Stayin’ alive in the gene pool – Part III

This is the third and final part of a comprehensive series on radiation that has been published on BNC in weekly instalments during November 2013. This week — cancer…

Guest Post by Geoff Russell. Geoff is a computer programmer, vegan, environmentalist, and more generally, a ‘by-the-numbers’ polymath. For a list of all of his posts on BNC, click here. He also has collections here and here.

Part I and Part II of this series showed that radiation, whether from reactor accidents or even nuclear war, pose no long term global risks for the biosphere.

If humans were malicious or stupid enough to engage in nuclear war, we would have much bigger things than radiation to worry about, both during and after. Worrying about the radiation impacts of a nuclear war is rather like worrying about the bad hair impacts of self immolation. The World War II atomic bombs killed most of their victims in exactly the same way that other bombs killed people. The fire bombing of Japanese cities killed more people and left a far larger legacy of horrific and frequently permanently painful burn injuries. During 1994 the humble machete killed over half a million people in Rwanda. In comparison with missing limbs and horrific burns, radiation’s impacts on most survivors was mundane. We’ll see later that sausages can increase cancer risk by more than being an atomic bomb survivor. The increased cancer rate in survivors gave them an average lifespan reduction of some two months and has had no long term impacts on later generations.

If you want to compare two causes of cancer then you count cases or perhaps deaths. Something that causes a million cancer deaths is worse than something that causes a thousand. Focusing on one person’s suffering in that thousand can cause a cruel, unjust and immoral allocation of resources away from the many to the few.

Peter, Paul and Mary and the no-nukes sales anthem

Thirty years of adverse branding has raised radiation’s minor disease contribution well above and beyond it’s station. Most of our current crop of politicians, including people like Bill Clinton, who killed the US Integral Fast Reactor program in 1994, grew up in a cultural soup of references to radiation as poison. For decades now, the anthem of the no-nukes movement has frequently been considered to be the Peter, Paul and Mary song “Power” with its many cover versions (here’s one … at 7:35). It has an ironic refrain:

Just give me the restless power of the wind
Give me the comforting glow of a wood fire
But please take all of your atomic poison power away.

Poetic license is no excuse for getting stuff back to front.

Wood fires are deadly. Cooking fires, mainly wood but also cattle dung, kill half a million children annually and another 3,000,000 adults. Woodsmoke is certainly natural. A naturally toxic soup of nasty natural chemicals.

It causes COPD … chronic obstructive pulmonary disease in adults and the irritation causes infections which kill children without access to first world medical care. Not only is wood smoke deadly, but wood dust is a class 1 carcinogen; just like ionising radiation. “Class 1” just means well proven in humans.

Neither wood dust, wood smoke or radiation is an existential risk to humanity, but wood smoke at common levels, unlike radiation, is quite deadly to individuals.

And then there’s the wood industry. It’s one of the more dangerous on the planet. In the decade of the 1980s when that anti-nuclear anthem featured in many a US and Australian rally, 1492 timber workers died in the US alone … with an injury toll in the tens of thousands. The number of dead loggers each year in the US has halved since then, but the death rate is still one of the highest of any industry at 70 deaths per 100,000 workers per year. Is that high? Motor vehicle fatalities in Australia are running at about 6 per 100,000 per year; down from about 20 during the 1980s. The US lung cancer death rate is about 30 per 100,000 people per year. Wood is indeed beautiful, but it’s production and use is deadly and toxic.

On the other hand, nuclear power makes for clean air, and as already mentioned, this puts it in a strong credit position having prevented 1.8 million premature deaths since the 1970s. Early underground mining practices of the 1950s exposed miners to radioactive radon gas and increased their lung cancer risk to levels more usual in smokers (compare here and here) but modern methods make uranium mining one of the safest of all mining operations. Put simply … deaths are quite unusual and radiation doses are measurable, therefore easily controlled. How do you measure wood smoke or dust inhalation or ingestion in a child whose mum cooks with wood? … you know the dose was too high when the child gets sick.

Peter, Paul and Mary screwed up. The no-nuke anthem has a great tune but the lyrics are just addled flotsam and jetsam where rhyme trumps reason.

