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

A Bayesian benchmark concentration analysis for urinary fluoride and intelligence in adults in Guizhou, China

Environmental fluoride exposure has been linked to numerous cases of fluorosis worldwide. Previous studies have indicated that long-term exposure to fluoride can result in intellectual damage among children. However, a comprehensive health risk assessment of fluorosis-induced intellectual damage is still pending. In this research, we utilized the Bayesian Benchmark Dose Analysis System (BBMD) to investigate the dose-response relationship between urinary fluoride (U-F) concentration and Raven scores in adults from Nayong, Guizhou, China. Our research findings indecate a dose-response relationship between the concentration of U-F and intelligence scores in adults. As the benchmark response (BMR) increased, both the benchmark concentration (BMCs) and the lower bound of the credible interval (BMCLs) increased. Specifically, BMCs for the association between U-F and IQ score were determined to be 0.18 mg/L (BMCL1 = 0.08 mg/L), 0.91 mg/L (BMCL5 = 0.40 mg/L), 1.83 mg/L (BMCL10 = 0.83 mg/L) when using BMRs of 1 %, 5 %, and 10 %. These results indicate that U-F can serve as an effective biomarker for monitoring the loss of IQ in population. We propose three interim targets for public policy in preventing interllectual harm from fluoride exposure.

Environmental fluoride exposure and implications on potential pediatric kidney health risks: an approach with urinary biomarkers

BACKGROUND

Environmental fluoride exposure at elevated levels is potentially linked to kidney injury, and may contribute to chronic kidney disease of uncertain etiology (CKDu) as a risk factor. However, this link remains unclear, and examining the risk of kidney damage from early life fluoride exposure may provide important insights. Hence, this study aimed to investigate associations of fluoride exposure with pediatric kidney health in CKDu impacted and unimpacted communities in Sri Lanka.

METHODS

Considering the geographical variations in environmental fluoride, climate, and prevalence of CKDu, four study groups were established within selected education zones in CKDu-endemic dry zone regions (D-En), and CKDu-nonendemic regions within the dry (D-NE), wet (W-NE), and intermediate (I-NE) climatic zones. The study population included 922 school students (11-18 years of age). Participants in each group were divided into four subgroups based on quartiles of respective urinary fluoride (UF) distribution for comparison of urinary kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and albumin-creatinine ratio (ACR).

RESULTS

UF levels in participants particularly in CKDu endemic dry zone regions were significantly high compared to the other regions. Significantly high median urinary NGAL (in D-NE) and ACR (in D-EN, and W-NE) levels were observed in subgroups of higher UF quartiles. Albuminuria was not particularly identified in subjects with high UF excretion. Urinary KIM-1 showed no significant variation across the UF quartile subgroups. Linear regression identified weak associations of UF with kidney injury biomarkers.

CONCLUSIONS

Fluoride exposure is particularly high in CKDu-endemic dry zone communities. As implied by kidney injury biomarkers, a strong link between fluoride exposure and pediatric kidney health was not evident at the observed exposure levels in the study regions.

Study of anaemia in pregnancy and low birth weight in fluoride endemic area of Western Rajasthan: a cohort study

Background

Fluoride is a noxious element known to destroy gastrointestinal mucosa, leading to erythrocytes' destruction and causing anaemia. The birth weight of newborn babies is a significant indicator of a child's vulnerability to the risk of childhood diseases and chances of existence.

Methods

This prospective cohort study was planned to find linkages between fluorosis and the low-birth weight of newborn babies with anaemic mothers. Antenatal mothers until the 20th week of gestation were followed up till delivery in the Antenatal Clinic of a District Hospital in one of the known fluoride-endemic districts (Nagaur) and the other not-so-endemic district (Jodhpur) of Western Rajasthan.

Results

Around 19% of the newborn in Jodhpur and around 22% in Nagaur had low birth weight. Mean fluoride values in water samples were measured to be 0.57 (range from 0.0 to 2.7 PPM) in Jodhpur and 0.7 (range from 0.0 to 3.4 PPM) in Nagaur.

Conclusions

Thus, in fluoride endemic areas, other factors should be included besides iron and folic acid supplementation for improving anaemia in pregnant women. This calls for assessing the effectiveness of de-fluoridation activities along with the area's most common indigenous food practices.

