Dermal absorption and skin damage following hydrofluoric acid exposure in an ex vivo human skin model.

The wide industrial use of hydrofluoric acid (HF) poses a high risk for accidental dermal exposure. Despite local and systemic hazards associated with HF, information on percutaneous penetration and tissue damage is rare. In the present ex vivo study, the dermal absorption of HF (detected in terms of fluoride ions) was quantified and the skin damaging potential as a function of concentration and exposure duration was assessed. Percutaneous penetration of HF (c=5, 30, and 50%) at 3 exposure durations (3, 5, and 10 min) was investigated in a static diffusion cell model using freshly excised human skin. Alterations of skin were histologically evaluated. HF rapidly penetrated through skin under formation of a considerable intradermal reservoir (∼ 13-67% of total absorbed fluoride). Histologically, epidermal alterations were detected already after exposure to 5% HF for 3 min. The degree of skin damage increased with rising concentration and exposure duration leading to coagulation necrosis. For HF concentrations of ≥ 30%, skin damage progressed into deeper skin layers. Topically applied HF concentration was the principal parameter determining HF induced skin effects. The intradermal HF retention capacity associated with progression and prolongation of HF induced skin effects must be considered in the review of skin decontamination procedures.

Fluoride metabolism.

Knowledge of all aspects of fluoride metabolism is essential for comprehending the biological effects of this ion in humans as well as to drive the prevention (and treatment) of fluoride toxicity. Several aspects of fluoride metabolism - including gastric absorption, distribution and renal excretion - are pH-dependent because the coefficient of permeability of lipid bilayer membranes to hydrogen fluoride (HF) is 1 million times higher than that of F(-). This means that fluoride readily crosses cell membranes as HF, in response to a pH gradient between adjacent body fluid compartments. After ingestion, plasma fluoride levels increase rapidly due to the rapid absorption from the stomach, an event that is pH-dependent and distinguishes fluoride from other halogens and most other substances. The majority of fluoride not absorbed from the stomach will be absorbed from the small intestine. In this case, absorption is not pH-dependent. Fluoride not absorbed will be excreted in feces. Peak plasma fluoride concentrations are reached within 20-60 min following ingestion. The levels start declining thereafter due to two main reasons: uptake in calcified tissues and excretion in urine. Plasma fluoride levels are not homeostatically regulated and vary according to the levels of intake, deposition in hard tissues and excretion of fluoride. Many factors can modify the metabolism and effects of fluoride in the organism, such as chronic and acute acid-base disturbances, hematocrit, altitude, physical activity, circadian rhythm and hormones, nutritional status, diet, and genetic predisposition. These will be discussed in detail in this review.

Hygroscopic properties of the workroom aerosol in aluminium smelter potrooms: a case for transport of HF and SO2 into the lower airways.

The hygroscopic behaviour of individual aerosol particles from workplaces in a primary aluminium smelter was investigated by environmental scanning electron microscopy. At a high relative humidity, comparable with the human respiratory tract, most particles encountered in the Søderberg and Prebake potrooms either undergo partial deliquescence (leading to a water droplet with an insoluble core) or form thin water films at the surface. As gaseous HF and SO(2) are highly soluble in water, the aerosol particles may act as carrier for these two gases into the alveolar region of the lower respiratory tract. Based on a one-dimensional mass balance model, it is estimated that under peak exposure conditions (particle surface area concentration of 10(-4) cm(2) cm(-3)) approximately 10% of the initial gaseous HF may be transferred to the particle phase. For SO(2), this fraction is much lower (approximately 1%). These results indicate that at least HF may penetrate deeper into the lung in the presence of soluble particles or particles that form surface water films compared to HF alone.

Analysis of hydrofluoric acid penetration and decontamination of the eye by means of time-resolved optical coherence tomography.

