Hydrogen fluoride effects on plasma membrane composition and ATPase activity in needles of white pine (Pinus strobus) seedlings pretreated with 12 h photoperiod

 Eastern white pine (Pinus strobus L.) seedlings were pretreated with 12 h photoperiod to induce dormancy. Dormant plants were fumigated with 0.5 ppb (0.4 μg m^–3) or 2.0 ppb (1.6 μg m^–3) hydrogen fluoride (HF) for 2 – 28 days. Plasma membranes were isolated from needles of treated and control seedlings to determine their chemical composition and ATPase activity. For all analyses, only those plants which did not show needle necrosis were selected. The amount of plasma membrane phospholipid expressed on a plasma membrane protein basis was higher after 2 days in the 0.5 ppb HF treatment as compared to controls. After 2 days of 2.0 ppb HF treatment as well as after 8 and 28 days of both HF treatments phospholipid to protein ratios in fluoride treated seedlings were lower as compared to control levels. A decrease in sterol levels could be observed after 2 days in both HF treatments. A large increase in the ratio of sterols to proteins was observed in plasma membranes of eastern white pine seedlings treated with 0.5 ppb HF for 28 days. Increased sterol to phospholipid ratios were observed after 8 and 28 days in 0.5 ppb and after 2 and 8 days of 2.0 ppb HF treatment. A decrease in ATPase activity was observed after 8 days with both fluoride treatments. Drastic increase of ATPase activity was observed after 28 days of HF treated plants. Observed changes of sterol and phospholipid levels after only 2 days of fumigation suggest early fluoride effects on plasma membrane composition during plant dormancy. Received: 25 October 1995 / Accepted: 24 May 1996     

Serum and urine ionic fluoride

The present study was undertaken to evaluate the fluoride status in the general healthy population of Barcelona. Serum and urine fluoride ionic concentration was determined in a random sample of 250 subjects (age range 15–90 yr) by the Orion fluoride electrode system to determine the normal range of fluoride in this population. The results obtained show that in the general population of Barcelona, fluoride ionic serum concentration ranges between 1 and 47 μg/L (x = 17.5 ± 9.7 μg/L) and fluoride ionic urine concentration ranges between 156 and 1990 μg/24 h (x = 671 ± 373 μg/24 h). The mean serum fluoride concentration of the younger population was shown to be significantly greater (p < 0.05) than that of the older group. No sex-related difference was found.     

Effects of cortisol and fluoride on ion-transporting ATPase activities in cultured osteoblastlike cells

