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Clive Elsworth's avatar

Great article - thanks.

The main threat to DNA is the occasional Reactive Oxidant Species (ROS). These are chemical radicals naturally produced by the oxidation of reductants (sugars etc.) in every animal cell. That oxidation provides energy, but ROS is occasionally released by accident. That's why we have anti-oxidants - to put out the 'fire-like mayhem' caused by ROS. At rest ROS is thought to cause about 10x the DNA damage of background radiation. Vigorous exercise increases the damage rate much more. It makes no difference how DNA gets damaged. The effect of DNA damage caused by ionizing radiation and ROS is the same.

Most damage happens to other cell proteins but as we know, DNA damage can cause long term problems. Fortunately, the double helix structure of DNA enables single strand breaks to get repaired quite quickly by the cell. Most double breaks take longer to repair by more complex cell processes. Where damaged DNA cannot be repaired the whole cell is sacrificed by apoptosis (immune response). Cancer cells develop in our bodies all the time and it is only as we age that our immune system weakens, raising the risk of developing cancer.

So yes, in an era where emissions from energy systems threaten mass extinction from Earth's climate, which is now warming at least 25x the warming rate that caused the worst mass extinction in geological history (End Permian or Great Dying), it would be laughable if it wasn't so sad that ALARA is used by misinformed ideologues to increase the cost of nuclear power.

Radioactive substances exist in all our food, our clothes, the ground, the structure of buildings, and the air - especially near coal plants, which emit uranium in their smoke. If you want to minimise the radiation you receive you should avoid go out on sunny days, and you should keep away from people and animals because they all have radioactive substances in their bodies. Carbon dating experts consider ideologues who declare themselves a radiation free zone 'in serious trouble': It means they must have dead at least 50,000 years.

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Manav's avatar

> In other areas of our lives, this assumption would seem obviously wrong. For example, the cumulative harm model applied to alcohol would say that drinking a glass of wine once a day for a hundred days is equivalent to drinking one hundred glasses of wine in a single day. Or that a jogger who ran a mile a day for a month was putting her body under greater strain than one who ran a marathon in a day. We recognise that the human body is capable of repairing damage and stress done to it over time.

This is a false, harmful equivalence. None of the parallels you suggest involve *directly mutating your DNA*! There is *no* safe radiation level, and Linear No Threshold is accurate!

The problem, as you suggest elsewhere in your great piece, is ALARA, which chases marginal (but real!) improvements at massive cost.

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