Development of a System for Field Assessment of Soil Contamination Risk
- First in Japan, quantitative assessment of site specific risks -

Soil contamination has become one of the most pressing problems in our society. With the aim of contributing to the solution of this problem, the National Institute of Advanced Industrial Science and Technology (AIST; Hiroyuki Yoshikawa, President) has developed, for the first time in Japan, a Geo-environmental Risk Assessment System (GERAS), which allows the quantification of health risks specific to each location. The system has been released to the public on this date.

URL: http://unit.aist.go.jp/georesenv/

Enforcement of the Soil Contamination Prevention Law has brought the need for suitable management measures concerning the risk from pollution of soil and groundwater. For that purpose, it has become necessary to carry out technical studies to evaluate the degree, scale and extent of contamination through surveying and monitoring of contaminated sites. However, although quantitative appraisal of the effect of pollution on human beings and ecosystems is necessary, there are no standardized techniques to measure these health risks. This makes it difficult for the diverse regions of Japan even to take the first steps toward completion of pollution evaluation surveys.

High expectations are held for the use of GERAS as a risk management tool which is easy to use in the field. This system can be used for independent environment risk management, for assessment of the risk posed by substances that are not subject to regulations, such as oils or poorly biodegradable chemical compounds, to grasp the effectiveness of soil decontamination measures, and to consider the characteristics of soil and underground water specific to the contamination site.

On the basis of the social circumstances and importance of risk assessment, the AIST has succeeded in developing the first computer system in Japan for scientific evaluation of the health risks posed by soil and groundwater pollutions. This quantitative assessment is based on the occurrence probability and toxicity on the health effect of chemical compounds.

Besides soil and underground water pollution risk assessment, the GERAS can be also used for assessment of environmental impact on ecosystems and of the effect of pollution countermeasures. Currently, efforts are oriented toward technology transfer and spreading of this risk assessment system for soil and groundwater pollution.

The GERAS consists of a "Screening Model" which is based on exposure assessment and risk evaluation to determine the health impact and set the target levels for purification measures, and a "Site Model" which takes into account the soil characteristics and decomposition characteristics of contaminants for risk assessment of individual sites. The "Screening Model" has already been applied on a trial basis by companies and local governments. This time, the AIST has completed a "Site Model" and made it available to the public after appraisal and evaluation by specialists.

The developed GERAS can calculate the exposure level in human beings and the risk level of chemical compounds which cause soil and groundwater pollution easily using a Windows PC. This is mainly an independent evaluation system to be used for risk management in business institutions. Besides the contaminants such as heavy metals and volatile organic compounds stipulated in the Soil Contamination Countermeasures Law, it is possible to evaluate the risks of other compounds such as oils, PCBs and dioxins.

In the present research, a methodology for exposure assessment and risk assessment for soil contamination has been established, and the validity of the arithmetic expression in the "Site Model" has also been verified. It was also possible to calculate the exposure to contaminants and the risk for people inside and outside contaminated sites by considering soil characteristics specific to Japan. Furthermore, an easy to use computer system has been created by incorporating a database of soil and groundwater characteristics, physical properties and toxicity of contaminants.

GERAS is distributed free in CD-ROM form. To obtain it, please access the following website.

URL: http://unit.aist.go.jp/georesenv/

(Contents of Research)

Geo-Environmental Risk Assessment System (GERAS)

A computer system for quantitative assessment of the risk of impact on health of human beings and on ecosystems posed by soil and groundwater in geo-environments. It makes it possible to evaluate the risk based on the appraisal of the level of contaminants under diverse environmental conditions and field conditions.

Risk Management

This is a process based on the assessment of the risk level to reduce or decrease diverse expected risks. In the case of soil contamination problems, it includes the understanding, investigation, supervision and cleaning measures of pollution related situations.

Soil Contamination Risk

The effect of soil contamination includes the impact on the health of human beings, the inhibition on growth of farm products and plants, and other effects on ecosystems. The impact on health of human beings comes from direct contact with the contaminated soil through the skin or the mouth, whereas indirect effects come from intake of underground water contaminated by harmful products dissolved in contaminated soil.

Exposure Assessment and Risk Assessment

Exposure assessment is one of the methods to evaluate the health impact in human beings. Exposure is the amount of a chemical substance that a person is in contact with through the environment. Exposure assessment refers to methods of measuring the amount of exposure to a substance under diverse conditions. Risk assessment is the methodology of calculating the health risk using the probability of occurrence and the toxicity value of any health effect caused by hazardous chemical substances.