Consistent with in vitro and animal research, studies of human populations have reported associations between fluoride exposure and damage to the male reproductive system. Most notably, a scientist at the Food & Drug Administration reported in 1994 that populations in the United States with more than 3 ppm fluoride in their water had lower “total fertility rates” than populations with lower fluoride levels. (Freni 1994). While 3 ppm is a higher concentration than used in water fluoridation programs (0.7 to 1.2 ppm), it is still considered a “safe” level by the EPA. According to the study:
“A review of fluoride toxicity showed decreased fertility in most animal species studied. The current study was to see whether fluoride would also affect human birth rates. A U.S. database of drinking water systems was used to identify index counties with water systems reporting fluoride levels of at least 3 ppm. These and adjacent counties were grouped in 30 regions spread over 9 states… Most regions showed an association of decreasing TFR [Total Fertility Rate] with increasing fluoride levels. Meta-analysis of the region-specific results confirmed that the combined result was a negative TFR/fluoride association with a consensus combined p value of .0002-.0004, depending on the analytical scenario. There is no evidence that this outcome resulted from selection bias, inaccurate data, or improper analytical methods. However, the study is one that used population means rather than data on individual women. Whether or not the fluoride effect on the fertility rate found at the county level also applies to individual women remains to be investigated.”
SOURCE: Freni SC. (1994). Exposure to high fluoride concentrations in drinking water is associated with decreased birth rates. Journal of Toxicology and Environmental Health 42:109-121.
To date, no U.S. health agency has attempted to replicate Freni’s findings. However, three studies of highly fluoride-exposed populations in China and India have reported that high fluoride exposure is associated with reduced male fertility. (Peizhong 1997; Hongde 1988; Neelam 1987). The Fluoride Action Network discovered the Peizhong and Hongde studies in 2012, and thus, when the U.S. National Research Council reviewed fluoride’s reproductive toxicity in 2006, it was not aware of these findings.
In addition to the fertility, five studies from China, India, Mexico, and Russia.have found that high-fluoride exposure is associated with reduced male testosterone levels, (Hao 2010; Ortiz 2003; Susheela 1996; Michael 1996; Tokar 1977), while a preliminary study of fluoride-exposed aluminum workers in Russia found associations between fluoride and damaged sperm. These studies are cited below.
Human Studies on Fluoride & Male Reproductive System
“OBJECTIVE: To study of endocrine disturbing effect of fluoride on human hypothalamus-hypophysis-testis axis hormones. METHODS: Sunying County, Kaifeng City was selected as polluted district which the fluoride in drinking water was 3.89 mg/L, and Shenlilou county was selected as control district which the fluoride was less than 1.0 mg/L. 150 individual lived there more than 5 years were selected randomly.
. . .RESULTS: There was no significant difference of serum level of [gonadotropin-releasing hormone] between fluoride polluted district and control district (P > 0.05). The serum level of [luteinizing hormone] in men of fluoride polluted district was significantly higher than that of control group (P < 0.05), and the serum level of [testosterone] in men of fluoride polluted district was significantly less than that of control group (P < 0.05). There was no significant difference of serum level of [luteinizing hormone] between fluoride polluted district and control district (P > 0.05), and the serum level of [testosterone] in women of fluoride polluted district was significantly higher than that of control group (P < 0.05). There was no significant difference of serum level of [estradiol] between fluoride polluted district and control district (P > 0.05). CONCLUSION: Fluoride could effect hormone levels of each layer of the hypothalamus-hypophysis-testis axis, and show the reproductive endocrine disturbing effects. The reproductive endocrine disturbing effects of male may be more severe than those of female.”
SOURCE: Hao P, et al. (2010). [Effect of fluoride on human hypothalamus-hypophysis-testis axis hormones]. [Article in Chinese]. Wei Sheng Yan Jiu. 39(1):53-5.
“Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3-27 mg/day (high-fluoride-exposed group-HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2-13 mg/day (low-fluoride-exposed group-LFEG). A significant increase in FSH (P< 0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P< 0.05) were noticed in the HFEG. When HFEG was compared to LFEG, a decreased sensitivity was found in the FSH response to inhibin-B (P< 0.05). A significant negative partial correlation was observed between urinary fluoride and serum levels of inhibin-B (r=-0.333, P=0.028) in LFEG. Furthermore, a significant partial correlation was observed between a chronic exposure index for fluoride and the serum concentrations of inhibin-B (r=-0.163, P=0.037) in HFEG. No abnormalities were found in the semen parameters studied in the present work, neither in the HFEG, nor in the LFEG. The results obtained indicate that a fluoride exposure of 3-27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs.”
SOURCE: Ortiz-Perez D, et al. (2003). Fluoride-induced disruption of reproductive hormones in men. Environmental Research 93:20-30.
“In order to explore the effects of excess fluoride on reproductive function of male adults, a research was conducted in 31 male adults from a hyperfluoride area and 26 subjects in normal area as control in present study. The results showed that the levels of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were markedly increased (P 0.001) for subjects in the hyperfluoride area; and that the serum level of testosterone(T) was significantly decreased (P 0.01 ) by comparing with control group. This indicated that hyperfluoride condition may affect the function of reproduction-endocrine system of male human body.”
