New Take on Impacts of Low Dose Radiation

Lawrence Berkeley National Laboratory ^ | December 20, 2011 | Lynn Yarris

[decimon]

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab), through a combination of time-lapse live imaging and mathematical modeling of a special line of human breast cells, have found evidence to suggest that for low dose levels of ionizing radiation, cancer risks may not be directly proportional to dose. This contradicts the standard model for predicting biological damage from ionizing radiation – the linear-no-threshold hypothesis or LNT – which holds that risk is directly proportional to dose at all levels of irradiation.

“Our data show that at lower doses of ionizing radiation, DNA repair mechanisms work much better than at higher doses,” says Mina Bissell, a world-renowned breast cancer researcher with Berkeley Lab’s Life Sciences Division. “This non-linear DNA damage response casts doubt on the general assumption that any amount of ionizing radiation is harmful and additive.”

Bissell was part of a study led by Sylvain Costes, a biophysicist also with Berkeley Lab’s Life Sciences Division, in which DNA damage response to low dose radiation was characterized simultaneously across both time and dose levels. This was done by measuring the number of RIF, for “radiation induced foci,” which are aggregations of proteins that repair double strand breaks, meaning the DNA double helix is completely severed.

[decimon]

Ping

[Sherman Logan]

LNT – which holds that risk is directly proportional to dose at all levels of irradiation.

Or low levels may actually be beneficial.

http://en.wikipedia.org/wiki/Hormesis

[allmendream]

This is surprising to who exactly?

Biologists have long known that there are radiation induced DNA repair mechanisms that can deal with low levels of radioactivity induced mutations.

But no amount of radiation is “safe” because any single mutation can cause fatal cancer. That being said most radiation will pass through you without causing a mutation, and most mutations will be repaired and of those mutations that are not repaired most will cause no harm.

[allmendream]

Not likely.

The known biological mechanisms induced via radiation can only repair DNA damage - they don’t foster good health.

Sort of like taking your car in to have superficial dents beaten out of it will not improve its performance. Better to avoid getting it all dented up in the first place.

[Hodar]

If low doseages of ionized radiation are something you wish to avoid, I would suggest travel by train, boat or car.

Spending hours in an aircraft at 30-40,000 ft will subject you to considerable dosages of ionized radiation, for protracted periods of time. This is exponentially longer durations than those doseages in the body scanner, at levels significantly greater than those used by the scanner.

Source

[Paradox]

Finally, a study which indicates that which probably most honest radiation researchers have felt for quite some time. Don’t tell the anti-nook folks though, they won’t listen anyway.

[Magic Fingers]

“Sort of like taking your car in to have superficial dents beaten out of it will not improve its performance.”

That’s not necessarily an accurate analogy. Hormetic responses to various stimuli do improve health. AFAIK it’s not been determined whether low dose radiation is one of those stimuli.

[Sherman Logan]

The theory behind hormesis is that low levels of toxins, radiation, etc. may have a stimulating tonic effect.

IOW, kicking the immune system into low gear regularly may help it keep in shape for the times it’s really needed.

The comparison might be to exercising a muscle rather than to repairing a car.

[SargeK]

I hate to be contrarian, but: (actually, that’s a lie. I rather enjoy being contrarian. But it’s all in good fun...)

http://dsc.discovery.com/videos/mythbusters-dimpled-car-minimyth.html

[oyez]

Whew! That takes a load off my mind.

[allmendream]

DNA is not a muscle and damage to it, and then possibly repairing that damage, is not exercising it.

I am not saying there is not a Mithritic effect (named for the King Mithridates who drank small amounts of poison every day to render himself immune) with some toxins - where a small dose of a toxin can acclimate someone to surviving a major toxic insult - but other toxins just accumulate to lethal levels.

The Mithritic effect is almost certainly through inducing the increased expression of the CYP enzymes in the liver that metabolize xenobiotics (foreign toxins).

Some toxins induce CYP enzymes and others do not - so not all toxins exhibit this effect.

The immune system is usually “kicking into low gear” via the introduction of foreign ‘epitopes’ or 3D molecular structures that an antibody will bind to.

Radiation tends to kill these antibody containing cells that would induce an immune response.

Not just toxins, but other types of biological “insult” can have a prophylactic effect. For example a small heart injury can help one survive a subsequent major heart attack - that is because the the first insult activates genes that code for proteins that have a protective function.

The only “protection” from radiation is a ‘clean up on Chromosome/aisle 3’ type of clearing up damage - it is not a case where activating DNA repair enzymes will foster good health - it just repairs mutations.

[kidd]

bad analogy.

It is more like sunlight.

Large doses of sunlight will give you a burn and will increase your risk for cancer.

Small doses of sunlight will help process vitamin D

[allmendream]

Two different mechanisms. The enzyme that makes vitamin D needs sunlight for the necessary energy. It is a molecular protein coded for by our DNA that is absorbing necessary amounts of sunlight. Excessive amounts cause burns, DNA damage - and thus an increase in cancer risk.

What is the mutation inducing ionizing radiation being absorbed by and to produce what that is beneficial?

DNA damage to your noncancerous somatic cells is never a good thing. Not any amount. Ever.

Ionizing radiation causes DNA damage.

[Razzz42]

Incomplete report, lacks long term affects unless you include overexposure to sunlight effecting everyone the exact same way.

The cure is worse than the disease, still stands.