Total fluoride intake and urinary excretion in German children aged 3-6 years

Fluoride Intake Through Dental Care Products: A Systematic Review

Fluoride (F) is added to many dental care products as well as in drinking water to prevent dental decay. However, recent data associating exposure to F with some developmental defects with consequences in many organs raise concerns about its daily use for dental care. This systematic review aimed to evaluate the contribution of dental care products with regard to overall F intake through drinking water and diet with measurements of F excretion in urine used as a suitable biomarker. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using keywords related to chronic exposure to F in the human population with measurements of F levels in body fluids, 1,273 papers published between 1995 and 2021 were screened, and 28 papers were finally included for data extraction concerning daily F intake. The contribution of dental care products, essentially by toothbrushing with kinds of toothpaste containing F, was 38% in the mean regardless of the F concentrations in drinking water. There was no correlation between F intake through toothpaste and age, nor with F levels in water ranging from 0.3 to 1.5 mg/L. There was no correlation between F intake and urinary F excretion levels despite an increase in its content in urine within hours following exposure to dental care products (toothpastes, varnishes, or other dental care products). The consequences of exposure to F on health are discussed in the recent context of its suspected toxicity reported in the literature. The conclusions of the review aim to provide objective messages to patients and dental professionals worried about the use of F-containing materials or products to prevent initial caries or hypomineralized enamel lesions, especially for young children.

Health risk assessment in children living in an urban area with hydrofluorosis: San Luis Potosí Mexico case study

BACKGROUND

Fluoride is an inorganic element, which can be found in high concentrations in groundwater. Its consumption and exposure have consequences on human health. The objective of this study was to evaluate fluoride exposure and develop a health risk assessment in children from an urban area with hydrofluorosis in Mexico.

METHODS

Water fluoride levels in active wells were provided by the Water State Agency and divided into three zones: agriculture zone (Zone A), metallurgical zone (Zone B), and industrial zone (Zone C). Urinary fluoride levels were determined by potentiometric method using an ion-selective electrode. Health risk assessment was performed through Monte Carlo model analysis and hazard quotient was calculated.

RESULTS

According to fluoride well concentration, all zones have high concentration especially Zone B (2.55 ± 0.98 mg/L). Urinary fluoride concentrations were highest in children in Zone B (1.42 ± 0.8 mg/L). The estimated median daily intake dose of fluoride was 0.084 mg/Kg-day for the children living in zone B. The highest mean HQ value was to Zone B (1.400 ± 0.980), followed by Zone C (0.626 ± 0.443).

CONCLUSION

The levels of fluoride exposure registered are a potential risk to generate adverse health effects in children in the San Luis Potosi metropolitan area.

A systematic review and meta-analysis of 24-h urinary output of children and adolescents: impact on the assessment of iodine status using urinary biomarkers

PURPOSE

Urinary iodine concentration (UIC (μg/ml) from spot urine samples collected from school-aged children is used to determine the iodine status of populations. Some studies further extrapolate UIC to represent daily iodine intake, based on the assumption that children pass approximately 1 L urine over 24-h, but this has never been assessed in population studies. Therefore, the present review aimed to collate and produce an estimate of the average 24-h urine volume of children and adolescents (> 1 year and < 19 years) from published studies.

METHODS

EBSCOHOST and EMBASE databases were searched to identify studies which reported the mean 24-h urinary volume of healthy children (> 1 year and < 19 years). The overall mean (95% CI) estimate of 24-h urine volume was determined using a random effects model, broken down by age group.

RESULTS

Of the 44 studies identified, a meta-analysis of 27 studies, with at least one criterion for assessing the completeness of urine collections, indicated that the mean urine volume of 2-19 year olds was 773 (654, 893) (95% CI) mL/24-h. When broken down by age group, mean (95% CI) 24-h urine volume was 531 mL/day (454, 607) for 2-5 year olds, 771 mL/day (734, 808) for 6-12 year olds, and 1067 mL/day (855, 1279) for 13-19 year olds.

CONCLUSIONS

These results demonstrate that the average urine volume of children aged 2-12 years is less than 1 L, therefore, misclassification of iodine intakes may occur when urine volumes fall below or above 1 L. Future studies utilizing spot urine samples to assess iodine status should consider this when extrapolating UIC to represent iodine intakes of a population.

Effect of altitude on urinary, plasma and nail fluoride levels in children and adults in Nepal

INTRODUCTION

A greater prevalence of dental fluorosis has been reported in higher- versus lower-altitude communities. This study, for the first time, examined several aspects of fluoride metabolism in children, aged 4-5 years, and their parent, living at lower altitude (<78 m) and higher altitude (>1487) areas in Nepal.