Fluoride exposure and pediatric kidney health in dry, wet and intermediate climatic zone communities in Sri Lanka: Implications from urinary Cystatin-C, and albumin-creatinine ratio

BACKGROUND

High fluoride exposure is increasingly discussed attributing to kidney injury as a causative factor. Depending on geochemistry, differential fluoride levels in drinking water are identified in different regions in Sri Lanka. However, the levels of fluoride exposure, and associations with kidney health has not been adequately studied in Sri Lanka, particularly in pediatric communities. Hence, the present study aimed to assess fluoride exposure in selected pediatric communities in the dry, wet and intermediate climatic zones in Sri Lanka, along with an assessment of renal health using urinary Cystatin-C (uCys-C), and albumin-creatinine ratio (uACR).

METHODS

We conducted a cross-sectional study with school students in selected education zones representing dry (N = 331), wet (N = 152), and intermediate (N = 292) climatic zones in Sri Lanka. Fluoride contents in urine and drinking water were assessed as measures of fluoride exposure.

RESULTS

The median (interquartile distance) urinary fluoride levels of participants in the dry, wet and intermediate zones were 1.63(1.04-2.85), 1.29(0.85-2.21), and 1.07(0.61-1.98) mg/gCr while the fluoride contents of drinking water samples were 1.76(1.36-2.30), 0.25(0.18-0.37), and 0.43(0.26-0.63) ppm respectively with significant differences among the three groups. Median uCys-C level (ng/mgCr) of the participants in intermediate zone [30.26(8.49-71.44)] was significantly low (p < 0.05) compared to that of the participants in dry zone [56.19(7.08-211.8)], and wet zone [66.29(30.43-125.20)]. The incidences of elevated uCys-C levels above reference intervals in participants of dry zone (47.7%), and wet zone (50.0%) were significantly high (p < 0.001) compared to the intermediate zone (26.4%).

CONCLUSION

Relatively high fluoride exposure is likely in dry and wet zone communities compared to the intermediate zone along with significantly higher incidence of uCys-C levels above reference intervals in study groups with higher fluoride exposure. However, to conclude a clear link between fluoride exposure and kidney health we need in-depth studies.

Longitudinal associations between early-life fluoride exposures and cardiometabolic outcomes in school-aged children

BACKGROUND/AIM

Fluoride is a natural mineral present in food, water, and dental products, constituting ubiquitous long-term exposure in early childhood and across the lifespan. Experimental evidence shows fluoride-induced lipid disturbances with potential implications for cardiometabolic health. However, epidemiological studies are scarce. For the first time, we evaluated associations between repeated fluoride measures and cardiometabolic outcomes in children.

METHODS

We studied ∼ 500 Mexican children from the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) cohort with measurements on urinary fluoride at age 4, and dietary fluoride at ages 4, 6, and 8 years approximately. We used covariate-adjusted linear mixed-effects and linear regression models to assess fluoride associations with multiple cardiometabolic outcomes (ages 4-8): lipids (total cholesterol, HDL, LDL, and triglycerides), glucose, HbA1c, adipokines (leptin and adiponectin), body fat, and age- and sex-specific z-scores of body mass index (zBMI), waist circumference, and blood pressure.

RESULTS

Dietary fluoride intake at age 4 was associated with annual increases in triglycerides [β per-fluoride-doubling = 2.02 (95 % CI: 0.37, 3.69)], cholesterol [β = 1.46 (95 % CI: 0.52, 2.39)], HDL [β = 0.39 (95 % CI: 0.02, 0.76)], LDL [β = 0.87 (95 % CI: 0.02, 1.71)], and HbA1c [β = 0.76 (95 % CI: 0.28, 1.24)], and decreased leptin [β = -3.58 (95 % CI: -6.34, -0.75)] between the ages 4 and 8. In cross-sectional analyses at age 8, higher tertiles of fluoride exposure were associated with increases in zBMI, triglycerides, glucose, and leptin (p-tertile trend < 0.05). Stronger associations were observed in boys at year 8 and in girls prior to year 8 (p-sex interaction < 0.05). Fewer but consistent associations were observed for urinary fluoride at age 4, indicating increased annual changes in HDL and HbA1c with higher fluoride levels.

