Here’s something that’s probably outside the scope of your job as a stormwater manager but that has nevertheless crossed your mind at least a couple of times in the last two weeks: How would you deal with reports of radioactivity in surface or groundwater?
The news from Japan about radiation from the Fukushima Daiichi power plant, damaged in the March 11 earthquake and tsunami, has been sometimes confusing and contradictory, but as of Monday it seems that small amounts of plutonium have been detected in the soil outside the plant. There are also reports of spreading contamination in the ocean, up to several miles from the plant, and of radioactive contamination in Tokyo’s tap water and in raw milk and vegetables from areas near the nuclear plant.
Part of the problem, fueling public fears not only in Japan but just about everywhere else, is that “radiation” is poorly understood and frightening partly for just that reason. Many people are not making distinctions among the types of radioactivity detected. For example, there are three different isotopes of plutonium found at the plant, with half-lives ranging from 87 to 24,000 years. By contrast, iodine-131—which has been found in milk and water supplies—has a half-life of only eight days, although if it’s ingested, especially by infants or children, it poses a significant cancer risk.
There is an imperfect analogy with something water-quality professionals deal with regularly: TMDLs. In setting total maximum daily loads, we’re acknowledging that some amount of a pollutant—mercury or zinc, for example—will exist in a body of water, and that more is going to be added; we’re just trying to determine the “safe” or least damaging amount that we can allow. The same questions apply to radiation: What exactly is it that people are being exposed to, and at what dose? What health risk does it pose?
More information is starting to appear online and in the news media in terms understandable to the general public. Some articles, like this one from the International Business Times on Monday, are now giving a fairly thorough breakdown of the isotopes that have been detected. There are a number of sources with good general information about radiation as well; for example, this brief primer on “radiation basics”—from a commercial producer of radiation detection devices—offers some quick facts on different types of radiation, what constitutes a dangerous dose, and how much people typically receive from various sources—naturally occurring sources in the environment, TV watching, air travel, chest x-rays, and so on.
When we set TMDLs, we’re assuring the public that the lake or river in question will meet water-quality standards—not that it’s free of pollutants, but that those pollutants are present at relatively safe levels. There is great skepticism among some people in Japan—and elsewhere—that the information they’re receiving about “safe” radiation levels is accurate. Do you think we, as water-quality professionals, do a sufficient job of explaining the levels of other pollutants in surface waters?