More than 64,000 children per day in Southern California will be exposed to an unsafe dose of fluoride when the Metropolitan Water District (MWD) begins adding fluoride to drinking water in October, according to an analysis by the Environmental Working Group (EWG). The water district’s plan to add fluoride to the water it supplies to 18 million customers in most of Los Angeles, Orange, San Diego, and parts of San Bernardino, Riverside, and Ventura counties will put 14.5% of children under 1 year old and 12.5% of children 1 to 2 years old over the recommended fluoride exposure limits published by the National Academy of Sciences’ Institute of Medicine and endorsed by the American Dental Association. In Los Angeles County alone, more than 40,000 children ages 2 and under will exceed the safe dose.

EWG used dietary information from the National Health and Nutrition Examination Survey and tap water fluoride data from the Centers for Disease Control to model total fluoride exposures from tap water, food, and toothpaste for children age 2 and under. It is a conservative estimate because it only counts children in the three largest counties served by MWD, and because some of the 26 local water agencies served by MWD already add fluoride to water after they receive it from the district.The full report is available here.

"The value of fluoride in toothpaste to dental health is clear," said Bill Walker, EWG’s vice president for the West Coast. "But a substantial and growing body of peer-reviewed science strongly suggests that adding fluoride to tap water is not the safest way to achieve the dental health benefits of fluoridation. Children who drink fluoridated water are at increased risk of developing fluorosis, a defect of the permanent teeth resulting in dark staining and, in severe cases, substantial corrosion of the enamel."

In November 2006, the ADA acknowledged for the first time the health risks of fluoride, and issued an Interim Guidance on Fluoride Intake for Infants and Young Children. It said that in areas where fluoride is added to tap water, if a child is being fed liquid concentrate or powdered infant formula mixed with water, parents should consider using fluoride-free bottled water.But far more serious health risks have been identified since 2003, when MWD made its decision to fluoridate. Since then, concern about fluoridation, for decades dismissed as unscientific, has re-emerged as a mainstream public health debate.

• A March 2006 report from the National Academy of Sciences/National Research Council (NAS/NRC) identified fluoride as a potent hormone disruptor that may affect normal thyroid function.

• The NAS/NRC report also cited concerns about the potential of fluoride to lower IQ, noting that the consistency of study results appears significant enough to warrant additional research on the effects of fluoride on intelligence.

• A 2006 peer-reviewed study by four Harvard scientists and doctors strongly supports concerns that fluoridated water is linked to osteosarcoma, an often fatal form of bone cancer, in teenage boys who drank fluoridated water as children.

EWG’s study is being released the same day as Metropolitan Water District board members will be briefed on developments in fluoride science since their 2003 decision.