CONCLUSION

Dietary fluoride exposures in early- and mid-childhood were associated with adverse cardiometabolic outcomes in school-aged children. Further research is needed to elucidate whether these associations persist at later ages.

Enamel fluorosis related with fluoride-containing water ingestion and urinary excretion in schoolchildren

Background

Natural water sources are considered as the major environmental exposure of fluoride, resulting in increased prevalence of enamel fluorosis. This type of natural exposure should be permanently monitored to avoid the interactions with other non-natural fluoride sources. We evaluated the prevalence of enamel fluorosis in Colombian schoolchildren and its relationship with fluoride-containing water ingestion exposure dose and urinary fluoride excretion.

Material and Methods

We included 923 schoolchildren aged 7-12 years residing in eight municipalities in Colombia. Sampling of consumption water was performed in major aquifers used for daily supply. Samples were collected in 98 polyethylene containers and refrigerated until analysis. Water and urine fluoride concentrations were measured using the fluoride selective electrode method. Enamel fluorosis was evaluated using Thylstrup and Ferjerskov Index (TFI). Demographic and anthropometric characteristics were assessed. Besides, other exposures to non-natural fluoride were also evaluated. Logistic regression was applied for multiple analyses.

Results

The median fluoride concentration in water and urine samples was 10.5 mg/L and 0.63 mg/L respectively, with the highest value found in Algarrobo-Magdalena, and the lowest value found in Manzanares-Caldas. The overall prevalence of enamel fluorosis was 86.1%, being more frequent the mild codes with TFI-1 to TFI-2. The highest prevalence was found in Margarita-Bolívar and Manzanares-Caldas, and the most severe codes (TFI-5 to TFI-9) were detected in Manzanares-Caldas. The multiple analysis revealed water ingestion exposure dose, urinary excretion, involuntary intake of toothpaste, amount of table salt consumption and sex as significant factors (p< 0.001).

Conclusions

The fluoride ingestion exposure dose and its subsequent urinary excretion could be used as estimators of past fluoride exposure, explaining the current prevalence of enamel fluorosis in Colombian schoolchildren. Key words:Fluoride, groundwater ingestion, enamel fluorosis, prevalence, severity.

Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water

INTRODUCTION

Fluoride is a naturally occurring substance that is also added to drinking water, dental hygiene products, and food supplements for preventing dental caries. Concerns have been raised about several other potential health risks of fluoride.

OBJECTIVE

To conduct a robust synthesis of evidence regarding human health risks due to exposure to fluoride in drinking water, and to develop a point of departure (POD) for setting a health-based value (HBV) for fluoride in drinking water.

METHODS

A systematic review of evidence published since recent reviews of human, animal, and in vitro data was carried out. Bradford Hill considerations were used to weigh the evidence for causality. Several key studies were considered for deriving PODs.

RESULTS

The current review identified 89 human studies, 199 animal studies, and 10 major in vitro reviews. The weight of evidence on 39 health endpoints was presented. In addition to dental fluorosis, evidence was considered strong for reduction in IQ scores in children, moderate for thyroid dysfunction, weak for kidney dysfunction, and limited for sex hormone disruptions.

CONCLUSION

The current review identified moderate dental fluorosis and reduction in IQ scores in children as the most relevant endpoints for establishing an HBV for fluoride in drinking water. PODs were derived for these two endpoints, although there is still some uncertainty in the causal weight of evidence for causality for reducing IQ scores in children and considerable uncertainty in the derivation of its POD. Given our evaluation of the overall weight of evidence, moderate dental fluorosis is suggested as the key endpoint until more evidence is accumulated on possible reduction of IQ scores effects. A POD of 1.56 mg fluoride/L for moderate dental fluorosis may be preferred as a starting point for setting an HBV for fluoride in drinking water to protect against moderate and severe dental fluorosis. Although outside the scope of the current review, precautionary concerns for potential neurodevelopmental cognitive effects may warrant special consideration in the derivation of the HBV for fluoride in drinking water.

