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Is seafood too tainted to eat?

Kyodo News

The effects of radioactive materials discharged by the Fukushima No. 1 nuclear plant have spread to marine products. The following are questions and answers regarding contaminated fish:

Why were radioactive materials detected in fish caught off Ibaraki Prefecture?

Marine life can roam, and then there’s tides and currents. The sub-Arctic Oyashio current, which flows southward along the Pacific coasts of Hokkaido and the Tohoku region, and the Black current, which flows northward from Kyushu and Shikoku, collide off Choshi, Chiba Prefecture, during this time of the year.

Thus the currents could have carried contaminated water from the Fukushima plant to Ibaraki, or radioactive materials carried by winds could have fallen into the sea in the area or were carried there by fish.

What are the effects on fish consumption?

The Fisheries Agency says unsafe fish will not be available as fisheries cooperatives have refrained from shipping them.

What are points to be careful of when cooking fish?

For vegetables, it is effective to wash or peel them because radioactive materials stick to the surface. For fish, however, radioactive materials ranging from iodine and cesium to highly toxic plutonium could be drawn into the body through seawater or via the food chain. These can be eliminated significantly by removing the insides. It is also important to wash the fish because there may be radioactive material on the skin, which authorities now advise not to eat.

Is it only fish that are affected by radioactive contamination of the sea?

No. The seaweed and shellfish around the nuclear plant are more susceptible to contamination than fish, which roam.

Seaweed has a tendency to absorb radioactive iodine, which has a half-life of eight days. This means its radioactivity weakens by half in eight days, one-fourth in 16 days and one-sixteenth in 32 days. It is not clear whether seaweed also absorbs cesium, which has a much longer half life of 30 years.

It also is not clear what the radioactive water from the plant will do to the shellfish — clams, oysters, scallops, etc. — or what toxic elements they will absorb from the reactor.

The only thing that is truly clear is that rates for cancer and leukemia tend to surge in people who consume or have been exposed to highly abnormal amounts of radioactive materials.

What impact will the cesium have on marine life?

Cesium tends to accumulate in the muscle tissues and can become more concentrated in the bigger fish in the food chain.

One study says half the cesium taken in by fish is eliminated in 50 days because it is expelled through the urine, skin and gills. But fish need to be monitored thoroughly over a long period if their waters are found to contain high levels of cesium.

Frozen, processed or dried fish may pose no hazard, especially if caught before March 11.