Studies of exposure to fluoride may use Geographic Information Systems to estimate population exposure by geo-referencing water supply zone (WSZ) monitoring data for public water supplies (PWS) to small areas. Geo-referenced fluoride PWS monitoring data were available from 2005-2015, but only non-referenced data from 1995-2004. We aimed to determine whether the geo-referenced fluoride concentrations in 2005-2015 could be used as a proxy for 1995-2004 population exposure. We also aimed to estimate population exposure to fluoride/fluoridation in PWS in England.We allocated annual average PWS fluoride concentrations and fluoridation scheme flagging data from national monitoring data to small areas using GIS. We obtained population data from routine data sources. Mean fluoride concentrations were estimated for each year in each WSZ (a ‘zone-year’), for the two periods 1995-2004 and 2005-2015, stratified by fluoridation scheme-flagging. We compared the WSZ-level period means using Spearman correlation. For the geo-referenced data, we estimated spatial and population distribution of the period-average fluoride concentration.Almost all (97%) of the 16,188 zone-years of PWS monitoring observations were linked to WSZ boundaries for 2005-15, but only 8249/21553 (38%) pre-2005 zone-years were linked to their post 2005 WSZs. Grand mean 1995-2004 (0.11mg/l (SD 0.12)) and 2005-2015 (0.11mg/l (SD 0.12)) fluoride concentrations were similar, and WSZ-level means were highly correlated in un-fluoridated zones (Spearman correlation 0.93), but differed (1995-2004 0.74mg/l (SD 0.22), 2005-15 0.78mg/l (SD 0.16)) and correlated weakly in fluoridated zones (correlation 0.31). Most (72%) of the population received PWS with <0.2mg/l fluoride, 18% 0.2-<0.7mg/l, and 10% with ≥0.7mg/l.We estimated population exposure to fluoride in PWS across England in the period 1995-2015. Fluoride concentrations appear stable over time in WSZs, more clearly in zones without a fluoridation scheme.
Environmental Health Perspectives is pleased to present this abstract on behalf of the International Society for Environmental Epidemiology (ISEE). This abstract was presented at a past ISEE annual meeting and has not been peer reviewed.
*Original abstract online at https://ehp.niehs.nih.gov/doi/10.1289/isesisee.2018.P03.0530