A Critical Examination of Mass Fluoridation: Legal and Scientific Implications of a Recent Federal Order
Introduction: The Debate Over Fluoridation
Mass fluoridation of water has been one of the most widely implemented public health interventions in the United States, implemented under the alleged directive to prevent dental decay. It has long been the subject of controversy and debate, particularly regarding its potential adverse effects on human health.
This article critically examines a recent Federal Order issued by Senior District Judge Edward Chen, an appointee of President Barack Obama, in the case of Food & Water Watch, Inc. v. United States Environmental Protection Agency (EPA), from the Northern District of California. The order scrutinizes the safety of mass water fluoridation in light of emerging scientific evidence and mandates the EPA to take regulatory action. Specifically, the court found that community water fluoridation at levels currently deemed optimal in the U.S. (0.7 mg/L) poses an unreasonable risk to cognitive development in children, particularly a reduction in IQ. The court's findings are grounded in recent scientific studies, many of which indicate that even low levels of fluoride exposure can have neurotoxic effects, particularly for pregnant women and young children.
The Legal Framework: The Toxic Substances Control Act (TSCA)
The Toxic Substances Control Act (TSCA) provides the legal foundation for the court’s ruling. Amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act, TSCA empowers citizens to petition the EPA to regulate chemicals that may pose an unreasonable risk to human health or the environment. If the EPA denies such a petition, citizens can seek judicial review, as seen in this case. Under the amended TSCA, the court conducts its review de novo, meaning it evaluates the risks associated with the chemical independently, without deferring to the EPA's decision.
In this case, Food & Water Watch and other plaintiffs petitioned the EPA under Section 21 of TSCA to regulate fluoride, arguing that fluoridated drinking water poses an unreasonable risk of neurological harm, particularly to children. After the EPA denied their petition, the plaintiffs filed suit in the Northern District of California. The court's task was to determine whether, via a preponderance of the evidence, i.e., more likely than not, fluoride poses an unreasonable risk to public health, especially in light of new scientific evidence [1, p. 1].
The Court’s Findings: Fluoride and Cognitive Development
The central question before the court was whether the plaintiffs could prove, by a preponderance of the evidence, that fluoridated water at typical U.S. levels presents an unreasonable risk of harm to human health. The court concluded that the plaintiffs had met this burden, primarily relying on a wealth of scientific studies showing that even relatively low levels of fluoride exposure can adversely affect children’s cognitive development, including IQ reduction [1, p. 5].
Fluoridation Levels and Risk
In its ruling, the court discussed the relationship between "hazard levels" (the level at which fluoride becomes harmful) and "exposure levels" (the amount of fluoride to which individuals are exposed through drinking water). The court found that the benchmark dose analysis indicated that a 1-point drop in IQ occurs for every 0.28 mg/L increase in maternal urinary fluoride [1, p. 5]. Given that the average fluoride exposure in U.S. pregnant women exceeds this threshold, the court concluded that many individuals are exposed to unsafe levels of fluoride [1, p. 5].
Additionally, the court noted that the margin of safety—designed to ensure a buffer between safe and hazardous levels—was insufficient. With the current U.S. standard of 0.7 mg/L for water fluoridation, exposure levels in many cases are too close to those associated with cognitive harm [1, p. 6].
Key Scientific Studies Cited by the Court
To substantiate its conclusions, the court drew heavily on several key scientific studies that were admitted into evidence at trial which link fluoride exposure to neurodevelopmental damage. These studies, many of which are recent, played a crucial role in the court’s determination that fluoridation poses an unreasonable risk.
1. National Toxicology Program (NTP) Review [1, p. 16] [2].
The National Toxicology Program (NTP) conducted a comprehensive systematic review of the literature concerning the neurodevelopmental effects of fluoride exposure. This review assessed 72 human epidemiological studies, many of which examined cognitive outcomes, particularly IQ, in children exposed to varying levels of fluoride. One of the critical findings of the NTP review was the association between fluoride exposure and reduced cognitive function. Importantly, the NTP's pooled benchmark dose analysis revealed that for every 0.28 mg/L increase in maternal urinary fluoride, a corresponding 1-point decrease in IQ in offspring could be observed.
The NTP review was critical in helping shift the debate about fluoride safety because it used rigorous methodology to analyze both high-exposure populations (such as in parts of China) and lower-exposure groups (more typical of U.S. conditions). The benchmark dose is particularly important because it represents the exposure level at which adverse effects are expected to occur in the population, providing a concrete numerical value that regulators can use to assess risk. This review thus formed a scientific basis for the court’s concern that fluoride exposure, even at levels considered safe in the U.S. (0.7 mg/L), might still pose a risk to children’s cognitive development. The court relied heavily on these findings to determine that current fluoride levels may be unsafe.