METHODS

The study assessed total daily fluoride intake (TDFI), 24 h urinary fluoride excretion (UFE), and fluoride concentrations of toe- and finger-nail (FC_toenail, FC_fingernail) in children and parents as well as fluoride concentration of plasma (FC_plasma) in parents. Fractional urinary fluoride excretion (FUFE) was calculated as the ratio between UFE and TDFI. FC_toenail, FC_fingernail and FC_plasma were normalised for TDFI by dividing the variables by TDFI and the ratio was reported as the percentage.

RESULTS

In total, 89 children and 80 parents took part in the study: 42 children and 41 parents from the lower altitude area; 47 children and 39 parents from the higher altitude area. Fluoride concentration of drinking water was significantly (P < 0.001) higher at lower altitude (0.395 mg F/l) than at higher altitude (0.104 mg F/l). TDFI was significantly (p < 0.001) higher in both children and parents living in lower altitude than those living at higher altitude. There was a statistically significant (p = 0.044) difference in the mean FUFE of children living at lower altitude (53%) and higher altitude (46%). However, no significant difference in FUFE was found between parents living at lower altitude (47%) compared with higher altitude (41%). In both children and parents, no statistically significant differences in normalised FC_toenail, FC_fingernail were found between the two altitude areas. However, normalised FC_plasma was statistically significantly (P = 0.005) higher in parents living at higher altitude (0.15%) compared with those living at lower altitude (0.11%).

CONCLUSION

The results suggest that higher altitude living results in decreased urinary fluoride excretion, and consequently increased fluoride retention in children for a given dose (amount) of fluoride.

The use of urinary fluoride excretion to facilitate monitoring fluoride intake: A systematic scoping review

BACKGROUND

As a recognised effective and economical agent for dental caries prevention, fluoride has been used in many different fluoridation schemes implemented across the world. Considering the narrow 'dose-gap' between the benefit of caries reduction and the risk of dental fluorosis, it is recommended that fluoride intake is monitored by measuring urinary fluoride excretion. The aim of this scoping review is to map the current literature/evidence on fluoride intake and excretion studies in relation to the study population, settings, type of study design, methodology, and analytical approach.

METHODS

Embase/Ovid, MEDLINE/Ovid, CINAHL/EBSCO, Scopus/Elsevier were searched for relevant articles until April 2018. Studies were included if they reported intake and excretion of fluoride in healthy humans of all age groups. Findings were explored using a narrative synthesis to summarise studies characteristics and outcome measures.

RESULTS

Removal of duplicates from the originally 2295 identified records yielded 1093 studies of which 206 articles were included. Only 21.6% of the studies were conducted in children (<8-year-olds). Most studies (38.8%) used drinking water concentration as a proxy for fluoride intake, whereas only 11.7% measured fluoride intake from all sources. Of the 72 studies that measured dietary fluoride intake, only 10 reported the validity of the employed dietary assessment method. Only 14 studies validated the urine sample collection methods. No information on the validity of the employed analytical method was reported by the majority (64.6%) of studies. Only a small proportion (8.7%) of the included studies investigated the association between fluoride intake and excretion.

CONCLUSION

The findings reveal much variability in terms of conducting the studies and reporting the findings, illustrating a high heterogeneity in data collection across settings and populations. Future studies should provide more detail on sampling technique, measurement protocols (including validation), and on clearly defining the relationship between intake and urinary excretion of fluoride.

A Physiologically-Based Pharmacokinetic Modeling Approach Using Biomonitoring Data in Order to Assess the Contribution of Drinking Water for the Achievement of an Optimal Fluoride Dose for Dental Health in Children

Due to an optimal fluoride concentration in drinking water advised for caries prevention purposes, the population is now exposed to multiple sources of fluoride. The availability of population biomonitoring data currently allow us to evaluate the magnitude of this exposure. The objective of this work was, therefore, to use such data in order to estimate whether community water fluoridation still represents a significant contribution toward achieving a suggested daily optimal fluoride (external) intake of 0.05 mg/kg/day. Therefore, a physiologically-based pharmacokinetic model for fluoride published in the literature was used and adapted in Excel for a typical 4-year-old and 8-year-old child. Biomonitoring data from the Canadian Health Measures Survey among people living in provinces with very different drinking water fluoridation coverage (Quebec, 2.5%; Ontario, 70% of the population) were analyzed using this adapted model. Absorbed doses for the 4-year-old and 8-year-old children were, respectively, 0.03 mg/kg/day and 0.02 mg/kg/day in Quebec and of 0.06 mg/kg/day and 0.05 mg/kg/day in Ontario. These results show that community water fluoridation contributes to increased fluoride intake among children, which leads to reaching, and in some cases even exceeding, the suggested optimal absorbed dose of 0.04 mg/kg/day, which corresponds to the suggested optimal fluoride intake mentioned above. In conclusion, this study constitutes an incentive to further explore the multiple sources of fluoride intake and suggests that a new balance between them including drinking water should be examined in accordance with the age-related physiological differences that influence fluoride metabolism.

