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Fluoride in Drinking Water

Fluoride in Drinking Water: Too Much of a Good Thing?

Two articles in published in January 2016 highlight the long running discussion among health workers and the public they serve on levels of fluoride exposure in drinking water.  As many people know, fluoride is added to drinking water to prevent dental caries but at levels that are NOT expected to cause adverse effects in humans.

A January 19, 2016 blog post by nurse activist Kathleen Krevetski, raises the question of the safety of adding fluoride to drinking water (http://vtdigger.org/2016/01/19/kathleen-krevetski-the-hazardous-waste-in-our-drinking-water/).  She characterizes fluoride additives as a waste product and, while noting that the material is certified by NSF International, expresses the opinion that this certification is not a guarantee of safety ( you can see the names of companies certified by NSF at http://info.nsf.org/).  In her article Ms. Krevetski says that fluoride is neurotoxic and an endocrine disruptor and that the precautionary principal ought to be applied when considering the addition of fluoride to water.  Some of these same concerns have been raised in a January 19 Inside EPA piece reporting on comments to the National Toxicology Program (NTP) on their proposal to review fluoride’s potential neurodevelopmental risks (http://insideepa.com/daily­news). In their comments, the Fluoride Action Network (FAN) provides an overview of sources of fluoride exposure.  Since the early use of fluoride in water to prevent dental caries, multiple products containing fluoride have become widely used, which leads to likely greater levels of fluoride exposure.

Should we be worried about this? 

The U.S. EPA is responsible for ensuring that humans are not exposed to unsafe levels of any chemical in drinking water.  They have been studying whether this increased potential exposure to fluoride is of concern, and they have been reviewing their safe level for fluoride in drinking water.  It is well known that too much fluoride can have adverse effects on bone and that unacceptable mottling of teeth is associated with lesser amounts of fluoride.  Too much of any chemical can be harmful (http://kidschemicalsafety.org/health/safe/). Groups of scientists and health care professionals don’t necessarily agree that there is enough evidence to support concerns about other effects that might be linked to exposure to low levels of fluoride in water. Comments to NTP have called for testing not only for neurotoxic effects but also for carcinogenicity and effects on hormonal systems.

It is certainly useful to have an open and objective dialogue on priorities for research, particularly on chemicals for which there is widespread, and in the case of fluoride intentional, exposure.  No one, however, is served by overstating a case or by inaccurate statements.  The blog post by Ms. Krevetski states categorically that fluoride is a neurotoxicant and an endocrine disrupter. While FAN and other groups are concerned that nervous system damage resulting in lowered IQ could happen in children exposed to amounts of fluoride currently in our drinking water, the American Association of Public Health Dentistry (AAPHD) states that neurotoxicity is not established in currently available studies on fluoride (https://ntp.niehs.nih.gov/ntp/about_ntp/bsc/2015/december/publiccomm/cappelli_pollick20151130_508.pdf).

The post by Ms. Krevetski further states “Recent science has shown fluoride to be . . .  in the same EPA classification of human carcinogens as arsenic and cyanide.”  This statement is misleading.  The U.S. EPA Integrated Risk Information System (IRIS) provides comprehensively peer-reviewed evaluations of environmental chemicals (available at http://www.epa.gov/iris). According to IRIS, the carcinogenicity of fluoride (soluble fluorine) has not been evaluated by U.S. EPA.  IRIS entries for 8 salts of cyanide say that either they have not been assessed by U.S. EPA or that the data are inadequate for assessment. Thus, neither fluoride nor cyanide have data that suggest they are cancer causing.  By contrast, inorganic arsenic is considered by U.S. EPA and by other authorities to cause cancer in humans.

The publication on-line and elsewhere of incorrect statements that can easily be checked for accuracy does not help the cause of environmental advocacy.   Whether Ms. Krevetski’s concerns are valid will best be resolved through systematic review and evaluation of the literature and identification of data gaps to be filled though the conduct of thoughtful research.