Determining the optimal concentration of fluoride in drinking water in Pakistan

The fluorosis conundrum: bridging the gap between science and public health

Fluorosis, a chronic condition brought on by excessive fluoride ingestion which, has drawn much scientific attention and public health concern. It is a complex and multifaceted issue that affects millions of people worldwide. Despite decades of scientific research elucidating the causes, mechanisms, and prevention strategies for fluorosis, there remains a significant gap between scientific understanding and public health implementation. While the scientific community has made significant strides in understanding the etiology and prevention of fluorosis, effectively translating this knowledge into public health policies and practices remains challenging. This review explores the gap between scientific research on fluorosis and its practical implementation in public health initiatives. It suggests developing evidence-based guidelines for fluoride exposure and recommends comprehensive educational campaigns targeting the public and healthcare providers. Furthermore, it emphasizes the need for further research to fill the existing knowledge gaps and promote evidence-based decision-making. By fostering collaboration, communication, and evidence-based practices, policymakers, healthcare professionals, and the public can work together to implement preventive measures and mitigate the burden of fluorosis on affected communities. This review highlighted several vital strategies to bridge the gap between science and public health in the context of fluorosis. It emphasizes the importance of translating scientific evidence into actionable guidelines, raising public awareness about fluoride consumption, and promoting preventive measures at individual and community levels.

Prevalence of Dental and Skeletal Fluorosis Among School Children in Rural Areas of YSR Kadapa District, Andhra Pradesh, India

Background Andhra Pradesh (AP) is one of the states in India found to have districts with endemic fluoride and YSR Kadapa district is one among them. Fluorosis is a well-known endemic disease affecting the hard tissues of the human body like teeth and bone and soft tissues like the kidneys, gastrointestinal system, nervous system, etc. Dental fluorosis is being proven as a biomarker for exposure to fluoride. This study evaluated the toxicity of fluoride in drinking water on the teeth (dental fluorosis) and on the bones (skeletal fluorosis) in YSR Kadapa district, AP. Material and methods A cross-sectional study was done in schools in the study areas and a total of 488 school children aged between eight to 14 years were screened for fluorosis. Consent from parents or legal representatives was taken. The information regarding personal details, source of drinking water, diet, and socio-demographic characteristics was obtained from children through a questionnaire. Oral examination of teeth was done to assess dental fluorosis by the Deans's fluorosis index and a general physical examination to assess skeletal fluorosis as per guidelines given by the Central Government of India in the National Program for Prevention of Fluorosis in India. Fluoride in drinking water samples and urine samples of school children was assessed by a fluoride ion meter. Statistical analysis was done using IBM SPSS Statistics for Windows, Version 25, (Released 2017; IBM Corp., Armonk, New York, United States). Descriptive statistics were used to assess the percentage distribution and Chi-square test of Independence for comparison between variables. Results The mean fluoride levels in water in the study areas ranged between 1.5mg/l to 4.2mg/l and there was a prevalence of 44.05% dental fluorosis and 0% skeletal fluorosis in the school children. A total of 48.47% of girls and 40.64% of boys were affected with dental fluorosis. A prevalence of 23.06% mild, 22.1% moderate, 5.31% very mild, and 4.55% severe dental fluorosis was observed in the examined children. Conclusion Our study results showed the presence of dental fluorosis with no clinical evidence of skeletal fluorosis among school children in the YSR Kadapa district of Andhra Pradesh. This indicates the fluoride toxicity on teeth in children confirming the exposure to fluoride in the YSR Kadapa district. So, further long-term follow-up surveys are necessary to evaluate skeletal fluorosis in these children though there was no clinical skeletal fluorosis. This highlights that measures need to be enforced by the local governance for the supply of defluorinated water in these areas.