Dentifrices for children differentially affect cell viability in vitro

Objectives

Child dentifrices vary in their composition, with possible differential impacts on cells in the oral soft tissue. While cytotoxicity studies have been performed on adult dentifrices, no respective studies have thus far been reported on child dentifrices.

Material and methods

Seventeen commercial dentifrices for children up to 12 years of age were evaluated with respect to their in vitro cytotoxicity on gingival fibroblasts, oral squamous cell carcinoma HSC-2 cells, and L929 mouse fibroblasts. Proliferation was analyzed and live-dead staining was performed.

Results

Ten child dentifrices greatly reduced cell viability with LC50 values below 5 %. Four dentifrices showed a moderate cytotoxicity with LC50 values between 5 and 20 %. Three child dentifrices showed almost no cytotoxicity with LC50 values above 95 %. The results of the assays for proliferation and live-dead staining supported these findings.

Conclusions

The different composition of the child dentifrices translated into a broad spectrum of in vitro cytotoxicity on cells of the oral cavity.

Clinical relevance

The in vitro data provide the scientific foundation for further in vivo research testing the clinical relevance of the present findings.

Estimation of daily dietary fluoride intake: 3-d food diary v. 2-d duplicate plate

The 3-d food diary method (3-d FD) or the 2-d duplicate plate (2-d DP) method have been used to measure dietary fluoride (F) intake by many studies. This study aimed to compare daily dietary F intake (DDFI) estimated by the 3-d FD and 2-d DP methods at group and individual levels. Dietary data for sixty-one healthy children aged 4-6 years were collected using 3-d FD and 2-d DP methods with a 1-week gap between each collection. Food diary data were analysed for F using the Weighed Intake Analysis Software Package, whereas duplicate diets were analysed by an acid diffusion method using an F ion-selective electrode. Paired t test and linear regression were used to compare dietary data at the group and individual levels, respectively. At the group level, mean DDFI was 0·025 (sd 0·016) and 0·028 (sd 0·013) mg/kg body weight (bw) per d estimated by 3-d FD and 2-d DP, respectively. No statistically significant difference (P=0·10) was observed in estimated DDFI by each method at the group level. At an individual level, the agreement in estimating F intake (mg/kg bw per d) using the 3-d FD method compared with the 2-d DP method was within ±0·011 (95 % CI 0·009, 0·013) mg/kg bw per d. At the group level, DDFI data obtained by either the 2-d DP method or the 3-d FD method can be replaced. At an individual level, the typical error and the narrow margin between optimal and excessive F intake suggested that the DDFI data obtained by one method cannot replace the dietary data estimated from the other method.

Biomonitoring Equivalents for interpretation of urinary fluoride

Exposure to fluoride is widespread due to its natural occurrence in the environment and addition to drinking water and dental products for the prevention of dental caries. The potential health risks of excess fluoride exposure include aesthetically unacceptable dental fluorosis (tooth mottling) and increased skeletal fragility. Numerous organizations have conducted risk assessments and set guidance values to represent maximum recommended exposure levels as well as recommended adequate intake levels based on potential public health benefits of fluoride exposure. Biomonitoring Equivalents (BEs) are estimates of the average biomarker concentrations corresponding to such exposure guidance values. The literature on daily urinary fluoride excretion rates as a function of daily fluoride exposure was reviewed and BE values corresponding to the available US and Canadian exposure guidance values were derived for fluoride in urine. The derived BE values range from 1.1 to 2.1mg/L (1.2-2.5μg/g creatinine). Concentrations of fluoride in single urinary spot samples from individuals, even under exposure conditions consistent with the exposure guidance values, may vary from the predicted average concentrations by several-fold due to within- and across-individual variation in urinary flow and creatinine excretion rates and due to the rapid elimination kinetics of fluoride. Thus, the BE values are most appropriately applied to screen population central tendency estimates for biomarker concentrations rather than interpretation of individual spot sample concentrations.

Total daily fluoride intake and the relative contributions of foods, drinks and toothpaste by 3- to 4-year-old children in the Gaza Strip - Palestine

BACKGROUND

Children in Gaza Strip suffer from a high prevalence of dental fluorosis.

AIMS

To estimate and compare total daily fluoride (F) intake (TDFI) and investigate the relative contributions of different sources of F to TDFI, in 3- to 4-year-old children in Gaza Strip, exposed to low (<0.7 mg/litre), moderate (0.7-1.2 mg/litre) or high (>1.2 mg/litre) F concentrations in tap water.

