Fluoride exposure and indicators of thyroid functioning in the Canadian population
Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation
Amanda M Barberio1,2, F Shaun Hosein3, Carlos Quiñonez4, Lindsay McLaren2
Author affiliations
Abstract
Background There are concerns that altered thyroid functioning could be the result of ingesting too much fluoride. Community water fluoridation (CWF) is an important source of fluoride exposure. Our objectives were to examine the association between fluoride exposure and (1) diagnosis of a thyroid condition and (2) indicators of thyroid functioning among a national population-based sample of Canadians.
Methods We analysed data from Cycles 2 and 3 of the Canadian Health Measures Survey (CHMS). Logistic regression was used to assess associations between fluoride from urine and tap water samples and the diagnosis of a thyroid condition. Multinomial logistic regression was used to examine the relationship between fluoride exposure and thyroid-stimulating hormone (TSH) level (low/normal/high). Other available variables permitted additional exploratory analyses among the subset of participants for whom we could discern some fluoride exposure from drinking water and/or dental products.
Results There was no evidence of a relationship between fluoride exposure (from urine and tap water) and the diagnosis of a thyroid condition. There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels. Rerunning the models with the sample constrained to the subset of participants for whom we could discern some source(s) of fluoride exposure from drinking water and/or dental products revealed no significant associations.
Conclusion These analyses suggest that, at the population level, fluoride exposure is not associated with impaired thyroid functioning in a time and place where multiple sources of fluoride exposure, including CWF, exist........
..............Since Peckham et al (2015)13 was the first population-level study to examine the relationship between CWF and thyroid problems (in particular, hypothyroidism), additional research is required to determine if these findings are consistent across different contexts, and when individual-level biomarkers of fluoride exposure are used.
The present study utilised high-quality Canadian survey data from a national population-based sample that includes individual-level estimates of fluoride exposure from urine and tap water samples, as well as measures of thyroid functioning. Our objectives were to examine the association between fluoride exposure and (1) the diagnosis of a thyroid condition and (2) indicators of thyroid functioning, specifically TSH and free T4 levels, among a population-based sample of Canadians........
Perhaps there is no objective world out there. We see and find what we want to see. Opposing experts examining the same evidence come to opposite conclusions.
Amanda M Barberio1,2, F Shaun Hosein3, Carlos Quiñonez4, Lindsay McLaren2
Author affiliations
Abstract
Background There are concerns that altered thyroid functioning could be the result of ingesting too much fluoride. Community water fluoridation (CWF) is an important source of fluoride exposure. Our objectives were to examine the association between fluoride exposure and (1) diagnosis of a thyroid condition and (2) indicators of thyroid functioning among a national population-based sample of Canadians.
Methods We analysed data from Cycles 2 and 3 of the Canadian Health Measures Survey (CHMS). Logistic regression was used to assess associations between fluoride from urine and tap water samples and the diagnosis of a thyroid condition. Multinomial logistic regression was used to examine the relationship between fluoride exposure and thyroid-stimulating hormone (TSH) level (low/normal/high). Other available variables permitted additional exploratory analyses among the subset of participants for whom we could discern some fluoride exposure from drinking water and/or dental products.
Results There was no evidence of a relationship between fluoride exposure (from urine and tap water) and the diagnosis of a thyroid condition. There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels. Rerunning the models with the sample constrained to the subset of participants for whom we could discern some source(s) of fluoride exposure from drinking water and/or dental products revealed no significant associations.
Conclusion These analyses suggest that, at the population level, fluoride exposure is not associated with impaired thyroid functioning in a time and place where multiple sources of fluoride exposure, including CWF, exist........
..............Since Peckham et al (2015)13 was the first population-level study to examine the relationship between CWF and thyroid problems (in particular, hypothyroidism), additional research is required to determine if these findings are consistent across different contexts, and when individual-level biomarkers of fluoride exposure are used.
The present study utilised high-quality Canadian survey data from a national population-based sample that includes individual-level estimates of fluoride exposure from urine and tap water samples, as well as measures of thyroid functioning. Our objectives were to examine the association between fluoride exposure and (1) the diagnosis of a thyroid condition and (2) indicators of thyroid functioning, specifically TSH and free T4 levels, among a population-based sample of Canadians........
Perhaps there is no objective world out there. We see and find what we want to see. Opposing experts examining the same evidence come to opposite conclusions.
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