Monitoring and prediction of high fluoride concentrations in groundwater in Pakistan

Concentrations of naturally occurring fluoride in groundwater exceeding the WHO guideline of 1.5 mg/L have been detected in many parts of Pakistan. This may lead to dental or skeletal fluorosis and thereby poses a potential threat to public health. Utilizing a total of 5483 fluoride concentrations, comprising 2160 new measurements as well as those from other sources, we have applied machine learning techniques to predict the probability of fluoride in groundwater in Pakistan exceeding 1.5 mg/L at a 250 m spatial resolution. Climate, soil, lithology, topography, and land cover parameters were identified as effective predictors of high fluoride concentrations in groundwater. Excellent model performance was observed in a random forest model that achieved an Area Under the Curve (AUC) of 0.92 on test data that were not used in modeling. The highest probabilities of high fluoride concentrations in groundwater are predicted in the Thar Desert, Sargodha Division, and scattered along the Sulaiman Mountains. Applying the model predictions to the population density and accounting for groundwater usage in both rural and urban areas, we estimate that about 13 million people may be at risk of fluorosis due to consuming groundwater with fluoride concentrations >1.5 mg/L in Pakistan, which corresponds to ~6% of the total population. Both the fluoride prediction map and the health risk map can be used as important decision-making tools for authorities and water resource managers in the identification and mitigation of groundwater fluoride contamination.

Knowledge Level and Consumption Behavior of Native Plants, Meats, and Drinking Waters with High Fluoride Concentrations about the Relation to the Potential Health Risk of Fluoride in Lamphun Province Thailand: A Case Study

Fluoride exposure from natural, agricultural, and industrial sources has harmed people living in fluoride-affected areas. Fluoride accumulates in the human body after being exposed to it through the food chain. The population consisted of 371 community health volunteers who were surveyed and chosen based on personal fluoride information. Only 39 residents were chosen to be interviewed and take part in the trial, which involved drinking fluoride-containing groundwater (>1.5 part per million: ppm) and urine testing that revealed urine fluoride level (>0.7 ppm). In addition, 47 biological samples and eight commercially bottled water specimens were examined. The information was gathered in four ways: (1) a questionnaire-based survey of fluoride knowledge, (2) food consumption behavior with locally grown vegetables, fruits, poultry, and meat, and commercially bottled water produced by groundwater in fluoride-affected areas, (3) a semi-food frequency questionnaire, and (4) fluoride content measurements using an ion-selective electrode. According to the analyses, the participants ranged in age from 51 to 60 years, with approximately 60.38% of them female and born and raised in polluted areas. The majority of subjects had a low level of fluoride knowledge (65.23%). The respondents’ primary source of drinking water (100.00%) was commercially bottled water; they chewed camellia sinensis 11.56% of the time (1 to 5 years) and they drank tea 9.16% of the time (during 1 to 5 years). Sus scrofa domesticus was responsible for the intake of vegetables and fruits, whereas Brassica chinensis, Jusl var para-chinensis (Bailey), and Tsen and Lee were responsible for the intake of poultry and animal flesh. They were all purchased at a local farm. The hazard quotient was greater than one, and the fluoride concentration (ppm) ranged between 75.00% (0.29–5.20), 57.14% (0.01–0.46), 88.89% (0.07–0.91), 100.00% (0.43–3.07), 100.00% (0.58–0.77), 42.86% (0.12–0.62 ppm.), 60.00% (0.11–1.44), and 33.33% (0.10–0.80) in drinking water, fruit, young and mature plants. Fluoride ingestion may pose a health concern. Under the 95th percentile condition, 74.47% consumed water with a high fluoride level, vegetables and fruits, and poultry and meats.

Presence of fluoride in water diminishes fast the SPR peak of silver nanocrystals showing large red shift with quick sedimentation - A fast sensing and fast removal case

The medicinal use of fluoride is beneficial up to a low ppm level but regular ingestion at high doses show many adverse effects in human. Fluoride may get ingested through drinking water specially through ground water near the hilly regions, where fluoride content is huge. Hence, fluoride sensing and removal of it from water is very important as fluoride contaminated water is transparent and not easily detectable. Here, we have studied colorimetric and spectrophotometric techniques for sensing of fluoride along with its fast removal from water by using prepared saponin capped silver nanoparticles (AgNPs). Colorimetric study has confirmed the presence of fluoride ions in water samples above the colorimetric detection limit of 10 ppm. But spectroscopic sensing further provides more lower limit of sensing with the total removal of fluoride ions up to 1.2 ppm level. On repeating this this study 15 times, sensing and removal of fluoride is found to be well reproducible. The interaction of fluoride ions with silver nanoparticles has resulted in sedimentation of fluoride ions in the form of fluoride-nanoparticles complex and that interaction has been confirmed by FTIR spectral study of the sedimented part. EDX analysis has also provided the information of easy removal of the fluoride ions from water as presence of fluoride peak has been found in EDX spectra.

