On July 17 and 18 steam was observed rising from Fukushima Daiichi Reactor 3, raising concerns that the damaged reactor’s nuclear reaction had started again. If this has happened, another large release of radioactive material from the planet is probable. Then, yesterday, Tokyo Electric Power admitted that radioactive groundwater had leaked from the plant into the sea. Levels of cancer-causing cesium 134 have increased by 110 percent in the past few days. So far, Tepco has not been able to explain this increase, but it would be consistent with new nuclear reactions taking place in the reactor’s core.

Since 2011, low levels of cesium 134 have been found in bluefin tuna being caught off the California coast. In addition, seaweeds along the coast have been discovered to contain concentrations of radiation From Fukushima. Tokyo Electric Power has maintained a policy of informing the public as little as possible about the extent of the disaster. The Fukushima meltdowns took place after a massive tsunami swept the power plant complex in 2011. Tokyo Electric Power had received permission from planners to place its diesel backup generators at ground level instead of building them onto raised platforms, despite the fact that the area was a known risk for tsunamis. As a result of this, the plants lost backup power and went critical after the disaster. Since then, it has never been clear how much radiation has actually been leaked from them.

Are Californians at risk if they eat bluefin tuna? Unlike heavier radioactive elements, Cesium-134 does not quickly sink to the bottom of the sea, but remains in the water column almost indefinitely. Bluefin tuna spawn in Japanese waters, then swim across the Pacific. By the time they reach California waters, any radioactive elements they may contain will have been concentrated by the amount of time the fish have been in the water.