By Eric Schiller
OWSAG received an inquiry and concern regarding fluoride addition to our tap water as a reason to drink bottled water. Below is a response to the inquiry.
Thank you for your comments on fluorides in our municipal tap water system. I will respond to your specific points but let me first make some general comments.
There are minerals in our drinking water. However, not all minerals are harmful. Some of them are beneficial. That is why some companies sell “mineral water”. Our regulated municipal water has various minerals in it. For example, calcium and magnesium have health benefits for us. When there is excessive calcium and magnesium in the water, we call it ‘hard water’. It is difficult to make soap suds and they leave a deposit when the water evaporates, but in moderate amounts these minerals are healthy.
There are some minerals that are highly toxic and have no known health benefits. These are minerals like arsenic, mercury, lead and cadmium. These minerals are truly harmful.
There is a third category some elements (not solid minerals), which though dangerous at high levels, can have beneficial effects at low levels. Chlorine is one of these elements. At low levels chlorine kills bacteria. Historically, the introduction of chlorination prevented many water-transmitted diseases (i.e. cholera and diphtheria). This saved millions of lives. However, at high doses, chlorine gas can kill people.
Fluoride at low doses can strengthen teeth and bones. However, in higher levels it can disfigure teeth with a brown colouring. This is called dental fluorosis. At the turn of the 20th century some Indigenous peoples in the southern USA had dental fluorosis from fluorides in their natural drinking water. They also had a high resistance to dental cavities.
Ottawa municipal tap water has a very low level of fluoride in the water (less than 0.7 mg/litre). As the accompanying graph (from the US Dept. of Health and Human Services) shows, a low level of fluoride does not produce fluorosis. Also, as the graph shows, the number of cavities decreases with the introduction of fluoridation. It is also true that an improved diet, sanitation and dental care has been shown to produce similar results. More on that later.
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Eric Schiller is a founding member of OWSAG and a retired University of Ottawa civil engineering professor.