I’d been planning on waiting a little longer before returning to the topics of Fukushima and radiation health effects, but a particularly egregiously bad New York Times op-ed piece deserves some attention. So once more into the breach.
Writing in the October 30 New York Times, pediatrician and anti-nuclear activist Helen Caldicott used the nuclear reactor accident in Fukushima as an opportunity to express her concerns about nuclear energy – a calling she has followed since the Three Mile Island reactor accident. Unfortunately, Caldicott included a number of errors in her editorial that are sufficiently serious as to invalidate her conclusions. I’d like to take an opportunity to take a look at these mistakes and to explain the science behind them.
In the first paragraph of her article, Caldicott states that “the mass of scientific and medical literature…amply demonstrates that ionizing radiation is a potent carcinogen and that no dose is low enough not to induce cancer.”
To the contrary, even the most conservative hypothesis (linear no-threshold) holds that low doses of radiation pose very little threat of cancer. Using a slope factor of 5% added risk of cancer fatality per 1 Sv (100 rem) of exposure, the risk of developing cancer from 1 rem of radiation is about 0.05% (5 chances in 10,000). This risk is far lower than the risk of developing cancer as a habitual smoker, from working with a number of solvents (e.g. benzene), working with a number of laboratory chemicals, and so forth. Epidemiologists have noted no increase in cancer rates among people living in areas with high levels of natural background radiation, as well as among the lowest-dose groups of atomic bomb survivors (in fact, people living in the states with the highest levels of natural radiation have lower cancer rates than do those who live in the lowest-dose rate states). Not only that, but age-adjusted cancer rates have dropped steadily (with the exception of smoking-related cancers) over the last century, in spite of dramatic increases in medical radiation exposure. In the words of respected radiation biologist Antone Brooks, these observations show us that “if (low levels of) radiation cause cancer it’s not a heavy hitter.” The bottom line is that, if even the lowest doses of radiation can cause cancer (which has not yet been shown to be either correct or incorrect), radiation is a weak carcinogen – not the “potent carcinogen” that Caldicott would have us believe.
In the second paragraph of her article, Caldicott states that “Large areas of the world are becoming contaminated by long-lived nuclear elements secondary to catastrophic meltdowns: 40% of Europe from Chernobyl, and much of Japan.”
This is a difficult statement to parse because it is such a nebulous statement. If, by “contaminated,” Caldicott means that radionuclides are present that would not otherwise be there, she is wrong – in fact, you can find traces of artificial radionuclides across virtually every square mile of Europe, Asia, and North America as opposed to the 40% she claims. But all that this means is that we can detect trace levels of these nuclides in the soil – doing the same we can also find traces from the atmospheric nuclear weapons testing in the 1940s through the 1960s. And for that matter, we can find lead contamination over virtually the entire world as well from the days of leaded gasoline. But lead contamination goes much deeper as well – scientists found traces of lead in Greenland glaciers that date back to the Roman Empire. But nobody is getting lead poisoning from the Ancient Romans’ pollution, just as nobody is getting radiation sickness (or cancer) from the minute traces of Cs-137 and Sr-90 that can be found across the Northern Hemisphere. But Caldicott can’t really comment on the fact that artificial nuclides have contaminated the world for nearly 70 years because this would shatter her claim that radioactive contamination from Fukushima and Chernobyl is causing death and destruction in Europe and Japan.
In the third paragraph, Caldicott states that “A New York Academy of Science report from 2009 titled ‘Chernobyl’ estimates that nearly a million have already died from this catastrophe. In Japan, 10 million people reside in highly contaminated locations.”
Caldicott is correct that the NYAS reported over a million deaths from Chernobyl. However, this report itself was highly criticized for being scientifically implausible – the NYAS is a respected organization, but in this case their conclusions are at odds with the reality noted on the ground by the World Health Organization. Specifically, the WHO concluded that in the first 20 years, fewer than 100 people could be shown to have died from radiation sickness and radiation-induced cancers and they further concluded that, even using the worst-case LNT model, fewer than 10,000 would eventually succumb from radiation-induced cancer as a result of this accident. This is not a trivial number – but it is less than 1% of the one million deaths the NYAS claims. And in fact the actual number is likely to be far lower, as physician Michael Repacholi noted in an interview with the BBC. In fact, even the WHO’s International Agency for Research on Cancer acknowledges that “Tobacco smoking will cause several thousand times more cancer in the same population.” Even if contamination from Chernobyl and Fukushima are sufficient to cause eventual health problems, we can do far more good to the public by devoting attention to smoking cessation (or, for that matter, to childhood vaccinations) than by spending hundreds of billions of dollars cleaning up contamination that doesn’t seem to be causing any harm.
In the fourth paragraph of her piece, Caldicott notes that “Children are 10 to 20 times more radiosensitive than adults, and fetuses thousands of times more so; women are more sensitive than men.”
To the contrary – the National Academies of Science published a sweeping 2006 report that summarizes the state of the world’s knowledge on the “Health Risks from Exposure to Low Levels of Ionizing Radiation” in which they conclude that children are between 2-3 times as sensitive to radiation as are adults – more sensitive as adults, but a far cry from Caldicott’s claim.