So now we must undo three decades of heart felt but grossly misleading branding. Just imagine how different the planet might be if for the past 23 years, every country on the planet had, like France, been generating electricity for just 80 grams of CO2 per kilowatt hour instead of the global average of 570 … with “no-nukes” Australia being close to world’s worst practice at 850 grams of CO2 per kilowatt hour.

That might have happened if only Peter, Paul and Mary had written:

Please spare me the transitory power of the wind
Give me that Cherenkov glow of a fission fire
And please take all your kiddie killing wood smoke away.

To move from the realm of protest song radiation experts through to that of real experts, we need more details on cancer.

What experts know about cancer

Let’s start with two big facts.

• surviving an atomic blast and getting a massive dose of radiation poses a far lower cancer risk than a carcinogenic lifestyle … smoking, eating plenty of red and processed meat, and being fat, inactive and tall, to name some major lifestyle causes of cancer and give them roughly the right ranking. The inclusion of “tall” in that list might surprise you, but I’ll get to it in due course.
• living on radioactive contaminated land from something like the Chernobyl accident and eating food grown in contaminated soil for decades is also demonstrably a non-starter in the cancer risk stakes compared to lifestyle cancers.

To a lay person with a protest song honours degree in Radiation 101, these facts are both astonishing and counter intuitive: “That can’t be right!” would be a predictable response. But an expert would more likely respond: “Yeah … of course … doesn’t everybody just know that?”. No, they don’t.

What do experts know that we don’t?

Let’s start by explaining a little of what experts know about the survivors of the atomic bombings during World War II compared to people living an Australian (or US, or UK) lifestyle. The risk of solid cancers (almost all cancers are solid cancers) in the Hiroshima and Nagasaki bombing survivors has been very well studied. It rose by around 11 percent. Experts know this but, the rest of us have to look it up. But of course we don’t and even if we do we may not have anything to compare it to. Is an 11 percent increase big?

No. Australia’s cancer rate, for example, is fully 50 percent higher than that in Japan. When numbers are standardised to account for different population age structures, Australia has 314 cancers per 100,000 people per annum compared with 201 in Japan. But even that 11 percent solid cancer increase in bomb survivors is misleading because it is an average inflated by the few survivors who received massive doses and suffered a much larger increase. The overwhelming majority of survivors suffered just a two percent solid cancer risk increase. The few survivors who skewed the average with their 60 percent risk increase were hit by a brief but massive wave of radiation about 300,000 times background levels, and even this massive dose only increased their risk by a tad more than an Australian lifestyle.

The other cancers are the non-solid ones, the leukemias, typically thought of as cancers of the blood. They are only ever 2-3 percent of cancers, so even if they doubled it does nothing to invalidate the above analysis. But they didn’t double. Leukemia in most survivors rose by 6 percent but a doubling of the rate in the few who received massive doses pushed the average up to 46 percent … still less than living an Australian lifestyle.

The Chernobyl accident, on the other hand, did nothing to cancer rates with the exception of some thyroid cancers. This is also well known to experts. As far as the general cancer impact of living in contaminated areas and eating food grown in contaminated soil, we just need to look at national cancer registries to see what has happened. Cancer registries are very simple things. You get a cancer diagnosis, it gets recorded and the figures get added up and some simple and transparent statistics are done on them. In the past 25 years, Ukraine Belarus and Russia have had about 14 million cancers. With Australian rates they’d have had 20 million. How do 6,000 thyroid cancers with about 15 deaths stack up against 6 million extra lifestyle cancers?

Lifestyle cancers trump atomic bombs and reactor accidents every time.

Anti-nuclear guru Helen Caldicott “warns” people of cancer risks of Turkish apricots because Turkey was contaminated by Chernobyl fallout. Cancer experts, on the other hand, know that the cancer rates in Turkey are less than half those in Australia or the US. In 2008 were about 95,000 new cancers in Turkey’s 73 million people compared with 107,000 new cancers in Australia’s 22 million. If this looks closer to a third than a half, it’s because experts adjust such rates to take into account Turkey’s different population age structure.

