Total fluoride intake and urinary excretion in 4–year–old Iranian children residing in low-fluoride areas

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.

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.

Fluoride exposure and pubertal development in children living in Mexico City

BACKGROUND

Previous animal and ecological studies have provided evidence for an earlier sexual maturation in females in relation to fluoride exposure; however, no epidemiological studies have examined the association between fluoride exposure and pubertal development in both boys and girls using individual-level biomarkers of fluoride. Capitalizing on an ongoing Mexican birth cohort study, we examined the association between concurrent urinary fluoride levels and physical markers of pubertal development in children.

METHODS

We conducted a cross-sectional study of 157 boys and 176 girls at age 10-17 years living in Mexico City. We used ion-selective electrode-based diffusion methods to assess fluoride levels in urine, adjusting for urinary specific gravity. Pubertal stages were evaluated by a trained physician. Associations of fluoride with pubertal stages and age at menarche were studied using ordinal regression and Cox proportional-hazard regression, respectively.

RESULTS

In the entire sample, the geometric mean and interquartile range (IQR) of urinary fluoride (specific gravity adjusted) were 0.59 mg/L and 0.31 mg/L, respectively. In boys, our analysis showed that a one-IQR increase in urinary fluoride was associated with later pubic hair growth (OR = 0.71, 95% CI: 0.51-0.98, p = 0.03) and genital development (OR = 0.71, 95% CI: 0.53-0.95, p = 0.02). No significant associations were found in girls, although the direction was negative.

CONCLUSIONS

Childhood fluoride exposure, at the levels observed in our study, was associated with later pubertal development among Mexican boys at age 10-17 years. Further research is needed to confirm these findings.

Fluoride intake and urinary fluoride excretion in 4- and 8-year-old children living in urban and rural areas of Southwest Nigeria

OBJECTIVES

To estimate and compare total daily fluoride intake (TDFI), daily urinary fluoride excretion (DUFE), daily fluoride retention (DFR), fractional urinary fluoride excretion (FUFE) and fractional fluoride retention (FFR) in 4- and 8 year-old Nigerians and explore associations between these outcomes to improve understanding of fluoride metabolism.

METHODS

Using a cross-sectional observational study, 72 four-year-olds and 72 eight-year-olds were recruited from nursery and primary schools (respectively) in lower and higher water F areas of urban and rural localities in Oyo State, southwest Nigeria. TDFI from diet and toothpaste ingestion was assessed using a validated Food Frequency Questionnaire and visual scale of toothpaste used during toothbrushing. DUFE was measured by collecting a 24-hour urine sample, FUFE estimated as the ratio between DUFE and TDFI, DFR estimated as TDFI-TDFE (where TDFE = DUFE + estimated faecal F excretion (ie TDFI × 10%), and FFR was estimated as [(TDFI-DFR)/TDFI] × 100. Data were analysed using ANOVA with post hoc tests and Student's t tests and strengths of associations between key variables measured.

RESULTS

Mean (SD) TDFI, DUFE, DFR, FUFE and FFR were 0.137 (0.169) mg/kg bw/d, 0.032 (0.027) mg/kg bw/d, 0.091 (0.147) mg/kg bw/d, 44% (44%) and 46% (44%), respectively, for 4-year-olds. Corresponding values for 8-year-olds (n = 63) were 0.106 (0.130) mg/kg bw/d, 0.022 (0.017) mg/kg bw/d, 0.073 (0.107) mg/kg bw/d, 36% (30%) and 54% (30%), respectively. Dietary contribution to TDFI was 79% and 75% (respectively), for 4- and 8-year-olds. Mean (SD) TDFI from toothpaste ingestion was 0.021 (0.013) mg/kg bw/d in 4-year-olds, 0.014 (0.010) mg/kg bw/d in 8-year-olds (P = .002) but with no differences between areas. Differences in dietary F intake determined the main differences in F exposure between areas. The positive correlation between TDFI and DUFE was weak for 4-year-olds (r = +.29) and strong for 8-year-olds (r = +.64). A strong positive correlation was observed between TDFI and DFR for both age groups: (r) = +.98 for 4-year-olds and (r) = +.99 for 8-year-olds.

