Japan Fallout: What That Radioactive Water Means

Should the Japanese be worried about the tens of thousands of tons of radioactive water that Tokyo Electric started dumping into the Pacific yesterday? Yes and no. The water around the Fukushima plant is likely to be contaminated for years, experts tell the Wall Street Journal, but the danger elsewhere is likely to be relatively minimal, because the ocean should dilute the radioactivity to minute, harmless levels. The water Tepco is dumping is also drastically less dangerous than what's already leaking out of the plant.

The iodine in the water will fade fast, though not before contaminating nearby seaweed. But the cesium-137 will settle on the ocean floor and contaminate shellfish—and with a 30-year half-life, “We’re talking about a few generations” before that dissipates. Other fish are in danger, too: the government adopted new radiation standards for fish today, according to the New York Times, and immediately announced that two fish caught about 50 miles away had exceeded them. (More Tokyo Electric Power Co. stories.)