How Worried Should We Be About Radiation
How Worried Should We Be About Radiation
MONTEREY: Many people are concerned about radioactivity leaking from the Fukushima nuclear reactors, especially how the disaster will affect the food chain. Most of this concern stems from a fear of the unknown or a lack of confidence in authorities and institutions that offer assurances. While we tend to side with the irrational, there are reasons to be wary.
Radiation is frightening, all the more so because most of us don’t think about it much. By now, most have heard that one microsievert is a trivial risk – much less than the dose one gets on a flight to from New York to Los Angeles. But that’s the head talking. If the airlines made everyone wear dosimeters on flights, there would be a mass panic. Consider, a person receives about 30 to 40 microsieverts during a four-hour flight across the US.
It doesn’t help that that the data presented to the public come in a variety of unfamiliar and strange sounding terms. In general, there are three measurements: the radiation absorbed, or grays; the biological effect of radiation absorbed, sieverts; and the activity of the source, becquerels. Despite impressive advances in nuclear research, doctors still don’t have a complete understanding of how radiation causes cancer, though there is strong evidence that ionizing radiation damages DNA, leading to harmful mutations. But cancer has many causes, and a cancer caused by radiation looks no different from the same cancer caused by something else. For example, exposure to radiation – such as iodine-131 – can cause thyroid cancer. For an individual, there is no way to determine what caused a specific cancer, although we can make inferences from epidemiological studies of the population as a whole.
Even today, morbid debate continues about just how many people will die from cancer related to the 1986 Chernobyl accident. A common statistic is that Chernobyl led to fewer than 50 deaths, most workers of acute radiation poisoning in the immediate weeks following the accident. Eventually, the World Health Organization expects 4,000 deaths. Some of the Chernobyl effects may be difficult to discern amidst poverty, alcoholism and other risk factors that afflict the Ukraine and Belarus.
Belarus and Ukraine did experience a spike in thyroid cancer – about 4,000 cases or up to five times the amount one might expect. Modern medicine fortunately saved the vast numbers of children, but nine still died.
So, if we are still trying to understand the effects of Chernobyl more than two few decades later, only fools would try to make early predictions about the Fukushima crisis. To date, the radiation release from Fukushima appears substantially lower than that at Chernobyl.
Still, even low levels of radiation can be harmful. In the US, the National Academies has made clear that no level of radiation can be demonstrated to be safe or healthy. At the same time, radiation is all around us. Many foods are ever so slightly radioactive. People who live in stone, brick or concrete homes, all other things being equal, will receive a slightly higher dose of radiation than those who do not. Because risk rises with exposure, from a public policy and personal view, our task is to manage that risk by limiting the cumulative dose over a lifetime, as well as avoiding any large doses – you can calculate your own annual radiation dose using this site from the US Environmental Protection Agency.
The Japanese government faces a difficult task, being honest and transparent with the people of Japan, while reassuring them and avoiding unnecessary panic. And from a policy perspective, Japan’s and other governments must analyze the implications for food safety from observed levels of radiation at Fukushima and take steps accordingly.
So far, the problem is local. Miniscule amounts of radioactivity have been detected in the United States. In Japan, local contamination is also small, but there are instances of concern. The most famous case to date is that officials found levels of radioactivity on spinach grown near Fukushima, above limits set by the Japanese government. The government tried to reassure individuals by noting that an individual would have to eat several hundred kilograms of spinach to endanger his health. “Can you imagine eating one kilogram of spinach every day for one year?" State Secretary of Health Minister Yoko Komiyama asked reporters.
No, but people do eat more than 2 kilograms of food each day. When policymakers set radioactivity limits for food, they don’t make a special exception for spinach. Rather radiation levels are set across the board, in order to manage an individual’s cumulative dose. If everything a person ate was as radioactive as Fukushima spinach, diners would accumulate risk.
At some level, the risk from Fukushima is much smaller than many dangerous tasks we chose to do every day. A chest X-ray results in a dose of about 0.1 microsieverts. A six-hour transatlantic flight is about five times that, plus 0.002 microsieverts from the machine that X-rays your baggage. And a chest CT scan is 7 microsieverts. Although these are all low doses, they add up. Airline workers and frequent flyers, for example, are popular subjects for epidemiological studies of cancer-mortality, while the FDA recently launched an initiative to discourage unnecessary CT scans. From this perspective, fixating on risk from Fukushima is irrational. At the same time, some people avoid certain risks – as is their right.
For those of us not living in close proximity to Fukushima, any dose received will be trivial compared to choices we make everyday. But this is not to say that we should be sanguine about the public-health impact of Fukushima. Rather, the problem here is more a public-policy challenge than a personal one. The doses may be much less than one receives on an airline flight, but flying is a choice. Many people who live in Japan have been and will continue to be exposed to small amounts of radiation without having made an informed choice, other than indirectly by living in a democratic society that relies on nuclear power.
Although the risk to society as a whole still looks to be small, the public concern in this sense is not irrational or unreasonable. Authorities have a serious responsibility to prevent or mitigate even small radiation risks. The risks of Fukushima may be small, but this is still serious business.