Bone Surface and Whole Bone as Biomarkers for Acute Fluoride Exposure

Abstract

This study compares fluoride concentrations ([F]) in surface and whole bone for up to 27 days following an acute oral dose of F. Four groups of rats received single oral F dose (50 mg/kg body weight), and the control group received deionized water (n = 10/group). Groups were euthanized at 1, 3, 9, or 27 days after F administration. Plasma and femurs were collected. F on the femur surface was removed from a circular area (4.52 mm(2)) by immersion in 0.5M HCl for 15 s. The solution was buffered with total ionic strength adjustment buffer and analyzed with an electrode. The subjacent bone was sectioned and ashed at 600 degrees C. Ash and plasma were analyzed for F with the electrode following hexamethyldisiloxane-facilitated diffusion. Data were analyzed by Kruskall-Wallis and Dunn's test and by linear regression (p < 0.05). Peak plasma and bone surface [F] occurred on day 1 (0.26 +/- 0.14 microg/mL and 1801 +/- 888 microg/g, respectively). Bone surface [F] at 3, 9, and 27 were not statistically different from control. A significant increase in whole bone [F] was observed 3 days after F administration and the [F] remained relatively constant thereafter. The mean (+/- SD) surface/whole bone [F] ratios for the control and F groups were 2.45 +/- 0.98, 3.92 +/- 1.32, 1.61 +/- 0.82, 1.73 +/- 0.39, and 1.09 +/- 0.28, respectively. Plasma and bone surface [F]s were positively correlated (r = 0.74). Thus, bone surface was found to be a suitable biomarker for acute, sublethal F exposure 1 day after F administration. Whole bone [F] were significantly increased at 3, 9, and 27 days after F administration.

Alkaline phosphatase activity in plasma and liver of rats submitted to chronic exposure to fluoride

“…Additionally, fluoride might have systemic toxic effects in other tissues when ingested in levels higher than optimal (Buzalaf et al, 2004;Buzalaf et al, 2005;Leite et al, 2008;Kobayashi et al, 2009). Plasma is an important indicator of fluoride levels in the body in both acute (Buzalaf et al, 2004;Pessan et al, 2005) and chronic (Carvalho et al, 2006) exposures.…”

“…Throughout the experimental period, the animals were kept in the cages receiving the food and water ad libitum. The food used was AIN-93 (Reeves et al, 1993) with low fluoride concentration (< 2 ppm), since in previous reports it was observed that the commercial diets might have high fluoride concentrations (Buzalaf et al, 2004;Buzalaf et al, 2005;Carvalho et al, 2006), which could affect the results.…”

Fluoride Toxicity in Animals

“…It was observed that F from sodium fluoride or disodium mono-fluorophosphate was absorbed up to 100 % when ingested along with water in a fasting state. However, a decrease in F absorption by 20-30 % occurs when they are ingested along with milk or baby formula (Whitford 2005). In simple-stomach animals, high protein in the diet favors F absorption by stimulating gastric acidity.…”

Differential Effects of Fluoride During Osteoblasts Mineralization in C57BL/6J and C3H/HeJ Inbred Strains of Mice

“…Fluoride is a trace element that can be incorporated during bone formation and substitutes hydroxyapatite by fluoroapatite [1,2]. The behavior of fluoride ions in biological systems has advantages and problems [3].…”