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Low-Level Radiation May be Mutagenic
The Night Watchman writes: "According to article on BBC news, scientists have determined that low doses of radiation can indeed cause alterations in human DNA that are then passed down to future generations. Apparently there was an 'unexpectedly high increase' in genetic mutuations in children born in the area after the Chernobyl disaster." This may shake up the scientific community, which has relied on studies of Hiroshima survivors to evaluate the long-term consequences of radiation exposure.
From what I know, much of the knowledge about how radiation effects humans comes from studies of the atomic bombs dropped on Japan during WWII. From these very high levels of radiation exposure, studies found that there was basically a linear relationship between the amount of radiation you received and the chance that you would get cancer. From this comes the "linear, no threashold" model of radiation exposure and the thought that all radiation, no matter how little, runs the risk of causing health problems. Most government regulations of radiation exposure is based on this linear, no threshold model.
There are other people who feel that the linear, no threshold model is seriously flawed when dealing with low levels of radiation. They point out that radiation is a natural part of world, and the amount of radiation you are exposed to varries widely depending on where you are. For example, people living in Denver get much more radiation than those living in San Francisco because of their higher elevation. Also, when life first started to evolve on earth, the background radiation levels were much higher than today. The basic claim is that the body can usually deal with low levels of radiation, and it is only when you pass a threashold and overload it, that you start seeing a linear increase in health problems.
Trying to determine if there is a threshold and how low levels of radiation really effect people is a hot area of study. Unfortunately, you can't ethically expose people to levels of radiation that might cause problems, so studies of Chernobyl survivers are of particular interest.
There is actually another group of people who think that low levels of radiation is good for you. These people believe in something called "radiation hormesis". These people are generally considered idiots and quacks by most other people who study radiation.
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As a former Reactor Physics Engineer at a UK powerstation I get very irritated by the BBC's irresponsible anti-nuclear scaremongering.
Nowhere on the article are the actual doses quoted. People who cleaned up Chernobly are not or were not exposed to "low levels of radiation" or "low radation doses" by Western standards. They were fried.
In this country the legal annual dose limit is 30 mSv (30 millisieverts) with a much smaller percentage allowable internal dose. The actual dosage to the most exposed workers at the Sellafield reprocessing plant is in the 10-15 mSv range per year, lower than the 20+ mSv ailine cabine crew recieve.
I wish someone would post the actual doses here, whether external or internal, lifetime dose, dose rate, natural background etc.
The BBC loves to stir up the publics' fear of nuclear power and reinforces their ignorance with their own biased tabloid style journalism.
If you want to find out the facts about radiation doses, medical effects, and radiological protection, visit the NRPB website:
http://www.nrpb.gov.uk/
Rant mode off.
I'm out of my tree just now but please feel free to leave a banana.
If you are concerned about radiation, you should support nuclear power. Coal fired power plants release much more radiation, in the form of Uranium and Thorium, into the environment than nuclear power plants. That doesn't include all of the other nasty stuff that is produced by burning coal.
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From the article: "There are several indications in the report that the real problem is internal radiation."
The article contrasts a hiroshima style massive external radiation burst vs. these Chernobyl defects which are from internal radiation. What does that mean? I thought all radiation was from an external source?
Back in 1992, there were two programs running at Argonne National Labs, near Chicago. The first was a fail-safe nuclear plant. It used liquid lithium as the transfer medium, with a gravity fed tank. The lithium protects against leaks, you can't cause a meltdown and when it retires, the reactor seals itself in. The second was a reactor that "burned" long half-life radioactive material and reduced it all to 50 year or less half-life material. That is MUCH easier to store, not requiring million year storage.
What happened to both programs? The Clinton administration killed both of them, supposedly at Al Gore's insistence. I was asked to refute the VP's evidence. In one word, his reasoning was crap. Working prototypes of both reactors existed, they performed as advertised and were truly safe. But they were "nuclear" so Al Gore wanted them killed. Pure lip-service environmentalism. I was there, I performed the analysis, I reviewed the documentation.
So long and thanks for all the fish . . . !!!
Well, here we go again. The powers that be have decreed that nuclear power is a Good Thing(tm), so now we have the forces opposing them are ramping up their efforts to show why this is not the case. I expect to see an increase in similar studies throughout the Bush/Cheney administration.
