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  • Risk Assessment Strategy Group

    Risk Assessment Strategy Group

    Wataru Naito
    Group Leader:Wataru Naito

    6 Researchers:
     Katsuhide Fujita, Yuichi Iwasaki, Masashi Kamo, Hiroyuki Mano, Akihiro Moriyama

    12 Contract Employees


    We are conducting risk assessment research on chemicals (including microplastics), nanomaterials, and SARS-Cov-2 viruses. Specifically, we develop methods for risk assessment necessary for promoting innovation of new materials such as nanomaterials, develop methods for obtaining missing data for risk assessment, evaluate risks in actual environments, and promote pragmatic risk assessment for solving social issues. Our goal is to contribute to the realization of a sustainable society where industry and the environment coexist.

    Research Highlights

    Methods for Risk Assessment and Management of Chemicals

    Development of Toxicity Prediction Methods for  Rapid and Efficient Risk Assessments

    • Development of hazard assessment methods for ecological risk using mathematical and statistical approaches
    • Development of methods for quantitative ecological risk assessment using species sensitivity distribution (SSD) and quantification of uncertainties.


    Fitting a statistical distribution to toxicity data for multiple biological species


    Development of Combined Toxicity and Population-Level Assessment Methods Using Mathematical Models

    • Development of models, statistical test theories, and combinatorial optimization methods for assessing the combined exposure effects of chemicals
    • Development of assessment methods for population-level ecological risk of chemicals


    An example of the mixture effects of two chemicals (A and B). The mixture effects differ depending on the combination of physical properties of the chemicals, and the effects are predicted by mathematical models.


    Pragmatic Risk Assessment of Freshwater and Marine Environments

    • Prediction and evaluation of ecological effects in natural environments based on field bioassessment
    • Performing practical environmental risk assessments considering regional characteristics using field measurements and modeling techniques.

    Sampling at river

    Risk Assessment and  Management Using Bioassays

    • Evaluation of ecological effects on natural environments from responses of living organisms to environment water
    • Investigation of methods for reducing impacts of wastewater at workplaces

    Devices and species for bioassay

    Environmental risk assessment of microplastics (MP)

    • Development of environmental risk assessment framework considering the characteristics of MPs
    • Trial risk assessment of MPs for Tokyo Bay
    • Estimation of species sensitivity distributions considering various MP characteristics


    Toxicity Test Methods and Evaluation of Nanomaterials

    Development of Toxicity Assessment Methods of Cellulose Nanofibers (CNFs)
    • Implementation of safety assessments for a variety of CNF slurries
    • Development of toxicity test methods (cell test, intratracheal installation test, ecotoxicity test, etc.) that companies can implement on their own.
    • Publication of a procedure manual and a safety valuation report

    EM image of CNFs


    Dissemination of Testing Methods and Safety Assessments of Nanomaterials
    • Publication of hazard assessment procedures and safety assessment documents
    • Dissemination of information on domestic and international trends through the Nanosafety Web site
    • Fundamental research for advancement and standardization of hazard testing methods for nanomaterials

    A manual for toxicity testing of CNFs


    Measurement and Estimation of exposure parameters for assessing risk of COVID-19
    • With the goal of contributing to the realization of effective infection risk mitigation measures, we conduct research to obtain evidence that contributes to assessment of risks and effectiveness of measures for preventing COVID-19 infection.
    • Measurement and estimation of ventilation and particle behavior in actual public transportation vehicles, etc.
    • Monitoring CO2 concentrations in outdoor and indoor environments in stadiums
    • Visualization and quantification of droplets and droplet nuclei using an exhalation and cough simulator

    Aerosols Testing Room

    (Collaborating with the Emission Exposure Analysis Group, working as a member of the Research Laboratory for Covid-19 Infectious Risk Asseement)