Scientific Jigsaw Puzzle: Fitting the Pieces of the Low-Level Radiation Debate

New submitter Lasrick writes "Skip past the dry abstract to Jan Beyea's main article for a thorough exploration of what's wrong with current 'safe' levels of low-level radiation exposure. The Bulletin is just releasing its 'Radiation Issue,' which is available for free for two weeks. It explores how the NRC may be changing recommended safe dosages, and how the studies for prolonged exposure have, until recently, been based on one-time exposures (Hiroshima, etc.). New epidemiological studies on prolonged exposure (medical exposures, worker exposures, etc.) are more accurate and tell a different tale. This is a long article, but reads well." Here's the free, downloadable PDF version, too.

Comments

Short summary

[Anonymous Coward]

Ionizing radiation causes cancer. More ionizing radiation causes more cancer. There is no "safe dose", though there is a certain unavoidable dose. So we're all at risk of cancer if we live long enough.

Re:Short summary

[History's Coming To]

Precisely - "low-level" at Sellafield in the UK used to mean "lower than the background level", and people still got hysterical about it. We need to stop with the wooly-language descriptions and simply use the established units, or units-above-background where applicable. Is low level gamma worse than high level alpha? Is holding a piece of uranium for 5 minutes more or less dangerous than sleeping 10ft away from it for a week? People have no idea, including most of the media, we need to throw out the "levels" model and actually educate people so they can understand the risks properly.

Re:Short summary

[vlm]

Ionizing radiation causes cancer... There is no "safe dose"

You seem to have not read the abstract, the whole point of which is at ultra unrealistically low levels, practically homeopathic low levels, the mechanism, the cause/effect seems to not make much sense or is under debate, both real scientific debate and crackpot astroturfing debate. But the article points out that at any realistic dosage level there is not much debate by anybody. So the article pragmatically suggests to only apply real world numbers to real world exposures and ignore the whole topic of unattainably asymptotic low levels. The article argument is the opposite of yours in some ways.

An example of a realistic question at the ultra-low end is, looking at how naturally radioactive some of our high potassium food is, you'd think we'd evolve a way to pee the bad stuff away. Presumably people evolved in granitic-source / volcanic-source soil would be better at it than people evolved in sedimentary-source soil. Another realistic area of cancer research is proving the presence or absence of two-step or catalysts of cancer. Your body is pretty good at dealing with mutant cells, except when it fails and then you die of cancer, whoops. So figuring out why your body fails to kill cancer cells is in many ways more important than trying to figure out how to reduce the number of cells caused by radiation because even if you zero that, you're still going to have random biochemical accidents. Its an interesting theoretical area of research but the article points out for normal human beings its at a level that doesn't matter.

Re:Short summary

[mhajicek]

Bananas.

Re:Short summary

[MozeeToby]

Exposure is always expressed in amounts over the background rate. So "Lower than background level" effectively means exposure to up to 2x the background level (background level + artificial); there's nothing illogical about being worried about it (though I wouldn't personally be concerned about a ~.0025 Sv per year exposure rate).

As for the rest of your comment, if you read the paper the summary links to, you'll see that all the evidence is pointing toward all exposure (presumably below radiation poisoning levels) carrying approximately the same relative risk. It doesn't matter high or low energy, it doesn't matter if you're exposed in 10 minutes or 10 years. Your total exposure level linearly maps to your risk of cancer (and, new information to me at least, heart attack and stroke).

Re:Short summary

[History's Coming To]

Your best bet is to read a high-school level introduction. Concisely, there are three types of radiation from radioactive atoms, alpha, beta and gamma. Alpha is a He nucleus, two protons and two neutrons - it can do a huge amount of damage to living cells, but is easily stopped by, eg, a sheet of paper. Beta is a high speed electron, less damaging but will penetrate clothing etc. Gamma is nasty - it can travel through a reasonable thickness of lead and still do harm.

If we look at the Uranium example, it gives off alpha, so you'd probably be quite safe with it on the other side of the room. Handling it, on the other hand, is an easy way to accidentally ingest some, which would probably be more harmful because it's then inside the body (this goes for any ionizing radiation source). When you see people being showered off after radiation exposure it doesn't stop any harm thats already been done, just reduces the chances that they are still in contact with a source.

This all ignores the fact that Uranium decays into several other isotopes which give off their own idiosyncratic radiation in turn, and a bunch of other things.

Cost benefit analysis

[hoggoth]

Low level radiation may be dangerous, but we have to weight that against the benefit to the corporations that sell airport scanners. Some amount of harm is worth it.