DESIGN

A 3-day food diary and samples of tap water, drinks, foods, toothpastes and toothbrushing expectorate were collected from 216 children receiving low (n = 81), moderate (n = 72) or high (n = 63) F concentrations in tap water. F concentration of samples was analysed using an F-ion-selective electrode. TDFI from all sources was estimated. Data were analysed by anova and Tukey's test.

RESULTS

The mean (±SD) F concentration in low, moderate and high F tap waters was 0.21(±0.15), 0.91(±0.13) and 1.71(±0.35) mg/litre, respectively. Mean (±SD) TDFI was 0.02(±0.01), 0.04(±0.01) and 0.05(±0.03) mg/kg bw/day, respectively (P < 0.0001). Foods made the largest contribution (63.9%) to TDFI.

CONCLUSION

Total daily fluoride (F) intake increased as F concentration in tap water increased. Foods were the primary source of F. Programmes for monitoring fluoride expose should consider the fluoride concentration of water used for food preparation and local dietary behaviours.

Fluoride intake from fluids and urinary fluoride excretion by young children in Kuwait: a non-fluoridated community

OBJECTIVES

To determine the pattern of fluid consumption, fluoride intake from the fluids and urinary fluoride excretion by children aged 1-9 years in Kuwait, a nonfluoridated community.

METHODS

Using the cluster sampling technique, children aged 1-9 years were chosen from 2000 randomly selected households in Kuwait. Questionnaires were then administered to their mothers to determine the children's daily fluid intake. Fluoride concentrations in tap water as well as all brands of bottled water and beverages consumed by the children were measured, using the fluoride ion-specific electrode. Fluoride excretion was determined in 400 randomly selected children, based on fluoride/creatinine ratio.

RESULTS

The mean daily fluid consumption by the children was high, being 1115-1545 ml. About 40% of the fluid intake was plain (tap and bottled) water and approximately 10% of the children drank bottled water exclusively. Fluoride concentration in tap water was low (0.04±SD 0.02 ppm), but was higher in bottled water (0.28±SD 0.40 ppm). Mean daily fluoride ingestion from fluids was 0.013-0.018 mg/kg body weight (bw). Even after allowing for fluoride ingestion from other sources, mean daily fluoride ingestion was still below 0.1 mg/kg bw set by the United States of America Institute of Medicine as the lowest-observed-adverse-effect level for moderate enamel fluorosis in children aged up to 8 years. Furthermore, the mean daily urinary fluoride excretion of 128-220 μg was below the provisional standard of 360-480 μg for optimal fluoride usage by children aged 3-5 years.

CONCLUSION

Fluoride ingestion from fluids and urinary fluoride excretion by the children were below the recommendations for optimal fluoride usage. Thus, there is room for an upward adjustment of fluoride level in public drinking water supplies in Kuwait, as a caries preventive measure.

Fractional urinary fluoride excretion of 6-7-year-old children attending schools in low-fluoride and naturally fluoridated areas in the UK

F is an important trace element for bones and teeth. The protective effect of F against dental caries is well established. Urine is the prime vehicle for the excretion of F from the body; however, the relationship between F intake and excretion is complex: the derived fractional urinary F excretion (FUFE) aids understanding of this in different age groups. The present study aimed to investigate the relationships between (1) total daily F intake (TDFI) and daily urinary F excretion (DUFE), and (2) TDFI and FUFE in 6-7-year-olds, recruited in low-F and naturally fluoridated (natural-F) areas in north-east England. TDFI from diet and toothbrushing and DUFE were assessed through F analysis of duplicate dietary plate, toothbrushing expectorate and urine samples using a F-ion-selective electrode. FUFE was calculated as the ratio between DUFE and TDFI. Pearson's correlation and regression analysis were used to investigate the relationship between TDFI and FUFE. A group of thirty-three children completed the study; twenty-one receiving low-F water (0·30 mg F/l) and twelve receiving natural-F water (1·06 mg F/l) at school. The mean TDFI was 0·076 (SD 0·038) and 0·038 (SD 0·027) mg/kg per d for the natural-F and low-F groups, respectively. The mean DUFE was 0·017 (SD 0·007) and 0·012 (SD 0·006) mg/kg per d for the natural-F and low-F groups, respectively. FUFE was lower in the natural-F group (30 %) compared with the low-F group (40 %). Pearson's correlation coefficient for (1) TDFI and DUFE was +0·22 (P= 0·22) and for (2) TDFI and FUFE was − 0·63 (P< 0·001). In conclusion, there was no correlation between TDFI and DUFE. However, there was a statistically significant negative correlation between FUFE and TDFI.