So far the study of chemical burns has lacked techniques to define penetration kinetics and the effects of decontamination within biological structures. In this study, we aim to demonstrate that high-resolution optical coherence tomography (HR-OCT) can close this gap. Rabbit corneas were exposed ex vivo to 2.5% hydrofluoric acid (HF) solution, and microstructural changes were monitored in the time domain by OCT imaging. HF application and penetration resulted in shrinkage of the corneal thickness, interpreted as a result of osmolar changes and of loss of water-binding capacity, and a substantial increase in OCT signal amplitudes. The effectiveness of different rinsing solutions on the chemical burn was also evaluated. With tap water and with 1% calcium gluconate, the deep corneal stroma remained clear until the end of the rinsing period but became opaque afterwards. With Hexafluorine, the cornea remained clear for 60 min after rinsing ceased. We conclude that HR-OCT can assist in the clinical evaluation of an ex vivo eye irritation test, and that decontamination of an HF burn using Hexafluorine is efficient.

The tissue distribution of fluoride in a fatal case of self-poisoning.

The purpose of this paper is to report a case of fluoride poisoning along with a discussion of poisoning characteristics, analytical procedures, and a review of previous reports of fatal intoxications with analytical data. A case of suicidal ingestion of 40 mL of a rust removal agent containing hydrofluoric acid and ammonium fluoride by a 33-year-old white male is presented. He had an organic personality disorder with residual schizophrenia and previous suicide attempts with therapeutic drugs and cleaning products. At admission, he presented with a Glasgow coma score of 3, third degree atrioventricular block, and asystole. Resuscitation efforts were performed during which the patient suffered two episodes of ventricular fibrillation followed by asystole. In spite of advanced resuscitation efforts and the administration of calcium chloride, he died 2.5 h after the ingestion. Analytical data in the hospital showed calcium levels of 3.1 mg/dL and metabolic acidosis. Internal findings were erosive gastritis, brain edema, and pulmonary and hepatic congestion. Quantitation of fluoride was performed using an ion-selective electrode for the anion. Disposition of fluoride in the different tissues was as follows: peripheral blood, 19.4 mg/L; urine, 670 mg/L; vitreous humor, 2.5 mg/L; liver, 40.0 mg/kg; kidney, 60.0 mg/kg; lung, 17.5 mg/kg; brain, 2.5 mg/kg; spleen, 30.0 mg/kg; bone, 0.5 mg/ kg; and gastric content, 1120 mg/L (67 mg total). Validation of the analytical method was performed using different spiked tissues, in a range of concentrations from 2.4 to 475 mg/L or mg/kg, and submitting them to dilution (1:25) to avoid the matrix effect and to bring these concentrations to the range of the aqueous calibration curve (0.19-19 mg/L). Limits of detection and quantitation were 0.02 and 0.1 mg/L, respectively. The linearity of the method, for all studies tissues, was excellent, with r(2) values of 0.999. Accuracy and precision were within 10.5% and 5.7%, respectively. Fluoride analyses using the ion selective electrode are simple, sensitive, and rapid. This report provides an extensive tissue distribution study of fluoride after a well documented case of acute poisoning. Based on the autopsy findings, patient history, toxicology results, and previously reported data the forensic pathologists ruled that the cause of death was due to a fluoride poisoning, and the manner of death was listed as suicide.

A fatality due to ingestion of hydrofluoric acid.

We report a fatal case of hydrofluoric acid (HF) ingestion with suicidal intent. Quantitation using an ion-selective electrode for fluoride in fresh bile, gastric contents, kidney, liver, skeletal muscle, urine, and vitreous humor yielded 6.5, 39.0, 10.0, 6.0, 4.5, 5.0, and 4.5 ppm, respectively. In addition to the unfixed specimens, fluoride ion was measured in the following fixed tissue: brain, heart, kidney, liver, pancreas, stomach, and heart. Tissues were measured directly and/or by using the technique of standard addition. Fluoride concentrations using either method were found to be comparable. Fluoride concentration in fresh tissue was consistent with toxicity, although the urine fluoride concentration was in the range observed for asymptomatic workers exposed to fluoride in air. Fixed tissue preparations revealed fluoride concentrations consistent with nonexposure, whereas examination of the formalin fixative revealed fluoride concentrations only slightly higher than negative control formalin. We conclude that fixed tissues are inappropriate for fluoride determination. This is the first case we are aware of that provides fluoride concentrations in skeletal muscle in a fatality involving HF ingestion.

