Radioactive cesium ( 134 C s and 137 C s) content in human placenta after the F ukushima nuclear power plant accident

Aim  The degree of contamination with radioactive cesium ( 134 C s and 137 C s) in the human placenta after the accident at F ukushima nuclear power plant ( FNP ), which occurred on 11  M arch 2011, has not been assessed. Material and Methods   134 C s and 137 C s contents were determined in 10 placentas from 10 women who gave birth to term singleton infants during the period between O ctober 2011 and A ugust 2012 using high‐purity germanium detectors for gamma ray spectrometry. Five women resided within 50 km of FNP (neighbor group) and gave birth by the end of F ebruary 2012, while the other five women resided within 210–290 km of FNP (distant group) and gave birth in J uly and A ugust 2012. Results  All except one of the 10 placentas contained detectable levels of 134 C s and 137 C s, ranging 0.042–0.742 Bq/kg for 134 C s and 0.078–0.922 Bq/kg for 137 C s. One placenta from a woman living in T okyo contained 0.109 Bq/kg 137 C s and no detectable level of 134 C s (<0.054 Bq/kg). 137 C s content was more than 0.2 Bq/kg in four and one placentas in the neighbor and distant groups, respectively. Conclusion  Degree of contamination of the placenta with radioactive C s was lower even in women who resided within 50 km of FNP compared to J apanese and C anadian placentas in the mid‐1960s after repeated nuclear tests and in northern I talian placentas from 1986–1987 after the C hernobyl power plant accident.