Fluoridated toothpaste: usage and ingestion of fluoride by 4- to 6-yr-old children in England

Fluoridated toothpaste is effective for dental caries control, yet may be a risk factor for dental fluorosis. This study aimed to quantify fluoride ingestion from toothpaste by children and to investigate the effects of age, gender, and social class on the amount of fluoride ingested per toothbrushing session. Sixty-one children, 4-6 yr of age, were recruited: 38 were from low socio-economic (LSE) areas of Newcastle, UK, and 23 were from high socio-economic (HSE) areas of Newcastle, UK. All expectorated saliva, rinse water (if used), and residual toothpaste were collected after brushing at home and were analysed for fluoride. Of the children, 74% and 69% from HSE and LSE areas, respectively, claimed that they brushed twice per day. The mean (SD) weight of toothpaste dispensed was 0.67 (0.36) g. The mean (SD) amount of fluoride ingested per toothbrushing session and per day was 17.0 (14.7) and 29.3 (32.8) μg kg(-1) of body weight, respectively. Daily fluoride intake per kilogram of body weight did not differ significantly between children from LSE and HSE areas. Fluoride intake per toothbrushing session was significantly influenced by weight of toothpaste, its fluoride concentration, and the child's age. Whilst the average amount of toothpaste used per toothbrushing session was more than twice the recommended amount (of 0.25 g), only one child had a daily fluoride intake that exceeded the tolerable upper intake level of 0.1 mg kg(-1) of body weight for this age group.

Urinary fluoride concentration in children with disabilities following long-term fluoride tablet ingestion

Urine is the most commonly utilized biomarker for fluoride excretion in public health and epidemiological studies. Approximately 30-50% of fluoride is excreted from urine in children. Urinary fluoride excretion reflects the total fluoride intake from multiple sources. After administering fluoride tablets to children with disabilities, urinary fluctuation patterns should be investigated. The purpose of this study was to monitor the short and long term fluctuating patterns of urinary fluoride concentration after fluoride tablets were ingested by children with disabilities. Children with disabilities aged 6-12 years old were selected randomly and were divided into three groups: Group A, 1.0mg fluoride tablet, Group B, 0.5mg fluoride tablet, and Group C, control group. The urine samples were collected in the morning (MU) and 2h after fluoride tablets were ingested (AU). Urine was collected on the day prior to fluoride intake (baseline), the first, the third, the fifth and the eighth day of fluoride ingestion for a short term, and once every 6 months for a total of 18 months for long-term observation. The AU sample showed statistically significantly higher concentrations of urine fluoride than those of the MU samples, and no statistically significant difference was noticed in the MU samples among the three groups. Group A showed the highest urinary fluoride concentration (UFC) among the three groups. UFC increased as ingested fluoride tablet dosage increased, and it returned to the baseline level on the following day and persisted throughout the study period.

Alimentary fluoride intake in preschool children

Background

The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste.

Methods

Daily alimentary fluoride intake was measured in a group of 36 children with an average age of 4.75 years and an average weight of 20.69 kg at baseline, by means of a double plate method. This was repeated after six months. Parents recorded their child's diet over 24 hours and collected duplicated portions of food and beverages received by children during this period. Pooled samples of food and beverages were weighed and solid food samples were homogenized. Fluoride was quantitatively extracted from solid food samples by a microdiffusion method using hexadecyldisiloxane and perchloric acid. The content of fluoride extracted from solid food samples, as well as fluoride in beverages, was measured potentiometrically by means of a fluoride ion selective electrode.

Results

Average daily fluoride intake at baseline was 0.389 (SD 0.054) mg per day. Six months later it was 0.378 (SD 0.084) mg per day which represents 0.020 (SD 0.010) and 0.018 (SD 0.008) mg of fluoride respectively calculated per kg bw/day.

When adding the values of unwanted fluoride intake from the toothpaste shown in the literature (0.17-1.21 mg per day) the estimate of the total daily intake of fluoride amounted to 0.554-1.594 mg/day and recalculated to the child's body weight to 0.027-0.077 mg/kg bw/day.

Conclusions

In the children studied, observed daily fluoride intake reached the threshold for safe fluoride intake. When adding the potential fluoride intake from swallowed toothpaste, alimentary intake reached the optimum range for daily fluoride intake. These results showed that in preschool children, when trying to maximize the benefit of fluoride in caries prevention and to minimize its risk, caution should be exercised when giving advice on the fluoride containing components of child's diet or prescribing fluoride supplements.

