Phosphoric Acid

1Identification

Name

Phosphoric Acid

IUPAC name

phosphoric acid

CAS number

7664-38-2

EC number

231-633-2

Molecular formula

H3O4P

Molecular weight

97.995 g/mol

InChIKey

NBIIXXVUZAFLBC-UHFFFAOYSA-N

SMILES

OP(=O)(O)O

PubChem CID

1004

Synonyms

Phosphoric acid, ORTHOPHOSPHORIC ACID, o-Phosphoric acid, Wc-reiniger, Acidum phosphoricum, Sonac, Phosphorsaeure, Evits, Acide phosphorique, Phosphoricum acidum, Acido fosforico, Phosphorsaeureloesungen, Fosforzuuroplossingen, Vococid

Recommended uses

• CIR ingredient: Phosphoric Acid
  Cosmetic Ingredient Review (CIR)
• . . . used in fertilizers, detergents, foods and beverages, water treatment, pickling and rust proofing metals, and for many other purposes. [ACGIH] Used in photography (platinum printing); [www.ci.tucson.az.us/arthazards/medium.html] Used as a wet etchant in semiconductor manufacturing at a standard concentration of 85%; [CSH, p. 46]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Acid and Alkali Cleaning of Metals [Category: Clean] Molding and Core Making [Category: Foundry] Electroplating [Category: Plate] Petroleum Production and Refining [Category: Industry] Semiconductor Manufacturing [Category: Industry] Sewer and Wastewater Treatment [Category: Industry] Photographic Processing [Category: Other]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Processing aids not otherwise specified Semiconductor and photovoltaic agent Abrasives Plating agent Antioxidant pH regulating agent Heat transferring agent Bleaching agent Solvent Polymerization promoter Flavoring and nutrient Anti-adhesive/cohesive Other Swelling agent Lubricating agent Adhesion/cohesion promoter Drier Etching agent Anti-static agent Chelating agent Anti-scaling agent Intermediate Processing aids, specific to petroleum production Oxidizing agent Surface modifier Defoamer Humectant Laboratory chemicals Dye Flame retardant Cleaning agent Soil amendments (fertilizers) Catalyst Corrosion inhibitor Not Known or Reasonably Ascertainable
  EPA Chemical Data Reporting (CDR)
• Binder Other Lubricating agent Solvent Polymerization promoter Anti-freeze agent Flavoring and nutrient Anti-adhesive/cohesive Chemical reaction regulator Plating agent pH regulating agent Bleaching agent Processing aids not otherwise specified Surfactant (surface active agent) Soil amendments (fertilizers) Not Known or Reasonably Ascertainable Corrosion inhibitor Flame retardant Cleaning agent Oxidizing agent Dye Anti-static agent Anti-scaling agent
  EPA Chemical Data Reporting (CDR)

Use categories: EPA Safer Chemical Functional Use Classes -> Oxidants and Oxidant Stabilizers · Safer Chemical Classes -> Yellow triangle - The chemical has met Safer Choice Criteria for its functional ingredient-class, but has some hazard profile issues · Food additives · Food Additives -> ACID; ANTIOXIDANT_SYNERGIST; SEQUESTRANT; SYNERGIST -> JECFA Functional Classes

Description

• Phosphoric acid appears as a clear colorless liquid or transparent crystalline solid. The pure solid melts at 42.35 °C and has a density of 1.834 g / cm3. Liquid is usually an 85% aqueous solution. Shipped as both a solid and liquid. Corrosive to metals and tissue. Used in making fertilizers and detergents and in food processing.
  CAMEO Chemicals
• Phosphoric acid is a phosphorus oxoacid that consists of one oxo and three hydroxy groups joined covalently to a central phosphorus atom. It has a role as a NMR chemical shift reference compound, a fertilizer, a solvent, a human metabolite and an algal metabolite. It is a conjugate acid of a phosphate ion and a dihydrogenphosphate.
  ChEBI
• The CIR Expert Panel concluded that the following 31 ingredients are safe in the present practices of use and concentration in cosmetics as described in this safety assessment, when formulated to be non-irritating...Phosphoric Acid...
  Cosmetic Ingredient Review (CIR)

2Hazard identification

Signal word

Danger

Pictograms

GHS05

Classification source

Regulation (EC) No 1272/2008 of the European Parliament and of the Council

Precautionary statements

Other reported classifications

5 classification records exist across sources. Differences usually reflect purity, physical form or impurities.