CONCLUSION

Fluoride intake in these 4- and 8-year-old Nigerians was much higher than the "optimal range" of 0.05-0.07 mg/kg bw/d in rural, higher F water areas, with diet as the main contributor. F retention was similar in both age groups, with almost half of TDFI retained in the body. In terms of risk vs benefit for fluorosis and dental caries, this finding should be considered when mitigating against excessive fluoride exposure and planning F-based prevention.

Prevalence and extent of enamel defects in the permanent teeth of 8-year-old Nigerian children

OBJECTIVES

Enamel formation is a vulnerable developmental process, susceptible to environmental influences such as excessive systemic fluoride (F) exposure and infant/childhood disease. This study determined prevalence and extent of developmental enamel defects (DDE) and dental fluorosis in 8-year-old Nigerians and explored associations with key predictors.

METHODS

A sample of 322 healthy 8-year-olds (155 males, 167 females) from primary schools in lower and higher water F areas of (i) rural and (ii) urban parts of Oyo State in south-west Nigeria (n = 4 areas) (in which the mean (SD) F concentration of community water supplies ranged from 0.07 (0.02) to 2.13 (0.64) mg F/L) were dentally examined using modified DDE (mDDE) and Thylstrup and Fejerskov (TF) indices. Drinking waters, cooking waters and toothpaste samples were analysed for F concentration using a F ion-selective electrode (F-ISE). Information on infant/childhood diseases, infant feeding and tooth cleaning practices was obtained from parents/legal guardians. Data were analysed using ANOVA, chi-square tests, Spearman correlation and binary logistic regression as appropriate.

RESULTS

Mean (SD) F concentration of actual drinking and actual cooking waters consumed by participants was 0.25 (0.20) and 0.24 (0.14) mg F/L respectively in the urban higher F area; 1.11 (1.00) and 1.16 (1.02) mg F/L, respectively in the rural higher F area (P < .05). Overall, mouth prevalence of DDE in the permanent dentition was 61.2% with a mean (SD) of 2.4 (2.2) index teeth affected. Dental fluorosis mouth prevalence was 29.8% with a mean of 2.1 (3.7) teeth affected. Prevalence and extent of DDE and dental fluorosis were greater in higher F than lower water F areas (P < .001). A weak positive correlation was seen between extent of dental fluorosis and drinking water F concentration (ρ = 0.28). The absence of infant/childhood disease was associated with a lower risk of DDE being present (P = .001), with an odds ratio of 0.43 (95% CI = 0.26, 0.71). Gender was a statistically significant (P = .014) predictor for dental fluorosis with females having a higher risk OR 1.94 (95% CI = 1.14, 3.28) of dental fluorosis than males.

CONCLUSIONS

In these Nigerian 8-year-olds (n = 322), mouth prevalence of DDE was 61.2% (mean (SD) teeth affected = 2.4 (2.2)), and a key positive predictor was a history of infant/childhood disease. With 29.8% of these children exhibiting dental fluorosis (mean (SD) teeth affected = 2.1(3.7)), drinking water F concentration was identified as a positive predictor, along with gender, with females more at risk of dental fluorosis than males.