Summary Na⁺,K⁺-ATPase, HCO ₃ ⁻ -ATPase, Ca²⁺,Mg²⁺,-ATPase, Ca²⁺-ATPase, and alkaline phosphatase activities were measured in cultures of osteoblastlike cells treated with fluoride and cortisol separately and in combinations. Low concentrations of cortisol increased HCO ₃ ⁻ -ATPase (10⁻¹¹ to 10⁻¹⁸ M cortisol) and alkaline phosphatase (10⁻¹¹ to 10⁻⁹ M cortisol) activities, but higher cortisol concentrations reduced these activities. Na⁺,K⁺-ATPase, Ca²⁺,Mg²⁺-ATPase, and Ca²⁺-ATPase activities tended only to be reduced by cortisol. Fluoride (10⁻⁶ and 5×10⁻⁶ M) increased HCO ₃ ⁻ -ATPase and alkaline phosphatase activities, but these activities were similar to controls in the presence of 10⁻⁵ M fluoride. Ca²⁺,Mg²⁺-ATPase activity was decreased and Na⁺,K⁺-ATPase activity was increased as the concentration of fluoride increased (10⁻⁶ to 10⁻⁵ M). Preliminary experiments with fluoride indicated that lower concentrations (10⁻⁷ M) were without effect. Cortisol concentrations of 10⁻⁹ and 10⁻⁸ M were chosen for studies with combinations of cortisol and fluoride because the effects of these concentrations on alkaline phosphatase activity were opposite, i.e. 10⁻⁹ M increased whereas 10⁻⁸ M decreased activity. Fluoride concentrations of 10⁻⁶, 5×10⁻⁶, and 10⁻⁵ M were chosen because a peak of alkaline phosphatase activity occurred at 5×10⁻⁶ M fluoride. Higher (10⁻⁴ M) and lower (10⁻⁷ M) fluoride concentrations were without effect. The effects of combinations of cortisol and fluoride depend on the enzyme activity measured. Fluoride (10⁻⁶ M) combined with cortisol (10⁻⁹ M) produced a peak of Na⁺,K⁺-ATPase activity. The increased activity obtained with all concentrations of fluoride alone was preserved when fluoride was combined with 10⁻⁸ M cortisol, although the activity tended to be reduced at 5×10⁻⁶ and 10⁻⁵ M fluoride. HCO ₃ ⁻ -ATPase activity was increased by fluoride combined with 10⁻⁸ M cortisol and decreased by fluoride combined with 10⁻⁹ M cortisol compared to the activities obtained with fluoride alone. The decrease in Ca²⁺,Mg²⁺-ATPase activity caused by fluoride alone was prevented by 10⁻⁹ and enhanced by 10⁻⁸ M cortisol, although all treatments produced the same activity at 10⁻⁵ M fluoride. Ca²⁺-ATPase activity tended to be increased by combinations of fluoride and cortisol, but significantly so only at 10⁻⁵ M fluoride in combinations with 10⁻⁸ and 10⁻⁹ M cortisol. Alkaline phosphatase activity was increased by fluoride combined with 10⁻⁹ M cortisol and decreased by fluoride combined with 10⁻⁸ M cortisol compared to the activities obtained with fluoride alone. These results suggest that the abilities of bone cells to regulate ion transport (as reflected in their ion-transporting ATPase activities) are modulated by glucocorticoids and fluoride. Inasmuch as these cells may regulate the ionic composition and concentrations of the bone extracellular fluid (ECF) in vivo, the modulation of their activities by cortisol and fluoride may result in altered bone ECF composition. This work was supported by Grant NAG-2-108 from the National Aeronautics and Space Administration, D.C., and Grant PO1 NS15767 from the National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, MD.     

Study on Blood Biochemical Diagnostic Indices for Hepatic Function Biomarkers in Endemic Skeletal Fluorosis

The aim of the study was to determine the relationship of fluoride in drinking water to liver function in individuals living in normal and seven endemic fluorosis areas of Punjab, India. The concentration of fluoride in drinking water of different areas varied from 5.9 to 24.5 mg/L. Study group consisted of 705 patients in the age group between 20 and 60 years (mean age of 39.35 ± 11.27) affected with osteodental fluorosis were compared with 300 age- and sex-matched controls (with mean age of 35.28 ± 8.25 years). Biochemical data was analyzed by one-way analysis of variance (ANOVA) with post hoc Tukey–Kramer and Bonferroni multiple comparison tests. The relationship between hepatic enzymes was calculated by Pearson’s correlation and linear regression. The results revealed significantly (P < 0.001) higher concentration of serum fluoride in patients when compared to control. The mean activities of cyclic adenosine monophosphate (AMP), alkaline phosphatase (ALKP), acid phosphatase (ACP), aspartate aminotransaminase (AST), and alanine aminotransaminase (ALT) were significantly (P < 0.05–0.001) elevated in patients from all fluoride areas. ANOVA with post hoc Turkey–Kramer and Bonferroni multiple comparison test demonstrated a significant (P < 0.0001) variance in the activities of cAMP, ALKP, ACP, AST, and ALT in fluorotic patients, with elevation in water fluoride levels. Maximum elevation of 196.14% (ACP), 99.31% (cyclic adenosine monophosphate; cAMP), 72.08% (ALT), 60.14% (AST), and least 21.35% (ALKP) was recorded in patients exposed to 24.5 mg/L fluoride in drinking water. There was positive correlation between water fluoride, serum fluoride and AST (r = 0.77, 0.91), ALT (r = 0.82, 0.90), ALKP (r = 0.88, 0.97), and ACP (r = 0.74, 0.85). Pearson’s correlation demonstrated highly significant (P < 0.05) positive relationship between water fluoride and cAMP (regression equation: Y = 0.9807 ×+ 22.081 Y = 0.9807 \times + 22.081 , = 0.84; r = 0.92, P < 0.05). The increased levels of transaminases in fluorotic patients suggest alteration in liver functions. The level of alkaline and acid phosphatase was increased during fluoride intoxication which is also an early marker of hepatic cell damage because of its specificity and catalytic activity. The elevated levels of enzymes are reflective of bone disorders, which are characterized by increased osteoblastic activity. There levels increased several times if cellular damage occurs in the liver. The results suggest that fluoride exposure intensifies the activities of hepatic function enzymes in osteofluorosis.     