The anti-nuclear movement is fond of scare stories about what radiation does to your DNA. Experts understand that every bloody thing under and including the sun buggers your DNA. Throwing around technical jargon to confuse and frighten is no substitute for hard data on real impacts, and when you consider these, nuclear risks are pretty much at the bottom of any risk table. They are similar in nature and very much smaller than other industrial or sporting or home renovation or transportation or cleaning-your-solar-panels accident risks and overwhelmingly offset by the 1.8 million premature deaths prevented by cleaner air.

When people grow up on a solid diet of “radiation is poison”, then it’s simply unbelievable to find that surviving an atomic bomb is less carcinogenic than, for example, eating sausages frequently, but that’s just the way it is. Cancer experts, like Robert Gale mentioned in Part II, understand this, but non-experts find it so astonishing as to be unbelievable. Let’s explain a little more of what it is that experts know that accounts for the difference.

DNA damage isn’t cancer

Remember back in Part I when we mentioned the threshold question? Is there a radiation dose below which there is no DNA damage and no mutations? Back when that question first got asked, most scientists guessed that it was equivalent to asking if there was a radiation dose below which you got no cancer.

They were wrong.

People with Laron syndrome get plenty of mutations and other DNA damage, but they don’t get cancer. They are just an example of a more general principle, namely that building cancerous tumours is a team effort involving the right set of mutations to co-opt, among other things, cellular growth proliferation factors while disabling the normal checks and balances. Cancer isn’t just a stick in your bicycle wheel, it’s a cooperating and evolving community of mutineers who co-opt normal bodily processes for their own nefarious ends. People with Laron syndrome are missing some of the key growth factors so cancer can’t use them. There is plenty of DNA damage but no cancer.

On the other hand, the people who get cancer at rates far higher than anything that even a poor lifestyle can produce are the ones with mutations which stop them repairing DNA damage efficiently. This is Angelina Jolie’s problem. It isn’t that her mutation causes additional DNA damage. Not at all. Her problem is that her BRCA1 mutation unleashes more of the mutational power behind normal DNA damage. A normal (unmutated) BRCA1 gene is part of a genetic trouble shooting super team which repairs normal damage. Keep in mind that normal damage is akin to being hit by radiation from seven or so Hiroshima bombings every day. So when any member of that repair team screws up, you are in trouble. Bloom syndrome sufferers (see Part II) have even less repair capacity.

Meet the cancer team

What does it mean to say a cell has become cancerous? Most commonly it means the cell has reproduced many times and the assembled offspring have all clumped together in a big mass. If the cancer is in your bowel, the lump can rupture your bowel wall or block it completely.

Normal cells don’t do that. For a normal cell to become cancerous, it needs to fundamentally change it’s way of life.

Normal cells don’t clump together because of mechanisms which keep them a little distant from their neighbours. These mechanisms need to be disabled. Normal cells are limited in the number of times they can divide and reproduce. The mechanisms that enforce this limit must be disabled. Normal cells self-destruct when they get damaged. This mechanism has to be turned off.

That’s just a few of perhaps a dozen ways in which cancer cells are different. The cellular changes needed to transform a normal cell into a cancer cell are made usually by mutations … changes to genes. But, of course, not just any genes. Fewer than one percent of genes are involved in the changes which turn a cell into a tumour. And within that one percent, researchers have found even fewer which look to be particularly important in giving a cell the many features which enable it to spawn a tumor.

But there is one big obvious difference between radiation and viral or chemical carcinogens like those found in cigarettes, diesel exhaust, wood dust, coal tar, soot (whether from a renewable energy biomass boiler or a forest fire or a camp fire) any meat cooked at high temperatures, red and processed meat, salted fish, or alcohol … to name some of the most common ones.

What is it? Radiation is an “equal opportunity” mutator.