SOURCE: Chen P, et al. (1997). Effects of hyperfluoride on reproduction-endocrine system of male adults. Endemic Diseases Bulletin 12(2):57-58. [See study]
“OBJECTIVE: The present study focuses on serum testosterone concentrations in patients with skeletal fluorosis, in order to assess the hormonal status in fluoride toxicity. METHODS: Serum testosterones were compared for patients afflicted with skeletal fluorosis (n = 30) and healthy males consuming water containing less than 1 ppm fluoride (Control 1, n = 26) and a second category of controls (Control 2, n = 16): individuals living in the same house as the patients and consuming same water as patients but not exhibiting clinical manifestations of skeletal fluorosis. RESULTS: Circulating serum testosterones in skeletal fluorosis patients were significantly lower than those of Control 1 at p < 0.01.Testosterone concentrations of Control 2 were also lower than those of Control 1 at p < 0.05 but were higher than those of the patient group. CONCLUSIONS: Decreased testosterone concentrations in skeletal fluorosis patients and in males drinking the same water as the patients but with no clinical manifestations of the disease compared with those of normal, healthy males living in areas nonendemic for fluorosissuggest that fluoride toxicity may cause adverse effects in the reproductive system of males living in fluorosis endemic areas.”
SOURCE: Susheela AK, Jethanandani P. (1996). Circulating testosterone levels in skeletal fluorosis patients. Journal of Toxicology and Clinical Toxicology 34(2):183-9.
“The present study was undertaken to investigate the various health problems caused by water-borne fluoride in endemic villages of Mehsana and Banaskantha districts of Gujarat. The study revealed high levels of fluoride in serum samples of the villagers. Mottling of teeth and skeletal complications were common. . . . Circulating levels of testosterone were decreased, but not significantly enough to indicate an effect on reproductive functions.” [NOTE: This study appears to have combined the data for both males and females, which makes it more difficult to discern an effect of fluoride on testosterone levels in men.]
SOURCE: Michael M, et al. (1996). Investigations of soft tissue functions in fluorotic individuals. Fluoride 29:63-71.
“A review of fluoride toxicity showed decreased fertility in most animal species studied. The current study was to see whether fluoride would also affect human birth rates. A U.S. database of drinking water systems was used to identify index counties with water systems reporting fluoride levels of at least 3 ppm. These and adjacent counties were grouped in 30 regions spread over 9 states… Most regions showed an association of decreasing TFR [Total Fertility Rate] with increasing fluoride levels. Meta-analysis of the region-specific results confirmed that the combined result was a negative TFR/fluoride association with a consensus combined p value of .0002-.0004, depending on the analytical scenario. There is no evidence that this outcome resulted from selection bias, inaccurate data, or improper analytical methods. However, the study is one that used population means rather than data on individual women. Whether or not the fluoride effect on the fertility rate found at the county level also applies to individual women remains to be investigated.”
SOURCE: Freni SC. (1994). Exposure to high fluoride concentrations in drinking water is associated with decreased birth rates. Journal of Toxicology and Environmental Health 42:109-121.
“A survey was made on fluoride contents in drinking water, mattled enamel, bone fluorosis, fluoride concentration in human spermatic fluid, and male infertility in fluoric area in Xinjiang Province. Is suggested that the fluorosis may be associated with human male infertility in fluoric areas.”
SOURCE: Liu H, et al. (1988). Analysis of the effect of fluoride on male infertility in regions with reported high level of fluoride (endemic fluorosis). Journal of the Medical Institute of Suzhou 8(4):297-99.
Married men in an endemic fluorosis area in India (with water fluoride levels ranging up to 38.5 ppm) are found to have higher rates of infertility than men from a non-fluorosis area.
SOURCE: Neelam, K, et al. (1987). Incidence of prevalence of infertility among married male members of endemic fluorosis district of Andhra Pradesh. In: Abstract Proc Conf Int Soc for Fluoride Res. Nyon, Switzerland.
“Preliminary studies in human subjects suffering from industrial fluorosis reported azoospermia and oligospermia, which may have been due to hypogonadism.”
SOURCE: Chinoy NJ, Narayana MV. (1994). In vitro fluoride toxicity in human spermatozoa. Reprod Toxicol. 8(2):155-9 (citing Tarinsky AP. (1972). The influence of some industrial factors of aluminum industry on generative function of men. PhD Thesis, Sverdlovsk).
“The radioimmunological method was applied to the study of blood testosterone, LH, and FSH content in 41 men suffering from fluorosis, aged from 33 to 45 years. Nineteen men who had no contact with fluorine compounds served as control. In comparison with healthy individuals testosterone content proved to be decreased and FSH content elevated in patients with fluorosis. Blood LH content was increased only in those patients with fluorosis who had long contact with fluorine compounds (over 15 years). The changes in the blood hormone concentration were connected with disturbances of the hormonal, and, possibly, of the germenative function of the testes. The hypophysis proved to suffer less, and the changes of its function were apparently secondary in character.”
SOURCE: Tokar VI, Savchenko ON. (1977). Effect of inorganic fluorine compounds on the functional state of the pituitary-testis system. Probl Endokrinol(Mosk). 23(4):104-7.
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