The nuclear crisis in Japan has now entered its third week. Despite claims over the weekend that “the tide had turned”, the news has once again shifted back to reporting on frequent evacuations, smoke plumes and radiation spikes. This crisis, it now appears, may go on for weeks or months. As the fallout begins to spread, now being detected all over the Northern Hemisphere, proponents of nuclear power are now having their own meltdown.
This storm of comment has come from every quarter. George Monbiot is reminding us that “renewables have impacts too”. Lawrence Solomon is stating that the radiation might even be good for people. Mark Lynas, an “environmental” author, warns that phasing out nuclear could be the difference between two and three degrees of climate change, and offers to eat contaminated food goods from Japan himself.
If there is one thing all of these writings and more have in common, it’s condescension. The overwhelming message is that people who oppose or fear nuclear power are ignorant, uninformed, “fear-mongerers” with an “agenda”. Those who favour nuclear power, in contrast, must be wise, educated and informed – and have a crucial public need to flout that and talk down to everyone. This kind of intellectual chest-thumping would be one thing in a debate, but with the amount of attention it’s received from our media, it begins to look as if it’s some sort of scientific consensus.
Science, though, isn’t so simple. Seeking answers, I cracked open a copy of Radiobiology for the Radiologist, from a friend who works in X-ray labs. After reading for a few days, scouring the internet, and running things by a couple of medical “experts”, what I’ve found doesn’t tend to line up with the rosy picture being painted. The long-term risks caused by radiation are widely known and don’t require doses above the Japanese Government’s “safe” level of 100 mSv.
“A Chest X-Ray”
When radioactive materials, like uranium, decay, they produce a fair bit of energy in the form of radiation. This takes various forms – alpha, beta and gamma are the three primary types (helium nuclei, electrons and photons). These are forms of ionizing radiation, as they are powerful enough to knock electrons off atoms in their path, which can be quite harmful to living tissue. The effects, though, are not so simple as taking a reading with a Geiger Counter. They depend on a wide number of factors: who is being affected, what kind of radiation they’re being exposed to, how much being exposed to it and how long that takes. Women are more vulnerable than men, and children are far more vulnerable than adults. Risks are most severe for unborn babies. Various kinds of radiation, likewise, affect the body far differently, even at equivalent dosage rates. And then, of course, there’s the matter of how long it takes to get a certain dose. In order to approximate the damage done by different kinds of radiation, dosages are calculated in Sieverts (Sv) with adjustments made for different kinds of radiation and exposure. Sieverts help us to put various kinds of exposure in perspective, and can draw paralells between chest x-rays and fallout levels. They don’t, however, give us any details on exactly what is going on, or what the particular risks may be from a certain case of exposure.
At high levels, the effects of radiation are easy to predict. Acute radiation poisoning in the range of several Sieverts or above is a very nasty way to die. However, this requires a very large dose, and would require an absolutely disastrous amount of environmental contamination to reach outside the current safe zone. Most risks of radiation come at far lower doses, and occur over a much longer term. You may never get enough smoke in a cigarette to die from smoke inhalation – they only give you a small fraction of that volume of smoke – but that doesn’t prove cigarettes aren’t dangerous. Like the dangers of smoking, low levels of radiation raise risks of disease which play out over lifetimes and even those who die of cancer in their wake may never really know if they would have otherwise. These dangers require far lower doses, in milisieverts (mSv), or thousandths of a Sievert, accumulated over a year. Above about two Sieverts the risk actually drops because of the amount of cell damage, so it’s clear that the dangers we’re facing don’t require large doses. And while 100 mSv is being touted as a maximum “safe” dose, it’s far from it. In my textbook readings, that’s the point where many doctors begin to advise therapeutic abortions to pregnant women.
The biggest fear that people have from the meltdowns at the Fukushima plant is not radiation, so much as it is the other products of fission: radioisotopes. When uranium fuel decays, it also produces other elements, which are generally unstable as well. These isotopes, such as Iodine-131, Cesium-137 or Strontium-90, can remain radioactive for days to thousands of years. When dispersed in a fire or steam release at an overheating reactor, they can travel as dust on the wind or on ocean currents until inhaled or eaten. Once inside our bodies, they can build up in areas like bones, tissues or glands, and are linked to many forms of cancer and other illnesses. Radiation received in this way is far more harmful than what you’d get from an X-ray, and while dosage estimates in Sieverts attempt to make up for that, these “adjustment factors” are likely an understatement.
This is what happened with Chernobyl, and why it was so much more devastating than nearly any other accident (or even weapons test) you can name. When the core breached it spewed radioactive materials into the air, which then floated on the winds across Europe. The threat wasn’t the direct radiation spewing from the reactor, but what people received later as the dust settled. Determining how many people died directly from Chernobyl is very difficult. Estimates range from about fifty to around a million. But because the effects take such a long time to set in, and because the dust cloud was dispersed over large parts of a continent, it’s very hard to get an accurate measurement. The effects of radiation can last a lifetime – people are still, over sixty years later, experiencing higher rates of cancer from Hiroshima.
