In Japan, the radiocesium activity concentration in milk must be less than 50 Bq/kg-fresh to meet shipping standards, and the radiocesium concentration of the diet fed to dairy cattle must be less than 500 Bq/kg-dry. After the Fukushima nuclear accident in 2011, we conducted two experiments to investigate whether Prussian blue (PB) could suppress the radiocesium (¹³⁴Cs + ¹³⁷Cs) activity concentration in Japanese cattle’ milk. In experiment 1, four cattle were fed a diet with a radiocesium activity concentration of 175 Bq/kg-dry, with or without PB supplementation. The PB intake ranged from 0 to 3.0 g/day, and the average radiocesium intake was 3.42 kBq/day in all treatments. The radiocesium activity concentration in milk decreased from 16.4 to 8.6 Bq/kg-fresh, and the transfer coefficient of radiocesium from diet to milk (Fm) decreased from 4.77 × 10⁻³ to 2.61 × 10⁻³ with increased PB intake. In experiment 2, three cattle were fed another diet including a radiocesium activity concentration of 927 Bq/kg-dry of with or without PB supplementation. The PB intake ranged from 0 to 18.9 g/day, and the average radiocesium intake was 15.2 kBq/day in all treatments. The milk's radiocesium activity concentration decreased from 24.3 to 4.2 Bq/kg-fresh, and the Fm decreased from 1.68 × 10⁻³ to 0.28 × 10⁻³ with increased PB intake. Our results suggest that both the radiocesium activity concentration in milk and Fm can be reduced by PB, and that Fm is affected by diet. We recommend cattle should be fed absorbents such as PB to minimize the risk of milk radiocesium activity concentration exceeding 50 Bq/kg-fresh even if the diet has a radiocesium activity concentration of less than 500 Bq/kg-dry.

在日本，牛奶中的放射性铯活度浓度必须低于50 Bq / kg-新鲜，才能达到运输标准，并且饲喂奶牛的日粮中的放射性铯浓度必须低于500 Bq / kg-干燥。在2011年福岛核事故之后，我们进行了两项实验，研究普鲁士蓝（PB）是否可以抑制放射性铯（¹³⁴ Cs +  ¹³⁷日本牛乳中的Cs）活性浓度。在实验1中，饲喂四头牛的放射性铯活性浓度为175 Bq / kg-干，添加或不添加PB。PB摄入量在0至3.0 g /天之间，所有治疗中平均放射性铯摄入量为3.42 kBq /天。牛奶中的放射性铯活性浓度从16.4 Bq / kg鲜肉降低至8.6 Bq / kg-kg，饮食中的放射性铯向牛奶的转移系数（Fm）从4.77×10 ^-3降低至2.61×10 ^-3PB摄入量增加。在实验2中，给三头牛喂食另一种日粮，包括添加或不添加PB的放射性铯活性浓度为927 Bq / kg干。PB摄入量在0到18.9 g /天之间，所有治疗中的平均铯摄入量为15.2 kBq /天。牛奶的放射性铯活性浓度从24.3降低至4.2 Bq / kg-fr，Fm从1.68×10 ^-3降低至0.28×10 ^-3PB摄入量增加。我们的结果表明，PB可以降低牛奶和Fm中的放射性铯浓度，并且Fm受饮食影响。我们建议给牛饲喂诸如PB之类的吸收剂，以使牛奶中放射性铯活性浓度超过50 Bq / kg-新鲜的风险降至最低，即使日粮中放射性铯活性浓度低于500 Bq / kg-干。