Determination of fluoride in foods by the highly sensitive method and estimation of the daily fluoride intake

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13670342
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Hygiene
• Research Institution: IWATE MEDICAL UNIVERSITY
• Principal Investigator: ITAI Kazuyoshi Iwate Medical University, Hygiene and Preventive medicine, associate professor, 医学部, 助教授 (10048572)
• Co-Investigator(Kenkyū-buntansha): OGURI Shigenori Iwate Medical University, Hygiene and Preventive medicine, instructor, 医学部, 助手 (60316354) ; ONODA Toshiyuki Iwate Medical University, Hygiene and Preventive medicine, assistant professor, 医学部, 講師 (00254748) ; OKAYAMA Akira Iwate Medical University, Hygiene and Preventive medicine, professor, 医学部, 教授 (60169159)
• Project Period (FY): 2001 – 2002
• Keywords: Fluoride / Flow injection analysis / Pyrohydrolysis / Ion selective electrode / Standard reference materials / Daily fluoride intake / Favorite food

Research Abstract

Analytical conditions of the method for the fluoride determination by pyrohydrolysis and flow injection analysis with a fluoride ion selective electrode were studied. Suitable conditions were set. Inorganic and organic fluoride compounds, such as NaF, were analyzed and recoveries were investigated. Recoveries of 100% for the fluoride compounds were obtained. Fluoride contents of standard reference materials, NIST SRM 1573a (Tomato Leaves), 1515 (Apple Leaves), 1568a (Rice Flour), 1577 (Bovine Liver), 1549 (Non-Fat Milk Powder) and NIES No.7 (Tea Leaves), were determined. Certified values of fluoride contents for these materials were not presented. Fluoride contents of these materials were determined within 10 % of relative standard deviations.
Hospital meals of 96 (breakfast, lunch and dinner of 32days) were collected in 2 university hospitals. Fluoride concentrations of these meals were determined. The distribution of daily fluoride intakes calculated from fluoride concentrations of these meals was not a normal distribution, biased to low levels. Eighty percent of 32 daily fluoride intakes was less than 0.5 mg and only one daily intake was over 1.0 mg. It is estimated that daily intakes of fluoride from meals in Japan are less than 1.0 mg. Fluoride concentrations of favorite foods, such as tea and juice, were determined. Fluoride concentrations in green tea and oolon tea were high, 1.0 - 1.5 mg/l. Fluoride intakes from these tea are estimated to be equal or higher than those from meals.