Personally, I'm still all for nuclear power. There just seems to be this weird yin/yang thing that governs the generation of power, and nuclear power seems to be the one that -- when done properly -- causes the least harm. Coal plants put massive quantities of shit into the air, windmills & solar arrays don't generate enough to be worthwhile, and hydroelectric dams a) dessimate vast sections of land, and b) let off crazy amounts of methane from decomposing vegetable matter.
So RAH for nuclear. It's cheap, lasts a long time, and apart and aside from the occasionally annoying meltdown, it's perfectly safe.
- Rev.
"Scientist recently discovered that radiation causes genetic mutations. These and other groundbreaking discoveries in the pages of the medical journal 'Duh'."
Oh well, at least it will kick-start biodiversity.
Hmm. I seem to be letting my humor get excessively dark.
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(Sorry... with all these X-Men references, I had to bring Donatello, Leonardo, Michaelangelo, and Raphael into it. Don't forget Splinter. Or Bebop and Rocksteady. Or any of the other mutants in the comics/cartoon.)
This is the important bit:
...
"These results indicate that low doses of radiation can induce multiple changes in human germline DNA."
... the germline cells are there, packed with chemicals that prevent mutations (antioxidants for instance). Most of this is to *prevent* mutations that occur through malicious chemicals. Radiation doesn't really work that way. It will just penetrate through and nock of some basepares from the DNA
However, most of the damage done by radiation is done by the creation of free radicals, which then damage the DNA by chemical reactions. So antioxidants are quite effective (though not perfect) at stopping radiation damage.
The antioxidants are "expensive" nutritionally, (and humans evolved with less nutrition than is available in developed countries). So there's a feedback process to adjust their levels to limit free radical damage to an acceptable level without draining sometimes-scarce resources useful elsewhere. The bulk of free radicals in a cell come from the mitochondria (the cell's own "power plants").
As evidenced by cancer rate vs. environmental radiation exposure, the location of the "thermostat" is such that if the cell is exposed to a CONTINUOUS, LOW LEVEL of ionizing radiation the free-radical scavenger production is increased so much that the net result is LESS mutation. Up to the point where free-radical scavenger production maxes out, continuous low-level ionizing radiation is actually a net gain. (The same is also true of certain free-radical producing chemicals - again with the continuous low-level caveat.)
The problem with Chernobyl is partly that the level was NOT low, but mostly because the level was not CONTINUOUS. A short-term exposure to a high level of radiation is NOT equivalent to the same amount of radiation spread over years for a number of reasons, and a very big one is that the damage takes place before the levels of protecting chemicals can be raised.
So finding damage to DNA in stem cells of people who were brought to Chernobyl to clean up, and thus suddenly exposed to a high rate of ionizing radiation for a short time, is no surprise, and has no bearing on the expected effect of long-term exposure to low levels of background radiation.
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The only unexpected negative consequence was an unusually high rate of thyroid cancer in children, but this is not a true low-dose effect because the thyroid efficiently concentrates radioactive iodine. Fortunately, thyroid cancer is relatively benign and there have only been four deaths from it.
Furthermore, a closer reading of the latest scare study shows that those exposed were not in the low dose group! They were workers at the facility after the event - those who were involved in cleaning things up. There is lots of evidence that low dose radiation is not as dangerous, per milli-severt, as high dose radiation. The linear dose-response model that is used by environmental agencies shows way too high a risk at low levels. This results in ridiculously low level requirements on nuclear plants - levels which, btw, coal burning plants exceed every day!
A hypothesis on the nonlinearity of the dose response is that it DNA is self-repairing, it may take near-simultaneous hits on the same DNA to defeat that mechanism. Simple statistics shows that the odds of this, relative to radiation dosage, are far from linear.
Does anyone remember the extremely high numbers of excess deaths expected from Chernobyl? To date, it has killed fewer people than a medium sized commercial airliner crash - and Chernobyl was a worst-case meltdown. Almost all of the deaths were among workers immediately after the event who received very high doses.
Chernobyl was an uncontained reactor with a positive coefficient - loaded with graphite which burned once the temperatures got too high.
And finally, if you really are worried about radiation, take a geiger counter in an airplane. You will watch the background level climb dramatically as the aircraft climbs. When I did this, it went from 26 clicks per minute to many hundreds - and I live in a high-background area.
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This story is completely useless since it uses two equivocal and incompatible defintions of "low" (at the beginning the story implies that "low" levels of radiation cause mutations, but later it implies that levels of radiation that cause mutation is lower than previously thought, which could still be a very high level of exposure).
They don't give the damn exposure data. Why can't they just give a rough range of the exposure that the people in this study faced?