The pharmacokinetics of 38% silver diamine fluoride in healthy children with dental caries: a quasi-experimental study

PURPOSE

Silver diamine fluoride (SDF) is a medication used for the arrestment of dental caries. This study aims to determine the pharmacokinetics (PK) of silver and fluoride following SDF application in healthy children with dental caries.

METHODS

A total of 15 subjects, aged 4 to 10 years, with at least one cavity on a primary tooth, were recruited for this study. Urine samples were collected at baseline, first 24 h (F1) and second 24 h (F2) after SDF treatment for analysis of silver and fluoride content. Hair samples were also collected at baseline and at 7, 14, 30, 60, 75, and 90 days after SDF treatment to analyze silver content.

RESULTS

Participants with under or over-collection of urine, or failure to provide urine collection were excluded for fluoride analysis. As a result, eight subjects' urine samples were eligible for fluoride analysis. Significant correlations were observed between baseline urinary fluoride levels and F1/F2 levels. Pairwise comparisons from Friedman's test showed significant differences between baseline and F1 fluoride levels. For silver analysis, 15 subjects were studied. F1 urinary silver levels were higher than baseline and F2 levels. Subsequent to SDF treatment, hair silver levels displayed fluctuations around the baseline. None of the participants reported adverse effects, and all caries teeth ceased progression within 30 days.

CONCLUSIONS

The urinary fluoride levels after SDF treatment, although higher, were not clinically significant. Urinary and hair silver levels were negligible. Therefore, SDF appears safe to be used among children.

Epidemiological analysis of drinking water-type fluorosis areas and the impact of fluorosis on children's health in the past 40 years in China

This study analyzed the effect of China's fluorosis prevention and control program, which has been in effect for more than 40 years, and the impact of fluorosis on children's health. Relevant research studies were retrieved from the following online databases from the time of their inception to May 2022: PubMed, ScienceDirect, Embase, Cochrane, China National Knowledge Infrastructure, and Wanfang. The Review Manager 5.3 software was used in statistical analyses. This article included seventy studies: Thirty-eight studies reported the effect of improving water quality and reducing fluoride content, the incidence rate of dental fluorosis in children, and the level of urinary fluoride, and thirty-two studies reported the intelligence quotient (IQ) and health status of children. Following water improvement strategies, the fluoride levels in drinking water decreased significantly; urinary fluoride levels and dental fluorosis decreased significantly in children. With regard to the effect of fluorosis on the IQ of children, the results showed that the IQ of children in areas with a high fluoride of fluorosis was lesser than that in areas with a low fluoride, and this difference was significant. Based on the prevalence of dental fluorosis and its effect on the intelligence of children, it appears that reducing fluoride levels in drinking water and monitoring water quality are important strategies for the prevention and treatment of fluorosis.

Research on natal and neonatal teeth in Africa: A systematic scoping review of empirical evidence

Background and Aims

In Africa, natal and neonatal teeth is a culture-bound phenomenon which is associated with several sociocultural connotations which might affect child survival. Different empirical studies have been conducted in Africa on natal and neonatal teeth; however, no known scoping review has been conducted to map the empirical evidence. This systematic scoping review (SSR) aims to document the available empirical evidence, research gaps, and hotspots on neonatal and natal teeth in Africa.

Methods

The methodology of this SSR was informed by the Joanna Brigg's Institute guidelines for SSRs, and it was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Eleven research databases were systematically searched to scooped out all literatures relevant to the scoping review question, after which they were screened for eligibility based on the review's selection criteria. Only the eligible literatures were included in the review. Data were extracted from the included literatures, after which the extracted data were collated, summarized, and presented as results.

Results

This review included only three journal articles. All the reviewed articles revealed knowledge gaps about natal/neonatal teeth. These articles also found misconceptions around natal/neonatal teeth; for example, nurses' and traditional birth attendants' beliefs about these teeth are contrary to scientifically known facts. Multiple myths associated with natal/neonatal teeth, as indicated in the reviewed studies, point to a poor understanding of the condition.

Conclusion

Neonates and infants are highly vulnerable persons; they require care and safeguarding from dental myths that could threaten their survival. Educative information concerning natal/neonatal teeth should be included in public health education programs to address the observed knowledge gaps among African populations and correct wrong beliefs on neonatal and natal teeth.

