Federal Fluoride Cap Too High
Thursday, August 16, 2007

Federal Fluoride Cap Too High

Fluoride in Southern California Tap Water Will Put 64,000 Kids at Risk

In the four years since the Metropolitan Water District (MWD) decided to add fluoride to the tap water of millions of Californians, the American Dental Association (ADA), scientists at Harvard University, and the prestigious National Research Council (NRC) of the National Academy of Sciences have all raised serious concerns about the safety of fluoridated water for infants and young children. This steady stream of science represents a growing consensus within the mainstream public health and dental community that the health risks of fluoride in tap water may substantially outweigh the modest dental benefits of tap water fluoridation.

MWD should put its fluoridation plans on hold until all of the latest science has been evaluated and until the serious outstanding toxicity concerns with fluoride have been resolved.

One specific issue raised by both the NRC and the ADA is that infants and children under two years old may be overexposed to fluoride because they consume more water than adults relative to their size. A new analysis by Environmental Working Group (EWG) confirms these concerns.

EWG analyses show that if the Metropolitan Water District (MWD) of Southern California proceeds with plans to add 0.8 parts per million fluoride to its water beginning in October, more than 64,000 children will be exposed to fluoride at doses above what government agencies consider safe (0.1 milligrams of fluoride per kilogram of body weight per day, or 0.1 mg/kg/d). This maximum safe dose is consistent with the recommended fluoride exposure limits published by the National Academy of Sciences' (NAS's) Institute of Medicine and endorsed by the American Dental Association, and is also consistent with the maximum dose currently considered safe by the Environmental Protection Agency (EPA) (0.11 mg/kg/d). Last year the NAS's National Research Council found that this EPA maximum "safe" dose is too high to protect children, and "should be lowered." In light of the NRC recommendations, EWG's analysis likely underestimates the number of children in Southern California who would be exposed to fluoride at levels of concern.

MWD'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 percent of children under 1 year old, and 12.5 percent of children 1 to 2 years old, over the federal government's acceptable daily intake for fluoride (0.1 milligrams of fluoride per kilogram of body weight per day). In Los Angeles County alone, more than 40,000 children age 2 and under will exceed the safe dose.


MWD's fluoride plan will expose 64,000 children in 3 counties to unsafe doses

  Children under age 1 at risk Children age 1-2 at risk Total children age 2 and under at risk
Los Angeles County 21,516 18,549 40,065
Orange County 6,449 5,560 12,009
San Diego County 6,405 5,522 11,927
Total 34,370 29,631 64,001

Note: Additional children in 3 other counties that are served in part by MWD will also be overexposed (San Bernardino, Riverside, Ventura)

SOURCE: Environmental Working Group, based on Centers for Disease Control data and U.S. Census estimates for July 2006


EWG’s computer-assisted analysis used dietary and water consumption information from the National Health and Nutrition Examination Survey (NHANES) and tap water fluoride data from the Centers for Disease Control (CDC) to model total fluoride exposures from tap water, food and toothpaste for children age 2 and under nationwide, who were selected as the focus of this exposure analysis because they are sensitive to fluoride's potential impacts on growth and development, and they receive a higher dose of fluoride, pound per pound, than any other segment of the population.

The exposure models were then compared to the government's published maximum safe exposure (0.1 milligrams per kilogram of body weight per day)1. Finally, the models were adjusted to reflect the amount of fluoride MWD plans to add (about 0.8 parts per million, compared to typical levels nationwide of 1 part per million) and the number of children age 2 and under in the six Southern California counties, according to U.S. Census estimates of July 2006.

The result is a conservative estimate of the number of children who will exceed the safe dose, because MWD also serves parts of Riverside, San Bernardino and Ventura counties. Also, some of the 26 local water agencies served by MWD already add fluoride to water after they receive it from the district. Customers of those utilities may be exposed to even higher levels of fluoride after the MWD fluoridation.


1 The NAS's Institute of Medicine and the American Dental Association recommend or endorse a maximum safe daily fluoride dose of 0.1 milligrams per kilogram of body weight per day (0.1 mg/kg/d). EPA’s Maximum Contaminant Limit for fluoride in drinking water is 4 parts per million. For the average person in the population (an adult weighing 70 kilograms, or 154 pounds, with EPA's standard assumption of 2 liters of water consumed daily), this is equivalent to a fluoride dose of 0.11 mg/kg/d, and this level of exposure has been historically considered EPA's maximum safe dose for fluoride in water. For infants, EPA has established a reference dose (safe daily dose) of 0.06 mg/kg/day, but this value has never been used for regulation or standard setting.


New Science on Fluoride’s Risks

The value of fluoride-containing toothpaste to dental health is clear; fluoride is a potent chemical that on contact kills microbes on the teeth, reducing the incidence of cavities. But a substantial and growing body of peer-reviewed science strongly suggests that ingesting fluoride in tap water does not provide the same dental benefits, and may present serious health risks.

