38 l © 2025 American Dental Association
Section 2: Safety
possible secondary health effects caused by fluorides consumed at optimal concentrations throughout
life has been the object of thorough medical investigations that have failed to show any impairment
of general health throughout life.27–45
According to the British Fluoridation Society, as of 2020, approximately 380
million people in 25 countries worldwide were supplied with water fluoridated
by adjustment.465
In scientific research, there is no such thing as “final knowledge.” New information is continuously
emerging and being disseminated. Government agencies, such as the US National Institute of Dental
and Craniofacial Research (NIDCR), along with other institutes of the National Institutes of Health
(NIH), and others continue to fund fluoride research. Two examples are highlighted here:
Fluoride and Neurodevelopmental Effects
One example is the National Toxicology Program’s (NTP) systematic review of the literature concerning
the association between fluoride exposure and neurodevelopmental and cognitive effects and its
efforts to determine the level of confidence in that evidence.192 A National Academies of Science,
Engineering, and Medicine (NASEM) committee reviewed two earlier drafts of a NTP monograph
and concluded that the evidence did not support their conclusion about neurodevelopmental effects.
Therefore, the NTP monograph removed the neurodevelopmental hazard statement. The monograph
found an association between high fluoride concentrations and lower IQ in children however, these
findings were based on exposures exceeding WHO guidelines (1.5 mg/L) and are not relevant to
US fluoridation practices. “The monograph and addendum do not address whether the sole
exposure to fluoride added to drinking water in some countries (i.e., fluoridation, at 0.7
mg/L in the United States and Canada) is associated with a measurable effect on IQ.” The
NTP report found no evidence that fluoride exposure negatively impacts adult cognition. The review
also highlighted limited mechanistic insight because animal studies were of poor quality and human
studies lacked clarity on biological pathways.192
Fluoride and Osteosarcoma
A comprehensive US study led by Harvard University researchers investigated the relationship
between fluoride exposure and malignant bone tumors, analyzing data from nine hospitals
over 8 years (1992–2000) with NIH support. An exploratory 2006 analysis193 suggested a
possible increased risk of osteosarcoma in boys aged 7, but the findings were likely influenced by
methodological limitations, such as fluoride exposure estimation based on climate. A follow-up 2020
analysis194 of the larger dataset found no association between osteosarcoma and fluoride exposure
through community water or other sources. Similarly, a 2011 study195 measuring actual fluoride
levels in bone samples from osteosarcoma patients and controls found no significant differences,
disproving a link between fluoride and bone cancer.
Section 2: Safety
possible secondary health effects caused by fluorides consumed at optimal concentrations throughout
life has been the object of thorough medical investigations that have failed to show any impairment
of general health throughout life.27–45
According to the British Fluoridation Society, as of 2020, approximately 380
million people in 25 countries worldwide were supplied with water fluoridated
by adjustment.465
In scientific research, there is no such thing as “final knowledge.” New information is continuously
emerging and being disseminated. Government agencies, such as the US National Institute of Dental
and Craniofacial Research (NIDCR), along with other institutes of the National Institutes of Health
(NIH), and others continue to fund fluoride research. Two examples are highlighted here:
Fluoride and Neurodevelopmental Effects
One example is the National Toxicology Program’s (NTP) systematic review of the literature concerning
the association between fluoride exposure and neurodevelopmental and cognitive effects and its
efforts to determine the level of confidence in that evidence.192 A National Academies of Science,
Engineering, and Medicine (NASEM) committee reviewed two earlier drafts of a NTP monograph
and concluded that the evidence did not support their conclusion about neurodevelopmental effects.
Therefore, the NTP monograph removed the neurodevelopmental hazard statement. The monograph
found an association between high fluoride concentrations and lower IQ in children however, these
findings were based on exposures exceeding WHO guidelines (1.5 mg/L) and are not relevant to
US fluoridation practices. “The monograph and addendum do not address whether the sole
exposure to fluoride added to drinking water in some countries (i.e., fluoridation, at 0.7
mg/L in the United States and Canada) is associated with a measurable effect on IQ.” The
NTP report found no evidence that fluoride exposure negatively impacts adult cognition. The review
also highlighted limited mechanistic insight because animal studies were of poor quality and human
studies lacked clarity on biological pathways.192
Fluoride and Osteosarcoma
A comprehensive US study led by Harvard University researchers investigated the relationship
between fluoride exposure and malignant bone tumors, analyzing data from nine hospitals
over 8 years (1992–2000) with NIH support. An exploratory 2006 analysis193 suggested a
possible increased risk of osteosarcoma in boys aged 7, but the findings were likely influenced by
methodological limitations, such as fluoride exposure estimation based on climate. A follow-up 2020
analysis194 of the larger dataset found no association between osteosarcoma and fluoride exposure
through community water or other sources. Similarly, a 2011 study195 measuring actual fluoride
levels in bone samples from osteosarcoma patients and controls found no significant differences,
disproving a link between fluoride and bone cancer.
