A Concentration Is Not a Dose

Fluoride Series Article Two

I do not support the use of fluoride in drinking water, supplements, or dental products. Fluoride is a toxic substance with documented harmful effects at sufficient exposure, including dental and skeletal fluorosis. My concern is the health of the whole person, and I favor a fluoride-free approach to dental care. Saying that a water supply contains a recommended concentration does not tell us how much an individual swallows, retains, or receives from other sources. That is the issue at the heart of this article. [1,2] Public-health policy should protect those most vulnerable to an exposure, rather than rely on an average that can obscure their circumstances.

Why I changed my position on fluoride

For the first 36 years of my dental hygiene career, I believed in fluoride. I trusted the American Dental Association and the American Dental Hygienists’ Association to have my patients’ best interests at heart. I accepted the assurances about safety and cavity prevention and repeated them to patients. I was focused on teeth. I had not examined the exposure question carefully enough or considered what swallowed fluoride might mean for the rest of the body.

When I began reading beyond the usual dental recommendations, my position changed. I looked at research on fluoride exposure, fluorosis, and childhood neurodevelopment, as well as the evidence for water fluoridation’s benefit. I could no longer treat a recommendation from an organization as the end of the conversation. In my 2023 article, “Fluoride the Destroyer—See the Dark Side,” I described that change in perspective. I remain opposed to deliberately adding fluoride to water or using it in dental care. [3]

The dose makes the poison, but concentration is not dose

Fluoridation advocates often answer concerns by saying, “The dose makes the poison.” Dose does matter. But that principle requires us to examine the dose actually received. The frequently repeated figure of 0.7 milligrams per liter is a water concentration, not an individualized dose. At that concentration, drinking one liter supplies 0.7 milligrams of fluoride from the water; drinking three liters supplies 2.1 milligrams. The water is identical, but the amount swallowed is three times greater.

The calculation must also account for body weight, fluoride from other sources, and exposure over time. The amount swallowed is not necessarily the amount retained, because absorption and elimination matter too. These differences do not establish that every person drinking fluoridated water is injured. They establish why citing a concentration cannot answer every question about a person’s exposure. I do not regard “the dose makes the poison” as a justification for adding fluoride to everyone’s drinking water. [1,2]

The body receives fluoride from more than water

Tea can contribute fluoride because tea plants accumulate it, with the amount in a cup varying by leaves, brewing, and consumption. Swallowed toothpaste, other dental products, and fluoride supplements can contribute additional exposure. A meaningful assessment considers these sources together, rather than treating the tap-water concentration as the whole story. [1,2]

Some fluorine-containing medications release inorganic fluoride during metabolism and can contribute to total exposure. Voriconazole is a documented example: its prescribing information warns about fluorosis and periostitis, inflammation around bone, during long-term treatment. However, chemically bound fluorine alone does not establish how much fluoride a medication releases. Exposure must be assessed drug by drug, considering dose, treatment duration, and kidney function. [4,5]

A pharmacist can help determine whether a particular medication is a documented source of fluoride exposure, although reliable measurements are not available for every drug. Patients can ask: “Does this medication release inorganic fluoride during metabolism, and is the amount clinically significant at my dose and treatment duration, especially given my kidney function?” A medication review should inform decisions with the prescribing clinician.

People who drink unusually large amounts of water may ingest more fluoride from that water. The National Research Council considered high-consumption groups, including outdoor workers, athletes, and people with conditions associated with excessive thirst. The kidneys are a major route of fluoride elimination, so impaired renal function can also affect retention. A uniform water concentration does not adjust for either circumstance. The NRC report examined EPA’s drinking-water standards and did not establish that 0.7 mg/L causes kidney disease. Its exposure analysis still matters when we ask who receives more fluoride and who clears it less efficiently. [1,2]

Fluorosis is evidence of toxicity

Dental fluorosis results from excessive fluoride ingestion while enamel is developing. Its appearance can range from subtle changes to more serious pitting and damage. Dental fluorosis is visible evidence that excessive systemic fluoride exposure affected the developing tooth. The change we see on the surface began while enamel was forming inside the body. I do not dismiss a patient’s concern about it as merely cosmetic. It deserves attention as an exposure marker, although dental fluorosis alone cannot tell us whether the brain, kidneys, bones, or other organs were harmed. It reflects exposure during childhood tooth development rather than necessarily indicating someone’s current fluoride intake. [1]

Long-term, sufficiently high exposure can also cause skeletal fluorosis. Bone and joint pain, stiffness, and other musculoskeletal changes may require a detailed exposure history when a clinician suspects it. Skeletal fluorosis is uncommon in the United States, and an aching joint is not evidence of fluoride toxicity. My concern is that substantial exposure may be overlooked when clinicians never ask about water intake, tea consumption, kidney function, or other fluoride sources. [1,2]

Protect the most vulnerable rather than dose to the middle

My objection is that a single water concentration cannot account for the people most vulnerable to increased intake, reduced clearance, or exposure during development. People with kidney disease, people whose diabetes causes excessive thirst, infants, and developing fetuses deserve explicit consideration. An average exposure estimate can obscure the circumstances of those who receive more fluoride or eliminate it less efficiently. A policy should explain how it protects those groups, not simply cite a target concentration. [1,2]