Urinary Fluoride Reference Values Determined by a Fluoride Ion Selective Electrode

As fluoride has a very short half-life in the body and the major route for fluoride excretion is via the kidney, human exposure is best measured in urine, where the concentration is expected to be highest. The urinary fluoride concentrations of 167 healthy Japanese adults were determined by means of a fluoride ion selective electrode. When the results were corrected for a specific gravity ρ = 1.024 g cm⁻³, the histogram of urinary fluoride concentrations highly skewed toward low values with sharp peakedness (skewness = 1.56, kurtosis = 3.08). The normality of the log-transformed histogram (skewness = 0.12, kurtosis = 0.07) and the straight line on log-probability paper clearly showed a key feature of lognormal distribution of urinary fluoride. A geometric mean (GM) of 613.8 μg/l and 95% confidential interval (CI) of 241.0–1633.1 μg/l were established as reference values for urinary fluoride. The results presented in this study will be useful as guidelines for the biological monitoring of fluoride in normal subjects and individuals at risk of occupational or environmental fluoride exposure.     

Removal of Fluoride and Arsenic by a Hybrid Constructed Wetland System

A pilot‐scale hybrid wetland system was constructed for the removal of fluoride and arsenic from synthetic wastewater. After five months of operation, the fluoride and arsenic removal rate were at the value of 65 % and 90 %, respectively. Through calculation, the accumulation of fluoride in plants only accounted for 1.63 % of the accumulation in substrates, and the accumulation of arsenic in plants accounted for 3.3 % of that in substrates. Both the accumulation of fluoride and arsenic in plants were much higher in roots than that in leaves. And for substrates, the accumulation in the first layer was higher than the second layer. The changes of microbial community in the substrate of the wetland during the operation were also analyzed to investigate the effects of operating condition on the microbial community and to study the role of microorganism on the removal of fluoride and arsenic. The results showed that the relative abundance of Firmicutes reduced, while the relative abundance of Proteobacteria increased, indicating that the fluoride and arsenic in solution had a great influence on the microbial community. Findings of this study suggest that the hybrid constructed wetland system may be a promising process for the removal of fluoride and arsenic from synthetic wastewater.     

Effect of calcium on the absorption and translocation of heavy metals in excised barley roots: Multi-compartment transport box experiment