2. Bashash et al. (2017) [1, p. 19] [3].
In the landmark study by Bashash et al. (2017), researchers assessed the relationship between prenatal fluoride exposure and cognitive outcomes in children from Mexico City. This study measured fluoride levels in the urine of 299 pregnant women and compared them to their children's cognitive test scores at ages 4 and 6-12. Urinary fluoride is considered a reliable biomarker of fluoride exposure because it reflects both the intake of fluoride through drinking water and food as well as its accumulation in the body.
The results were striking: for every 0.5 mg/L increase in maternal urinary fluoride, there was a 3.15-point reduction in children’s cognitive scores at age 4, and a 2.50-point reduction in IQ at ages 6-12. This study was notable for its longitudinal design, which allowed researchers to track cognitive development over several years, and for its rigorous control of confounding variables, including socioeconomic status, birth weight, and exposure to lead. The findings provided strong evidence that fluoride exposure during pregnancy has long-lasting effects on neurodevelopment.
The significance of the Bashash et al. study lies in its demonstration that prenatal exposure to fluoride can have neurotoxic effects at levels lower than previously thought, particularly in populations that are considered "moderate-fluoride" areas. This study helped to provide a biological mechanism for the observed cognitive declines, implicating in utero fluoride exposure as a critical period of vulnerability.
3. Green et al. (2019) [1, p. 20] [4].
The Green et al. study expanded on the findings of Bashash et al. by examining a cohort of 512 mother-child pairs in Canada. This study investigated both maternal urinary fluoride levels and estimated fluoride intake from water, comparing them to IQ scores in the children at age 3-4. The study is notable because it involved communities with both fluoridated and non-fluoridated water, allowing for a direct comparison of outcomes across different exposure levels.
One key finding was that for boys, an increase of 1 mg/L in maternal urinary fluoride was associated with a 4.49-point reduction in IQ, while girls showed no statistically significant effect. The sex-specific differences observed in this study were intriguing and have led to further investigations into the potential mechanisms by which fluoride may differentially affect male and female neurodevelopment.
Green et al. also found that daily fluoride intake from water was associated with a 3.66-point IQ reduction across both sexes. The fact that this effect was observed in a population with exposure levels typical of fluoridated regions in North America lent additional weight to the argument that even low-to-moderate fluoride exposure levels can impair cognitive development. The study underscored the importance of re-evaluating water fluoridation policies in light of these findings.
4. Till et al. (2020) [1, p. 21] [5].
In the Till et al. study, the focus was on infants, particularly formula-fed infants who are exposed to fluoride through formula reconstituted with fluoridated water. This study used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort, involving over 600 mother-child pairs from six cities across Canada. It was one of the first studies to specifically examine the impact of fluoride exposure during infancy on cognitive development.
The researchers found that formula-fed infants exposed to fluoridated water had significantly lower IQ scores than breastfed infants, with an 8.8-point IQ decrement, even after adjusting for prenatal fluoride exposure. This finding is critical because it highlights the vulnerability of infants during the early stages of brain development, suggesting that fluoride exposure during this period may be particularly detrimental.
The study also pointed to a potentially concerning disparity: infants who are exclusively formula-fed are disproportionately exposed to higher levels of fluoride compared to breastfed infants, as breast milk contains very low levels of fluoride. This research provided additional support for the idea that water fluoridation, while beneficial for dental health, may have unintended adverse effects on infant neurodevelopment.
5. Xiang et al. (2003a) [1, p. 21] [6].
Xiang et al. conducted one of the earliest and most influential studies on the relationship between fluoride exposure and children’s IQ. This research took place in China, where fluoride levels in drinking water are often much higher than those in the U.S. The study compared children from high-fluoride areas (2.5–4 mg/L) with children from low-fluoride areas (0.7 mg/L or less) and found that children in the high-fluoride areas had significantly lower IQ scores.
The results from Xiang et al. laid the groundwork for subsequent research on fluoride's neurotoxic effects. The study showed that children exposed to high levels of fluoride (well above the U.S. standard) were at a much higher risk of developing cognitive impairments, but it also hinted that even lower levels of fluoride exposure could have an impact on IQ.
6. Choi et al. (2015) [1, p. 19] [7].
Choi et al. further contributed to the body of evidence by examining fluoride exposure in children in China. This study explored the lifetime exposure to fluoride in children, including both drinking water and dietary sources, and how this affected their cognitive functions. The results indicated a clear inverse relationship between fluoride exposure and IQ, supporting the idea that fluoride’s effects are cumulative over time.
This study was notable for its inclusion of lifetime fluoride exposure, showing that long-term exposure, even at lower levels, could lead to cognitive deficits. The court considered these findings significant in affirming that the neurotoxic effects of fluoride may not be limited to short-term, high-dose exposures, but can accumulate and manifest later in life.