A Systematic Review and Meta-Analysis of the Relationship Between the Severity of Dental Fluorosis and Fluoride Biomarkers in Endemic Areas

The intake of high concentrations of fluoride, mainly through drinking water, diet and fluoridated dentifrices, produces fluorosis, which in its early stages is manifested as dental fluorosis (DF). To recognize exposure to fluoride in endemic areas and to evaluate the risk of developing health impairment, the WHO has established several biomarkers that are used to determine systemic fluorine (F^-) exposure. Thus, the aim of this study was to conduct a systematic review and meta-analysis of the relationship between the severity of DF and fluoride biomarkers in endemic areas. The protocol of this study was previously registered as CRD42021244974. A digital search was carried out in PubMed/Medline, SpringerLink, Scopus, Cochrane and Google Scholar by employing the keywords "urine", "nails", "hair", "plasma", "saliva" and "dental fluorosis" for the original studies with content associated with F^- for the biomarkers and DF. The mean difference was established as the effect measure for the meta-analysis. Seven studies fulfilled the eligibility criteria, among which five assessed urine and two employed nails as fluoride biomarkers. A positive significant difference was found between the biomarkers and the severity of DF (0.27, p < 0.001) and individually for each biomarker (urine: 0.14, p = 0.001; nails: 0.88, p < 0.05). The F^- concentration in urine and nails is correlated with the severity of DF, with the most evident differences between healthy individuals and those with mild severity. Both biomarkers are adequate to assess this relationship in endemic areas of fluoride and DF.

Mapping the evidence for monitoring fluoride exposure in community prevention programmes for oral health using nail clippings and spot urine samples: a scoping review

BACKGROUND

There is an increased interest in identifying practical and accurate biomarkers for fluoride exposure. Due to the narrow 'dose-gap' between the benefit of caries reduction and the risk of dental fluorosis, monitoring of fluoride exposure is vital when introducing any fluoridation programme for the prevention of dental caries. This scoping review aimed to ascertain the nature and extent of the available evidence on how spot urine and nail clippings are used to measure fluoride intake/exposure, by using a unique approach of mapping the studies according to population, setting, type of study design, methodology and analytical approach in community prevention programmes.

METHODS

Multiple relevant databases were searched up to July 2021 for any study designs, including randomised controlled studies, quasi-experimental studies, surveys, retrospective and prospective cohort studies, case studies, phenomenological studies, and expert opinions.

RESULTS

The search retrieved 9,222 studies of which 155 met the inclusion criteria. A high proportion of the studies (25.2%) originated from Latin America and the Caribbean continent subregion. However, per country, China recorded the highest number, followed by India and Mexico. The majority (62.6%) employed a cross-sectional study design, and 65.8% combined participants from different age groups. Of the included studies, 82.6% used spot urine samples as a biomarker for assessing fluoride intake/exposure. Water fluoride concentration was reported in 66.5% of the studies with 46.6% of all included studies reporting a water fluoride concentration of > 1.2 mg/L. The methods used in assessing oral hygiene and dietary intake were not reported in 72.3% and 71.0% of the included studies, respectively. Only 35.5% of the included studies assessed the relationship between fluoride exposure and excretion.

CONCLUSIONS

This review revealed a large variability in the way in which spot urine samples and/or nail clippings are used to measure fluoride exposure in different settings and situations. Particularly, there are inconsistencies in the methodologies and the analytical approaches used in assessing fluoride exposure. Therefore, there is a need for more rigorous primary research studies using standardised approaches to determine the suitability of spot urine samples and nail clipping as biomarkers for monitoring fluoride exposure.

Association of maternal urinary fluoride concentrations during pregnancy with size at birth and the potential mediation effect by maternal thyroid hormones: The Swedish NICE birth cohort

BACKGROUND

Observational studies have indicated that elevated maternal fluoride exposure during pregnancy may impair child neurodevelopment but a potential impact on birth outcomes is understudied.

OBJECTIVES

To evaluate the impact of gestational fluoride exposure on birth outcomes (birth size and gestational age at birth) and to assess the potential mediating role of maternal thyroid hormones.