What does that mean? When radioactive particles or waves hit a cell, they have no physical way of targeting particular genes, they just bounce around like a mouse in a China shop, rather randomly. The bouncing around produces damaging by-products, but they too aren’t particularly focused because these by-products are the same by-products produced by other normal processes and there is nothing involved you could confuse with targeted malice. This means that most radiation damage will be in genes or other structures which are irrelevant to cancer formation. One of the by-products, for example, of radiation hitting water in a cell (most of any cell is just water) is hydrogen peroxide, the stuff that makes “peroxide blondes”. It’s a normal cellular by-product which can cause DSBs and there are plenty of natural and much easier ways to boost your hydrogen peroxide induced DNA damage than arranging a large dose of radiation. We saw one in Part I … hard exercise.

Now, compare this with something like a cancer causing virus. First, what makes it a cancer causing virus instead of just a sneeze causer? A cancer causing virus can target very particular parts of a cell. It can even target precisely one or more genes involved in cancer. For example, a protein in the human papilloma virus very specifically targets and can inactivate a single very special gene (called p53) … which is a cancer suppressor gene sometimes given the illustrious title of The Guardian of the Genome. It’s one of the genes that tobacco carcinogens target. It would require a very high dose or extraordinary bad luck for radiation to hit p53. It’s this lack of specificity that explains radiation’s solid track record as a carcinogenic wimp.

Chemical carcinogens can also take out specific tumor suppressor genes. For example while the anti-nuclear movement has concentrated on things that might go wrong with nuclear power plants, coal plants operating normally have been busily pumping out pollution containing chromium and nickel which can deactivate another of the tumor suppressing genes, p16, and arsenic which can inactivate the magic p53. The nickel and arsenic from coal power plant emissions can get taken up by trees and end up in wood smoke and hitch a ride into lungs both young and old.

But we need to quantify the difference that specificity can make.

In a 2012 study researchers irradiated mice with a 4 Gray radiation dose. This is a massive dose. It’s about 20 times bigger than the average for survivors of the Hiroshima bombing. It’s just below the dose that would have killed the mice.

Bingo, the mice developed cancer, but it took 77 weeks. This is a really long time in a mouse’s life, roughly like 40 to 50 years of human life, and as mentioned previously, mice are far more prone to cancer than people. On the other hand, give mice large doses of the chemical carcinogen PhIP and you can give them full blown cancer in a just a few weeks. That’s the difference between random gun fire and a good sniper. Yes, radiation can cause cancer, but it gets an F-minus for efficiency.

What’s PhIP and why are people feeding it to mice? PhIP is one of a number of molecules found in all kinds of meat cooked at high temperatures like being grilled on a BBQ. There’s a group of these which cause cancer in mice when given at massive doses … just like radiation, but much more efficient. Is there a safe dose? Of course not. Is there an absolutely safe distance you can drive each year? Of course not. But some patterns of driving are very low risk.

Is PhIP a high risk carcinogen … meaning does it cause many cases of cancer? That’s not at all clear but you’ll find warnings about cooking meat at high temperatures buried in the fine print of most official cancer prevention literature. The doses used in the above research were, as I said, massive and far too large to have any direct relevance to human intake. My money is on heme iron as the primary cause of bowel cancer in red meat eaters, but plausible suspects are many.

And what about being tall? Why was that in the risk factor list for bowel (and breast) cancer? It’s not tallness per se that causes cancer but some of the factors that cause tallness which are dangerous. In particular, tall people have undergone more cell divisions stimulated by growth hormones which provides more potential for DNA damage. The statistical relationship is clear, and experts can kind of see what is happening, but a detailed explanation is probably some years off.

Note carefully what I’m doing here. I’m not trying to prove that Chernobyl only had a tiny cancer impact. That’s just a recorded fact. All I’m doing is trying to fill in a little of the context that makes this unsurprising to experts. Whenever facts seem counter-intuitive, then it’s easy to buy into cover-up theories. Once you understand why experts didn’t expect much from Chernobyl, you’ll understand why there wasn’t anything to cover up.

The new kid on the block

Before finishing, I just want to cover something touched on in Part II … epigenetics.

