Domestic and overseas efforts on response to accidents and disasters with release of chemical substances were investigated, mainly from the viewpoint of exposure level. To prioritize chemical substances that should be managed in emergency in Japan, acute exposure levels used in Europe and the United States were combined with available information on the amount of chemical substances in Japan. Regarding the amount information, two groups of substances, industrial use substances (substances related to the Chemical Substitution Law and PRTR law) and pesticides, were targeted. Priority substance list was prepared by linking with the toxic judgment value. In preparing the lists, some substances were excluded by individual judgment due to existence of existing management system, concern of risk to the public, etc. Therefore, some substances which is not focused under the existing environmental regulations were listed as high priority substances.

Environmental contamination by chemical spill or discharge in water is high concern especially in resources of water suppliers. As for chemical contamination accidents in drinking water source, we hereby demonstrate some case studies. In 2012, hexamethylenetetramine contamination was detected by formaldehyde produced in chlorination in drinking water treatment process, which caused a great water suspension in the metropolitan area. Chemical contamination was also found in rivers in Niigata which caused mal odor in drinking water in 2016. The compound was finally identified using accurate mass spectrometry. In these cases, combination of chemical analysis and information collection including treatability is a key to solve chemical contamination. Comprehensively administrative countermeasures in drinking water supply systems are described, i.e. water safety plans and 'continuous water supply with restriction for drinking.'

As the result of promoting notification of the plan for environmental risk reduction measures for the large-scale disasters to a given size or larger factories and business establishments, the plans have been submitted from all of the 482 target entities during fiscal years of 2014-2016.
In order of handling amount of designated chemical substances in Osaka prefecture, chemical industry, petroleum and coal products industry, and warehousing business were ranked in classifying by industry, and Toluene, Xylene, and Benzene by substance. Handling amount of chemical substances were about 5,000-30,000 times as large as those of release amount, and they were the largest at the area of Senshu and Sakai-City where industrial complex of oil and chemical factories has been located in the coastal area.

Automated identification and determination system using a gas chromatograph-mass spectrometry (AIQS-GC) is a technology that enables semi-identification and quantification of substances without using the standard substance. Using this method, environmental water monitoring around the disaster temporary storage area after the Great East Japan Earthquake was conducted. Di (2-ethylhexyl) phthalate, pyrene, etc. were detected at high concentration. Some substances showed high concentration near the temporary storage area, suggesting the possibility of elution from disaster waste. Thus, AIQS-GC was effective in emergency monitoring such as disasters. The authors held several workshops to disseminate this system. We have also started joint research with the local environment research institute on the improvement of AIQS-GC. In this joint research, we have a plan to add the number of listed substances, expand the applicable equipment manufacturers, and study the inter-apparatus and inter-laboratory error. In addition, AIQS can be analyzed retrospectively, accumulated and aggregated measurement data is expected.