How do we make sense of radiation? It comes down from the sky and up from the earth, it constantly surrounds us, but we can’t feel it. It’s beneficial in medicine but too much can cause cancer or an even faster demise. And it’s the scary part of nuclear energy, yet more is released from the burning of fossil fuels than anything else we do.
Well, it turns out radiation doesn’t differ so much from other stuff which is harmful in excessive amounts. The difference is that it’s made of invisible particles that shoot through the air, or paper, or concrete, or skin — depending on what types they are. It’s measured in different units depending on time, dose or effect, or what organs it’s aimed at. It gets confusing fast, but the important thing is the overall dose.
So to help, try thinking of radiation as different forms of transport travelling on a road. Large doses are like articulated trucks. Small doses are like bicycles. If the road is a metaphor for a human body, the bicycles are the constantly present natural background radiation. In some parts of the world it’s lone cyclists; in others which feature dramatically higher background radiation, it’s more like whole pelotons. But the measurable damage to roads from bicycles is nil either way, even over whole years.
Road wear becomes more noticeable for cars, over time, though it’s still impossible to tell from a solitary car. This is like the heavier radiation doses, say from repeated medical procedures or for aircraft crew. In unfortunate cases a car can crash and gouge or burn the road, but these are rare. Far more routine damage occurs as the weight of road freight takes its toll on the road material — like constant human exposure to dangerously high doses of radiation.
Extreme doses are like a train derailing and catastrophically snaking down the road, ripping massive ruts through the asphalt and rendering it unuseable.
Like the road, our bodies are fit for purpose — they naturally resist the lighter doses that earth’s biology has evolved within for aeons. Scientific observation tells us that the rare train derailment is a sudden dose of several Sieverts (a measure of the energy deposited over weight of body tissue), while natural cyclist and car traffic is on the order of a thousandth of a Sievert, or milliSievert, over a whole year. To illustrate, the annual dose (on top of average background) from weekly visits to the Misasa radium baths is 0.4 milliSieverts (mSv), while the returning residents of Minamisoma in Fukushima prefecture may receive no more than 1.5 mSv; living in Guarapari, Brazil means a 6.4 mSv annual dose.
So, at what point do our body-roads face heavy traffic-style radiation? When does it start to wear us down, leading to things like cancer?
What professionals working in this field of science largely agree on is that, if illnesses are ever caused by doses of 100 mSv or less, they are so few and far between that they’re lost in the general level of disease in the human population. To be on the safe side, annual limits are generally set by regulators between 5 and 100 times lower than this, as detection of and protection from radiation is quite straightforward. Consequently, the health impacts in populations living near well-run and regulated nuclear facilities are nil, as confirmed in Canada, the UK and the US — there simply isn’t enough extra radiation.
In fact, there probably isn’t enough even when things go wrong: no observable increase in rates of cancer is expected following the Japanese accident in 2011. This may be partially thanks to the comprehensive evacuation… however, conservative analysis of potential radiation-related deaths in nursing home residents versus the numbers who actually died as a result of evacuating put the latter as the greater hazard.
This presents a quandary for groups who have spent decades opposing civilian nuclear energy. The idea of radiation as a unique and extrordinarily harmful threat is kind of their core belief — but the evidence has steadily stacked up against it. Often forgotten in the discussion and rhetoric is the fact that nuclear energy revolves around nuclear science, and as a branch of science it advances and improves with time.
Also neglected are the impacts from alternative sources of deployable and reliable large-scale energy. In 2013 the air pollution from fossil fuel combustion led to 5.5 million deaths, without requiring any accidents at the countless, unprotested coal power stations of the world (or effects from the forgotten radiation emissions), while NASA researchers calculated 1.84 million lives saved from pollution through use of nuclear energy over a prior 38 year duration. By 2050, they projected up to 7 million additional lives saved.
If these numbers reflect the true balance of the costs and benefits of nuclear energy and the extend of its associated radiation hazards, then the words of pioneering scientist Marie Curie are more relevant today than ever.
Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.