Fluoride Action Network

Fluoride Studies funded by the U.S. Government

The first U.S. government-funded Mother-Offspring study on fluoride's neurotoxic effects was published in 2017 - some 67 years since fluoridation of drinking water began. There are now more studies since 2017 that have revealed that in fluoridated communities the fetus and the formula-fed infant are the most vulnerable to fluoride’s neurotoxicity. These and other studies funded by the U.S. government on fluoride's toxicity are presented here.

Animal Studies on Fluoride’s Toxicity

US-agencies funding the studies:

NIEHS (National Institute of Environmental Health Sciences) has responsibility for the NTP (National Toxicology Program). The NIEHS is the research arm of U.S. regulatory agencies. The NTP is best known for its Reports on Carcinogens.

NIDCR (National Institute of Dental and Craniofacial Research) is a pro-fluoridation federal agency. It funds the majority of studies on dental research.

EPA (Environmental Protection Agency) has responsibility for ensuring “safe” fluoride levels in drinking water. The EPA has never performed a risk assessment on pregnant women, the fetus, or the formula-fed infant living in fluoridated communities. According to the Mother-Offspring fluoride studies, these are the very populations most at risk to fluoride’s neurotoxicity.

CDC (Center for Disease Control and Prevention). The Division of Oral Health at the CDC are the nation’s promoters of fluoridation. They recently contracted to bring to market a system to fluoridate small communities using ‘sodium fluorosilicate tablets’ which they estimate will allow up to 19 million more Americans to drink fluoridated water.

NOTE: Not all studies funded by U.S. agencies are listed below, but we will attempt to identify all the studies as we find them. If you know of studies that should be included here, please email us


Author, Study




Signes-Pastor et al., Exposure to a Mixture of Metals and Growth Indicators in 6–11-Year-Old Children from the 2013–2016 NHANES.

“… A reduced growth is associated with high Pb and F exposure; however, little is known about their impact on children’s body size…

“We investigated the joint effects of exposure to a metal mixture (Pb, Mn, Hg, and Se in blood and F in plasma) on 6–11-year-old US children’s anthropometry (n = 1634)… Our findings suggest that metal co-exposures may influence children’s body mass and linear growth indicators, and that such relations may differ by the exposure levels of the components of the metal mixture.”



Tian et al., Deregulation of autophagy is involved in nephrotoxicity of arsenite and fluoride exposure during gestation to puberty in rat offspring. “… Collectively, these results suggest that nephrotoxicity of F and As for offspring exposed to the pollutants from in utero to puberty is associated with deregulation of autophagy and there is an antagonism between F and As in the toxicity autophagy process.”



Ruszkiewicz et al. C. elegans as a model in developmental neurotoxicology “…  C. elegans studies have the potential to predict possible effects of developmental neurotoxicants in higher animals, and may be used to identify new molecular pathways behind neurodevelopmental disruptions, as well as new toxicants.”



McPherson et al., An Evaluation of Neurotoxicity Following Fluoride Exposure from Gestational Through Adult Ages in Long-Evans Hooded Rats.

This study was hailed by fluoridation proponents who said that no adverse neurotoxic effects were found in this study.

Spencer & Limeback identified flaws in the study.

Another flaw in this study that hasn’t been mentioned is that the rats were dosed with fluoride in drinking water from gestational day 6. The average gestation time for black hooded Long Evans rats is 20 to 23 days (Janvier Labs). The average gestation time for other rats, not identified as to species, is 21 to 23 days (Merck). (EC)

2016 Gutowska et al., Lead enhances fluoride influence on apoptotic processes in the HepG2 liver cell line.



Heindel et al., Developmental toxicity evaluation of sodium fluoride administered to rats and rabbits in drinking water. “Sodium fluoride (NaF; Cas No. 7681-49-4) is used in fluoridating municipal water supplies, resulting in chronic exposure of millions of people worldwide. Because of a lack of pertinent developmental toxicity studies in the literature, sodium fluoride was administered ad libitum in deionized/filtered drinking water (to mimic human exposure) to” rats and rabbits.



Toxicology and Carcinogenesis Studies of Sodium Fluoride in F344/N Rats and B6C3F1 Mice (Drinking Water Studies).

The principal finding of NTP’s study, performed by Battelle Columbus Laboratories, was a dose-dependent increase in osteosarcoma (bone cancer) among the fluoride-treated male rats.

However, despite the fact that

1) the cancer occurred in the target organ (bone) for fluoride accumulation,
2) the increase in bone cancer was statistically-significant,
3) the doses of fluoride were low for an animal cancer study, and
4) NTP acknowledged it is “biologically plausible” that fluoride could induce bone cancer,

the NTP ruled that the study only provided “equivocal evidence” that fluoride was the cause of the cancer.
See more here AND here

The Sprando & Collins Animal Studies

EPA invested a lot of credence in the Sprando and Collins rat studies. Their studies found negligible effects of sodium fluoride on developmental toxicity and male reproduction at levels up to 250 ppm NaF. One of the findings that raises serious questions about these studies is the notably low incidence and severity of dental fluorosis in their treated animals. Even in the highest dosed animals (250 ppm NaF) the only dental fluorosis that was observed, according to the authors, was mild in nature. This is in stark contrast to most other studies which typically find severe changes to tooth enamel at concentrations < 100 ppm. (Den Besten et al. 1984,1985; NTP 1990). In the 1990 NTP cancer study, for instance, at 79 ppm, animals exhibited severe fluorosis of the enamel. Thus, the abnormally mild nature of the fluorosis observed in the Sprando and Collins studies suggests that the level of bio-available fluoride in these studies may be less than the authors assumed.

In contrast to the findings of over 150 animal studies from other research teams, the Sprando & Collins team reported virtually no evidence of reproductive toxicity among animals treated with very high levels of fluoride exposure. The reasons for this discrepancy remains unclear.

Comments on the Sprando & Collins studies
submitted to the National Research Council in 2004
submitted to the EPA in 2005


Date Published

Author, Study

FDA 2001 Colins, Sprando, et al. Multigenerational evaluation of sodium fluoride in rats.
FDA 2001 Collins, Sprando, et al., Developmental toxicity of sodium fluoride measured during multiple generations.
FDA 1998 Sprando, Collins, et al. Testing the potential of sodium fluoride to affect spermatogenesis: a morphometric study.
FDA 1997 Sprando, Collins, et al. Testing the potential of sodium fluoride to affect spermatogenesis in the rat.
FDA 1996 Sprando, et al. Effect of intratesticular injection of sodium fluoride on spermatogenesis.
FDA 1995 Collins, Sprando, et al. Developmental toxicity of sodium fluoride in rats.

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