Radioactivity tests on grass and milk around Sizewell B power station have been carried out by the Food Standards Agency following a higher than normal release of radioactive iodine from the plant.Based on the results, the Agency can reassure the public that food has not been affected by this incident and there has been no risk to public health through food.The Environment Agency told the Food Standards Agency on Tuesday (3 October) about the incident and tests were carried out immediately to determine any potential risks to human health through food.Iodine 131 is a short-lived radioactive substance that decreases in activity by half every eight days. The main concern for public health is the possibility of the iodine entering the food chain by milk via cows grazing on contaminated pastures.The results of the tests showed a small increase above normal levels of radioactivity in one grass sample. But analysis of milk samples taken from farms close to the site showed no increase in iodine 131 levels above natural levels.These results confirmed an initial assessment of the effect of the incident, which happened during a routine maintenance operation between September 26, and 30.The initial assessment, based on a worse case scenario, showed that levels of iodine 131 in food produced close to the site would be less than 5% of the relevant European intervention level of 500 Bq per litre of milk.The Food Standards Agency will continue to monitor radioactivity levels in the area in accordance with its routine monitoring programme.