METHODS

We studied 583 mother-child dyads in the NICE cohort in northern Sweden. Maternal fluoride exposure was assessed by measuring urinary concentrations at late pregnancy (median: 29th gestational week) using an ion selective electrode. Plasma levels of free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH) were measured with electrochemiluminescence immunoassays. The infant's weight, length, head circumference, and gestational age at birth were extracted from hospital records.

RESULTS

Median urinary fluoride concentration was 0.71 mg/L (5th-95th percentile 0.31-1.9 mg/L; specific gravity adjusted). In multivariable-adjusted regression models, every 1 mg/L increase of maternal urinary fluoride was associated with a mean increase in birth weight by 84 g (95%CI: 30, 138), length by 0.41 cm (95%CI: 0.18, 0.65), head circumference by 0.3 cm (95%CI: 0.1, 0.4), and with increased odds of being born large for gestational age (OR = 1.39, 95%CI: 1.03, 1.89). Every 1 mg/L increase of maternal urinary fluoride was also associated with a mean increase of the plasma fT3:fT4 ratio (B = 0.007, 95%CI: 0.000, 0.014), but not with the hormones or TSH. In mediation analyses, the maternal fT3:fT4 ratio did not explain the urinary fluoride-birth size relationships.

DISCUSSION

Gestational urinary fluoride concentrations were associated with increased size at birth and even with increased odds of being born large for gestational age. The fluoride-related associations with increased size at birth were not explained by changes in maternal thyroid hormone levels.

Dietary Influences on Urinary Fluoride over the Course of Pregnancy and at One-Year Postpartum

Dietary factors are known to influence urinary fluoride (UF) levels in nonpregnant people. Maternal UF is used as a biomarker of fluoride exposure; however, dietary influences on UF during pregnancy are unknown. We compared UF levels and assessed the associations between UF and five select dietary influences in pregnancy vs. one-year postpartum: dietary fluoride (F), calcium intake from diet (Ca-diet), calcium intake from supplements (Ca-sup), dietary acid load (AL), and table salt use (TS) in 421 women exposed to fluoridated salt in the Mexican diet. Spot UF (mg/L) was measured by microdiffusion/fluoride-specific electrode and dilution-corrected with specific gravity (SG). Dietary variables were estimated from a validated Food Frequency Questionnaire. Comparisons among UF in pregnancy vs. one-year postpartum were performed with non-parametric tests. Associations between dietary variables and UF were assessed using random effect models (for pregnancy) and linear regression (for one-year postpartum). SG-corrected UF (median, range) during pregnancy (0.77, 0.01-4.73 mg/L) did not significantly differ from one-year postpartum (0.75, 0.15-2.62 mg/L) but did increase every 10 gestational weeks, β = 0.05 (CI: 0.00-0.10). Different dietary influences on UF were identified at each state. Although Ca-diet and AL were not associated with UF in either state, Ca-sup decreased UF only during pregnancy, β =  - 0.012 mg/L (CI: - 0.023-0.00). Reporting TS use was associated with 12% increase in UF only at one-year postpartum (p = 0.026). These results suggest different dietary influences on UF in the pregnant state, which need consideration when using UF as a biomarker of fluoride exposure.

A Phase 1 Trial to Evaluate the Relationship Between Fluoride Intake and Urinary Fluoride Excretion in Healthy Participants