Effect of discontinuation of fluoride intake from water and toothpaste on urinary excretion in young children

As there is no homeostatic mechanism for maintaining circulating fluoride (F) in the human body, the concentration may decrease and increase again when intake is interrupted and re-started. The present study prospectively evaluated this process in children exposed to F intake from water and toothpaste, using F in urine as a biomarker. Eleven children from Ibiá, Brazil (with sub-optimally fluoridated water supply) aged two to four years who regularly used fluoridated toothpaste (1,100 ppm F) took part in the study. Twenty-four-hour urine was collected at baseline (Day 0, F exposure from water and toothpaste) as well as after the interruption of fluoride intake from water and dentifrice (Days 1 to 28) (F interruption) and after fluoride intake from these sources had been re-established (Days 29 to 34) (F re-exposure). Urinary volume was measured, fluoride concentration was determined and the amount of fluoride excreted was calculated and expressed in mg F/day. Urinary fluoride excretion (UFE) during the periods of fluoride exposure, interruption and re-exposure was analyzed using the Wilcoxon test. Mean UFE was 0.25 mg F/day (SD: 0.15) at baseline, dropped to a mean of 0.14 mg F/day during F interruption (SD: 0.07; range: 0.11 to 0.17 mg F/day) and rose to 0.21 (SD: 0.09) and 0.19 (SD: 0.08) following F re-exposure. The difference between baseline UFE and the period of F interruption was statistically significant (p<0.05), while the difference between baseline and the period of F re-exposure was non-significant (p>0.05). The findings suggest that circulating F in the body of young children rapidly decreases in the first 24 hours and again increases very fast after discontinuation and re-exposure of F from water and toothpaste.

Urinary fluoride excretion in children exposed to fluoride toothpaste and to different water fluoride levels in a tropical area of Brazil

The aim of this study was to evaluate the urinary fluoride excretion of 2- to 7-year-old children exposed to different water fluoride concentrations in the city of Catolé do Rocha, PB, Brazil. Forty-two children were allocated to 3 groups according to the concentration of fluoride in the water: G1 (n=10; 0.5-1.0 ppm F), G2 (n=17; 1.1-1.5 ppm F) and G3 (n= 15; >1.51 ppm F). The study was carried out in two 1-week phases with 1-month interval between the moments of data collection: in the first phase, the children used a fluoride toothpaste (FT) (1,510 ppm F) for 1 week, whereas in the second phase a non-fluoride toothpaste (NFT) was used. The urine was collected in a 24-h period in each week-phase according to Marthaler's protocol. The urinary fluoride excretion data expressed as mean (SD) in µg/24 h were: G1-FT= 452.9 (290.2); G1-NFT= 435.1 (187.0); G2-FT= 451.4 (224.0); G2-NFT= 430.3 (352.5); G3-FT=592.3 (390.5); and G3-NFT=623.6 (408.7). There was no statistically significant difference between the water fluoride groups, and regardless of the week phase (ANOVA, p>0.05). The use of fluoride toothpaste (1,510 ppmF) did not promote an increase in urinary fluoride excretion. There was a trend, though not significant, as to the increase of urine fluoride concentration in relation to fluoride concentrations in the water. The excretion values suggest that some children are under risk to develop dental fluorosis and information about the appropriate use of fluoride is necessary in this area.

Fluoride in drinking water and human urine in Southern Haryana, India

The objective of this study was to determine the fluoride content in drinking water and urine samples of adolescent males aged 11-16 years living in Southern Haryana, India. A total of 30 drinking water sources in the studied habitations were assessed for fluoride contamination. Fluoride was estimated in the urine of 400 male children randomly selected from these habitations. The fluoride concentration in drinking water and urine samples was determined using USEPA fluoride ion selective electrode method. The mean fluoride concentration in drinking water samples of Pataudi, Haily Mandi and Harsaru villages was 1.68+/-0.35, 3.22+/-1.18 and 1.78+/-0.12 mg/l, respectively. The mean urinary fluoride concentration was 2.26+/-0.024 mg/l at Pataudi, 2.48+/-0.77 mg/l at Haily Mandi and 2.43+/-0.84 mg/l at Harsaru village. The higher fluoride levels in the urine of children may be associated to higher fluoride levels in drinking water. The accuracy of measurements was assessed with known addition method in water and urine. Mean fluoride recovery was 98.0 and 99.1% in water and urine. The levels obtained were reproducible with in +/-3% error limit.

Determination of exposure and probable ingestion of fluoride through tea, toothpaste, tobacco and pan masala

Levels of water soluble and acid soluble fluoride in tea, toothpaste, tobacco and pan masala (mouth freshener) were estimated. These items are, generally, ignored while calculating the total dietary intake of fluoride. Tea, toothpaste, tobacco, pan masala (with tobacco and without tobacco) frequently expose human body to 3.88-137.09, 53.5-338.5, 28.0-113.0, 16.5-306.5 and 23.5-185.0 microg of fluoride per gram of these items, respectively. An effort was also made to quantify, on the basis of available studies, the probable human ingestion of fluoride through these substances. Increased leaching of fluoride from some of these substances has been observed in acidic conditions in the present study. The results can be extrapolated to acidic conditions of human stomach.

