Special Issue

Quantitative Risk / Exposure Assessment and Management of Chemical Substances

Review

Mathematical Models Used in Exposure and Risk Assessment of Chemicals

Abstract

In order to enjoy the maximum benefit of commercialized chemicals within the limits of public consensus, we must manage the chemicals on the basis of scientifically assessed risk of them to human and the environment. In assessing human health risk, the key process is exposure assessment, in which doses of chemicals actually or potentially absorbed into human body is quantified. Mathematical models describing transfer processes of chemicals from sources to human tissues are essential tools to estimate chemical doses via various exposure pathways. This paper presents an overview of such models used in exposure assessment todate.

Key words: human health risk, exposure assessment, mathematical model, environment, intake,  pharmacokinetics

(Language: Japanese)

Review

Numerical Simulation Models to Evaluate Atmospheric Chemical Substances in Exposure and Risk Assessment

Abstract

A numerical simulation model is one of the most effective tools in exposure and risk assessment of chemical substances. Two different type models are available for estimating the atmospheric concentration. One is unit box and multi compartment type model and the other is atmospheric dispersion model. These models should be used in different suitable situations because each model has both advantage and disadvantage.

Estimation of the long-tem average Concentration in a comparatively wide region into which substances are continuously discharged is required in the environmental assessment of chemical substances. We developed a model to estimate long-tem average atmospheric concentrations of chemicals. The model validation was conducted for trichloroethylene and tetrachloroethylene concentrations in the atmosphere by comparing calculated values and observed values. Good agreement with the measured values was obtained for the monthly average concentration. The model is capable of estimating the long-term (such as monthly) average distribution of concentration of chemicals in wide flat areas such as the Kanto plain.

Key words: chemical substances, fate model, exposure assessment, risk assessment

(Language:Japanese)

Review

Exposure Assessment of Chemical Substances from Soil and Groundwater Environment

Abstract

Exposure information due to hazardous chemicals in the environment is essential to assess risk to individual person， especially in soil and groundwater environmental media. In this paper scenarios of exposure from soil and groundwater environmental media and methodologies of exposure assessment are summarized to provide fundamentals for site and generic risk assessment of categorized chemicals. The methodologies of fate and exposure models are also discussed by conducting the case studies of exposure assessment for heavy metals， organic compounds， and dioxin compounds. In addition， the structure of exposure models and available data for model calculation are examined to make clear more realistic exposure scenarios and the application to the practical environmental issues.

Key words: Exposure assessment, Exposure model, Soil, Groundwater, Subsurface environment

(Language:Japanese)

Review

Exposure/Risk Assessment beyond Concentration Assessment in the Environment:
Risk Assessment of Benzene and NO₂ in Kanto Area

Abstract

The exposure assessment required for the regional risk assessment of chemical substances, in particular, air pollutants, was discussed. In exposure assessment, it is important to obtain the information on the individual variability in exposure level. However， it is difficult to increase the spatial resolution of regional assessment or to extend the area of individual exposure assessment into regional scale. Then, supposing the practical resolution of regional exposure assessment to be approximately 25km² (5km by 5km)， the individual variability of exposure levels to air pollutant were determined for a small district with the area of approximately 25km². six surveys were conducted in fall to winter periods. The obtained values of individual variability (geometric standard deviation) were l.36 for NO₂ and l.57 for benzene. By applying those values to the risk assessment of NO₂ and benzene in Kanto area, the distributions of risk levels were obtained

(Language:Japanese)

Review

Quantification and Economic Valuation of the Health Effects of Particulate Matter

Abstract

The accumulation of the epidemiological studies facilitates the quantification of the health effects of air pollution and the accumulation of the valuation studies which monetize the reduction of mortality and morbidity risks also facilitates the economic assessment of the health effects due to air pollution. Therefore, many quantification and monetization studies have been implemented in many places in the world. In this report, in the first place, we review recent epidemiological progresses and introduce linear type and log-linear type exposure response functions. Next, we collect the case studies that adopted these kinds of exposure response functions and estimated the number and economic cost of lives lost due to air pollution. We also introduce how to monetize mortality and morbidity risks. Not only the concept of 'value of a statistical life', but also 'value of a statistical life-year' is explained. In the last place, we estimate the health effects of the exposure to particulate matter in Japan, regarding particulate matter as the index of the air pollution mix.

Key words: Particulate matter, epidemiological studies, exposure response function， quantification, economic valuation

(Language:Japanese)