Chronic overexposure to fluoride can have deleterious effects in the musculoskeletal system. Some fluorine‐containing therapeutics, such as voriconazole, release fluoride through metabolism. Therefore, drug‐related fluoride exposure should be assessed for novel therapeutics suspected of releasing fluoride through metabolism. Two trials were conducted to identify the optimal method of assessing drug‐related fluoride exposure. In trial 1, designed to assess reproducibility of fluoride pharmacokinetics in urine and plasma, 14 participants were administered a fluoride‐restricted diet and once‐daily doses of sodium fluoride (2.2 mg [1 mg of fluoride] on days 1 and 2; and 13.2 mg of sodium fluoride [6 mg of fluoride] on days 3 and 4). In trial 2, designed to confirm the selected method for fluoride detection, 12 participants were administered a fluoride‐restricted diet and randomized to receive voriconazole (400 mg twice, 12 hours apart, on day 1 [131 mg/d of fluoride maximum], then 3 doses of 200 mg every 12 hours [65.3 mg/d of fluoride maximum]) or placebo. Plasma fluoride concentrations and urinary fluoride excretion were assessed in each trial. Assessment of plasma fluoride concentrations in trial 1 was limited by 301 of 854 samples (35.2%) below the lower limit of quantitation. Urine fluoride excretion was readily measured and demonstrated a decrease from baseline during the fluoride‐restricted diet phase, as well as dose‐proportional increases with fluoride administration. In trial 2, increases in urine fluoride were successfully observed in participants administered voriconazole. In conclusion, fluoride exposure was optimally assessed by urinary fluoride excretion in conjunction with strict dietary fluoride restrictions, as measurements were consistent and reproducible.

Urinary minerals excretion among primary schoolchildren in Dubai-United Arab Emirates

Introduction

Urinary excretion of calcium (Ca), magnesium (Mg), phosphorus (P), iodine and fluoride is used to assess their statuses and/or the existence of metabolic abnormalities. In the United Arab Emirates (UAE), the urinary concentration of these minerals among children have not been documented.

Materials and methods

A cross-sectional study, including 593 subjects (232 boys and 361 girls), was conducted among healthy 6 to 11-year-old Emirati children living in Dubai. Non-fasting morning urine samples and anthropometrical measurements were collected and analyzed. Results were expressed as per mg of creatinine (Cr).

Results

On average, estimated Cr excretion was 17.88±3.12 mg/kg/d. Mean urinary Ca/Cr, Mg/Cr and P/Cr excretions were 0.08±0.07 mg/mg, 0.09±0.04 mg/mg, and 0.57±0.26 mg/mg respectively. Urinary excretion of Ca, Mg and P were found to decrease as age increased. Urinary excretion and predicted intake of fluoride were lower than 0.05 mg/kg body weight per day. Surprisingly, more than 50% of the children were found to have urinary iodine excretion level above adequate.

Conclusion

The Emirati schoolchildren had comparable levels of urinary Ca, Mg and P excretion to other countries. The 95% percentile allows the use of the current data as a reference value for the detection of mineral abnormalities. Fluoride excretion implies that Emirati children are at low risk of fluorosis. The level of urinary iodine excretion is slightly higher than recommended and requires close monitoring of the process of salt iodization to avoid the harmful impact of iodine overconsumption.

Assessment of fluoride levels during pregnancy and its association with early adverse pregnancy outcomes

Background and Aim:

There is sparse data available on human subjects regarding the affect of excessive fluoride exposures on pregnancy. The aim of this study was to examine the association between elevated urinary fluoride levels during early pregnancy and maternal anemia and adverse fetal outcome.

Patients and Methods:

We enrolled 600 pregnant patients with gestational age less than 20 weeks and with a high urinary fluoride levels(>1 mg/L).We also documented the fluoride levels in the tap water and ground water samples collected from the areas where these women resided during pregnancy. These patients were also evaluated for hemoglobin levels and detailed fetal examination by ultrasound. Data was assessed by SSPS version 16.0 software and P < 0.05 was considered to be significant.

Results:

Urinary fluoride averaged 2.65 mg/L and ranged from 1.0 to 4.3 mg/L while all the water samples revealed fluoride levels greater than WHO prescribed the limit of 1.5 mg/L. A total of 402 patients (67%) were found to be anemic with hemoglobin levels ranging from 6.2 to 11.9 g/dl (9.28 ± 1.29). Eighty one patients (13.5%) had adverse fetal outcomes that comprised abortions, congenital abnormalities, and intrauterine deaths (IUDs). There was a negative correlation between urinary fluoride and hemoglobin levels (P = 0.031, r= -0.59) and females with elevated urinary fluoride levels were found to have a strong association with the pregnancy complications, i.e., anemia, miscarriage, abortion, and still birth (χ² = 9.23, P < 0.05).

Conclusions:

Excess fluoride exposures can have deleterious effects on the expecting mother and fetus and is associated with adverse pregnancy outcomes.