The best known isotope at the moment is Iodine-131, a common by-product of uranium decay and often associated with fallout. It’s short-lived (a half-life of about a week), but quite radioactive and can build up in your thyroid the same way other types of iodine do, mainly in the thyroid gland. This can lead to thyroid cancer and other diseases, and is quite well documented. It’s also why iodine pills are given out in these situations, to build up your body’s natural supply and prevent the absorption of any more. Aside from this, Iodine does not protect you from radiation, nor does it protect you from other isotopes such as thorium or cesium. Iodine-131 is also a prime example of why using adult males to measure risk distorts data so much – an adult male has little or no risk of developing thyroid cancer from this kind of exposure, while women and children are at risk at quite low levels.
Almost all data we have on this type of danger comes from studies done of survivors of the Hiroshima and Nagasaki bombs. This is not only because we’ve seen enough time elapse to study the population over large parts of their lives, but because the doses were so concentrated over individual populations. It’s worth noting that Chernobyl put out a lot more fallout than either of these atom bombs, as did American nuclear tests, but the populations affected were far more spread out and hard to study. This type of research is very difficult, and much of what we know is based on assumptions. Nevertheless, current research seems to indicate links between the isotopes found in fallout and a wide range of cancers (thyroid, leukemia, breast, lung and bone). It also holds the potential for birth defects and hereditary mutations. Measuring rare cancers among large populations, though, can be very difficult, and getting statistically significant results is often impossible. Since harm is so often calculated in excess cases of cancer per 100 000, it can be difficult to measure effectively even with cities of several hundred thousand.
Most experts now base their estimates in what is known as the linear no-threshold assumption, which holds that damage caused by radiation is roughly proportional to the dosage (adjusted), and that no level of radiation is safe, but some produce less than we can measure accurately. This is based on the idea that while certain kinds of damage become less likely with lower dosages, a deadly cancer is still a deadly cancer, and only needs a single “hot particle” to create. So, as the theory goes, cutting the dosage in half would also cut the number of new cancers in half. And since cancer rates are so variable for many other reasons, below a certain number of new cases, it’s just not possible to achieve “statistically significant” results. Most studies, at this point, reflect this model, by finding strong links between low-level ionizing radiation and cancers, birth defects and other ills, just below statistically significant levels. The lowest dose, so far, that I’ve been able to locate which has been found to have “significant” links is 34 mSv and breast cancer, though the generally accepted rate for most cancers is around 100 mSv per year. At this dosage, in under a year, an estimated 800 new cancers are created in 100 000 people. There are a thousand times that many people living in Tokyo, so if the city were to receive a large dose, it would need to give cancer to a population of over 800 000 to be “significant”, statistically.
There are many obvious problems with any of these estimates, some of which have been greatly overplayed lately. The first is that we’re exposed to a fair bit of background radiation on a regular basis, and much more if we get X-rays or CT scans. This is totally true, but neglects to mention that ionizing radiation causes cumulative damage – every mSv you receive in a year or more counts. We’re not going to stop receiving background radiation any time soon, and unless we do, dumping half a year’s “safe” dose on us in a week or two is still going to risk pushing us over the edge. Also, it’s worth noting, that X-rays and CT scans aren’t exactly harmless. The second common criticism is that of the Horomesis theory, a rival of the linear no-threshold model, which states that low levels of radiation can be beneficial, and that even lower levels may actually be harmful. This point, too, neglects to mention that we’re already getting this ‘helpful dose’ from natural sources, and anything we receive from fallout happens on top of that dosage. And of course, while a certain amount of (some forms of) radiation may be beneficial in some ways, that doesn’t mean that those dosages can’t also cause cancer, especially when received from fallout. So far, most studies seem to indicate more cancers, not less than expected by the linear model at dosages in this range.
Traces of radioactive particles such as Iodine-131 have now been detected as far away as British Columbia, California, Colorado, Newfoundland, Hawaii and Iceland. Levels in these places are still very low, but it suggests that a large amount of them have been dispersed into the air, and are likely far more concentrated closer to the reactors themselves. Local levels in seawater have risen very high, and traces in tapwater, milk, spinach and mizuna are now also prompting warnings. What we now know about radiation in Japan is limited by what has been measured, and so far we have very few measurements to go on.
At this point, it’s unclear how many people beyond the immediate repair crews have been exposed to a serious dose, significant or otherwise. I have yet to find much to be worried about in microsievert-level doses (millionths of a Sievert), but it is enough to set off alarms. We can only hope that at this point, the warning bells have been just that – warnings. Even if not single member of the general public gets cancer, this disaster has painted the northern hemisphere with a frightening map of where this fallout could land. Fukushima could have already been far worse than what we’ve seen, and that doesn’t prove nuclear power is safe, it proves the exact opposite. It is only a matter of time until another disaster strikes, and it could be far worse.
After a few days of reading and research, I’d probably take pains to avoid exposing a population to anything which gave off any more than a milisievert, and work much harder if women or children were involved. You could top the yearly 100 mSv “safe” limit with as little as one every 3-4 days. A couple of doses of 5-10mSv in food, water and air, even over a few weeks, could easily mean cancer for tens of thousands of Tokyo residents, even by very conservative numbers. And yes, that’s about the equivalent of a few CT scans. To put that in perspective, across Japan, the quake’s official toll is just over ten thousand dead. The risks to an individual may not be high, but spread across a population of millions, these risks are deadly serious. I’m not writing this to inspire terror and panic, but to put these risks in perspective. Nuclear disasters like Fukushima are far from safe and there’s nowhere near the kind of data at the moment to assume that it is.