Summary The effect of Ca on the absorption and translocation of Mn, Zn and Cd in excised barley roots was studied using a multi-compartment transport box technique. A radioisotope (⁵⁴Mn,⁶⁵Zn or^115mCd)-labelled test solution was supplied to the apexes of excised roots and the distribution pattern in the roots was examined in the absence or presence of Ca. Results obtained were as follows. Addition of Ca to the test solution reduced the absorption of Mn and inhibited drastically its translocation in excised roots. With increasing concentrations of Ca in test solutions, its inhibitory effects on the absorption and translocation of Mn became severe. Similar results were observed for the absorption and translocation of Zn. Ca in the test solution decreased the absorption and inhibited drastically the translocation of Zn; as in the case of Mn, higher concentrations of Ca had severe effects on these functions. It was also evident that the addition of Ca to the test solution reduced the absorption of Cd at all levels of Cd concentration (1, 10, and 100 μM). Cd absorption decreased with increasing concentrations of Ca in the test solution. However, Ca accelerated the translocation of Cd in excised roots supplied with test solutions containing up to 10μM Cd. At 100μM Cd, addition of Ca caused a negligibly small acceleration of Cd translocation. The accelerating effect of Ca on Cd translocation, especially “xylem exudation”, decreased markedly with the addition of 2,4-dinitrophenol, but not with the addition of chloramphenicol or p-chloromercuribenzene sulphonic acid. When barley plants were supplied with only CaSO₄ during the entire growing period, that is, plants were not supplied with nutrient solution on the last day of this period, Ca had no accelerating effect on Cd translocation in excised roots.     

Salivary Fluoride Concentrations and Fluoride Ingestion Following Application of Preparations Containing High Concentration of Fluoride

The aim of the study was to assess salivary fluoride concentrations and ingestion of fluorides after five different techniques of topical fluoride treatment. Ten volunteers received applications of fluoride gel, toothpaste, and foam. Fluoride concentrations were determined using ion-selective fluoride electrode in the samples of unstimulated saliva before and after procedures. The amounts of fluoride applied, recovered from the mouth, and retained in the mouth were calculated for each treatment. It was proved that fluoride ingestion following tray application of fluoride foam was significantly lower than ingestion following tray applications of fluoride gel (p < 0.01). The use of limited amounts of fluorides on a tray resulted in similar fluoride retention and lower ingestion comparing to the method which involves a large portion of fluorides followed by rinsing. Tooth brushing resulted in high salivary retention rates per amount of fluorides used in the procedure. These data provide initial concept about the possible advantages of some methods of topical fluoride application over others.     

Effect of sulfur and potassium on zinc absorption by barley

Summary Maximum uptake of Zn in barley (Hordeum vulgare L.) seedlings occurred from nutrient solutions containing SO₄−S at 3.5 ppm and K at 6 ppm. Decreased translocation of Zn from roots to tips was observed when plants were grown with lower levels of S and K. Cysteine substituted for SO₄-ion as a source of S in Zn absorption, and more Zn was absorbed with cysteine than with sulfate. The effect of K on Zn absorption seems to be influenced by S nutrition in plants.     

Hydrogen fluoride effects on plasma membrane composition,ATPase activity and cell structure in needles of eastern white pine (Pinus strobus) seedlings

Eastern white pine (Pinus strobus L.) seedlings were grown in controlled environment growth cabinets and fumigated with 0.4 and 1.6 g m^–3 hydrogen fluoride for 2–28 days. Plasma membranes were isolated from needles of treated and control seedlings and their chemical composition and ATPase activity examined to determine early effects of hydrogen fluoride action. In plants treated for 2 days with both fluoride levels, ratios of plasma membrane free sterols:phospholipids and sterols:proteins were drastically higher than ratios in control plants. Seedlings treated with hydrogen fluoride for 8 days contained plasma membranes with elevated phospholipid:protein and sterol:protein ratios and their plasma membrane ATPase activity was higher than that of control plants. Prolonged, 28-day hydrogen fluoride treatment with 1.6 g m^–3 level was the only treatment which produced a drastic inhibition of plasma membrane ATPase activity. During the initial stages of hydrogen fluoride treatment, treated cells did not show alterations of ultrastructure which were previously shown in cells of plants treated with soil applied sodium fluoride. The results of the present study indicate that the plasma membranes may be among the initial sites of hydrogen fluoride injury to plants as well as initial sites of defense reaction.     