Re:Low level radiation

[InterGuru]

There might be a level at which radiation is beneficial. This is called hormesis

From Wikipedia

Hormesis (from Greek hórmsis ...) is the term for generally favorable biological responses to low exposures to toxins and other stressors. A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses

The concept is vigorously debated, but has been shown to work in some animal experiments. In humans, small doses of alcohol, a toxin, seems to improve heart health.

Humans, as all life, have evolved under low level background radiation. We may be adapted to it.

Re:Low level radiation

[XiaoMing]

There is no threshold below which radiation is 'safe'. There is a threshold below which is become statistically indistinguishable from random events, but that is not the same thing. We've known even "low" levels of radiation can be dangerous -- look at the cancer clusters showing up in TSA screeners.

Unfortunately, what you say is at best inconclusive, but at worst wrong. Google "hormesis".
Studies "including for example the respected "Iowa Radon Lung Cancer Study" of Field et al. (2000), which also used sophisticated radon exposure dosimetry....argue that radon exposure is negatively correlated with the tendency to smoke and environmental studies need to accurately control for this; people living in urban areas where smoking rates are higher usually have lower levels of radon exposure due the increased prevalence of multi-story dwellings".
http://en.wikipedia.org/wiki/Radiation_hormesis

I know that hormesis sounds like a crackpot theory along with holistic super-diluted medicinal honey therapy, but some of the greatest minds in Medical Physics believe it exists. It is basically the hypothesis that low levels of additional radiation can actually make you healthier than no additional radiation at all (including daily dosage of cosmic rays). Hence the quote about high background radon studies and inverse correlations with health outcomes.

One of the main mechanisms that is thought to possibly explain it is that while the additional radiation exposure is not enough to cause significant DNA damage, it still activates certain dormant mechanisms for DNA repair, resulting in a healthier-than-average individual.

So in short, there is at least very suggestive evidence for a "safe" (and even moreso than safe) level of radiation.

Re:Extended exposure is riskier, and no superpower

[vlm]

The standard /. car analogy breaks down in that running my car engine up to 80% of redline RPM for a half hour a day is a pretty stupid idea that will only wear it out faster. Yet daily aerobic exercise seems to be a brilliant idea for long term cardiovascular health.

You can also have hilarious fun making vaccine analogies. "You mean, you'd intentionally inject small amounts of possibly fatal microbes into a healthy body? Madness I tell you! Madness!" Sadly there are highly educated actresses and pr0n models who pretty much use this argument when providing their valuable medical advice, along with the usual folks doing the FUD-for-profit thing.

Bad article, little information [Re:Short summary]

[Geoffrey.landis]

Ionizing radiation causes cancer. More ionizing radiation causes more cancer.

Of course. The question is, how much more cancer is caused by a given dose of radiation?

Unfortunately, this is a question that the paper in question does not answer, because it completely neglects to mention actual numbers. (The pretty colored graphs have units of "excess relative risk." How do you convert that to deaths? You can't. What are the units-- per year? Per lifetime? they don't say. Relative to what? They don't say.) I'd like to see a number, like "excess cancers per year per sievert of exposure," but they don't give one. They compare different studies, but never discuss whether the differences are statistically significant.

There is no "safe dose", though there is a certain unavoidable dose.

That is a question. That is what is known as the "linear no threshold" model-- but although these authors assert the validity of that model, you can't tell it from the data they show. Figure 1 shows too much scatter below 0.3 Sv to give much information about thresholds, and Figure 2 sure looks like it would be well fit by a threshold model.

In short, I'd like to have seen an article with real information.

Re:Anti-nuclear publication

[imjustmatthew]

Do note that the "Bulletin of the Atomic Scientists" is a generally an anti-nuclear, scare-mongering publication. These are the people whose count-down to nuclear disaster has been just a few minutes before midnight for decades. Whatever they publish should be viewed with this in mind.

As a strong supporter of nuclear power I feel this attitude is exactly what makes it so easy to scare up opposition to nuclear power. That article was extremely well written and researched. IMO it presented a fairly balanced view of the existing studies and the overall challenges to new research and regulation. Yes their are concerns about low and protracted doses, and yes the industry has tried to downplay and bury that research. Just like the "green power" industry doesn't want anyone to look at the lifecycle costs on those PV cells and LiPo batteries.

The only way to stop fear mongering and get new power plants is with open and honest research - not making attacks on an article that tries to present the facts.