Association between Community Water Fluoridation Implementation and Bone Health

Abstract

Objectives: The community water fluoridation (referred to as CWF) was conducted in Cheongju City in South Korea from 1982 to 2004. The purpose of this study was to evaluate epidemiologically the risk of CWF for adverse health effect, specifically bone related diseases (hip fracture, osteoporosis, and bone cancer).

Design: This study was an ecological study based on natural experiment design.

Methods: Study participants were residents in Cheongju from 2004 to 2013 and data were collected by National Health Insurance Service database. Hip fracture, osteoporosis, and bone cancer among adverse health diseases were selected. We ensured the trend of medical use trend after CWF ceased in Cheongju and analyzed the prevalence of selected disease to evaluate the risk of CWF. The Hierarchical Bayesian spatio-temporal Poisson regression model which consider spatial and temporal correlation was performed to analyze the association between implementation of CWF and the prevalence of selected diseases of residents in Cheongju. Conditional autocorrelation (CAR) which is frequently used to control spatial correlation was applied in this analysis. The calculation method for Bayesian estimation was based on the R-INLA.

Results: After CWF ceased in Cheongju, we observed increasing trend in hip fracture, osteoporosis and bone cancer in both areas (fluoridated and non-fluoridated areas). However, there was no statically significant difference in the prevalence of selected bone diseases in CWF area (RR = 0.95, 95% CrI: 0.87-1.05; RR = 0.94, 95% CrI: 0.87-1.02; RR = 1.20 95% CrI: 0.89-1.61, respectively).

Conclusions: We used a spatiotemporal method to analyze the medical use of selected bone diseases from 2004 to 2013 in Cheongju with small area unit by using National Health Insurance Service data. Our study verified that there was no statistically different in prevalence of selected bone disease between CWF and non-CWF areas after CWF was ceased. With this results, we confirmed that fluoridation has no negative impacts on adverse health effects. There was no clear evidence that exposure of CWF increased the risk on health effects. Our study provided one of the scientific evidence and it is necessary to research and develop as a public health prevention program continuously.