National and sub-national drinking water fluoride concentrations and prevalence of fluorosis and of decayed, missed, and filled teeth in Iran from 1990 to 2015: a systematic review

Fluoride intake, fluorosis, and dental caries could affect quality of life and disease burden worldwide. As a part of the National and Sub-national Burden of Disease Study (NASBOD) in Iran, we conducted a systematic review to evaluate province-year-specific mean drinking water fluoride concentrations and prevalence of fluorosis and of decayed, missed, and filled teeth (DMFT) in Iran from 1990 to December 2015. We did electronic searches of all English and Persian publications on PubMed, ScienceDirect, Google Scholar, and Iranian databases. Results revealed that the weighted mean drinking water fluoride concentration in Iran from 1990 to 2015 has been about 0.65 ± 0.38 mg/l. However, based on the WHO guideline value (1.50 mg/l) and the maximum permissible Iranian national fluoride standard (1.40 to 2.40 mg/l depending on the region's climate), there have been some regions in Iran with non-optimum fluoride concentrations in their drinking water (up to 7.0 mg/l). Overall, concentrations have been higher in southern parts of Iran and in some areas of Azerbaijan-e-Gharbi Province in the northwest and lower in the rest of the northwest and central parts of Iran. In addition, some hotspots have been found in Bushehr Province, southwest of Iran. The highest prevalence of dental flourosis has been reported in normal index while the lowest prevalence has been expressed in severe index. The lowest DMFT (about 0.1) was in Arsanjan City in Fars Province, and the highest (about 6.7) was for Najaf Abad City in Isfahan Province. Prevalence of fluorosis has been rather high in studied areas of Iran (e.g. 100 % in Maku City in Azarbaijan-e-Gharbi Province), and there was discrepancy for DMFT, but a lack of studies renders the results inconclusive. Further studies, health education and promotion plans, and evidence-based nutrition programs are recommended.

Association between estimated fluoride intake and dental caries prevalence among 5-year-old children in Korea

Background

The purposes of this study were to estimate the fluoride intake from food and drink in 5-year-old Korean children, and to measure the association between estimated fluoride intake and dental caries prevalence.

Methods

The study involved a secondary analysis of raw data from the 4^th Korea National Health and Nutrition Examination Survey (KNHANES; 2007–2009). The study subjects were 167 boys and 147 girls aged 5 years who had undergone both physical and nutritional examination as part of the survey. The KNHANES comprised a health questionnaire, a physical examination, and a nutritional examination. The nutritional examination of KNHANES consisted of 3 parts: a dietary life survey, a food-frequency questionnaire, and a food intake investigation. The food intake investigation used the 24-h recall method, with information being provided by the children’s parents. On the basis of this information, we evaluated the fluoride content in a total of 310 food items using the hexamethyldisiloxane (HMDS)-facilitated diffusion method, modified using Taves’ microdiffusion method. As part of the KNHANES survey, oral examinations were conducted at a mobile examination centre by trained dentists using dental mirrors under a fluorescent light. These examinations were performed using methods proposed by the World Health Organization.

Results

The dietary fluoride intake of 5-year-old Korean children was estimated to be 0.35 mg/day, or 0.016 mg/kg/day. The “decayed or filled surfaces” (dfs) indices of primary teeth were higher in children who had a lower dietary intake of fluoride. There was a significant inverse association between dietary fluoride intake and the prevalence of dental caries.

Conclusion

The inverse association between dietary fluoride intake levels and prevalence of dental caries implies that the introduction of community caries prevention programmes may be beneficial. Such programmes would include water fluoridation and a fluoride supplementation programme.

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.

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 exposure from groundwater as reflected by urinary fluoride and children's dental fluorosis in the Main Ethiopian Rift Valley