Chromium in a series of Portuguese plants used in the herbal treatment of diabetes

Chromium (Cr³⁺) is an essential micronutrient for humans. Its main action is thought to be the regulation of blood sugar, because chromium deficiency is associated with diabetic-like symptoms, and chromium supplementation is correlated with increased glucose tolerance and insulin sensivity. Some Portuguese aromatic plants are utilized as tisanes by diabetic people as medicinal plants. Their active principle is not yet known, and the importance of their chromium content in the claimed therapeutic properties should not be discarded. Therefore, determination of chromium in some Portuguese medicinal plants was performed by flameless atomic absorption. All the analyzed plants contain chromium at the normal level for this element, but the plants used to prepare tisanes to help diabetic conditions contain higher levels (2.2 μg/g dry wt ±0.88;n=11) than the others (0.88 μg/g dry wt±0.18;n=17).     

Alterations in Electrocardiographic Parameters after Subacute Exposure of Fluoride and Ameliorative Action of Aluminium Sulphate in Goats

Fluorosis or crippling disease is one of the existing environmental challenges for animal and human beings in most parts of the globe. In the present study, sodium fluoride alone and with aluminium sulphate (ameliorative agent) was administered orally daily for 30 days in healthy goats of group 1 and 2, respectively, to access the effect on the electrocardiogram. All waves of Lead I, Lead II, Lead III, aVR, aVL and aVF in electrocardiographs were recorded before and after 30 days exposure of fluoride. A significant (P < 0.05) increase in P–R, Q–T and S–T intervals were observed in goats of group 1 as compared to their pre treatment values. The T wave duration was also significantly (P < 0.05) prolonged and as a result, bradycardia was observed after subacute exposure of fluoride for 30 days in group 1. But, in group 2, no such changes were observed. On the basis of results, it may be concluded that subacute toxicity of fluoride produces significant changes in different waves of electrocardiogram and aluminium sulphate has ameliorative efficacy.     

Gastrointestinal Absorption and Renal Excretion of Fluoride After Ingestion of a High-Fluoride Dentifrice

This study aimed to evaluate the gastrointestinal absorption and renal excretion of fluoride after the ingestion of high-fluoride dentifrice. Twelve volunteers participated in this in vivo, crossover, and blinded study. In three experimental phases, the volunteers were randomly assigned to one of three treatment groups, who ingested either the following: distilled and deionized water (control), conventional dentifrice (1100 μg/g), or high-fluoride dentifrice (5000 μg/g). Both dentifrices contained fluoride in the form of NaF/SiO₂. To determine the rate of fluoride absorption, non-stimulated saliva was collected for up to 120 min after ingestion and the area under the curve of the salivary fluoride concentration was plotted as a function of time and the maximum concentration determined. All urine produced during the 24 h before and after ingestion was collected, and urinary excretion was calculated from the difference between the urinary fluoride concentrations in the two periods. A specific ion electrode coupled to an ion analyzer was used to measure fluoride concentrations. Statistical analysis was performed by ANOVA followed by Tukey’s test with p set at 5%. All measured parameters were highest after the ingestion of the dentifrice with 5000 μg/g (p < 0.001), confirming that this has an increased level of bioavailable fluoride compared with the conventional dentifrice. The high-fluoride dentifrice increases the concentration of salivary fluoride, which may explain its greater anticaries effect. However, it poses a potential risk of causing dental fluorosis and so should not be used by children.

     

Effects of Fluoride on Synaptic Membrane Fluidity and PSD-95 Expression Level in Rat Hippocampus

The objective of this study is to investigate the neurotoxicity of drinking water fluorosis on rat hippocampus. Just weaning male Sprague–Dawley rats were randomly divided into four groups and given 15, 30, and 60 mg/L NaF solution and distilled water, respectively, for 9 months. The fluidity of brain synaptic membrane and expression level of postsynaptic density 95 (PSD-95) were tested. Results showed that the fluidity of brain synaptic membrane decreased gradually with increasing of fluoride concentration, and it was significantly decreased (P < 0.05) in moderate-fluoride group compared with control group, and expression level of PSD-95 was significantly decreased (P < 0.01) in moderate-fluoride group when compared with that of control group. These results indicate that decrease of synaptic membrane fluidity and PSD-95 expression level may be the molecular basis of central nervous system damage caused by fluoride intoxication; PSD-95 in CA3 region of hippocampus is probably a target molecule for fluoride.     

