"The levels detected wouldn't harm the health of the mothers or their infants, so they can keep breast-feeding as normal," a Health, Labor and Welfare Ministry official said.
The ministry sampled breast milk from 23 women from Fukushima, Ibaraki, Chiba and Saitama prefectures and Tokyo on April 24 and 25.
Traces of radioactive material were detected in seven of the samples provided for what was the first survey of its kind since the March 11 earthquake and tsunami triggered a crisis at the Fukushima No. 1 nuclear power plant.
Provisional safe levels for radiation in breast milk have not yet been set.
However, up to 100 becquerels of radioactive iodine per kilogram of drinking water and milk is considered safe for infants, while up to 200 becquerels of radioactive cesium per kilogram is deemed safe for children and adults.
Breast milk from seven of the women showed 2.2 becquerels to 8 becquerels of radioactive iodine, and one also showed 2.4 becquerels of radioactive cesium--well below the levels deemed safe for water and milk.
Materials detected in the breast milk are thought to have come from radiation leaks at the crippled Fukushima nuclear plant.
Shunichi Yamashita, dean of the Nagasaki University Graduate School of Biomedical Sciences, was not surprised by the survey findings, but said there was no need for alarm.
"Radioactive material has been dispersed into the air and water and will be absorbed by the human body, so I expected tests on breast milk would reveal traces of radiation," said Yamashita, an authority on radiation exposure.
"However, the levels detected were very low and can be ignored. There's no health risk, so I urge mothers to keep breast-feeding their babies," Yamashita said.
(May. 2, 2011)