Reduced kidney function can impair fluoride elimination and increase retention. Diabetes presents a different exposure concern: when poorly controlled blood glucose causes excessive thirst, greater water consumption means greater fluoride intake at the same concentration. Diabetes can also coexist with kidney disease. These mechanisms should not be treated as interchangeable, and a diabetes diagnosis alone does not establish fluoride toxicity. The degree of renal impairment and a person’s actual intake matter. [1,2]

Dialysis requires a further distinction. Water used to prepare hemodialysis fluid must undergo special treatment and comply with strict contaminant controls, including controls for fluoride. This is different from a universal instruction that dialysis patients must avoid drinking fluoridated water. The National Kidney Foundation has not issued specific recommendations on fluoride intake in kidney disease because the research is limited. Kidney Health Australia’s 2018 statement advises monitoring fluoride intake and avoiding fluoride-rich substances in stage 4 or 5 kidney disease, while supporting community fluoridation at recommended levels. Individual advice about drinking water and total fluid intake belongs with the patient’s nephrologist. [6,7,8]

For formula-fed infants, mixing water can contribute repeatedly to intake relative to a very small body weight. During pregnancy, the concern includes exposure during fetal brain development, which is the focus of the prenatal studies discussed below. The evidence differs across these groups; it does not establish that every person in them will develop toxicity from water at 0.7 mg/L. Greater intake or retention is not the same as a demonstrated injury, and developmental studies leave important questions unresolved. Those distinctions help us identify what needs protection and measurement. [1,2,9,10]

Repeated intake and retention over time also matter. Some absorbed fluoride is eliminated, chiefly through the kidneys, while some is retained, especially in bone. Continued exposure can contribute to accumulation, and impaired clearance can increase that burden. Long-term, sufficiently high exposure can cause skeletal fluorosis. This is why a single day’s intake or a single water measurement cannot describe a lifetime of exposure. Accumulation is not the only concern, however: an overfeed can raise short-term intake, and exposure during development raises questions about timing as well as amount. The relevant questions are how much enters the body, how much leaves, what is retained, and when exposure occurs. [1,2]

My position is that these differences strengthen the case against intentionally adding fluoride to a shared water supply. I do not accept a population average as sufficient reassurance for a person with impaired clearance or a child exposed during development. The people who are least able to control their exposure should be central to the decision. For me, protecting them means choosing fluoride-free water and individualized prevention that addresses the causes of dental disease.

Pregnancy and infancy deserve special protection

An infant’s small body mass makes intake per kilogram especially relevant. Formula prepared with fluoridated water can provide a repeated route of exposure when that formula supplies most or all nutrition and fluid. Breast milk generally contains less fluoride, although its concentration is not always zero. These are distinct exposure situations, and a population average cannot describe every infant. [1]

The same fluoride concentration can deliver a much larger intake relative to an infant’s body weight. Consider an illustrative comparison using water containing 0.7 mg/L fluoride: a 5-kilogram infant receiving formula prepared with 0.75 liter of mixing water in a day would receive 0.525 milligrams of fluoride from that water, or 0.105 mg/kg. A 70-kilogram adult drinking two liters would receive 1.4 milligrams, or 0.020 mg/kg. In this example, the infant receives less fluoride in total but approximately five times as much per kilogram of body weight. [11]

These assumptions illustrate the calculation; they are not a feeding recommendation. The comparison counts only the water and excludes fluoride in formula ingredients and other sources in the adult’s diet. It does not establish injury. “An adult dose” is therefore too vague a description. The concern is repeated intake relative to a small body mass during development. CDC acknowledges an increased chance of mild dental fluorosis when an infant consumes only formula mixed with fluoridated water. [12]

A 2026 review by Soleimani and colleagues combined nine studies reporting fluoride measurements in 1,394 breast-milk samples. The authors found variation and used modeling to flag some exposure scenarios for closer attention. They did not measure harm in infants or establish that community fluoridation caused the fluoride detected in milk. I include the review because infant exposure deserves careful measurement, not because it establishes that breastfeeding is unsafe. [13]

My opposition also reflects concern about prenatal exposure and the developing brain. Pregnant women and infants cannot be treated as smaller versions of a healthy average adult. Even a substantial dental benefit would not persuade me to accept an avoidable risk to brain development. That is the value judgment guiding my position; the studies themselves must still be described accurately.