The Untold Story of Fluoridation: Revisiting the Changing Perspectives

The discovery of fluoride in dentistry has revolutionized treatment modalities with a new aspect of prevention and conservation of tooth structure coming into foreplay. Since then, there has been a lot of research on both topical and systemic fluoridation in an overzealous attempt to control the most debilitating dental problem of caries. Although topical fluoride is still being widely used as a preventive measure for dental caries, systemic administration of the same has gained major criticism worldwide due to the low margin of safety of fluoride and no control over the amount of individual intake when administered on a community level. This problem is more prevalent in countries with presence of natural fluoride belts that extend from Turkey to China and Japan through Iraq, Iran, and Afghanistan increasing the chances of both dental and skeletal fluorosis and hence increasing the focus toward defluoridation. This historical review highlights the distribution of fluoride worldwide and in India and also discusses about the various claims of the antifluoride lobby.

Tracing environmental aetiological factors of chronic kidney diseases in the dry zone of Sri Lanka-A hydrogeochemical and isotope approach

Chronic kidney disease of unknown aetiologies (CKDu) is increasingly recognized in tropical regions and is now considered a global health problem. A detailed hydrogeochemical investigation has been performed in three CKDu hotspots in Sri Lanka to assess the geo-environmental aetiological factors influencing this disease. A total of 71 ground- and 26 surface water samples were collected from Girandurukotte, Wilgamuwa and Nikawewa regions and analysed for major constituents and trace elements. The affected regions are dominated by Ca-Mg-HCO₃ facies groundwater that is mainly controlled by silicate weathering. Higher levels of fluoride associated with higher hardness is the main feature of groundwater from CKDu regions compared to non-CKDu regions. Results showed that 65% of the wells in the affected regions exceeded the fluoride concentration of 0.5mg/L. Environmental isotopes of groundwater in the CKDu regions are represented by the regression line of δ²H=5.42δ¹⁸O-3.59 (r²=0.916) with a clear isotopic differentiation between local precipitation and groundwater. None of the trace elements exceeded the recommended scales and in most cases levels are negligible in both surface and groundwater in study areas. Therefore, the involvement of trace elements such as Cd, As and Pb can be ignored as causative factors for CKDu. This study highlights the synergistic influence of fluoride and hardness that could enhance the disease, and thereby refute earlier theories that attribute trace elements as causative factors for CKDu. Higher hardness in drinking water also restricts sufficient water uptake, particularly by farmers and which affects the physiological, biochemical and nutritional requirements.

"Borderline" fluorotic region in Serbia: correlations among fluoride in drinking water, biomarkers of exposure and dental fluorosis in schoolchildren

This study explores relation between dental fluorosis occurrence in schoolchildren, residents of Ritopek, a small local community near Belgrade, and fluoride exposure via drinking water. Additionally, fluoride levels were determined in children's urine and hair samples, and efforts were made to correlate them with dental fluorosis. Dental fluorosis and caries prevalence were examined in a total of 52 schoolchildren aged 7-15 years (29 boys and 23 girls). Fluoride levels in three types of samples were analyzed using composite fluoride ion-selective electrode. Results showed high prevalence of dental fluorosis (34.6 %) and low prevalence of dental caries (23.1 %, mean DMFT 0.96) among children exposed to wide range of water fluoride levels (0.11-4.14 mg/L, n = 27). About 11 % of water samples exceeded 1.5 mg/L, a drinking-water quality guideline value for fluoride given by the World Health Organization (2006). Fluoride levels in urine and hair samples ranged between 0.07-2.59 (n = 48) and 1.07-19.83 mg/L (n = 33), respectively. Severity of dental fluorosis was positively and linearly correlated with fluoride levels in drinking water (r = 0.79). Fluoride levels in urine and hair were strongly and positively correlated with levels in drinking water (r = 0.92 and 0.94, respectively). Fluoride levels in hair samples appeared to be a potentially promising biomarker of fluoride intake via drinking water on one hand, and severity of dental fluorosis on the other hand. Based on community fluorosis index value of 0.58, dental fluorosis revealed in Ritopek can be considered as "borderline" public health issue.