7. Ding et al. (2011) [1, p. 21] [8].
In the study by Ding et al., researchers examined the relationship between urinary fluoride levels and IQ scores in children from areas with varying levels of fluoride exposure in Hulunbuir, Inner Mongolia. The results indicated that higher fluoride levels in the children’s urine were correlated with lower IQ scores, reinforcing the growing body of evidence linking fluoride exposure to cognitive decline.
This study, like others from China, provided compelling evidence of a dose-response relationship between fluoride exposure and intelligence, meaning that as fluoride levels increased, IQ scores tended to decrease. The consistency of these findings across multiple regions and populations lent further credence to the argument that fluoride exposure poses a real and measurable risk to cognitive health.
Review of the Additional Relevant Studies
The attached studies further illuminate the connection between fluoride exposure and reduced IQ, complementing the findings already discussed by the court. While not directly cited in the court’s order, these studies provide essential context for understanding the global scope of fluoride research.
1. Valdez-Jiménez et al. (2010): Effects of Fluoride on the Central Nervous System
This review from Mexico addresses the prolonged impact of fluoride exposure on the nervous system, emphasizing that chronic fluoride ingestion, even at 1 part per million (ppm), can lead to changes in brain morphology and biochemistry, which affect cognitive processes such as learning and memory. The study suggests that these effects may not manifest until many years after exposure, supporting the court’s findings that even relatively low levels of fluoride can cause long-term neurological harm [9].
2. Wang et al. (2007): Arsenic and Fluoride Exposure in Shanxi Province, China
This study assessed the effects of high fluoride exposure on children's IQ in Shanxi Province, China. It found that children exposed to fluoride concentrations of approximately 8.3 mg/L had significantly lower IQs compared to children in control groups with lower fluoride exposure. This aligns with the court’s concerns about fluoride’s cognitive effects, although the court primarily relied on studies conducted in the U.S. and Canada [10].
3. Tang et al. (2008): Fluoride and Children’s Intelligence: A Meta-analysis
This meta-analysis reviewed 16 case-control studies from China and concluded that children in high-fluoride areas were five times more likely to develop low IQ compared to children in areas with low fluoride exposure. The results of this meta-analysis reinforce the court’s findings that fluoride exposure at levels historically deemed safe may still pose significant risks to cognitive development [11].
The Court’s Risk Analysis
The court's analysis revolved around the benchmark dose analysis from the NTP, which revealed that fluoride exposure at levels commonly found in U.S. drinking water could result in reduced IQ in children. The court also considered the EPA’s use of a margin of exposure (MOE), which serves as a safety buffer. The court found that current fluoridation levels of 0.7 mg/L exceeded the safe margin, particularly for pregnant women and children, making regulatory intervention necessary [1, p. 6].
Implications for EPA’s Role
While the court acknowledged that the EPA has discretion in how it regulates chemicals, it stressed that the agency cannot ignore the significant evidence of harm from fluoride exposure. The court directed the EPA to take regulatory action, though it left the specifics of that action to the agency's discretion. Possible responses range from lowering the recommended fluoridation level to implementing public advisories or even banning fluoridation altogether [1, p. 9].
Conclusion: Reassessing Fluoridation in Light of New Evidence
The recent Federal Order on fluoridation highlights the need for a reassessment of long-standing public health practices in light of new scientific evidence. As the body of research linking fluoride exposure to neurodevelopmental harm continues to grow, the risks associated with fluoridation may outweigh its benefits in preventing dental decay.
The court's decision underscores the importance of protecting vulnerable populations, such as pregnant women and children, from potential harm and heed warning to both the long-standing and emerging evidence of fluoride's risks to cognitive development.
References
[1] Food & Water Watch, Inc. v. United States Environmental Protection Agency, Case No. 17-cv-02162-EMC, U.S. District Court for the Northern District of California (2024), https://www.cand.uscourts.gov/wp-content/uploads/2024/09/17-cv-2162-Food-_-Water-Watch-Inc.-et-al.-v.-EPA-et-al-Opinion.pdf.
[2] https://ntp.niehs.nih.gov/sites/default/files/2024-08/fluoride_final_508.pdf
[3] https://pubmed.ncbi.nlm.nih.gov/28937959/
[4] https://jamanetwork.com/journals/jamapediatrics/fullarticle/2748634
[5] https://www.sciencedirect.com/science/article/pii/S0160412019326145
[6] https://www.fluorideresearch.org/362/files/FJ2003_v36_n2_p84-94.pdf
[7] https://pubmed.ncbi.nlm.nih.gov/25446012/
[8] https://pubmed.ncbi.nlm.nih.gov/21237562/
[9] https://www.sciencedirect.com/science/article/pii/S0213485310003191
