Effects of microplastics on growth, fertility, eye, and kidney of medaka, Oryzias latipes

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K10606
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 58020:Hygiene and public health-related: including laboratory approach
• Research Institution: Kyorin University
• Principal Investigator: Chisada Shinichi 杏林大学, 医学部, 学内講師 (90639791)
• Co-Investigator(Kenkyū-buntansha): 吉田 正雄 杏林大学, 医学部, 准教授 (10296543) ; 苅田 香苗 杏林大学, 医学部, 教授 (40224711)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: マイクロプラスチック / 生体影響 / メダカ

Outline of Final Research Achievements

Our aim was to evaluate the adverse effects of polyethylene microplastic beads (MPs, 10-63 um diameter) with respect to growth, reproduction, and the eyes and kidneys of medaka (Oryzias latipes) under experimental conditions to contribute to future research involving LOAEL determinations. Fish were exposed to 0.07 to 5.0 mg-MPs/g-body weight (BW) for 12 weeks. Growth inhibition was recognized in fish exposed to 5.0 mg-MPs/g-BW. Decreased fertility and changes in the eyes were observed in fish exposed to >0.25 mg-MPs/g-BW. The eyes exhibited thinning of the optic nerve fiber layer and dilatation of retinal veins compared with medaka not treated with MPs. The expansion of mesangial matrix in the glomerulus of kidney was observed in fish exposed to >0.5 mg-MPs/g-BW. Our data should prove useful for determining the LOAELs of polyethylene beads on vertebrates and enhance understanding of the mechanism underlying the biological toxicity of polyethylene MPs.

Free Research Field

公衆衛生学

Academic Significance and Societal Importance of the Research Achievements

水環境中のMPは大小の水棲生物の口やエラから容易に取り込まれるため、水棲生物そのものへの影響や、その後の生物濃縮による人体への影響が懸念されていた。しかしながら、生体影響とMPの経口曝露量の関連は明らかでなかった。本研究では、メダカを用いてその関連を示すとともに、毒性を示さない経口曝露量を示した。この研究成果は、MPの生体毒性を評価するための基礎的な成果として学術的意義をもつ。また、ヒトの健康におけるMPの許容濃度の設定において基礎的な成果であり、社会的意義をもつ。