Fluoride

Current fluoridating agents, sodium hexafluorosilicate and hexafluorosilicic acid, which replaced sodium fluoride by 1980, differ from the calcium fluoride in naturally fluoridated water, which was the basis for claims of tooth decay prevention in early epidemiologic studies. Studies reported in the past 15 years support only possible slight benefits from water fluoridation for the deciduous teeth of 5-year-old children, although topical fluoride treatments may be effective.

Key industry data regarding harm from chronically inhaled fluoride have been unavailable publicly for decades. Recent unveiling of unpublished reports reveals three examples of data mishandling that disguised the need for more stringent occupational standards for particulate and gaseous fluorides and fluorine. Injury reports from workers handling chemicals show that unjustifiable reductions of injury and disability numbers in the process of publication shifted concern from respiratory to mineralized tissue damage. Selective editing and data omissions allowed bias that fluoride reduces caries without detrimental effects. Finally, industry’s failure to publish an important industry-funded laboratory study buried knowledge of low thresholds for fluoride-induced lung disease. Data from that study are presented to clarify the dose- and duration-dependent changes caused by chronic inhalation of calcium fluoride.

Water fluoridation has been described by the Centre for Disease Control as one of the ten most important public health advances of the 20th Century1. In this brief paper, I will describe the history of water fluoridation and discuss the value of this policy in the early years of the 21st Century.

RESULTS: During 1999-2002, among children aged 2-11 years, 41% had dental caries in their primary teeth. Forty-two percent of children and adolescents aged 6-19 years and approximately 90% of adults had dental caries in their permanent teeth. Among children aged 6-19 years, 32% had received dental sealants. Adults aged >/=20 years retained a mean of 24 of 28 natural teeth and 8% were edentulous. Among persons aged 6-39 years, 23% had very mild or greater enamel fluorosis. Disparities were noticed across all age groups, among racial/ethnic groups, persons with lower education and income, and by smoking status. From 1988-1994 to 1999-2002, four trends were observed: 1) no change in the prevalence of dental caries in primary teeth among children aged 2-11 years, 2) a reduction in prevalence of caries in permanent teeth of up to 10 percentage points among persons aged 6-19 years and up to six percentage points among dentate adults aged >/=20 years, 3) an increase of 13 percentage points in dental sealants among persons aged 6-19 years, and 4) a six percentage point reduction in total tooth loss (edentulism) among persons aged >/=60 years.

INTERPRETATION: The findings of this report indicate that the dental caries status of permanent teeth has improved since the 1988-1994 survey. Despite the decrease in caries prevalence and severity in the permanent dentition and the increase in the proportion of children and adolescents who benefit from dental sealants, disparities remain.

The aim of this study was to investigate the fluoride release and fluoride recharge behaviors of two conventional glass-ionomer cements (GICs) and two polyacid-modified composite resins (PMCRs) after exposure to mouthwash and toothpaste. Fluoride released from the materials was measured at 1st, 2nd, 3rd, 4th, 7th, 14th, 21st, and 28th days. At 28th day, the specimens were divided into three groups. Specimens in the control group were stored in deionized water. For the other two groups, the specimens were exposed to 0.05% NaF solution and fluoridated toothpaste for one month. After refluoridation, fluoride amount was measured at 30th, 31st, 32nd, 36th, 44th, 52nd, and 60th days. All materials released fluoride. The highest amount of fluoride was obtained during the first 24 hours, and there was a statistically significant difference between the amounts of fluoride released from GICs and PMCRs (p < 0.0001). After exposure to mouthwash and fluoridated toothpaste, all materials were recharged and continued releasing fluoride. While the amount of fluoride release from the materials increased after reflouridation, the increase was higher in GICs.

