Fluoridation is the act of artificially adding fluoride to a substance, whether drinking water, food, or etc. You are correct about he WHO recommending 1.5mg/L, but it is important to understand why these numbers are in place. This is exactly what I was discussing in my previous post. The WHO (WORLD is the key word), makes recommendations based on what they feel are the benefits and risks across the world. The EPA in this case is a better indicator for the US. Currently, the EPA has 2 guidelines for water fluoridation
1) 4 mg/L, which is the enforceable EPA MCLG standard for serious health effects. Meaning that no serious health effects are likely to occur at said levels.
2) 2mg/L MCLG standard, which is the secondary and not enforceable fluoridation limit. Past this level there is some occurence of "cosmetic" dental fluorosis.
The second standard, as well as the WHO standard, is based on the fact that there are natural sources of fluoride that occur, which are not included in this fluoridation limit. So, when considering geographical regions where large amounts of granite and gneiss appear, causing increased natural fluoride "contamination", it is safer for an organization such as the WHO to recommend a lower MCLG. In the US, this happens quite a lot in California and the Great Lakes area. Children living in these areas are most likely to suffer from dental fluorosis.
My point here is that we should all be careful with numbers and statistics.....
Regards,
Chris