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.

Fluoride content of commercially-available bottled water in Bangkok, Thailand

AIM

To determine the fluoride content of commercially-available bottled water in Bangkok.

METHODS

 Thirty brands of bottled water (17 bottled plain water and 13 bottled mineral water) were obtained from supermarkets in Bangkok. Two randomly-selected samples of each brand were purchased 6 months apart. A 5-mL sample was mixed with 5 mL of total ionic-strength adjusting buffer III. The fluoride content of each sample was determined in triplicate by a fluoride ion-selective electrode. Fluoride standards ranging in concentration from 0.01 to 1.00 ppm were used to calibrate the measurements. Data were analyzed by Statistical Package for the Social Sciences software, version 13.0.

RESULTS

The fluoride content of bottled water in Bangkok ranged from 0.03 to 0.72 ppm, with a mean ± standard deviation of 0.17 ± 0.16 ppm. The mean fluoride content of bottled mineral water was slightly higher than that of bottled plain water, but the difference was not statistically significant.

CONCLUSIONS

Most commercially-available bottled water in Bangkok contains negligible amounts of fluoride. This serves as baseline data for dentists prescribing a fluoride supplement to make the utmost use of the fluoride caries preventive effect, while avoiding adverse effects, such as dental fluorosis.

Associations among dental caries experience, fluorosis, and fluoride exposure from drinking water sources in Saudi Arabia

OBJECTIVES

a) To correlate fluoride levels in drinking water sources with caries experience and dental fluorosis in Saudi Arabia, and suggest appropriate fluoride concentration for drinking water in the country.

METHODS

Fluoride levels were determined from 3,629 samples obtained from drinking water sources in 11 regions of Saudi Arabia. Based on the fluoride concentrations, a stratified sample of subjects aged 6-7, 12-13, and 15-18 years was obtained from the regions. A total of 12,200 selected subjects were examined for dental caries according to the World Health Organization criteria, and dental fluorosis, using Thylstrup and Fejerskov classification.

RESULTS

There was an inverse relationship between fluoride exposure and caries experience, but the prevalence of dental fluorosis increased with increase in fluoride concentration. There was no significant difference in caries experience or in the prevalence of dental fluorosis when fluoride levels increased from 0.3 ppm to 0.6 ppm. In contrast, caries experience was lower, while severity of fluorosis was significantly higher at fluoride levels above 0.6 ppm.

CONCLUSIONS

a) Fluoride levels in drinking water sources in Saudi Arabia correlate significantly with caries experience and prevalence of dental fluorosis. b) Appropriate fluoride concentration for drinking water in Saudi Arabia may be about 0.6 ppm.

Determining the optimal fluoride concentration in drinking water for fluoride endemic regions in South India

Fluoride ion in drinking water is known for both beneficial and detrimental effects on health. The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through drinking water owing to more than 90% bioavailability. The objective of this study is to predict optimal fluoride level in drinking water for fluoride endemic regions by comprising the levels of fluoride and other water quality parameters in drinking water, prevalence of fluorosis, fluoride intake through water, food and beverages such as tea and coffee and also considering the progressive accumulation of fluoride in animal bones, by comparing with non fluoride endemic areas comprise of the same geological features with the aid of regression analysis. Result of this study shows that increase of fluoride level above 1.33 mg/l in drinking water increases the community fluorosis index (CFI) value more than 0.6, an optimum index value above which fluorosis is considered to be a public health problem. Regression plot between water fluoride and bone fluoride levels indicates that, every increase of 0.5mg/l unit of water fluoride level increases the bone fluoride level of 52 mg/kg unit within 2 to 3 years. Furthermore, the consumption of drinking water containing more than 0.65 mg/l of fluoride can raise the total fluoride intake per day more than 4 mg, which is the optimum fluoride dose level recommended for adults by the Agency for Toxic Substances and Disease Registry. From the result, the people in fluoride endemic areas in South India are advised to consume drinking water with fluoride level within the limit of 0.5 to 0.65 mg/l to avoid further fluorosis risk.

