1. 1) The Bureau of Waterworks, Tokyo Metropolitan Government: The outcome of the survey on radioactive materials in tap water,
<http://www.waterworks.metro.tokyo.jp/press/h22/press110323-01.html>, (in Japanese).
2. 2) Water Supply Division, Health Service Bureau, Ministry of Health, Labour and Welfare: Detection of radioactive materials in tap water in Fukushima Prefecture and Tokyo,
<http://www.mhlw.go.jp/english/topics/2011eq/dl/march_23_01.pdf>
3. 3) Water Supply Division, Health Service Bureau, Ministry of Health, Labour and Welfare: Measures for infants' ingestion of tap water (No. 1-0321 issued on March 21, 2011), (in Japanese).
4. 4) Ohara, T., Morino, Yu, Tanaka A.: Atmospheric behavior of radioactive materials from Fukushima Daiichi Nuclear Power Plant, J. Natl. Inst. Public Health, 60(4), 292-299(2011).
5. 5) ADVANTEC®: Quantitative filter papers, Type: No. 5A,
<http://www.advantec.co.jp/en/products/detail/?id=704>