Hydrogeogenic fluoride in groundwater and dental fluorosis in Thai agrarian communities: a prevalence survey and case–control study

Abstract

Background Dental fluorosis can be a disease of social inequity in access to safe drinking water. This dental public health issue becomes prominent in socially disadvantaged agrarian communities in fluoride endemic areas where the standard irrigation system is unavailable and groundwater containing natural fluoride is the major drinking water source. This study aimed to determine the prevalence and severity of dental fluorosis in children and to evaluate its association with fluoride in groundwater in the aforementioned setting in Thailand. Methods A cross-sectional survey of 289 children in Nakhon Pathom Province was conducted in 2015. Children with very mild to severe fluorosis were regarded as ‘cases’ while their counterparts were ‘controls’ for a subsequent case–control study. Records of fluoride concentrations in groundwater used for household supply corresponding to resident and number of years by age of each child during 2008–2015 were retrieved. Other exposure variables were measured using a questionnaire. Prevalence ratio (PR), a measure indicating the relative effect of different levels of fluoride on dental fluorosis, was obtained from Poisson regression with robust standard error. Result There were 157 children with very mild to moderate dental fluorosis (54.3% prevalence). The univariable analysis revealed that the prevalence of dental fluorosis among children with fluoride concentrations in water sources of 0.7–1.49 (index category 1) and ≥ 1.5 ppm (index category 2) was 1.62 (95% CI; 0.78, 3.34) and 2.75 (95% CI; 1.42, 5.31) times the prevalence among those with fluoride < 0.7 ppm (referent category). After adjusting for all covariates, the adjusted prevalence ratios in both index categories were 1.64 (95% CI; 0.24, 11.24) and 2.85 (95% CI; 0.44, 18.52) which were close to their corresponding crude estimates. Since the magnitude of confounding, measured by (PRcrude–PRadjusted)/PRadjusted, were less than 10% for both index categories; this indicated the limited confounding effect of all covariates. Conclusions In fluoride endemic areas, groundwater containing natural fluoride utilized for household consumption resulted in high dental fluorosis prevalence, particularly in the groundwater with fluoride concentrations of ≥ 1.5 ppm.

Identifying the oral microbiome of adolescents with and without dental fluorosis based on full-length 16S rRNA gene sequencing

“…This decreases enamel mineral content and increases enamel porosity ( Gu et al, 2020 ). Dental fluorosis is prevalent in areas where fluoride is widely distributed, especially in groundwater with fluoride concentrations ≥1.5 ppm ( Rojanaworarit et al, 2021 ). It has been reported in various regions worldwide, including Australia, the Americas, Brazil, India, and China ( Verma et al, 2017 ; Do et al, 2020 ; Zhang et al, 2020 ; Guo et al, 2021 ; Martignon et al, 2021 ).…”

Saliva microbiome alterations in dental fluorosis population

“…The prevalence of dental fluorosis is rising throughout the world due to higher levels of fluoride exposure, with a prevalence of roughly 89.7% in 12–17-year-olds in Northern Tanzania [ 4 ] and 63.7% among 12-year-olds in Quito, Ecuador [ 5 ]. The prevalence of dental fluorosis among Mexican 6–12-year-olds and Thai 8–12-year olds is 98% and 53.4%, respectively [ 6 , 7 ], and the average prevalence of dental fluorosis in Jilin, China is 30.5% (range: 8.33% − 64.17%) [ 8 ].…”

Spatial distribution, formation mechanism, and health risk assessment of high-fluoride groundwater at the largest antimony mine in Hunan Province, China

“…Factors such as temperature, rainfall, evaporation, and human activities all contributed to environmental pollution. Generally, the F − present in groundwater originates from two sources, namely, anthropogenic input and geological genesis(Onipe et al 2021, Rojanaworarit et al 2021). Geological genesis includes the dissolution and precipitation of F-bearing minerals, the evaporation effects, competitive adsorption, and cation exchange (Duggal and Sharma 2022).…”