This study looks at arsenic as an impurity in a chemical used to add fluoride to drinking water. The NSF/ANSI standard 60 addresses these questions and making such studies generally unnecessary. What is overlooked is the obvious question is whether adding fluoride to water is a benefit at all. Indeed, it has become a sacred cow enabling advocates to feel good about themselves preventing dental decay without actually having much of a benefit.
Peterson E, Shapiro H, Li Y, Minnery JG, Copes R. Arsenic from community water fluoridation: quantifying the effect. Journal of water and health. 2016 Apr;14(2):236-42. doi: 10.2166/wh.2015.105.
Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.