Characterization of Chlorophyll–protein Complexes Isolated from Two Marine Green Algae, Bryopsis maxima and Ulva pertusa, Growing in the Intertidal Zone

Three Chl–protein complexes were isolated from thylakoid membranes of Bryopsis maxima and Ulva pertusa, marine green algae that inhabit the intertidal zone of the Pacific Ocean off the eastern coast of Japan by dodecyl-β-d-maltoside polyacrylamide gel electrophoresis. The slowest-moving fractions showed low Chl a/b and Chl/P-700 ratios, indicating that this fraction corresponds to complexes in PS I, which is large in both algae. The intermediate and fastest-moving fractions showed the traits of PS II complexes, with some associated Chl a/b–protein complexes and LHC II, respectively. The spectral properties of the separated Chl–proteins were also determined. The absorption spectra showed a shallow shoulder at 540 nm derived from siphonaxanthin in Bryopsis maxima, but not in Ulva pertusa. The 77 K emission spectra showed a single peak in Bryopsis maxima and two peaks in Ulva pertusa. Besides the excitation spectra indicated that the excitation energy transfer to the PS I complexes differed quite a lot higher plants. This suggested that the mechanisms of energy transfer in both of these algae differ from those of higher plants. Considering the light environment of this coastal area, the large size of the antennae of PS I complexes implies that the antennae are arranged so as to balance light absorption between the two photosystems. In addition, we discuss the relationships among the photosystem stoichiometry, the energy transfer, and the distribution between the two photosystems.     

Fluoride Ingestion After Brushing with a Gel Containing a High Concentration of Fluoride

The aim of the study was to evaluate the amount of fluoride remaining in the oral cavity of children after brushing with fluoride gel (1.25% F). The study involved six groups of 7-year-old and six groups of 11-year-old children. The procedure was carried out according to the manufacturer’s recommendations. Fluoride concentrations were determined using ion-selective fluoride electrode. No statistically significant difference was found between the amount of fluorides that remained in the oral cavity of younger and older age group (1.2 and 1.3 mg, respectively; p > 0.05). The amount of fluorides swallowed during the procedure in both age groups proves to be within acceptable limit, as far as risk of acute poisoning symptoms is concerned. The individual daily fluoride exposure during the day of procedure seems to be twice as high compared to average fluoride intake from diet and dentifrice, and it does not exceed Tolerable Upper Intake Level for children more than 8. In younger children, it seems justifiable to reduce the amount of the preparation applied on a toothbrush, especially when daily use of the gel is recommended.     

Removal of fluoride contamination in water by three aquatic plants

Phytoremediation, popularly known as ‘green technology’ has been employed in the present investigation to examine the potential of fluoride removal from water by some aquatic plants. Fluoride contamination in drinking water is very much prevalent in different parts of the world including India. Batch studies were conducted using some aquatic plants e.g., Pistia stratiotes, Eichhornia crassipes, and Spirodela polyrhiza which profusely grow in natural water bodies. The experimental data exhibited that all the above three aquatic floating macrophytes could remove fluoride to some relative degree of efficiency corresponding to initial concentration of fluoride 3, 5, 10, 20 mg/l after 10 days exposure time. Result showed that at lower concentration level i.e., 3 mg/L removal efficiency of Pistia stratiotes (19.87%) and Spirodela polyrhiza (19.23%) was found to be better as compared to Eichhornia crassipes (12.71%). Some of the physiological stress induced parameters such as chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, total protein, catalase, and peroxidase were also studied to explore relative damage within the cell. A marginal stress was imparted among all the plants for lower concentration values (3 mg/L), whereas at 20 mg/l, maximum damage was observed.     

