaition to high concentrations of heavy water are most attract an attention of medical scientists as a simple way for creating a fully deuterated forms of DNA and special enzymes could well be working in a certain biotechnological processes required the presence of heavy water. Secondly, if the structure of fully deuterated proteins may be stabilized in heavy water in a view of duarability of deuterated bonds, it would be very interesting to study the thermo-stability of deuterated proteins for using them directly in processes going at high temperatures.
It would be very perspective in future to create the thermo-stable proteins simply via deuteration of the macromolecules by growing a cell-producent on heavy water with 99% of deuterium. Third, particular interest have also the studies on the role of primodial deuterium in molecular evolution. The solution of these obscure questions concerning the biological adaptation to heavy water should cast a new light on molecular evolution in a view of the preferable selection of macromolecules with difined deuterated structures.


You didn't read the wiki article, did you? Deuterium oxide is not toxic. It's in our oceans...technically there's naturally some deuterium oxide in every bit of water you would drink every day. There's even some chefs in Norway that use deuterium oxide ice to make neato drinks.

The comments to this entry are closed.

September 2011

Sun Mon Tue Wed Thu Fri Sat
        1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30  
Blog powered by Typepad