Hydrofluoric toxic effects

Hydrofluoric add is a particular illustration because it assodates the elementary mechanism of the add and the mechanism of a chelation causing a major toxic effect. 

I. Mechanism of toxicity. HF is a skin and respiratory irritant. Hydrofluoric acid is a relatively weak acid (the dissociation constant is about 1000 times less than that of hydrochloric acid), and toxic effects result primarily from the highly reactive fluoride ion. 

Hydrogen fluoride and hydrofluoric acid are very corrosive and additionally very toxic. This synergism is responsible for their extreme danger in consequence of their very corrosive property the skin is damaged immediately and the compound very quickly reaches the target organ and can develop very toxic effects. Therefore,... 

For instance, hydrogen peroxide (H2O2) is both an acid and an oxidizer. Hydrofluoric acid is a particular illustration because it associates the elementary mechanism of the acid and the mechanism of a chelation causing a major toxic effect. Chelation can be defined as the appropriation of mainly metallic atoms by a molecular entity, the size of which is often bigger than the chelated... 

Workers exposed to an airborne fluoride concentration of 5mg/m complained of eye and respiratory tract irritation and nausea. The lethal oral dose of sodium fluoride for humans has been estimated to be 32-65 mg F/kg of body weight. Effects from ingestion are diffuse abdominal pain, diarrhea, and vomiting excessive salivation, thirst, and perspiration painful spasms of the limbs and sometimes albuminuria." Gastrointestinal effects produced after the acute ingestion of toxic amounts of fluoride likely arise from the corrosive action of hydrofluoric acid, which is produced within the acidic environment of the stomach. Cardiac arrest after accidental exposure to high levels of fluoride has been attributed to the development of hypocalcemia and/or hyperkalemia. ... 

Recent work done on physical vapor barriers was performed by the Industrial Cooperative HF Mitigation/Assessment Program (ICHMAP) (Petersen and Radcliff, 1989). This program studied the effects of vapor fences and vapor boxes. The primary objective of the study was to determine the effectiveness of these devices to retard the transport and to dilute heavier-than-air (HTA) releases of a toxic material like hydrofluoric acid (HF). Because vapor barriers could also see releases of flammable materials, an effort was made to determine their impact on the consequences of a vapor cloud explosion. 

Designated work areas should be established for handling materials with a high degree of acute toxicity (such as chemicals with corrosive effects, e.g., nitric, sulfuric, and hydrochloric acids hydrofluoric acid sodium hydroxide or chemical asphyxiants such as carbon monoxide and hydrogen sulfide). 

DOT CLASSIFICATION 6.1 Label KEEP AWAY FROM FOOD SAFETY PROFILE Poison by ingestion and intraperitoneal routes. Moderately toxic by subcutaneous route. Experimental teratogenic effects. A corrosive irritant to the eyes, skin, and mucous membranes. Mutation data reported. A very reactive material, When heated to decomposition it emits toxic fumes of K2O and F". Used in etching glass, as a preservative, as an insecticide, and in organic synthesis. See also FLUORIDES and HYDROFLUORIC ACID. 

Hydrofluoric acid finds occasional use in conjunction with other acids in attacking steels that dissolve with difficulty in other solvents. Because hydrofluoric acid is extremely toxic, dissolution of samples and evaporation to remove excess reagent should always be carried out in a well-ventilated hood. Hydrofluoric acid causes serious damage and painful injury when brought into contact with the skin. Its effects may not become evident until hours after expo.sure. If the acid comes into contact with the skin, the affected area should be immediately washed with copious quantities of water. Treatment with a dilute solution of calcium ion, which precipitates fluoride ion, may also be of help. 

The dark side of hydrofluoric acid is its toxicity and corrosiveness. Aqueous and anhydrous HF readily penetrate the skin, and, because of its locally anesthetizing effect, even in very small quantities can cause deep lesions and necroses [4, 5]. An additional health hazard is the systemic toxicity of fluoride ions, which interfere strongly with calcium metabolism. Resorption of HF by skin contact (from a contact area exceeding 160 cm ), inhalation, or ingestion leads to hypocalcemia with very serious consequences, for example cardiac arrhythmia. 

Hydrofluoric acid itself is one of the most hazardous reagents used in fluorine chemistry, possibly more so than elemental fluorine itself. Reasons are the low boiling point of aHF (19.5 °C) and its topical and systemic toxicity in combination with its local anesthetizing effect. 

The toxicity of hydrofluoric acid did not go unnoticed amongst the early chemists working with this material. The vapours were known to be corrosive and incautious inhalation can produce many damaging effects. Contact with the skin is also gravely dangerous, a problem difficult to avoid as the acid rapidly produced holes in, and escaped from, apparatus designed to produce and contain it. 

The problem of the speciation of metals in sediments continues to attract attention, both from the point of measurement techniques and from the point of bioavailabihty and, consequently, effects such as toxicity. Some workers prefer to measure total metals after full digestion of sediments with hydrofluoric acid, others favor sequential extractions [84]. The concentrations of heavy metals in coastal sediments are remarkably similar world-wide [85] Cu30pg/g, Ni 30 )ig/g, Pb 40 )ig/g, Zn 120 pg/g, Ag 1 pg/g, Cd 1 pg/g, Hg 0.5 pg/g dry sediment containing at least 20% of silt and clay, respectively. High levels are about... 

Fluorine Hydrofluoric acid (HF) is a by-product of aluminum production by electrolysis cind the synthesis of chlorofluorocarbons (CFCs). Although in water HF is a weak acid, it s extremely toxic. HF poisoning causes deep ulceration or scarring of body tissue with a delayed effect, slowly replacing calcium in bodily tissue (flesh and bones). There s no pain at first because it s a weak acid, but when the calcium in the bones starts to be replaced by the more electronegative fluorine it feels similar to growing pains, and may be too late. Merely five-minute iexposure to 10,000 ppm concentration in the air is fatal to humans. 

Toxicology LD50 (oral, rat) 175 mg/kg toxic by inh., ing., skin contact irritating to eyes, skin, respiratory system exposure can cause stomach pains, vomiting, diarrhea may cause tremors, cyanosis, Gl effects target organs heart, kidneys, nerves, Gl system TSCA listed Precaution Reacts violently with water contact with acids, heat, or moisture may liberate highly toxic, corrosive hydrofluoric acid incompat. with acids... 

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