Perfluorochemicals are widely used in the manufacturing and processing of a vast array of consumer goods, including electrical wiring, clothing, household and automotive products. Furthermore, relatively small quantities of perfluorochemicals are also used in the manufacturing of food-contact substances that represent potential sources of oral exposure to these chemicals. The most recognizable products to consumers are the uses of perfluorochemicals in non-stick coatings (polytetrafluoroethylene (PTFE)) for cookware and also their use in paper coatings for oil and moisture resistance. Recent epidemiology studies have demonstrated the presence of two particular perfluorochemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human serum at very low part per billion levels. These perfluorochemicals are biopersistent and are the subject of numerous studies investigating the many possible sources of human exposure. Among the various uses of these two chemicals, PFOS is a residual impurity in some paper coatings used for food contact and PFOA is a processing aid in the manufacture of PTFE used for many purposes including non-stick cookware. Little information is available on the types of perfluorochemicals that have the potential to migrate from perfluoro coatings into food. One obstacle to studying migration is the difficulty in measuring perfluorochemicals by routine conventional analytical techniques such as GC/MS or LC-UV. Many perfluorochemicals used in food-contact substances are not detectable by these conventional methods. As liquid chromatography-mass spectrometry (LC/MS) develops into a routine analytical technique, potential migrants from perfluoro coatings can be more easily characterized. In this paper, data will be presented on the types of perfluoro chemicals that are used in food packaging and cookware. Additionally, research will be presented on the migration or potential for migration of these chemicals into foods or food simulating liquids. Results from migration tests show mg kg(-1) amounts of perfluoro paper additives/coatings transfer to food oil. Analysis of PTFE cookware shows residual amounts of PFOA in the low microg kg(-1) range. PFOA is present in microwave popcorn bag paper at amounts as high as 300 microg kg(-1).

Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently, systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on: recent water fluoridation schemes in California, USA; salt fluoridation in Jamaica; milk fluoridation in Chile; and the development of “affordable” fluoride toothpastes in Indonesia. Common themes are the concern to reduce demands for compliance with fluoride regimes that rely upon action by individuals and their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher-than-acceptable levels.

The prevalence of dental fluorosis in the United States has increased during the last 30 years. In this study, we used a mathematical model commonly employed by the U.S. Environmental Protection Agency to estimate average daily intake of fluoride via all applicable exposure pathways contributing to fluorosis risk for infants and children living in hypothetical fluoridated and nonfluoridated communities. We also estimated hazard quotients for each exposure pathway and hazard indices for exposure conditions representative of central tendency exposure (CTE) and reasonable maximum exposure (RME) conditions. The exposure pathways considered were uptake of fluoride via fluoridated drinking water, beverages, cow’s milk, foods, and fluoride supplements for both age groups. Additionally, consumption of infant formula for infants and inadvertent swallowing of toothpaste while brushing and incidental ingestion of soil for children were also considered. The cumulative daily fluoride intake in fluoridated areas was estimated as 0.20 and 0.11 mg/kg-day for RME and CTE scenarios, respectively, for infants. On the other hand, the RME and CTE estimates for children were 0.23 and 0.06 mg/kg-day, respectively. In areas where municipal water is not fluoridated, our RME and CTE estimates for cumulative daily average intake were, respectively, 0.11 and 0.08 mg/kg-day for infants and 0.21 and 0.06 mg/kg-day for children. Our theoretical estimates are in good agreement with measurement-based estimates reported in the literature. Although CTE estimates were within the optimum range for dental caries prevention, the RME estimates were above the upper tolerable intake limit. This suggests that some children may be at risk for fluorosis.

“A laboratory scale electro-ultrafiltration (EUF) system was developed and used to explore the removal of arsenic and humic substances (HSs) from water. As a negatively charged species, arsenate(V) was readily removed after applying voltage to the EUF cell. Arsenite(III) was removed via EUF after the pH of the water had been adjusted. Meanwhile, the rejection of HSs increased due to the presence of an electric field. This study also showed that the removal of arsenite(III) from water relies primarily on electrostatic and non-electrostatic mechanisms. In the presence of HSs, arsenate(V) complexed with the HSs and was then able to be removed by EUF. This study demonstrates that EUF is a highly promising means of removing arsenic from water. “

The Nutrient Data Laboratory (NDL), Agriculture Research Service, USDA, coordinated the development of the USDA National Fluoride Database of Selected Beverages and Foods subsequently described as the National Fluoride Database–a critical element of the comprehensive multi-center National Fluoride Database and Intake Study
(NFDIAS).  This second release of the USDA National Fluoride Database includes a column with mean values reported in parts per million, some data changes, and some new data resulting from aggregations of the Jackson (Jackson et. al., 2002) data and new data from University of Minnesota(UMN), Nutrition Coordinating Center and University of Iowa (UIowa), College of Dentistry data (UMN-UIowa) along with data from other literature and unpublished sources.  These new aggregations have resulted in increases in the number of data points and in the number of studies resulting in tighter minimum to maximum values ranges, tighter lower and upper Error Bounds, and in some cases improved confidence codes.  The National Fluoride Database has been incorporated into a computer-based fluoride assessment tool being developed by the University of Minnesota, Nutrition Coordinating Center (NCC), as a module of the Nutrition Data System for Research (NDS-R) software.