We need error-detecting and correcting DNA. Someone get on this.
I understand that there are a lot of environmental activists that strongly oppose the use of nuclear energy, however I would very much like to know what their main arguments are.
It is true that Chernobyl was a humanitarian/environmental disaster of global proportions, however I feel that since that incident, nuclear power has been stereotyped as a devil energy souce.
First of all, Chernobyl was a very old (one of the first designs, if not the first "production" design) nuclear power plant of the soviet era. Today besides the stigma arround nuclear energy, many advances have been made to nuclear energy powerplants, and there are designs of powerplants today which produce reclyclable radioactive wastes.
Look at France. France produces, as far as I can remember (don't take my numbers for granted) 70% of its engery with nuclear power plants. Although their designs are much more modern than the Chernobyl design, they are not of the type that produce very little recyclable waste. I often feel that this is the case becasue research and development into nuclear energy power plants is avoided because of all the environmental PR hassle.
I would be very interested to hear from some Nuclear Physisists out here that could enlighten us a little further on nuclear power energy, and how safe it REALLY is. France doesn't have an energy problem, and I think this is largely due to its heavy use of nuclear power plants.
I can understand there must be a lot of pro-nuclear energy publicity coming out of the current Bush administration - since they probably feel that this is one of the ways to curb the energy problem in the US without creating too much polution from it.
Again, I would love to hear some hard facts from Nuclear Physisists about the dangers and advantages of the current or potential nuclear power plant designs.
The /. article title: Low-Level Radiation May be Mutagenic is pretty misleading. The article concerned a study of people who cleaned up after Chernobyl. I wouldn't exactly call that "low level radiation". The focus of the study was to see if somatic DNA was being affected by the radiation, making the offspring of the cleanup crew have a greater rate of mutation than normal. The study results were pretty scary, but this is not something that was unknown.
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Actually, I attended a research seminar at the University of Connecticut Health Center, where someone else had shown that low-level doses of radiation actually "trains" the DNA-repair enzymes to be able to fix damaged DNA more accurately and with more efficiency. It was shown that if you subjected cells to low levels of radiation over a long period of time, and then exposed them to high levels, fewer cells mutated than if naive cells had been exposed to high levels of ionizing radiation without the "pre-treatment".
We use to work with radioactive iodine and phosphorus more often then I cared to, and had to wear the appropriate gear - including a radiation badges. One got left in the hood for some reason or other, and it was a little hotter than normal.
Anyhow, a week after one of the new grad students starts working with our group, one of my cohorts picks up a Geiger counter, adjusts the sensitivity, and says, "lets check to see if your thyroid is doing OK". With one hand he placed the badge near his neck and moved the GC close enough to make a delightful pops.... The look on his face was priceless. Oh... did we get into the doghouse for that one....
Anyhow, true low-level radiation is pretty safe. The cleanup crew at Chernobyl would not be dealing with levels I would call "low". Electricity scares the hell out of me, however. Few things terrified me as much as installing a new ceiling fan for my wife.
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This is the important bit:
"These results indicate that low doses of radiation can induce multiple changes in human germline DNA."
Mammals (including humans) have 'special' cells that have very low degradation in DNA. Normal cells are mutated all the time. This is not a problem as the DNA can take an enormous amount of mutations without changing its function (in fact, in a gene every third base can pretty much be changed at random without the gene product changing one bit). So, you don't want to make new organisms out of skin cells. Therefore the germline cells are there, packed with chemicals that prevent mutations (antioxidants for instance). Most of this is to *prevent* mutations that occur through malicious chemicals. Radiation doesn't really work that way. It will just penetrate through and nock of some basepares from the DNA. Remember: once a basepair is changed, the cell can never again figure out what the correct base was! Anyway, if you are exposed to a large amount of radiation, it can only be expected that the germline is effected as well.
If an experiment works, something has gone wrong.
I've spent 4 years working in reactor chemistry, and over the 4 years have recieved 492 mrem of ionizing radiation exposure. When you train in a nuclear frield (I did with the US Navy) they basically tell you that small somatic doses of radiation are practically harmless. The real danger lies in a large chronic dose. We were always told that once a cell was radiated, for things could occur. The cell could have a good daughter, a bad daughter, a dead daughter, or no daughter. One of those things is not like the others, it's the bad daughter. It's cancer. Statistically if you are exposed to 1000 mrem (with data collected from Chernobyl) you increase your risk of cancer 0.06%. I would be curious to see if scientits will say is a dose that could change your DNA.