Thursday, April 7, 2011
TOKYO, April 7, Kyodo
The effects of radioactive material leakage from the tsunami-ravaged Fukushima Daiichi nuclear power plant in Fukushima Prefecture have spread to marine products. The following are questions and answers regarding fish found to be contaminated by radioactive substances.
Q: Why were radioactive materials detected in fish caught off Ibaraki Prefecture?
A: Roughly speaking, the sub-arctic Oyashio current, which flows southward along the Pacific coasts of Hokkaido and the Tohoku region, and the Kuroshio current, which flows northward from the Kyushu and Shikoku regions, collide off Choshi, Chiba Prefecture during this period of the season. It is possible that contaminated water which leaked from the troubled Fukushima Daiichi nuclear power plant has reached Ibaraki by moving with the sea current. It is also possible that radioactive materials carried by winds have fallen into the sea or that the fish had been in waters near the nuclear plant.
Q: What are the effects on fish consumption?
A: The Fisheries Agency says unsafe fish will not be available to consumers as local fisheries cooperatives have refrained from shipping them.
Q: What are points to be careful of when cooking fish?
A: For vegetables, it is effective to wash or peel them as radioactive materials get attached to the surface. For fish, however, radioactive materials could be drawn into the body through seawater and feed, so they can be eliminated significantly by removing offal. It is also important to wash the fish because there may be some radioactive materials left on the surface. It is recommended to avoid eating fish skin.
Q: Is it only fish that are affected by radioactive contamination in the sea?
A: It is said that seaweed and shellfish around the nuclear plant are more susceptible to radioactive contamination than fish which swim around in the sea. Seaweed also has the tendency to accumulate radioactive iodine. But radioactive iodine has a half-life of eight days, meaning that its effect will be reduced to half in eight days, one-fourth in 16 days and one-sixteenth in 32 days. So there should not be too much concern about consuming frozen, processed or dried fish as a certain amount of time has passed after they were caught.
Q: What effects does radioactive cesium have?
A: Cesium tends to accumulate in the muscle and has a half-life of 30 years. It is also possible for it to become concentrated in bigger fish in the food chain. There is a study which shows that half the cesium taken in by fish is eliminated in 50 days as it will be discharged to seawater in the form of urine as well as from the skin and gills. But fish need to be monitored thoroughly over a long period of time if seawater is found to contain high levels of radioactive cesium.