Environmental and Individual Factors Associated with Nail Fluoride Concentration

Abstract

Nails have been suggested as suitable biomarkers of exposure to F, with the advantage of being easily obtained. The effect of water F concentration, age, gender, nail growth rate and geographical area on the F concentration in the fingernail and toenail clippings were evaluated. Volunteers (n = 300) aged 3–7, 14–20, 30–40 and 50–60 years from five Brazilian communities (A–E) participated. Drinking water and nail samples were collected and F concentration was analyzed with the electrode. A reference mark was made on each nail and growth rates were calculated. Data were analyzed by ANOVA and linear regression (α = 0.05). Mean water F concentrations (± SE, mg/l) were 0.09 ± 0.01, 0.15 ± 0.01, 0.66 ± 0.01, 0.72 ± 0.02, and 1.68 ± 0.08 for A–E, respectively. Mean F concentrations (± SE, mg/kg) ranged between 1.38 ± 0.14 (A, 50–60 years) and 10.20 ± 2.35 (D, 50–60 years) for fingernails, and between 0.92 ± 0.08 (A, 14–20 years) and 7.35 ± 0.80 (E, 50–60 years) for toenails. Among the tested factors, geographical area and water F concentration exerted the most influence on finger- and toenail F concentrations. Subjects of older age groups (30–40 and 50–60 years) from D and E showed higher nail F concentrations than the others. Females presented higher nail F concentration than males. Water F concentration, age, gender and geographical area influenced the F concentration of finger- and toenails, and hence should be taken into account when using this biomarker of exposure to predict risk for dental fluorosis.

Validation of Fingernail Fluoride Concentration as a Predictor of Risk for Dental Fluorosis

“…However, this occurs at the long term, i.e. it is possible to see a significant increase in nail fluoride concentration of 3-to 7-year-old children compared with 30-to 40-year-old or 50-to 60-year-old volunteers, but not with 14-to 20-year-old volunteers [Fukushima et al, 2009]. Thus, it is unlikely that this small variation in the age range of the volunteers (2-3 vs. 6-7 years of age) might have influenced the results of this study.…”

“…It is important to mention that there was a small variation in the age range of the volunteers included in the present investigation (2-7 years) ( table 1 ), since they were recruited among participants of previous studies with different designs. It has been shown that nail fluoride concentration is expected to increase with age [Fukushima et al, 2009] as a conse- quence of an increase in plasma fluoride concentration [Buzalaf and Whitford, 2011] . However, this occurs at the long term, i.e.…”

“…The participants of this study were recruited from among volunteers of previous studies conducted by our research group who had had their fingernail fluoride concentrations evaluated when they were 2-7 years [Whitford et al, 1999;Correa Rodrigues et al, 2004;Pessan et al, 2005;Fukushima et al, 2009]. This was done because we wanted to relate the fingernail fluoride concentrations that were determined when the teeth were forming to the prevalence and severity of dental fluorosis after the teeth erupted.…”

“…Although the fingernail fluoride concentrations were obtained from previous studies and analyzed in two different laboratories (Bauru Dental School and Georgia Health Sciences University), the analytical method employed was essentially the same, as described in the original publications [Whitford et al, 1999;Correa Rodrigues et al, 2004;Pessan et al, 2005;Fukushima et al, 2009].…”

Factors Associated with Fluoride Concentrations in Whole and Parotid Ductal Saliva

“…As only the absorbed fluoride is implicated in fluorosis development, measurement of total exposure through analysis of body fluids or tissues is more likely to be of value in epidemio- M ean annual temperatures in the communities located in the Northeast region are higher than in those located in the Southeast. In general, residents of B, D and E have monthly incomes similar to each other, but approximately half and one third the income of A and B, respectively (data from Fukushima et al [2009]). …”