NFPA 704 rating

• 3 - Materials that, under emergency conditions, can cause serious or permanent injury.
  Hazardous Substances Data Bank (HSDB)
• 0 - Materials that will not burn under typical fire conditions, including intrinsically noncombustible materials such as concrete, stone, and sand.
  Hazardous Substances Data Bank (HSDB)
• 0 - Materials that in themselves are normally stable, even under fire conditions.
  Hazardous Substances Data Bank (HSDB)

Health hazards

• Burns on mouth and lips, sour acrid taste, severe gastrointestinal irritation, nausea, vomiting, bloody diarrhea, difficult swallowing, severe abdominal pains, thirst, acidemia, difficult breathing, convulsions, collapse, shock, death. (USCG, 1999)
  CAMEO Chemicals
• · TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury or death. · Contact with molten substance may cause severe burns to skin and eyes. · Avoid any skin contact. · Fire may produce irritating, corrosive and/or toxic gases. · Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental contamination.
  Emergency Response Guidebook (ERG)

Fire hazards

• Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. For electric vehicles or equipment, ERG Guide 147 (lithium ion or sodium ion batteries) or ERG Guide 138 (sodium batteries) should also be consulted. (ERG, 2024)
  CAMEO Chemicals
• · Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. · Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). · Corrosives in contact with metals may evolve flammable hydrogen gas. · Containers may explode when heated. · For electric vehicles or equipment, GUIDE 147 (lithium ion or sodium ion batteries) or GUIDE 138 (sodium batteries) should also be consulted.
  Emergency Response Guidebook (ERG)
• Not combustible. Gives off irritating or toxic fumes (or gases) in a fire. Risk of fire and explosion on contact with incompatible substances. See Chemical Dangers.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Hazards summary

• Liquid or solid form causes second degree burns after contact for a few minutes; [CHRIS] Usually shipped as a solid or 85% solution. [CAMEO] Phosphoric acid > 70% is corrosive to skin. [Quick CPC] Phosphoric acid is an eye, skin, and upper respiratory tract irritant. [ACGIH] The risk of pulmonary edema is very small. [Desai H. Phosphorus and Phosphorus Compounds. In: Sullivan JB, Krieger GR (eds). Hazardous Materials Toxicology. Baltimore: Williams & Wilkins, 1992; p. 938.] Corrosive to the skin, eye, and respiratory tract; [ICSC] If phosphoric acid is used as a catalyst, phosphine can be formed in the strongly reducing atmosphere of the hot emissions.
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases

3Composition / information on ingredients

This page describes the pure substance. Commercial products may be solutions or mixtures. Check Section 3 of your supplier's SDS for concentrations and other ingredients.

4First-aid measures

• Excerpt from NIOSH Pocket Guide for Phosphoric acid: Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: WATER FLUSH IMMEDIATELY - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly. Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once.
  CAMEO Chemicals
• General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).
  Emergency Response Guidebook (ERG)
• (General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly. Breathing: Respiratory support Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.
  The National Institute for Occupational Safety and Health (NIOSH)

Symptoms of exposure

• Cough. Sore throat. Burning sensation. Shortness of breath. Laboured breathing.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Blisters. Serious skin burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Severe burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)

