Fingernail may not be a reliable biomarker of fluoride body burden from dentifrice

Abstract

Fingernail has been suggested as a biomarker of fluoride (F) body burden, but there is no consensus if it would be a reliable indicator of F exposure from dentifrice. Therefore, the present study was conducted to investigate if fingernails would have sensitivity to detect F exposure from dentifrice in young children. Twenty-three 1-3-year-old children living in the city of Piracicaba (0.72 ppm F in water), Brazil, were enrolled in two phases of different F exposure: in phase A (1st to 11th week), they were exposed to the combination of F from diet (solids and liquids) and dentifrice (1,500 µg F/g as MFP), and in phase B (12th to 29th week), only to F from diet (the use of F dentifrice was interrupted). Fingernails were weekly clipped during 35 weeks for F determination. F intake from diet and dentifrice in each phase was also determined. Both analyses were made with ion-specific electrode. F intake (Mean ± SD) was significantly higher (p<0.01) when the children were exposed to F from diet+dentifrice than only to F from diet (0.086 ± 0.032 and 0.040 ± 0.009 mg F/day/kg body weight, respectively). However, F concentrations in nails collected during the whole experimental period of 35 weeks presented great variation with no trend of decreasing after F dentifrice intake interruption. The findings suggest that fingernail may not be a reliable F biomarker of body burden from dentifrice.

Biomarkers of chronic fluoride exposure in groundwater in a highly exposed population

“…The levels of F − in fingernails measured up to 34 mg/Kg in this study are among the highest reported in the literature, which mostly addressed low-F − cases of fluoridated water, salt, milk, and toothpaste exposure (e.g., Whitford et al, 1999; Levy et al, 2004; Pessan et al, 2005; Buzalaf et al, 2006 and 2011; de Almeida et al, 2007; Lima-Arsati et al, 2010). To our best knowledge, no population-based studies are available from regions of endemic exposure linking the F − concentrations in fingernail clippings to EF (or SF).…”

“…Furthermore, once F − is incorporated into nail at growth end, it will be unaffected by more recent F − intake and physiological variables (Whitford, 2005). Fingernail analysis of F − has previously been used to assess low-level exposures in communities with fluoridation of water, tooth paste, salt, and milk use (e.g., Buzalaf et al, 2011; Lima-Arsati et al, 2010; de Almeida et al, 2007; Buzalaf et al, 2006; Pessan et al, 2005; Levy et al, 2004; Whitford et al, 1999), but epidemiological studies that evaluate the suitability and sensitivity of this biomarker in populations with endemic fluorosis are virtually absent.…”

Longitudinal evaluation of fluoride levels in nails of 18–30‐month‐old children that were using toothpastes with 500 and 1100 μg F/g

“…Analysis over time seems to be an important factor for the verification of dose–response because data might vary (Figs and ) and there was one study did not identify the effect of fluoride intake from toothpaste . This suggests that studies comparing different fluoride concentrations must be conducted over time.…”

Fluoride concentration in public water supply: 72 months of analysis

“…However, care must be taken, since excessive exposure to fluoride by water consumption combined with other fluoride sources may result in undesirable effects, such as dental fluorosis (7)(8)(9). To achieve the expected results with this preventive method, a strict control of the process of water fluoridation is required, avoiding the undesirable effects of over-dosage, as well as avoiding underdosage, which does not offer the maximum benefits (2).…”