Sources of dietary fluoride intake in 6-7-year-old English children receiving optimally, sub-optimally, and non-fluoridated water

OBJECTIVES

Due to increased consumption of pre-packaged drinks, tap water may no longer be the principal source of water intake and consequently fluoride intake. Little is known about the importance of solid foods as fluoride sources and how the relative contribution of foods/drinks to fluoride intake is affected by residing in fluoridated or non-fluoridated areas. This study investigated the relative contributions of different dietary sources to dietary fluoride intake and compared this in children residing in optimally artificially fluoridated, sub-optimally artificially fluoridated, and non-fluoridated areas.

METHODS

Thirty-three healthy children aged 6 years were recruited from fluoridated and non-fluoridated communities and categorised into three groups based on fluoride content of home tap water: optimally fluoridated (< or =0.7 mgF/L), sub-optimally fluoridated (> or =0.3 to < or =0.7 mgF/L) and non-fluoridated (50.3 mgF/L) drinking water. A 3-day dietary diary collected dietary information. Samples of foods/drinks consumed were collected and analyzed for fluoride content.

RESULTS

Drinks provided 59%, 55% and 32% of dietary fluoride intake in optimally, sub-optimally and non-fluoridated areas respectively. Tap water, fruit squashes and cordials (extremely sweet non-alcoholic fruit flavoured drink concentrates) prepared with tap water, as well as cooked rice, pasta and vegetables were important sources of fluoride in optimally and sub-optimally fluoridated areas. Carbonated soft drinks and bread were the most important contributors to dietary fluoride intake in the non-fluoridated area.

CONCLUSION

The main contributory sources to dietary fluoride differ between fluoridated and non-fluoridated areas. Estimating total fluoride intake from levels of fluoride in tap water alone is unlikely to provide a reliable quantitative measure of intake. Studies monitoring dietary fluoride exposure should consider intake from all foods and drinks.

Fluoride ingestion after brushing with a gel containing a high concentration of fluoride

The aim of the study was to evaluate the amount of fluoride remaining in the oral cavity of children after brushing with fluoride gel (1.25% F). The study involved six groups of 7-year-old and six groups of 11-year-old children. The procedure was carried out according to the manufacturer's recommendations. Fluoride concentrations were determined using ion-selective fluoride electrode. No statistically significant difference was found between the amount of fluorides that remained in the oral cavity of younger and older age group (1.2 and 1.3 mg, respectively; p > 0.05). The amount of fluorides swallowed during the procedure in both age groups proves to be within acceptable limit, as far as risk of acute poisoning symptoms is concerned. The individual daily fluoride exposure during the day of procedure seems to be twice as high compared to average fluoride intake from diet and dentifrice, and it does not exceed Tolerable Upper Intake Level for children more than 8. In younger children, it seems justifiable to reduce the amount of the preparation applied on a toothbrush, especially when daily use of the gel is recommended.

Fluoride exposure from ingested toothpaste in 4-5-year-old Malaysian children

OBJECTIVE

The aim of this study was to assess (by direct determination) the fluoride (F) exposure from ingested toothpaste among 4-5-year-old Malaysian children.

METHODS

This was part of a larger study to determine fluorosis status and F exposures. A total of 1343 10-11-year-old subjects were sampled by two-stage systematic random sampling for assessment of fluorosis. Two hundred 4-5-year-old siblings of these index subjects were sub-sampled for determination of F exposures from ingested toothpastes and other sources. Estimations of F ingested from toothpaste (FI) was made by the method of difference between 'F in toothpaste taken for use' and the 'F in toothpaste used but not swallowed', by the duplicate technique under normal home conditions. F ions were determined with the combination selective ion electrode.

RESULTS

The subjects ingested 32.9% of the toothpaste placed on the brush. Fluoride exposure from ingested toothpaste was highly variable and the mean was 426.9 +/- 505.5 microg (SEM 38.9)/48 h, or 213.5 microg/day and 131.9 microg per brushing.

CONCLUSIONS

The amount of ingested fluoride (FI) per brushing in this study was the lowest of all studies reporting this parameter and was within the pea-size range of 125-250 microg. Because of the highly statistically significant correlations between the FI from toothpaste and the amount of toothpaste dispensed (Pearson's correlation coefficient 0.647, P = 0.000), parents should assume responsibility for placement of toothpaste and limit the amount of toothpaste used.

Total fluoride intake in children aged 22-35 months in four Colombian cities

OBJECTIVE

To obtain information on the level of total fluoride intake from food, beverages and toothpaste by children at the age of 22-25 months of low and high socioeconomic status (SES) in major Colombian cities.

METHODS

Daily fluoride intake was assessed by the duplicate plate method and by recovered toothpaste solution during a 3-day period and afterwards analysed by the microdiffusion method.