5Fire-fighting measures

• Use water spray to keep fire-exposed containers cool. Extinguish fire using agent suitable for surrounding fire.
  Hazardous Substances Data Bank (HSDB)
• If material /is/ involved in /a/ fire, extinguish fire using agent suitable for type of surrounding fire. (Material does not burn or burns with difficulty.) Use water in flooding quantities as fog. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible.
  Hazardous Substances Data Bank (HSDB)
• If material /is/ on fire or involved in /a/ fire, extinguish fire using agent suitible for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Use dry chemical, dry sand, or carbon dioxide. Do not use water on material itself. If large quantities of combustibles are involved, use water in flooding quantities as spray or fog. Use water spray to knock-down vapors. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. /Phosphoric acid, corrosive liquids N.O.S./
  Hazardous Substances Data Bank (HSDB)

Hazardous combustion products

• ... Combustion by-products include oxides of phosphorus.
  Hazardous Substances Data Bank (HSDB)

6Accidental release measures

Isolation and evacuation

• Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary. FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
  CAMEO Chemicals
• Immediate precautionary measure · Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Spill · For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances. · For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary. Fire · If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
  Emergency Response Guidebook (ERG)

Spill cleanup

• Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Do NOT let this chemical enter the environment. Sweep spilled substance into covered containers. Carefully collect remainder. Then store and dispose of according to local regulations.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Ventilate area of spill or leak. If in the solid form, collect spilled material in the most convenient and safe manner for reclamation or for disposal in a secured sanitary landfill. If in the liquid form, collect for reclamation or absorb in vermiculite, dry sand, earth, or a similar material.
  Hazardous Substances Data Bank (HSDB)
• Cellosized absorbent material may be used for vapor suppression and containment of spills.
  Hazardous Substances Data Bank (HSDB)
• Air spill: Apply water spray or mist to knock down vapors. Vapor knockdown water is corrosive or toxic and should be diked for containment.
  Hazardous Substances Data Bank (HSDB)

7Handling and storage

• Dry. Well closed. Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Store in an area without drain or sewer access.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Store in cool, dry, well-ventilated location. Separate from alkalies and most metals.
  Hazardous Substances Data Bank (HSDB)
• The hot concentrated acid attacks porcelain and granite ware. Phosphoric acid may be stored in suitable stainless steel containers.
  Hazardous Substances Data Bank (HSDB)

8Exposure controls / personal protection

Personal protective equipment

• Excerpt from NIOSH Pocket Guide for Phosphoric acid: Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact. Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact. Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated. Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced. Change: DAILY - Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.
  CAMEO Chemicals
• Personnel protection: Wear appropriate chemical protective gloves, boots and goggles. If contact with the material /is/ anticipated, wear appropriate chemical protective clothing.
  Hazardous Substances Data Bank (HSDB)
• Goggles or face shield
  Hazardous Substances Data Bank (HSDB)
• Wear rubber gloves, and overalls prepared with a total seal.
  Hazardous Substances Data Bank (HSDB)

Respirator recommendations

• NIOSH/OSHA Up to 25 mg/m3 : (APF = 25) Any supplied-air respirator operated in a continuous-flow mode* Up to 50 mg/m3 : (APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters. (APF = 50) Any self-contained breathing apparatus with a full facepiece (APF = 50) Any supplied-air respirator with a full facepiece Up to 1000 mg/m3 : (APF = 2000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has…
  The National Institute for Occupational Safety and Health (NIOSH)

9Physical and chemical properties

10Stability and reactivity

Reactivity

• PHOSPHORIC ACID reacts exothermically with bases. May react with active metals, including such structural metals as aluminum and iron, to release hydrogen, a flammable gas. Can initiate the polymerization of certain classes of organic compounds. Reacts with cyanide compounds to release gaseous hydrogen cyanide. May generate flammable and/or toxic gases in contact with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and strong reducing agents. Forms explosive mixture with nitromethane. Reacts violently with sodium tetrahydroborate. In the presence of chlorides can corrode stainless steel to form explosive hydrogen gas.
  CAMEO Chemicals
• Soluble in water with small release of heat.
  CAMEO Chemicals