Responses of dry weight growth under SO2 stress in an SO2-tolerant plant,Polygonum cuspidatum

The effects of exposure to 0.5–0.7 ppm SO₂ for about one month on the dry weight growth and net photosynthesis ofPolygonum cuspidatum were investigate. Furthermore, the carbon and nitrogen concentrations in each plant organ were measured. The results obtained showed no significant decrease in the total dry weight of SO₂-treated plants in comparison with controls. On the other hand, the leaf area (LA) and/or leaf dry weight of SO₂-treated plants were increased, and the root dry weight (RW) was decreased, in comparison with controls. The leaf carbon assimilation rate (CAR) in SO₂-treated plants was slightly decreased in spite of a clear decrease in net photosynthesis, and the value of (SW+RW)/LA (SW stem dry weight) was decreased in comparison with controls, thus minimizing the reduction in CAR. Furthermore, the ratio of total leaf carbon absorption (leaf area x CAR) to total root nitrogen absorption (root dry weight x nitrogen assimilation rate) in SO₂-treated plants was similar to that in controls. From these results, it can be concluded that an increase in leaf area and/or leaf dry weight and a decrease in root dry weight inP. cuspidatum under SO₂ stress may be induced in order to compensate for the decrease in CAR and to maintain the ratio of total leaf carbon absorption to total root nitrogen absorption in the early stage of vegetative growth.     

Serum Parathyroid Hormone Levels in Chronic Endemic Fluorosis

Endemic waterborne fluorosis is a public health problem in Isparta, a city located in southern Turkey. Fluoride is a cumulative element that increases metabolic turnover of the bone and also affects the homeostasis of bone mineral metabolism. There are number of similarities between the effects of excess parathyroid hormone (PTH) and fluorosis on bone. So fluoride might show its effect via PTH. We aimed to determine PTH levels in patients with endemic fluorosis to estimate the possible toxic effects of chronic fluoride intake. Fifty-six patients with endemic fluorosis and 28 age-, sex-, and body-mass-index-matched healthy controls were included in this study. Endemic fluorosis was diagnosed according to the clinical diagnosis criteria of Wang. The urine fluoride levels of fluorosis patients were significantly higher than those of control subjects as expected (1.9 ± 0.1 vs. 0.4 ± 0.1 mg/L, respectively; P < 0.001). PTH levels in fluorosis group were significantly higher than control group (65.09 ± 32.91 versus 47.40 ± 20.37, respectively; P = 0.01). The results of our study demonstrate that serum PTH levels are increased in patients with endemic fluorosis. Fluoride, by interfering calcium balance, may be the cause of secondary hyperparathyroidism.     

Teeth of the red fox <Emphasis Type="Italic">Vulpes vulpes</Emphasis> (L., 1758) as a bioindicator in studies on fluoride pollution

An examination was made of fluoride content in the mandibular first molars of the permanent teeth of the red fox Vulpes vulpes living in north-west (NW) Poland. The teeth were first dried to a constant weight at 105°C and then ashed. Fluorides were determined potentiometrically, and their concentrations were expressed in dry weight (DW) and ash. The results were used to perform an indirect estimation of fluoride pollution in the examined region of Poland. The collected specimens (n = 35) were classified into one of the three age categories: immature (im, 6–12 months), subadult (subad, from 12 to 20 months) and adult (ad, >20 months). The mean concentrations (geometric mean) of fluoride were similar in the im and subad groups (230 and 296 mg/kg DW and 297 and 385 mg/kg ash, respectively), and significantly smaller than in the ad group (504 and 654 mg/kg, respectively, in DW and ash). Basing on other reports that the ∼400 mg/kg DW concentration of fluoride in bones in the long-lived wild mammals generally reflects the geochemical background, it was found that 57% of the foxes in NW Poland exceeded this value by 9% to 170%. This indirectly reflects a moderate fluoride contamination in the tested region.