RESULTS

Mean daily fluoride intake was 0.11 (+/-0.10), 0.14 (+/-0.12), 0.10 (+/-0.07) and 0.07 (+/-0.06) mg/kg body weight (bw)/day in Bogota, Medellin, Manizales and Cartagena, respectively. The total fluoride intake was higher in low-SES subjects in the cities of Medellin and Bogota. In the high-SES children of the four cities, the average intakes ranged from 0.06 to 0.09 mg F/kg bw, whereas, the low-SES children in three cities had intakes between 0.11 and 0.21 mg F/kg bw (Cartagena, 0.07). Toothpaste (containing 1000-1500 ppm F, with 1500 ppm F being more common) accounted for approximately 70% of total fluoride intake, followed by food (24%) and beverages (<6%). More than half the children had their teeth brushed by an adult, on average twice a day, using 0.22-0.65 g of toothpaste.

CONCLUSION

Children from three Colombian cities have a mean total daily fluoride intake above the 'optimal range'. Health authorities should promote an appropriate use of fluoridated dentifrices discouraging the use of dentifrices containing 1500 ppm F in children younger than 6 years of age and promoting a campaign of education of parents and oral health professionals on adequate toothbrushing practices.

Urinary fluoride excretion by preschool children in six European countries

OBJECTIVE

To measure and compare 24-h urinary fluoride excretion in children aged 1.5-3.5 years from European study sites and to use these data to estimate the 24-h fluoride intake.

METHOD

Twenty-four-hour urine samples were collected from 3-year-old children (n = 86) who were already participating in a European multicentre study. Samples were collected from Cork, Ireland (n = 19) where the water is fluoridated to a concentration between 0.8 and 1.0 ppm and from five sites with a water fluoride concentration <0.15 ppm: Knowsley, England (n = 18); Oulu, Finland (n = 18); Reykjavik, Iceland (n = 4); Haarlem, the Netherlands (n = 6); Almada/Setubal, Portugal (n = 21). The volume of the samples was measured; they were analysed for fluoride concentration and the 24-h urinary fluoride excretion was calculated. From this an estimate of the daily fluoride intake was made.

RESULTS

It was found that the mean fluoride excretion in response to the usual conditions of fluoride intake in the children in the nonfluoridated areas ranged from 0.16 mg (+/-0.08) in Oulu to 0.33 mg (+/-0.27) in Almada/Setubal with an overall mean of 0.23 mg (+/-0.19). The mean 24-h fluoride excretion in fluoridated Cork was 0.37 mg (+/-0.11). There was a significant difference between the fluoride excretion in the nonfluoridated areas and that in the fluoridated areas, and the data were broadly in agreement with WHO standards.

CONCLUSIONS

The daily urinary fluoride excretion and estimated fluoride intake in these children appeared to be within acceptable limits.

Seasonal variation of fluoride intake by children in a subtropical region

Since the optimum fluoride concentration in drinking water established for temperate countries has been considered not to be appropriate for tropical and subtropical climates, this study was conducted in Piracicaba, a subtropical, optimally fluoridated Brazilian community. The daily fluoride intake by 23 children (aged 20-30 months) from diet (liquids and solids) during the four seasons of the year was evaluated. Duplicate-plate samples of foods and beverages were collected for 2 days in each season of the year. The difference of fluoride intake during the 4 seasons was not statistically significant (p>0.05). However, the adjusted data, based on the volume of the diet collected and on the assumption of a constant fluoride concentration in the drinking water, showed that fluoride intake during spring-summer was statistically higher than that observed during the fall-winter seasons (p<0.05). The fluoride dose to which the children were submitted during the hot seasons would be 19% higher than that found during the cold ones. Although this dose difference would not to be a concern for a subtropical area, it could be relevant for a region with a genuine tropical climate.

Influence of fluoridated salt on urinary fluoride excretion of adults

After the introduction of fluoridated table salt in the staff cafeteria (VZM) of the Heidelberg University Medical and Dental School, the opportunity was taken to determine urinary fluoride excretion of those eating their main daily meals there. Subjects collected 24-hour urine in three fractions (mornings, afternoons, evenings/nights) before fluoridated table salt was introduced in the VZM, and at 6, 12 and 24 months afterwards. The fluoride concentration in the urine was determined. After 24 months, 127 of the original 200 test persons (study group) and 33 of the 60 persons in the control group could be examined. During this period, each participant in the study group took an average of 3.1 of the main meals each week at noon in the VZM. After fluoridated table salt was introduced at the VZM, fluoride excretion increased only in the afternoon urine of the test group; in this respect, the baseline examination disclosed an average of 33.98 +/- 21.18 microg/h, while the follow-up examinations revealed averages of between 39.72 +/- 22.58 and 42.44 +/- 26.16 microg/h. This difference was statistically significant (Kruskal-Wallis test, p < 0.05). It is recommended that in studies of similar questions, fractions of urine should be collected over 24-hour periods.