Prevalence and Severity of Dental Caries in Adolescents Aged 12 and 15 Living in Communities with Various Fluoride Concentrations

OBJECTIVES

To determine the experience, prevalence, and severity of dental caries in adolescents naturally exposed to various fluoride concentrations.

METHODS

A cross-sectional census was conducted on 1,538 adolescents aged 12 and 15 years living at high altitude above sea level (> 2,000 m or > 6,560 ft) in above-optimal fluoridated communities (levels ranging from 1.38 to 3.07 ppm) of Hidalgo, Mexico. Sociodemographic and socioeconomic data were collected using questionnaires. Two previously trained and standardized examiners performed the dental exams.

RESULTS

Caries prevalence was 48.6 percent and mean of decay, missing, and filling teeth (DMFT) for the whole population was 1.15 +/- 1.17. In terms of severity, 9.6 percent of the adolescents had DMFT > or = 4, and 1.7 percent had > or = 7. The significant caries index (SiC) was 2.41 in the group of 12-year-olds, and 3.46 in the 15-year-olds. Higher experience and prevalence were observed in girls, in children with dental visit in the past year, those in the wealthiest socioeconomic status (SES) (quartiles 2, 3, and 4), those whose locale of residence is in San Marcos and Tula Centro, and in fluorosis-free children and those with moderate/severe fluorosis. In an analysis of caries severity (DMFT > or = 4), both adolescents with very mild/mild and moderate/severe dental fluorosis have higher caries severity.

CONCLUSIONS

The results indicated that caries experience, prevalence, and severity as well as SiC index among 12- and 15-year-old adolescents were relatively low. Sociodemographic and socioeconomic variables commonly associated with dental caries were also observed in Mexican adolescents. Unlike other studies, we found that caries increased with higher SES. Fluoride exposure (measured through fluorosis presence) does not appear to be reducing the caries prevalence (DMFT > 0) or caries severity (DMFT > or = 4) in these high-altitude communities.

Dental fluorosis in cohorts born before, during, and after the national salt fluoridation program in a community in Mexico

OBJECTIVE

To determine the prevalence and severity of dental fluorosis, as well as factors associated with its occurrence, in seven cohorts of children before and after the implementation of a fluoridated salt program in 1991.

MATERIAL AND METHODS

A cross-sectional study was carried out in 1,373 children aged from 6 to 12 years in Campeche, Mexico. Data were collected by means of a questionnaire administered to mothers and a dental examination of the children. Modified Dean's criteria were used to diagnose dental fluorosis. A multivariate logistic regression model was used to evaluate the relationship between dental fluorosis and independent variables.

RESULTS

The prevalence of dental fluorosis was 51.9%. The most common degree of dental fluorosis was very mild, with 84.7%, followed by mild, moderate, and severe with 13.1%, 1.7%, and 0.6%, respectively. The multivariate model adjusted by number of additional sources of fluoride, age at the beginning of use of toothpaste, and level of schooling of the mother, showed that children born in 1990 (OR = 1.74; CI 95% = 1.36-2.22), 1991 (OR = 4.03; CI 95% = 2.58-6.28), and 1992 (OR = 10.41; CI 95% = 5.77-18.78) were more likely to have dental fluorosis than those born in the period 1986-1989. The frequency of toothbrushing (OR = 1.63; CI 95% = 1.37-1.95) was also associated with dental fluorosis.

CONCLUSIONS

A close relationship was found between exposure to toothpaste and dental fluorosis. Implementation of the fluoridated salt program greatly increased the risk of fluorosis.