Who are the 10%? Characteristics of the populations and communities receiving fluoridated water in England.

OBJECTIVES: In England, around 10% of the population receive optimally fluoridated water. This coverage has evolved through a combination of historical local decision-making and natural geography, rather than being strategically targeted at the national level. It is important to understand if the current distribution is equitable according to indicators of oral health need and to identify any population-level differences in socio-demographic characteristics that could introduce bias to studies evaluating the effectiveness of water fluoridation. BASIC RESEARCH DESIGN: Descriptive analysis comparing the census characteristics of populations that received optimally fluoridated (=/⟩ 0.7 mg F/L) and non-fluoridated water (⟨0.7 mg F/L) between 2009 and 2020. RESULTS: Populations receiving fluoridated water between 2009-2020 were on average slightly younger, more urban, more deprived, with lower education levels, higher unemployment and lower car and home ownership than the populations who received non-fluoridated water. They are more ethnically diverse, with a higher proportion of Asian ethnicity and a lower proportion of White ethnicity, compared to the non-fluoridated population. DISCUSSION: This descriptive analysis provides evidence that water fluoridation coverage within England is targeted reasonably equitably in relation to population-level indicators of need. It also confirms the need to consider the impact of underlying differences in age, deprivation, rurality, and ethnicity when evaluating the impact of water fluoridation on health outcomes in England.

Water fluoride concentrations in England, 2009-2020.

OBJECTIVES: Contemporary research, surveillance and monitoring of water fluoridation requires an understanding of the population coverage of this intervention. The aims of this research are to create the first publicly available record of water fluoride concentrations in England and to describe and visualise the observed variation in water fluoride concentrations and optimal fluoridation (⟩/= 0.7 mg F/L) between 2009-2020. BASIC RESEARCH DESIGN: Routine water quality sampling data were requested from water companies in England from 2009-2020 under the provisions of the Environmental Information Regulations 2004. Fluoride concentrations of Water Supply Zones (WSZs) were assigned to Lower Super Output Areas (LSOAs) using population-weighted centroids. RESULTS: Between 2009-2020 4247 LSOAs (12.9%) had an annual mean water fluoride concentration of ⟩/= 0.7 mg F/L in at least one year, and 3019 LSOAs (9.1%) had a grand mean fluoride concentration of ⟩/= 0.7 mg F/L. Coverage of optimal fluoridation varied over time; from 10.9% of LSOAs in 2014 to 6.3% in 2016. DISCUSSION: This study confirms previous work identifying variability in the coverage and achieved concentrations of water fluoridation programmes. The current provision for accessing, collating and utilising these data are a barrier to essential monitoring, surveillance and research. An annually maintained and publicly accessible database of water fluoride concentrations is urgently required.