Radioactive strontium up to 240 times the legal concentration limit has been detected in seawater samples collected near an intake at the crippled Fukushima Daiichi nuclear plant, Tokyo Electric Power Co. said Sunday.
The utility said the substance was also found in groundwater near the plant's Nos. 1 and 2 reactors. The government's Nuclear and Industrial Safety Agency said it is the first time that the substance has been found in groundwater.
The agency said it is necessary to carefully monitor the possible effects of the strontium on fishery products near the plant.
Strontium tends to accumulate in bones and is believed to cause bone cancer and leukemia.