Radioactive caesium concentrations in pigs fed brown rice contaminated by the Tokyo Electric Power Company Fukushima Daiichi nuclear power plant

Abstract This experiment was conducted to determine radioactive caesium levels in the tissues of pigs fed brown rice contaminated by the fallout from the Tokyo Electric Power Company Fukushima Daiichi nuclear power plant accident that occurred after the Great East Japan Earthquake of March 2011. We prepared a control diet mainly consisting of imported corn and a test diet including brown rice (700 g/kg diet) grown in Fukushima Prefecture during 2011. The radioactive caesium concentrations in the control diet were below the limits of detection. Concentrations of 134 Cs and 137 Cs in the test diet were 15.0 Bq/kg and 20.0 Bq/kg, respectively. Twelve barrows, Duroc×(Large White×Landrace), aged 8 weeks were assigned to each diet for 3 weeks after which samples of longissimus dorsi muscle, liver, and digestive tract (from stomach to ileum) were then taken. Radioactive caesium levels in control group tissues were close to the limits of detection or less, while 134 Cs and 137 Cs were detected in the tissues taken from the test group ( 134 Cs: muscle 13.3 Bq/kg, liver 11.7 Bq/kg, digestive tract 10.3 Bq/kg; 137Cs: muscle 18.5 Bq/kg, liver 15.3 Bq/kg, digestive tract 13.7 Bq/kg). The results clearly demonstrate oral uptake and retention of radioactive ceasium in pigs fed on a fallout-contaminated diet.