This cross-sectional study explores the relationships between children's F(-) exposure from drinking groundwater and urinary F(-) concentrations, combined with dental fluorosis (DF) in the Main Ethiopian Rift (MER) Valley. We examined the DF prevalence and severity among 491 children (10 to 15 years old) who are life-long residents of 33 rural communities in which groundwater concentrations of F(-) cover a wide range. A subset of 156 children was selected for urinary F(-) measurements. Our results showed that the mean F(-) concentrations in groundwater were 8.5 ± 4.1 mg/L (range: 1.1-18 mg/L), while those in urine were 12.1±7.3 mg/L (range: 1.1-39.8 mg/L). The prevalence of mild, moderate, and severe DF in children's teeth was 17%, 29%, and 45%, respectively, and the majority (90%; n=140) of the children had urinary F(-) concentrations above 3 mg/L. Below this level most of the teeth showed mild forms of DF. The exposure-response relationship between F(-) and DF was positive and non-linear, with DF severity tending to level off above a F(-) threshold of ~6 mg/L, most likely due to the fact that at ~6 mg/L the enamel is damaged as much as it can be clinically observed in most children. We also observed differential prevalence (and severity) of DF and urinary concentration, across children exposed to similar F(-) concentrations in water, which highlights the importance of individual-specific factors in addition to the F(-) levels in drinking water. Finally, we investigated urinary F(-) in children from communities where defluoridation remediation was taking place. The lower F(-) concentration measured in urine of this population demonstrates the capacity of the urinary F(-) method as an effective monitoring and evaluation tool for assessing the outcome of successful F(-) mitigation strategy in relatively short time (months) in areas affected with severe fluorosis.

Common risk factor approach to address socioeconomic inequality in the oral health of preschool children--a prospective cohort study

BACKGROUND

Dental caries remains the most prevalent chronic condition in children and a major contributor to poor general health. There is ample evidence of a skewed distribution of oral health, with a small proportion of children in the population bearing the majority of the burden of the disease. This minority group is comprised disproportionately of socioeconomically disadvantaged children. An in-depth longitudinal study is needed to better understand the determinants of child oral health, in order to support effective evidence-based policies and interventions in improving child oral health. The aim of the Study of Mothers' and Infants' Life Events Affecting Oral Health (SMILE) project is to identify and evaluate the relative importance and timing of critical factors that shape the oral health of young children and then to seek to evaluate those factors in their inter-relationship with socioeconomic influences.

METHODS/DESIGN

This investigation will apply an observational prospective study design to a cohort of socioeconomically-diverse South Australian newborns and their mothers, intensively following these dyads as the children grow to toddler age. Mothers of newborn children will be invited to participate in the study in the early post-partum period. At enrolment, data will be collected on parental socioeconomic status, mothers' general and dental health conditions, details of the pregnancy, infant feeding practice and parental health behaviours and practices. Data on diet and feeding practices, oral health behaviours and practices, and dental visiting patterns will be collected at 3, 6, 12 and 24 months of age. When children turn 24-30 months, the children and their mothers/primary care givers will be invited to an oral examination to record oral health status. Anthropometric assessment will also be conducted.

DISCUSSION

This prospective cohort study will examine a wide range of determinants influencing child oral health and related general conditions such as overweight. It will lead to the evaluation of the inter-relationship among main influences and their relative effect on child oral health. The study findings will provide high level evidence of pathways through which socio-environmental factors impact child oral health. It will also provide an opportunity to examine the relationship between oral health and childhood overweight.

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.

Geological sources of fluoride and acceptable intake of fluoride in an endemic fluorosis area, southern Iran

The present study is the first attempt to put forward possible source(s) of fluoride in the Dashtestan area, Bushehr Province, southern Iran. In response to reports on the high incidence of dental fluorosis, 35 surface and groundwater samples were collected and analysed for fluoride. The results indicate that dissolved fluoride in the study area is above the maximum permissible limit recommended by the World Health Organization (WHO). An additional 35 soil and rock samples were also collected and analysed for fluoride, and rock samples were subjected to petrographic investigations and X-ray diffraction. The results of these analyses show that the most likely source for fluoride in the groundwater is from clay minerals (chlorite) and micas (muscovite, sericite, and biotite) in the soils and rocks in the area. We also note that due to the high average temperatures all year round and excessive water consumption in the area, the optimum fluoride dose level should be lower than that recommended by the WHO.

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.

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.

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.