In fact, 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. The CDC says that about 30 percent of children who drink fluoridated water have some degree of fluorosis.

In November 2006, the American Dental Association 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 has 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. Fluoride's potential to impair thyroid function is most clearly illustrated by the fact that until the 1970s, European doctors used fluoride as a thyroid-suppressing medication for patients with hyperthyroidism. Today, many people living in communities with fluoridated tap water are ingesting doses of fluoride that fall within the range of doses once used by doctors to reduce thyroid activity in hyperthyroid patients (NRC 2006).
  • 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." That finding was echoed by a December 2006 study published in the prestigious peer-reviewed journal The Lancet that identified fluoride as an “emerging” neurotoxin (Grandjean & Landrigan 2006).
  • 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 boys. The Harvard study found a five-fold increase in bone cancer among teenage boys who drank fluoridated water from ages 6 through 8, compared to those drinking non-fluoridated water (Bassin et al 2006).


Fluoride and Bone Cancer

Osteosarcoma, while rare, is the third most common form of cancer in children. Osteosarcoma accounts for about 3 percent of all childhood cancers. The five-year mortality rate is around 50 percent, and nearly all survivors have limbs amputated, usually legs.

The overall weight of the evidence strongly supports the conclusion that exposure to fluoride in tap water during the mid-childhood growth spurt between ages 5 and 10 increases the incidence of osteosarcoma in boys ages 10 through 19. Fifty percent of ingested fluoride is deposited in bones, and fluoride stimulates bone growth in the growing ends of the bones where the osteosarcoma occurs. Fluoride is also a confirmed mutagenic agent in humans, which suggests that fluoride can cause genetic damage in bone cells where it is actively deposited, in this case precisely where the osteosarcoma arises.

Animal studies add further credence to the potential link between fluoride and bone cancer in males. Only two animal cancer bioassays have been conducted with fluoride; both show rare bone tumors, many of which were malignant, in male but not female test animals.

In the Harvard study, elevated bone cancer risks in boys were identified at fluoride levels that are commonly found in American water supplies, and equivalent to the level that would be added to southern California water by the MWD (0.8 ppm). For drinking water systems with fluoride levels far below EPA's limit in drinking water (4 ppm), and 30 to 99 percent of the amount recommended by the CDC (0.7 to 1.2 ppm), the study reports elevated risks for exposure from ages five through ten, with a five-fold risk of osteosarcoma for those exposed at age seven. At 100 percent or more of the recommended level (and still far below legal maximum levels), the risk for exposure at seven years old rises to 7.2-fold.



In August 2007, over 600 medical, dental, scientific, academic, public health and environmental professionals signed a petition to Congress urging a moratorium on fluoridation until hearings and additional research are conducted. Signers include Dr. Arvid Carlsson, winner of the 2000 Nobel Prize for Medicine, who said, "Fluoridation is against all principles of modern pharmacology. It's really obsolete." (FAN 2007.)

Public water supplies should be safe for all consumers, young and old alike. It is deeply troubling that children in Southern California, including bottle-fed infants, will be drinking fluoridated water in spite of the many serious health concerns identified by recent science. We believe the evidence is clear that fluoride exposure should be limited to toothpaste, where it provides the greatest dental benefit and presents the lowest overall health risk.

We call on MWD to reconsider its 2003 decision to add fluoride to its water supplies. If this unnecessary and irresponsible action goes forward, we urge the district to take aggressive and comprehensive steps to inform its 18 million customers of the risks. This information should be provided to every residential water customer in the district, as well as to the news media, health centers, pediatricians, hospitals, obstetricians' offices, dental clinics and water departments.



ADA (American Dental Association). 2006. Interim Guidance on Fluoride Intake for Infants and Young Children. Nov. 8, 2006. http://www.ada.org/prof/resources/positions/statements/fluoride_infants.asp

Bassin EB, Wypij D, Davis RB, Mittleman MA. 2006. Age-specific Fluoride Exposure in Drinking Water and Osteosarcoma (United States). Cancer Causes and Control, April 2006.

FAN (Fluoride Action Network). 2007. “End Fluoridation,” Say 600 Physicians, Dentists, Scientists, and Environmentalists. Fluoride Action Network press release, Aug. 9, 2007. http://www.fluorideaction.org/statement.press.release.html

Grandjean P, Landrigan P 2006. Developmental neurotoxicity of industrial chemicals. The Lancet, Nov. 8, 2006.

NRC (National Research Council). 2006. Fluoride in Drinking Water: A Scientific Review of EPA’s Standards. Washington, DC: The National Academies Press. [Available at http://www.nap.edu/catalog/11571.html]