1. 1) Official Notification Letter from Bureau of Health, Ministry of Health, Labour and Welfare (2003, 2007) No. 1010004, Oct.10, 2003, No.1115003 revised in Nov. 15, 2007 and in effect in Apr. 1, 2008.
2. 2) WHO (2004) Guidelines for Drinking Water Quality, 3rd edition, Geneva.
3. 3) WHO (2008) Evaluation of Certain Food Additives and Contaminants, 68th report of the Joint FAO/WHO Expert Committee on Food Additives.
4. 4) National Research Council (2005) Health Implications of Perchlorate Ingestion, National Academies Press, Washington, D. C.
5. 5) US EPA (2005) Occurrence data accessing unregulated contaminant monitoring data. http://www.epa.gov/OGWDW/ucmr/data.html