Observation of morphological abnormalities in silkworm pupae after feeding 137CsCl-supplemented diet to evaluate the effects of low dose-rate exposure

• Published in: Scientific reports Vol. 10; no. 1; p. 16055
• Main Authors: Tanaka, Sota, Kinouchi, Tadatoshi, Fujii, Tsuguru, Imanaka, Tetsuji, Takahashi, Tomoyuki, Fukutani, Satoshi, Maki, Daisuke, Nohtomi, Akihiro, Takahashi, Sentaro
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.09.2020; Nature Publishing Group
• Subjects: 704/172; 704/172/4081; Artificial diets; Butterflies & moths; Cesium radioisotopes; Contamination; Diet; Humanities and Social Sciences; Ingestion; Larvae; Morphology; multidisciplinary; Nuclear accidents & safety; Nuclear power plants; Radiation; Science; Science (multidisciplinary); Wings
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-72882-y

Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities in lepidopteran insects, such as shrinkage and/or aberration of wings, have been reported. Butterflies experimentally exposed to radiocesium also show such abnormalities. However, because of a lack of data on absorbed dose and dose–effect relationship, it is unclear whether these abnormalities are caused directly by radiation. We conducted a low dose-rate exposure experiment in silkworms reared from egg to fully developed larvae on a 137 CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate morphological abnormalities in pupal wings. We used 137 CsCl at 1.3 × 10 3  Bq/g fresh weight to simulate 137 Cs contamination around the FDNPP. Absorbed doses were estimated using a glass rod dosimeter and Monte Carlo particle transport simulation code PHITS. Average external absorbed doses were approximately 0.24 (on diet) and 0.016 mGy/day (near diet); the average internal absorbed dose was approximately 0.82 mGy/day. Pupal wing structure is sensitive to radiation exposure. However, no significant differences were observed in the wing-to-whole body ratio of pupae between the 137 CsCl-exposure and control groups. These results suggest that silkworms are insensitive to low dose-rate exposure due to chronic ingestion of high 137 Cs at a high concentration.