In late August, the seasonal fish delicacy known as ainame or fat greenings, caught within 15 miles of the crippled nuclear power plant, were tainted with radioactive cesium beyond the government’s limit of 100 becquerels per kilogram.
But recent Health Ministry studies have found that the isotope has not been detected in most vegetables, even though many were declared unsafe last year.
The greatest contamination remains in food from forests, rivers and lakes in the Tohoku and northern Kanto regions, including mushrooms, mountain vegetables, wild game and freshwater fish.
Experts caution that radiation levels are often highest in forests, where contaminated leaves fall and accumulate radioactivity in the soil.
Bottom-feeding fish in the sea also tend to have higher levels of cesium.