The impact of the hyperacid Ijen Crater Lake: risks of excess fluoride to human health

The Asembagus irrigation area (East Java, Indonesia) receives a high input of fluoride (F) via surface water that partially originates from the hyperacid crater lake of the Ijen volcano. Endemic dental fluorosis among local residents has been ascribed to F in water wells. In this study, the total F intake by children and adults was estimated, based on concentrations in well waters and foods throughout the area. These values were compared with the Lowest Observed Adverse Effect Level (LOAEL) for dental fluorosis among children and skeletal fluorosis among adults. Fluorosis hazard maps were prepared, identifying the most hazardous locations in the area. It was concluded that there is not only a high risk of dental fluorosis, but also of skeletal fluorosis. Based on the total daily intake, the lowest F concentration in drinking water that poses a risk of developing fluorosis is approximately 0.5 mg/l for dental fluorosis and 1.1 mg/l for skeletal fluorosis. This is below 1.5 mg/l, which is both the guideline value for drinking water from the World Health Organization (WHO) and the Indonesian drinking water standard. This is the first documented case of human health problems that may be directly associated with natural pollutants originating from a volcano-hosted crater lake.

Fluoride as an essential element in the prevention of disease

The concentration of fluoride in drinking water has been shown to be inversely correlated with the incidence of dental caries and cancer. It is proposed that dental caries, cancer and possibly other diseases are the result of a nutritional deficiency in fluoride.

Fluoride ingestion from toothpaste: background to European Union-funded multicentre project

As in most other established market economies throughout the world the prevalence of dental caries has declined in most Member States of the European Union (EU). There is evidence that the increased use of fluoride toothpaste has been a major factor in this improvement. Recently there has been increasing debate on the alleged link between increased use of fluoride toothpaste, particularly by infants and young children, and increased levels of enamel fluorosis. Central to these discussions are two issues, namely measurement of the amount of fluoride ingested by infants and young children and measurement of enamel opacities including fluorosis. The aims of the project described in this special issue addressed these two measurement issues. Seven EU Partners participated. Standardized methods for recording the amount of fluoride ingested when using fluoride toothpaste were developed and used in the seven sites. Similarly a standardized photographic method for recording enamel opacities, including fluorosis, was developed.

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.

Development of a standardized method for comparing fluoride ingested from toothpaste by 1.5-3.5-year-old children in seven European countries. Part 1: Field work

OBJECTIVES

To develop a standardized method for measuring the variables affecting fluoride ingestion from toothpaste in young children between the ages of 1.5 and 3.5 years, and to use the method at seven European sites.

METHODS

Random samples of children were invited to take part in the study. Parents who gave consent were visited at home. The children brushed their teeth using the toothpaste brand and toothbrush type currently in use. Variables measured were: type of toothpaste used, fluoride concentration of toothpaste used, weight of toothpaste used, frequency of brushing and body weight of the child.

RESULTS

It was not possible to follow the agreed protocol in all seven countries and in three countries appropriate alternative methods were employed. There was considerable variation between countries in the variables investigated. Use of children's toothpaste ranged from 69% in Ireland to 98% in Portugal. In the Netherlands up to 60% of the children were using toothpaste containing <400 ppm F and in Finland up to 27% of children were using toothpaste containing >1200 ppm F. Over half of the children used <0.25 g of toothpaste per brushing and the majority of children brushed once or twice per day.

CONCLUSION

Although adherence to the agreed protocol was not possible at all study sites there was a clear picture of considerable variation in the oral hygiene practices of young children throughout Europe.

