JOURNAL OF APPLIED TOXICOLOGY, VOL. 12(4), 301-303 (1992)
Toxicology Update
PHOSPHORIC ACID/PHOSPHATES Synonyms: Phosphoric acid; phosphoric anhydride; phosphoric oxide; inorganic phosphate. CAS no.: 7664-38-2, orthophosphoric acid; 37267-86-0, metaphosphoric acid. Boiling point: 213°C. Color: Colorless, sparkling liquid or transparent crystals, depending on temperature and concentration. DOT designation: Non-flammable. Flammable limits: As an acid, this material can develop a strong exothermic reaction upon neutralization. Melting point: 42.3"C. Molecular formula: H3P04. Molecular weight: 98. Odor: Odorless. pH: 0.1 N aqueous solution has a p H of 1.5; 1% solution has a p H of 2.0-2.2. Solubility: Miscible and soluble in water (548 g 100 ml-' cold water); soluble in alcohol and ether. Specific gravity: 1.834 at 18°C. Vapor density: 3.4 (air = 1) at the boiling point of phosphoric acid. Vapor pressure: 0.03 mmHg at 20°C. Viscosity: 3.86 mPas (40% solution at 20°C). (From Refs 1-3).
and stomach. Hyperphosphatemia with accompanying acidosis and hypocalcePhosphoric acid is used in the manufacmia may occur. Vomiting can produce ture of fertilizers, phosphate salts, polymucoid and 'coffee ground' material and phosphates, detergents, activated carmay lead to an aspiration p n e ~ m o n i t i s . ~ bon, animal feed, ceramics, dental Case studies of patients who ingested cement, pharmaceuticals, soft drinks, significant amounts of phosphoric acid gelatin, rust inhibitors, wax and rubber indicate corrosion, coagulative necrosis latex. Additionally, exposures may and perforation of gastrointestinal occur in the electropolishing, engraving, organs. Signs of obstruction and scarring sugar refining and water treatment may occur weeks to months after the industries. Phosphorus trichloride and initial exposure. Gastric and pyloric pentachloride are used in the manufacstrictures may require surgical repair. ture of dyes, gasolines additives, plasPermanent scars may appear.6 Clammy ticizers, saccharin, acetylcellulose and skin, weak and rapid pulse. shallow surfactants. Phosphorus pentasulfide respirations and scanty urine may also and tetraphosphorus trisulfide are used be observed. Circulatory collapse in the manufacture of insecticides, lubattributable to shock is the most ricating oil additives, ignition comimmediate cause of death. If the patient pounds and 'strike anywhere' m a t c h e ~ . ~ is maintained in a state of shock for Phosphoric acid has also found use several hours, renal failure and ischemic in the treatment of lead poisoning or lesions in the liver and heart may occur.6 other conditions where mild acidosis is desired, such as the prevention of kidInhalation. Inhalation of mists of ney stones. It has been administered at phosphoric acid can be irritating to the a rate as high as 60 ml daily.5 upper respiratory tract. However, the
Uses
Acute toxicity
Composition
Although exposure to phosphoric acid may result in effects attributable to the acid component, there is no evidence that phosphorus poisoning can occur on exposure to phosphoric acid.5
Elemental phosphorus does not occur free in nature but is found in the form of phosphates. Phosphorus and phosphoric acid are prepared commercially from 'phosphate rock' deposits in southern USA. Phosphorus, once formed, is immediately converted to a less toxic material, such as phosphoric acid or phosphorus oxides, or reacts to form phosphorus trichloride.'
Ingestion. Depending upon its concentration, ingestion of phosphoric acid solutions may produce a sensation of warmth or a burning pain in the throat and abdomen. Ingestion of concentrated solutions can produce nausea, vomiting, abdominal pain, hematemesis, bloody diarrhea, shock and burns of the mucosa of the mouth, esophagus
Table 1. Toxicity rating and irritation potential of some phosphate salts Compound
Toxicity rating
Irritation rating
Monocalcium phosphate monohydrate Disodium phosphate Tetrasodium diphosphate Tripotassium phosphate Trisodium phosphate (anhydrous)
Practically non-toxic
Non-irritating
Practically Practically Practically Practically
Minimally irritating Non-irritating Minimally irritating Minimally irritating
(Source: Ref. 9.)
