Radiocesium Activity in Tea Leaves and Stems Classified through the Refining Process

Abstract

Radiocesium release following the accident at the Fukushima Dai-ichi Nuclear Power Plant, operated by the Tokyo Electric Power Company, caused severe contamination of new tea plant shoots in many prefectures in eastern Japan in 2011. Consequently, many studies to reduce the radiocesium levels in tea have since been conducted. In this study, we investigated the radiocesium activity in tea leaves and stems classified through the refining process. The radiocesium activity in stems was 14% and 23% higher than those in ara-cha (unrefined tea) and tea leaves classified through the refining process, respectively. However, stems only make up approximately 10% of ara-cha, and thus only a minimal reduction of radiocesium activity in sen-cha can be expected by removing stems during the refining process.