Restauración directa con resina compuesta sobre resina compuesta antigua / No disponible

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Short-term effects of hydrogen fluoride on Nicotiana tabacum L.

Data on the short-term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.

Effect of different exposure compounds on urinary kinetics of aluminium and fluoride in industrially exposed workers.

OBJECTIVE: To conduct a field study to obtain information on the urinary concentrations of aluminium (Al) and fluoride (F-) depending on the different compounds exposed to in the aluminum industry. METHODS: 16 workers from one plant that produced aluminium fluoride (AlF3), and from two plants that produced aluminium electrolytically by two different processes participated in the study for one working week. Pollutants were monitored by eight hour personal sampling every day, and urine samples were collected during the week. Al and F- were analysed in both atmospheric and urine samples by atomic absorption spectrometry and an ion selective electrode. RESULTS: The principal results show different characteristics of kinetic curves of Al and F- excretion in workers with different exposures. Some characteristics of excretory peaks were linked to specific exposures--for instance, after exposure to AlF3 there was one delayed Al peak associated with one delayed F- peak about eight hours after the end of the daily shift, and after mixed exposure to HF and AlF3, two F- peaks were noted, one fast peak at the end of the shift and another delayed peak at 10 hours synchronised with an Al peak. In one of the electrolysis plants, the exposure to Al and F- compounds led to the simultaneous excretion of Al and F- peaks, either as a single peak or two individual ones depending on the type of technology used on site (open or enclosed potlines). The average estimated half life of Al was 7.5 hours, and of F- about nine hours. Quantitative relations between excretion and exposure showed an association between the F- atmospheric limit value of 2.5 mg/m3 with a urinary F- concentration of 6.4 mg/g creatinine at the end of the shift, a peak of 7.4 mg/g creatinine, and 7.4 mg excreted a day. For Al, the exposure to 1.36 mg/m3 during the shift corresponded to a urinary concentration at the end of the shift of 200 microgram/g creatinine. Daily excretion of 200 micrograms corresponded to an exposure to 0.28 mg/m3. CONCLUSION: Particular differences in the behaviour of Al and F- in urine depended upon the original molecular form in the pollutant. These results reinforce the principle that, in biological monitoring, the sampling strategy and the choice of limit value should be dependent on kinetic data that take the exposure compound of the element in question into account.

Elemental analysis of hair among hydrofluoric acid exposed workers.

The concentrations of fluorine (F), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), phosphorus (P), calcium (Ca), iron (Fe), nickel (Ni), zinc (Zn) and iodine (I) in the hair of 142 hydrofluoric acid (HF) exposed workers and 273 control subjects were analyzed by wavelength dispersive X-ray fluorescence spectrometry. Postshift urine and serum specimens were also collected for the determination of fluoride. To determine whether external contamination influences hair analysis, the control hair samples were kept in the work environment for one week. With the exception of lower K and Fe values, the levels of F and other elements in the hair of HF workers were higher than in the control subjects. The concentrations of F in hair and in postshift urine were in good correlation (r = 0.65). In the hair of HF workers F and Ca, F and Mg, F and P, F and Al were well correlated with each other (r greater than 0.6). F concentration in the hair increased after the sample was retained, however, it decreased to the reference value after washing. The levels of Ca, Mg and other elements did not change during the experiment.

Influence of pH on intestinal fluoride transport in vitro.

The effect of pH on intestinal fluoride (F) absorption was investigated in vitro using isolated segments of dog jejunum in a 2-chamber system. The pH of the mucosal buffer was varied in the range 6.5-8.2, and F concentration in the range 0.11-1.1 mM (2.1-21 ppm F). The serosal buffer was held constant at pH 7.5. No effect of pH within this physiological range was observed on F transport across the intestinal segment. Much lower pH values on the mucosal side inhibited F transport, but this appeared to be secondary to toxic effects on the epithelium, including an inhibition of water transport. Within the range tested, no evidence was found supporting the concept that F transport across intestinal epithelium occurs as the undissociated hydrogen fluoride (HF).