Incompatible materials and hazardous reactions

• Reacts with metals to liberate flammable hydrogen gas.
  Hazardous Substances Data Bank (HSDB)
• With sodium tetrahydroborate: Interaction of sodium and other tetrahydroborates with anhydrous acids (phosphoric acid) to generate diborane is very exothermic, and may be dangerously violent with rapid mixing.
  Hazardous Substances Data Bank (HSDB)
• Heat generated with: Alcohols and glycols; Aldehydes; Amides; Amines; Azo-compounds; Carbamates; Caustics; Esters; Ketones; Phenols and cresols; Organophosphates; Epoxides; Combustible materials; Explosives; Unsaturated halides; And organic peroxides.
  Hazardous Substances Data Bank (HSDB)

11Toxicological information

Target organs

• Respiratory
  EPA Integrated Risk Information System (IRIS)
• Eyes, skin, respiratory system
  The National Institute for Occupational Safety and Health (NIOSH)

Short-term exposure effects

• The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Inhalation may cause asthma-like reactions (RADS). Exposure could cause asphyxiation due to swelling in the throat. Inhalation of high concentrations may cause lung oedema, but only after initial corrosive effects on the eyes and the upper respiratory tract have become manifest. Inhalation of high concentrations may cause pneumonitis.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Long-term exposure effects

• The substance may have effects on the upper respiratory tract and lungs. This may result in chronic inflammation and reduced lung function . Mists of this strong inorganic acid are carcinogenic to humans.
  ILO-WHO International Chemical Safety Cards (ICSCs)

12Ecological information

Not available in the public sources we compile. Check Section 12 of the supplier's SDS.

13Disposal considerations

• SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.
  Hazardous Substances Data Bank (HSDB)
• Technology appropriate for incineration: Rotary kiln.
  Hazardous Substances Data Bank (HSDB)
• Technology appropriate for incineration: Venturi scrubber.
  Hazardous Substances Data Bank (HSDB)

14Transport information

UN number: UN 1805

Shipping name

• IMO 8.0; Phosphoric acid
  Hazardous Substances Data Bank (HSDB)
• UN 1805; Phosphoric acid
  Hazardous Substances Data Bank (HSDB)

DOT hazard class

• Phosphoric acid, solid
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• UN3453
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• Class 8 Corrosive material (49 eCFR § 173.136)
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172

DOT label

• Corrosive
  CAMEO Chemicals

UN classification

• UN Hazard Class: 8; UN Pack Group: III
  ILO-WHO International Chemical Safety Cards (ICSCs)

Emergency Response Guidebook

• 1805 154
  Emergency Response Guidebook (ERG)
• 3453 154
  Emergency Response Guidebook (ERG)

How DOT hazard classes work →

15Regulatory information

• Residues of phosphoric acid are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest. Use: buffer. Limit: none.
  Hazardous Substances Data Bank (HSDB)
• Residues of the following chemical substances are exempted from the requirement of a tolerance when used in accordance with good manufacturing practice as ingredients in an antimicrobial pesticide formulation, provided that the substance is applied on a semi-permanent or permanent food-contact surface (other than being applied on food packaging) with adequate draining before contact with food. ... (b) The following chemical substances when used as ingredients in an antimicrobial pesticide formulation may be applied to: Dairy processing equipment, and food-processing equipment and utensils. Phosphoric acid is included on this list.
  Hazardous Substances Data Bank (HSDB)
• Phosphoric acid is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.
  Hazardous Substances Data Bank (HSDB)
• Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 5000 lb or 2270 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).
  Hazardous Substances Data Bank (HSDB)
• Phosphoric acid used as a multiple purpose GRAS food substance in food for human consumption is generally recognized as safe when used in accordance with good manufacturing practice.
  Hazardous Substances Data Bank (HSDB)

Overview of SDS regulations (OSHA HazCom, WHMIS, REACH/CLP) →

16Other information

Compiled from PubChem CID 1004 and the sources it aggregates (attributed inline). Data retrieved 2026-10-12. This summary describes the pure substance and is not a supplier SDS.