Bone surface and whole bone as biomarkers for acute fluoride exposure.

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.

Nail and bone surface as biomarkers for acute fluoride exposure in rats.

When acute exposure to fluoride is thought to be the cause of death, confirmation often depends on the analysis of some body fluid or tissue. The aim of this study was to evaluate the use of nails and the periosteal surface of bone as indicators of acute exposure to fluoride. Six groups of rats were given a single oral dose of fluoride (50 mg/kg body weight), while the control group was given deionized water. The rats were killed at 2, 4, 8, 16, 24, and 48 h after fluoride administration. Plasma and nails (the proximal halves) were collected and analyzed for fluoride with an ion-specific electrode after hexamethyldisiloxane-facilitated diffusion. A circular area of the femur (4.52 mm(2)) was etched with 0.5M HCl for 15 s, and, after the addition of a buffer, the solution was analyzed with an ion-specific electrode. Peak plasma concentration occurred at 2 h, followed by progressively declining concentrations. Peak nail fluoride concentrations occurred at 8 h. The mean nail concentrations at 8, 16, and 24 h were significantly higher than that of the control group. Bone surface concentrations were significantly higher than that of the control group at 4 h and thereafter. Thus, the proximal portion of nails and bone surface are suitable biomarkers for acute fluoride exposure in rats.