What the IQ research tells us

The National Toxicology Program’s 2024 review concluded, with moderate confidence, that higher fluoride exposure, such as drinking water above 1.5 mg/L, is associated with lower IQ in children. It also stated that the data were insufficient to determine whether water at 0.7 mg/L affects children’s IQ. That limitation does not establish safety at 0.7 mg/L, and it does not prove harm at that exact concentration. For me, unresolved developmental concerns are a reason to avoid intentionally adding fluoride while better evidence is sought. [9]

Dr. Philippe Grandjean and colleagues analyzed maternal urinary fluoride and child IQ in prospective birth cohorts. Their 2022 analysis of Canadian and Mexican data estimated lower confidence bounds near 0.2 mg/L in maternal urine for a modeled one-point IQ difference. A later analysis adding a Danish cohort reported a pooled lower bound of 0.28 mg/L in maternal urine. The Danish cohort alone did not show a statistically significant association with full-scale IQ. These values are statistical benchmarks, not guarantees of an individual child’s outcome or direct drinking-water limits. [14,15]

The Canadian cohort underlying the analysis included mothers in fluoridated communities with a mean water concentration of 0.59 mg/L. Higher maternal urinary fluoride was associated with lower IQ in boys; that urine association was not statistically significant in girls. Urinary fluoride reflects exposure from multiple sources and cannot simply be equated with the same number in drinking water. These findings are relevant to ordinary exposure circumstances, but they do not prove that exactly 0.7 mg/L in water causes a specified IQ loss. The concern is total prenatal exposure, which a target water concentration cannot fully describe. [10]

Why I choose fluoride-free care

My concern begins with the person receiving the exposure. Water concentration alone cannot describe intake, kidney clearance, retention over time, or exposure during development. Those differences deserve attention in clinical care and public policy. [1,2]

I oppose adding fluoride to drinking water and do not support fluoride supplements or topical products. Its documented toxicity and the unresolved questions about developmental exposure lead me to choose fluoride-free care and individualized prevention. Protecting vulnerable people should be central to that decision. Before repeating that a recommended concentration is safe, we should ask: safe for whom, at what total intake, and over what period of time? A concentration is not a dose, and an average cannot stand in for the patient.

As a profession, we have an obligation to protect the entire person. In my view, our approach to fluoride has been shortsighted: we have focused too narrowly on teeth while giving insufficient attention to total exposure, kidney function, developmental vulnerability, and the questions raised by current research. I include myself in that criticism. For decades, I repeated what I had been taught without examining it closely enough. Our responsibility is to keep reading, question our assumptions, explain uncertainty honestly, and reconsider our recommendations when the evidence warrants it. Protecting teeth must be part of protecting the person who carries them.

In Article Three, “Fluoride in Your Water: What Else Comes With It?”, I examine fluoridation additives, possible contaminants, and treatment overfeeds—including the implications for infant formula, refrigerator water, and ice—and explain why transparency and informed consent matter.

Thank you for reading to the end, for staying curious, and for caring about the health and well-being of the people who trust us with their care. I know how challenging it can be to reconsider something we have believed and taught for years. I have walked that path myself, and I am still learning.

My hope is that you will keep reading, ask thoughtful questions, and make room for conversations that challenge familiar assumptions. We share a desire to help our patients thrive. Let that care guide us as we keep learning how to protect the whole person.

Warmly,

Barbara Tritz

The Queen of Dental Hygiene, fierce protector of the body and advocate for whole body healing

References

1. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Fluorides Hydrogen Fluoride and Fluorine. 2003. Source

2. National Research Council. Fluoride in Drinking Water A Scientific Review of EPA’s Standards. National Academies Press; 2006. doi:10.17226/11571. Source

3. Tritz BK. Fluoride the Destroyer See the Dark Side. Queen of Dental Hygiene. February 2023. Source

4. VFEND (voriconazole). Prescribing information. Section 5.12 Skeletal Adverse Reactions. Source

5. Wermers RA, et al. Fluoride excess and periostitis in transplant patients receiving long-term voriconazole therapy. Clin Infect Dis. 2011;52(5):604–611. Source

6. Centers for Disease Control and Prevention. Water Use in Dialysis. March 26, 2024. Source

7. National Kidney Foundation. Fluoride. Accessed October 1, 2026. Source

8. Kidney Health Australia. Fluoride Position Statement 2018 Review. April 2018. Source

9. National Toxicology Program. Fluoride Exposure Neurodevelopment and Cognition. 2024 monograph and assessment summary. Source

10. Green R, et al. Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA Pediatr. 2019;173(10):940–948. Source

11. Institute of Medicine. Dietary Reference Intakes for Calcium Phosphorus Magnesium Vitamin D and Fluoride. National Academies Press; 1997. Chapter 8 Fluoride. Source

12. Centers for Disease Control and Prevention. Community Water Fluoridation Frequently Asked Questions. Infant formula guidance. Source

13. Soleimani H, et al. Occurrence of fluoride in breast milk a worldwide systematic literature review and human health risk assessment by Monte Carlo simulation. Int J Environ Health Res. 2026;36(8):2102–2116. doi:10.1080/09603123.2026.2616406. Source

14. Grandjean P, et al. A benchmark dose analysis for maternal pregnancy urine-fluoride and IQ in children. Risk Anal. 2022;42(3):439–449. doi:10.1111/risa.13767. Source

15. Grandjean P, et al. Dose dependence of prenatal fluoride exposure associations with cognitive performance at school age in three prospective studies. Eur J Public Health. 2024;34(1):143–149. doi:10.1093/eurpub/ckad170. Source