Spotlight: Fluoride in Drinking Water
In the early 1900s, a medical doctor named Frederick McKay
noticed that children living near the Pike's Peak region of
Colorado had teeth with mottled stains but fewer cavities than
other children did. Decades of research ultimately revealed
that these effects were caused by naturally occurring fluoride
in the water supply. Fluoride can enter water supplies from
natural sources, such as runoff from fluoride-containing rocks
and soils, through the use of certain chemicals, or through
industrial discharges and emissions.
By the middle of the 20th century, various U.S. municipalities
had begun to add fluoride to water to help prevent tooth decay.
Fluoridation of drinking water was named one of the ten
Great Public Health Achievements in the 20th Century by the
Centers for Disease Control and Prevention (CDC) for its role in
the decline in tooth decay during the second half of the 1900s.
In places where fluoride is artificially added to water, the
fluoride concentration is kept at a safe level between 0.7 and
1.2 mg/L.  For communities with naturally fluoridated water,
however, maintaining optimal fluoride concentrations can be
challenging. Studies in the early 1990s revealed that of the
approximately 10 million Americans with naturally fluoridated
public water supplies, around 200,000 had fluoride concentrations
at or exceeding 4 mg/L (the maximum concentration
allowed under U.S. Environmental Protection Agency (EPA)
standards). At this concentration, approximately 10 percent
of children experience severe enamel fluorosis, which has
effects ranging from mild tooth discoloration ("mottling") to
severe staining, loss of enamel, and pitting. This problem is explored in the National Research Council report Fluoride in Drinking Water: A Scientific Review of EPA's Standards (2006).
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