Title of Research:
18_R05-01

Study on the contribution of microplastics to bioaccumulation andbiological magnification towards fish
Principal Investigator:
Tatarazako Norihisa（Professor, Ehime University, Graduate School of Agriculture）
3-5-7 Tarumi, Matsuyama, Ehime, 790-8566 Japan
Collaborators:
Tatsuhiro Niino (LSI Medience Corporation)
1000 Kamoshidacho, Aoba-ku, Yokohama-shi, Kanagawa 227-0033, Japan
Shin Takahashi（Ehime University, Graduate School of Agriculture）
3-5-7 Tarumi, Matsuyama, Ehime, 790-8566 Japan
Yoshifumi Horie (Akita Prefectural Univesity)
241-438 Kaidobata-Nishi Nakano Shimoshinjo Akita City 010-0195 Japan
Summary of Research:
The microplastics (MPs) are known to adsorb chemical substances and there is a concern about
those chemicals may be taken more efficiently to organisms intermediated by MP and that
biological concentration or biological magnification is accelerated. Our study will try to clarify
whether the chemical substances adhered to MP are eluted, and absorbed / transferred /accumulated in the body of organisms.
In previous report, the concentration analysis of the PAHs which is adsorbed to MP, and uptaken
and bioaccumulated by fish were conducted presuming that comparison of the applied dose andchemical concentration of fish meat calculates the accumulation factor. It was found by analyzing
the 13 kinds of PAHs that the amount of chemical substances adsorbed varies depending on thetype of MP and environmental conditions, and that the more hydrophobic the substance, the moredifficult it is to desorb once it is adsorbed on the MP surface.From the result of examining theuptake of MP, medaka did not affected by MPs of all sizes and Daphnia did not affected by MPswith a diameter of 1 ㎛ or more. By using the fluorescent plastics, the MP beads were observedto accumulate in the gastrointestinal tract but not transferred to the outside of the gastrointestinal
tract. Also, no translocation of MP from Daphnia to medaka was observed by feeding the Daphnia
which had exposed (and taken) MP, to medaka.
There were difficulties to explain the presence or absence of the vector effect only by analyzing
the chemical concentration accumulated in the body, we employed new method to detect whether
the toxicity changes under the condition of coexistence of the MP and chemical, and to confirm thevector effect indirectly. As a result, in the closed experimental system, the presence of MP withsizes of uningested by living organisms reduced the concentration of chemical substances byadsorption, and the toxicity was mitigated. In the case of medaka, the toxic effect was mitigatedeven with the sizes of ingested MP and any harmful effect due to the vector effect were notconfirmed. Only Daphnia exhibited adverse effects when the intakes were high, but it was due tointestinal obstruction by MP.
In conclusion, the vector effect of MP exists in the theory, though it is estimated that the amount ofMP in the environment has no harmfulness in reality.
Timeline:
March 1, 2020 - February 28, 2021
Topics:Oral presentation at JCIA LRI Annual Workshop 2020 “Study on the contribution of microplastics
to bioaccumulation and biological magnification towards fish” (On-line, August 21st, 2020)
Publications:
1. Norihisa Tatarazako, ”Ecotoxicity of microplastics”, Society of Environmental Hormone,NewsLeter 23-2（2020）

2. Norihisa Tatarazako, ”Ecotoxicity of microplastics”, Microfiber lecture（Japan Chemical FiberAssociation）, on web, 27/11/2020
3. Norihisa Tatarazako, Yukiyo Okazaki, Ecotoxicity of microplastics, The 22nd UK-Japan Annual
Scientific Workshop,Research into Environmental Endocrine Disrupting Chemicals &Chemicals of Emerging Concern, on web, 27/10/2020