Our estimate of additional arsenic (0.078 μg/L) in fluoridated systems when compared to non-fluoridated systems is consistent with information found in different peer reviewed and non-peer reviewed sources. We used the results of five published studies and one unpublished study, which estimated the arsenic content of fluoride additives for drinking water (Weng et al. 2000; Casale 2001; Brown et al. 2004; Hirzy et al. 2013; NSF International 2013), to estimate the arsenic contribution to drinking water from fluoridation. Based on these studies, we would anticipate an increase in arsenic concentration of 0.004 μg/L to 0.35 μg/L in optimally fluoridated water as defined by Health Canada (see Table 3) (see supplementary material for original data and methods, available with the online version of this paper). The result we obtained is within this expected range, and likely provides a more extensive picture of what occurs in current day practice.
Expected arsenic in drinking water calculated based on levels of arsenic measured in the additive found in the peer reviewed and non-peer reviewed literature
| . | Number . | Arsenic concentration (μg/l) at 0.7 mg/L of fluoride in watera . | |
|---|---|---|---|
| Study . | of samples . | Lower limit . | Upper limit . |
| NSF International (2013) | 461 | NAb | 0.35 |
| Brown et al. (2004) | 4 | 0.025 | 0.162 |
| Weng et al. (2000) c | Unknown | None given | 0.168 |
| Casale (2001) c,e | 60d | 0.027 | 0.17 |
| Ministry of Environment (Deshpande S., Personal Communication 2013) | 8 | 0.004f | 0.018 |
| Hirzy et al. (2013) | 11 | 0.007f | 0.27 |
| . | Number . | Arsenic concentration (μg/l) at 0.7 mg/L of fluoride in watera . | |
|---|---|---|---|
| Study . | of samples . | Lower limit . | Upper limit . |
| NSF International (2013) | 461 | NAb | 0.35 |
| Brown et al. (2004) | 4 | 0.025 | 0.162 |
| Weng et al. (2000) c | Unknown | None given | 0.168 |
| Casale (2001) c,e | 60d | 0.027 | 0.17 |
| Ministry of Environment (Deshpande S., Personal Communication 2013) | 8 | 0.004f | 0.018 |
| Hirzy et al. (2013) | 11 | 0.007f | 0.27 |
aThis assumes that the raw water contains no fluoride, and that the concentration of 0.7 mg/L of fluoride is made up completely by the additive.
bA lower limit is not appropriate since the method used in this study would result in arsenic concentrations below the level of detection.
cArsenic content was from information provided by manufacturer.
dThis number was not given explicitly in the paper, but inferred from the information given in tables.
eAssumed in a 25% solution.
fThis was not the lowest result found but rather the limit of detection.