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Toxicology Update
PHOSPHORIC ACID/PHOSPHATES Synonyms: Phosphoric acid; phosphoric anhydride; phosphoric oxide; inorganic phosphate. CAS no.: 7664-38-2, orthophosphoric acid; 37267-86-0, metaphosphoric acid. Boiling point: 213°C. Color: Colorless, sparkling liquid or transparent crystals, depending on temperature and concentration. DOT designation: Non-flammable. Flammable limits: As an acid, this material can develop a strong exothermic reaction upon neutralization. Melting point: 42.3"C. Molecular formula: H3P04. Molecular weight: 98. Odor: Odorless. pH: 0.1 N aqueous solution has a p H of 1.5; 1% solution has a p H of 2.0-2.2. Solubility: Miscible and soluble in water (548 g 100 ml-' cold water); soluble in alcohol and ether. Specific gravity: 1.834 at 18°C. Vapor density: 3.4 (air = 1) at the boiling point of phosphoric acid. Vapor pressure: 0.03 mmHg at 20°C. Viscosity: 3.86 mPas (40% solution at 20°C). (From Refs 1-3).
and stomach. Hyperphosphatemia with accompanying acidosis and hypocalcePhosphoric acid is used in the manufacmia may occur. Vomiting can produce ture of fertilizers, phosphate salts, polymucoid and 'coffee ground' material and phosphates, detergents, activated carmay lead to an aspiration p n e ~ m o n i t i s . ~ bon, animal feed, ceramics, dental Case studies of patients who ingested cement, pharmaceuticals, soft drinks, significant amounts of phosphoric acid gelatin, rust inhibitors, wax and rubber indicate corrosion, coagulative necrosis latex. Additionally, exposures may and perforation of gastrointestinal occur in the electropolishing, engraving, organs. Signs of obstruction and scarring sugar refining and water treatment may occur weeks to months after the industries. Phosphorus trichloride and initial exposure. Gastric and pyloric pentachloride are used in the manufacstrictures may require surgical repair. ture of dyes, gasolines additives, plasPermanent scars may appear.6 Clammy ticizers, saccharin, acetylcellulose and skin, weak and rapid pulse. shallow surfactants. Phosphorus pentasulfide respirations and scanty urine may also and tetraphosphorus trisulfide are used be observed. Circulatory collapse in the manufacture of insecticides, lubattributable to shock is the most ricating oil additives, ignition comimmediate cause of death. If the patient pounds and 'strike anywhere' m a t c h e ~ . ~ is maintained in a state of shock for Phosphoric acid has also found use several hours, renal failure and ischemic in the treatment of lead poisoning or lesions in the liver and heart may occur.6 other conditions where mild acidosis is desired, such as the prevention of kidInhalation. Inhalation of mists of ney stones. It has been administered at phosphoric acid can be irritating to the a rate as high as 60 ml daily.5 upper respiratory tract. However, the
Uses
Acute toxicity
Composition
Although exposure to phosphoric acid may result in effects attributable to the acid component, there is no evidence that phosphorus poisoning can occur on exposure to phosphoric acid.5
Elemental phosphorus does not occur free in nature but is found in the form of phosphates. Phosphorus and phosphoric acid are prepared commercially from 'phosphate rock' deposits in southern USA. Phosphorus, once formed, is immediately converted to a less toxic material, such as phosphoric acid or phosphorus oxides, or reacts to form phosphorus trichloride.'
Ingestion. Depending upon its concentration, ingestion of phosphoric acid solutions may produce a sensation of warmth or a burning pain in the throat and abdomen. Ingestion of concentrated solutions can produce nausea, vomiting, abdominal pain, hematemesis, bloody diarrhea, shock and burns of the mucosa of the mouth, esophagus
Table 1. Toxicity rating and irritation potential of some phosphate salts Compound
Toxicity rating
Irritation rating
Monocalcium phosphate monohydrate Disodium phosphate Tetrasodium diphosphate Tripotassium phosphate Trisodium phosphate (anhydrous)
Practically non-toxic
Non-irritating
Practically Practically Practically Practically
Minimally irritating Non-irritating Minimally irritating Minimally irritating
(Source: Ref. 9.)
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