What Is Phosphoric Acid?
The New Jersey Department of Health describes phosphoric acid as a colorless, odorless solid or a thick, clear liquid used in rustproofing metals, fertilizers, detergents, foods, beverages and water treatment. In food, federal regulations at 21 CFR 182.1073 say phosphoric acid is generally recognized as safe when used in accordance with good manufacturing practice, and the NIH Office of Dietary Supplements says phosphate additives such as phosphoric acid are present in many foods, especially processed foods, where they are used for purposes such as preserving moisture or color and enhancing and stabilizing frozen foods.
Phosphoric acid is corrosive. The New Jersey Department of Health says contact can irritate and burn the eyes, and that breathing it can irritate the nose, throat and lungs, causing coughing and wheezing. The NIOSH Pocket Guide lists exposure through inhalation, ingestion and skin or eye contact, with symptoms including irritation of the eyes, skin and upper respiratory system, eye and skin burns, and dermatitis.
NIOSH notes that phosphoric acid readily reacts with metals to form flammable hydrogen gas and warns not to mix it with solutions containing bleach or ammonia. For workplaces, it lists a recommended exposure limit of 1 mg/m3 as a time-weighted average and 3 mg/m3 as a short-term limit, and an OSHA permissible exposure limit of 1 mg/m3.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Regulatory filingFederal regulations at 21 CFR 182.1073 say phosphoric acid is generally recognized as safe in food when used in accordance with good manufacturing practice. US FDA, 21 CFR 182.1073 (eCFR) ↗
- Medical referenceThe New Jersey Department of Health says phosphoric acid is used in rustproofing metals, fertilizers, detergents, foods, beverages and water treatment. New Jersey Department of Health ↗
- Government sourceThe New Jersey Department of Health says phosphoric acid is corrosive, can burn the eyes, and can irritate the nose, throat and lungs when breathed. New Jersey Department of Health ↗
- Regulatory filingThe NIOSH Pocket Guide lists phosphoric acid limits of 1 mg/m3 as a time-weighted average and 3 mg/m3 short term, and an OSHA limit of 1 mg/m3. NIOSH, CDC ↗
- Government sourceNIOSH lists phosphoric acid symptoms including irritation of the eyes, skin and upper respiratory system, eye and skin burns, and dermatitis. NIOSH, CDC ↗
- Government sourceNIOSH says phosphoric acid readily reacts with metals to form flammable hydrogen gas and should not be mixed with solutions containing bleach or ammonia. NIOSH, CDC ↗
- Government sourceThe NIH Office of Dietary Supplements says phosphate additives such as phosphoric acid are in many processed foods, used for purposes such as preserving moisture or color. NIH Office of Dietary Supplements ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.