The reproductive effects of radiation are also well-known – fetal radiation exposures of less than 5 rem are incapable of causing birth defects according to our best science, and the Centers for Disease Control flatly states that exposure to even higher radiation doses is not a cause for alarm under most circumstances. This conclusion, by the way, is based on studies of hundreds of thousands of women who were exposed to radiation from medical procedures as well as during the atomic bombings in Japan – it is based on a tremendous amount of hard evidence.
This claim of Caldicott’s, by the way, is particularly egregious and has the potential to do vast harm if it’s taken seriously. Consider – in the aftermath of the Chernobyl accident it is estimated that over 100,000 women had abortions unnecessarily because they received poor medical advice from physicians who, like Caldicott, simply didn’t understand the science behind fetal radiation exposure. There are estimates that as many as a quarter million such abortions took place in the Soviet Union, although these numbers can’t be confirmed.
But even in this country we see this level of misinformation causing problems today – during my stint as a radiation safety officer I was asked to calculate nearly 100 fetal radiation dose estimates – primarily in pregnant women who received x-rays following serious traffic accidents – and many of the women were seriously considering therapeutic abortions on the advice of their physicians. When I performed the dose calculations there was not a single woman whose baby received enough radiation to cause problems. And it doesn’t stop there – we also had parents who refused CT scans for their children, preferring exploratory surgery and its attendant risks to the perceived risks from x-ray procedures. The bottom line is that this sort of thinking – that children and developing babies are exquisitely sensitive to radiation – can cause parents to choose needless abortions and places children at risk; by espousing these views, Caldicott is transgressing the Hippocratic oath she took to “first do no harm” and she should be taken to task for doing so.
Finally, in the last paragraph of her tirade, Caldicott claims that “Radiation of the reproductive organs induces genetic mutations in the sperm and eggs, increasing the incidence of genetic diseases like diabetes, cystic fibrosis, hemochromatosis, and thousands of others over future generations. Recessive mutations take up to 20 generations to be expressed.”
All that I can say to this is that Caldicott decided to go out with a bang. The fact is that there is not a single case in the medical or scientific literature in which birth defects or genetic disease is linked to pre-conception radiation exposure. This is not my conclusion – it’s the conclusion of Dr. Robert Brent, who knows more about this topic than anyone else in the world. Eggs and sperm might be damaged, but Dr. Brent notes that there is a “biological filter” that prevents cells that are damaged from going on to form a baby. Another line of reasoning supports Brent’s claim – areas with high levels of natural radiation also have no increase in birth defects compared to areas with lower levels of natural radiation. Caldicott’s claim that low levels of radiation exposure cause long-term genetic damage are simply not supported by the scientific or medical literature or by any observations that have been made.
Caldicott’s claim that radiation is also responsible for a host of genetic diseases is similarly dubious. The world’s premier radiation science organizations (the International Council on Radiation Protection, the United Nations Committee on the Effects of Atomic Radiation, and the National Council on Radiation Protection and Measurements) all agree that, if radiation contributes to multi-factorial disease then the effect is very weak indeed – possibly too weak to be distinguished from natural sources of these diseases. Specifically, UNSCEAR calculated that – if pre-conception radiation exposure can cause these problems – exposing the population of each generation to 1 rem of radiation each might lead to an additional 100 cases of dominant genetic disease per million births per generation and 15 cases of recessive genetic disease (ICRP calculated similar, but lower rates). This is far lower than the background incidence of genetic disease in the population as a whole. Oh – UNSCEAR also determined that “multifactorial diseases are predicted to be far less responsive to induced mutations than Mendelian disease, so the expected increase in disease frequencies are very small” – a statement with which the ICRP is in agreement. In other words, Caldicott’s claim runs contrary to the best work of the most-respected scientific organizations that specialize in radiation health effects.
With respect to the length of time required for genetic effects – if any – to manifest themselves, I honestly don’t know where Caldicott pulled the number of 20 generations from. This is a number I haven’t seen anywhere in the scientific literature, nowhere in any of the genetics classes I took in grad school, and nothing I ever calculated or saw calculated. As near as I can tell, she is either repeating something she heard somewhere or she made the number up to impress the reader.
The bottom line is that Caldicott’s editorial is grounded more on invective than on scientific or medical fact. The Fukushima accident was bad, but it pales in comparison to the natural disaster that set it off. The aftereffects of the accident are bad enough – thousands of families displaced, hundreds of thousands of Japanese who were evacuated from their homes, along with the stress, anxiety, and depression they have been suffering. TEPCO and the Japanese government will have to spend billions of dollars tearing down the plant and billions more cleaning up the contaminated area – in many cases, cleaning up places not because they pose a genuine risk to life and health but because contamination levels exceed an arbitrary level. Things are bad enough, and Caldicott is trying to score cheap points by making claims that have no connection to scientific or medical reality, simply in order to advance her anti-nuclear agenda. Her article does nothing to advance the debate – it only serves to use the tragedy in Japan to inflame the public’s fears.
The post Once more into the breach appears on ScienceWonk, FAS’s blog for opinions from guest experts and leaders.