Sources of dietary iron in urban and provincial 4-year-old children in Iran

Iron-deficiency anaemia is prevalent in childhood, especially in developing countries. Nutritional deficiency is one of the main causes of iron-deficiency anaemia, although absorption varies considerably between different dietary items. Information on the sources of iron in young children is limited. A study was therefore undertaken to investigate the different dietary sources of iron in 151 healthy children aged 4 years who were selected from two districts of Fars province, Iran. Two 3-day dietary diaries with pre- and post-interview were used to record the dietary intake of the children. Food and drinks were categorised into four groups (animal, plant, drinks and other) to measure the relative importance of different sources of iron. Sixty-eight percent of the children completed the 3-day dietary diaries in both summer and winter. The results showed no statistically significant differences in total daily iron intake between the two seasons or between genders. However, the difference in the total daily iron intake between children in the city and the provincial district was significant: 7.73+/-1.75 mg/day and 10.33+/-2.9 mg/day, respectively (P < 0.001). About 75 and 60% of iron intake came from plant sources in the provincial district and city, respectively. The three most important sources of iron for children of the provincial district were bread (51%), fruit and vegetables (12%) and meat (7%). This pattern was also observed for children living in the city, but with different percentages: 27%, 16% and 16%, respectively. In conclusion, total iron intakes were similar to those recorded in European countries, but little of the intake came from animal sources and substantial differences between city and provincial children were recorded.

Fluoride levels in drinking water in the Central Province of Saudi Arabia

BACKGROUND

This study was designed to assess the fluoride levels in drinking water in the Central Province of Saudi Arabia.

MATERIALS AND METHODS

A total of 817 water samples were collected from 260 locations in Central Saudi Arabia. An atomic absorption spectrophotometer [HACH instrument, model DR 3000] was used in the analyses of water samples for fluoride levels.

RESULTS

The results showed that fluoride levels vary between 0.00 and 6.20 ppm. About 75% and 6% of the population in Riyadh and Qassim regions, respectively, were exposed to very low fluoride levels (0.00-0.03 ppm), while less than 3% of the population in both regions were exposed to fluoride levels ranging from 0.61 to 0.80 ppm. A higher percentage of the population in Qassim than Riyadh region were exposed to high fluoride levels (>0.81 ppm); 28.63% than in Riyadh with 9.24%.

CONCLUSION

The findings of this study can serve as a baseline data for water fluoridation and other dental preventive programs in the area.

The fluoride content of foods and beverages from negligibly and optimally fluoridated communities

In the spring of 1996, foods and beverages most commonly consumed by adolescents were analyzed for fluoride as part of a larger investigation. These foods were selected by interviewing 711 adolescents, 12-14 years of age, who were long-time residents of either an optimally or negligibly fluoridated community. The brand names of the identified foods and beverages most commonly purchased were determined by interviews with the parents. A total of 441 brand-name food and beverage items were purchased from both communities and were individually analyzed for fluoride. These analyses were done in order to estimate the fluoride content of various kinds of foods and beverages and to determine whether or not there was a significant difference between the two communities in the amount of fluoride ingested from these dietary sources. The food and beverage items were classified into dietary groups based on US Department of Agriculture (USDA) guidelines. Overall, the fluoride content of the sampled foods and beverages was low. In addition, there was no significant difference in the fluoride content of the same pre-packaged or ready-to-eat food or beverage items purchased in the two communities. However, a significant difference was found between the two communities in the fluoride content of fountain beverages and in cooked or reconstituted foods prepared using local water from the respective communities. Based on these results, we have estimated the mean daily, dietary fluoride intake for 3-5-year-old children who are more susceptible to developing dental fluorosis.

Occurrence and management of dental fluorosis

The prevalence of dental fluorosis is on the increase in different parts of the world, even in areas with fluoride-deficient public water supplies. This may be due to increased use of fluoride in preventive dentistry. In some countries, exposure to apparently low fluoride concentrations in drinking water has resulted in severe dental fluorosis in some children. This underscores the importance of taking into consideration all sources of fluoride intake in a community before prescribing fluoride supplements or recommending appropriate fluoride concentration for the public water supply. Preventive management of dental fluorosis includes de-fluoridation of drinking water in endemic areas, cautious use of fluoride supplements and supervision of the use of fluoride toothpaste by children aged below 5 years. Aesthetically objectionable discolouration of fluorosed teeth may be managed by bleaching, micro-abrasion, veneering or crowning. The choice between these treatments depends on the severity of the fluorosis and this may be satisfactorily determined by the Thylstrup and Fejerskov index.