Understanding cancer is considered to be fundamental to treating it. This is a view that’s tough to disagree with, but the stunning depth of detailed knowledge over the the past 20 years hasn’t been matched by similar levels of treatment success. As each fundamental mechanism is explored, it is peeled back to reveal another layer which is even more complex than the last. On of the latest layers at the leading edge of research is called epigenetics. The genes in our DNA are not our blueprint, as originally thought. Instead, they are just a blueprint for a bunch of tools. The biological software that controls how and when the tools are deployed is probably all in the DNA, but not in the genes. And the first in perhaps a couple more layers of that software is the epigenetic layer. This layer defines mechanisms to control the activation each gene in each cell.

Here’s what’s relevant given our focus.

Some people have DNA mutations that render them very likely to get bowel cancer in the same way that BRCA1 mutations can make women very prone to breast cancer. As in BRCA1 mutations, these mutations also turn off with genes that fix DNA damage and anything which interferes with your DNA damage repair systems spells trouble. These bowel cancer mutations are responsible for 5 to 10 percent of bowel cancers. They are what cause the low levels of bowel cancer in countries without the normal western risk factors of red and processed meat, obesity, alcohol and inactivity and tallness

But epigenetic mechanisms can turn off genes just as effectively as mutations, but they do it without changing your DNA sequence. Epigenetic mechanisms are controlled by really mundane things like what you eat, how worried you are, and probably more than a few things we know nothing about … yet.

So if your cancer is driven by epigenetic changes, it can look just like a cancer caused by a mutation, but when doctors go looking for the mutation, there isn’t one. There will be plenty of news about epigenetics during the next couple of decades, but don’t expect miracles.

But epigenetics is at the heart of how our lifestyles impact on our health status, so it will fundamentally change how we view ourselves. For example, epigenetics has demolished all those arguments that run like this: “We’ve been doing X for hundreds of thousands of years, it’s in our genes, there hasn’t been sufficient time for genetic change, so X is in our nature”. For X you can substitute various behaviours: “violence”, “raping women”, “eating meat”, “monogamy”, “being heterosexual”. Epigenetics demonstrates that the argument is based on false premises. Epigenetics allows the modification of the way our DNA genetic tool kit is deployed over timespans of just days and weeks. When a cat doesn’t lick her kitten enough during the early life the result is reflected in semi-permanent adverse genetic alterations that can not only last a lifetime, but be passed on to the following generation(s) in the genes. More than a few kittens have suffered to prove this result in cats and there’s excellent reason to think similar things happen in people.

If licking a kitten can change gene activation patterns in cells that affect the animal’s future feline life, then what about radiation from a nuclear accident … such as from cesium-137? A recent piece of research (in vitro) found that even huge doses of gamma radiation from cesium-137 didn’t match the lick of a cats tongue. Radiation had no impact on gene activation patterns.

Concluding remarks

The latest IPCC assessment report is quite clear that if we don’t change direction, then we’ll end up where we are heading … with a planet which is three or more degrees hotter by the beginning of the next century.

This would be a very different planet. As well as more of the spectacular tragedies of Haiyan or the 2010 Pakistan floods, we could expect that the current figure of close to a billion undernourished people would dramatically increase and be accompanied by further wildlife extinctions as increasing numbers of wealthy people on the planet embrace the dominant cultural food habits of the rich and famous. The infatuation with slogans over substance could see a rise in renewable energy which will add solar and biofuel farms to the traditional primary deforestation forces of grazing and livestock feed production.

Currently, many environmental groups act as if the risks associated with nuclear accidents are commensurate with the risks associated with climate change. They seem positively gung-ho about betting the planet on recycling the renewable energy technologies that failed in the 1970s when rolled out to tackle the oil crisis: wind and solar power. On the other hand many are unwilling to consider the only technology which successfully displaced oil as an electricity fuel source and in so doing ended that 1970 oil crisis: nuclear power.

It’s my contention that the primary reason for this irrationality is that the public in general and most environmental activists in particular know little or nothing about the things that frighten them. Which is why they frighten them. This series has tried to rectify that deficit. While many in the general public have neither the time nor the inclination to delve into the detail required to make rational energy decisions, our political and environmental opinion makers are duty bound to do so. It is imperative that they consider the science and in so doing join that growing list of people who realise that to be anti-nuclear is to be anti-future. It really is that simple.

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