Home Safety / Compounds / Oxalic acid

Oxalic acid in your home: a safety profile

Moderate risk for your home

Not medical or professional safety advice, and not a substitute for a qualified clinician — consult one. Full disclaimer →

Dust and aerosolised vapor are associated with upper-respiratory irritation; oxalic-acid mist in rust-removal and wood-bleaching operations damages mucous membranes and is associated with chemical pneumonitis at high concentration.

What is oxalic acid?

Also known as: ethanedioic acid, Aktisal, Aquisal, Oxiric acid.

IUPAC name
oxalic acid
CAS number
144-62-7
Molecular formula
C2H2O4
Molecular weight
90.03 g/mol
SMILES
C(=O)(C(=O)O)O
PubChem CID
971

Risk for your household

Moderate risk

Dust and aerosolised vapor are associated with upper-respiratory irritation; oxalic-acid mist in rust-removal and wood-bleaching operations damages mucous membranes and is associated with chemical pneumonitis at high concentration.

Regulatory consensus

5 regulatory and scientific bodies have classified Oxalic acid. The classifications differ — that's the data.

AgencyYearClassificationNotes
EPA CTX / Genetox—Genotoxicity: negative (Ames: negative, 0 positive / 5 negative reports)
EPA CTX / Genetox—Genotoxicity: negative (Ames: negative, 0 positive / 5 negative reports)
FDA—GRAS as natural food component; no specific food additive approval
ECHA—H302 harmful if swallowed; H312 harmful in contact with skin
OSHA—PEL 1 mg/m3 TWA (respirable)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where your home encounter oxalic acid

  • Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
  • Occupational Environments — Factories, Warehouses, Transportation vehicles
  • Food — processed food, beverages, candy, baked goods
  • Natural Foods — spinach, rhubarb, beets, Swiss chard, star fruit
  • Cleaning Products — Bar Keepers Friend, wood bleach/deck brightener, rust removers, metal polish
  • Industrial — marble polishing, textile bleaching, wastewater treatment (precipitant)
  • Automotive — radiator flush, aluminum brightener

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Oxalic acid:

  • Fragrance-free formulations
    Trade-offs: Consumer preference for scented products
    Relative cost: Lower (ingredient elimination)
  • Essential oil-based fragrances (with disclosure)
    Trade-offs: Natural does not mean safe — many essential oils are skin sensitizers
    Relative cost: 2-5× conventional

Frequently asked questions

Is oxalic acid safe for your home?

Dust and aerosolised vapor are associated with upper-respiratory irritation; oxalic-acid mist in rust-removal and wood-bleaching operations damages mucous membranes and is associated with chemical pneumonitis at high concentration.

What products contain oxalic acid?

Oxalic acid appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); processed food (Food).

Why do regulators disagree about oxalic acid?

Oxalic acid has been classified by 5 agencies including EPA CTX / Genetox, EPA CTX / Genetox, FDA, ECHA, OSHA, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Oxalic acid in the home app

Look up products containing oxalic acid, compare to alternatives, and explore the full data record.

Open in home View raw API data

Sources (3)
  1. NIOSH: Oxalic Acid — calcium chelation; calcium oxalate nephrolithiasis; hypocalcemia; rhubarb leaf toxicity; industrial cleaner hazard; primary hyperoxaluria; ethylene glycol metabolism (2019) (2019) — regulatory
  2. CDC/ATSDR: Oxalic Acid Toxicological Profile — plant sources; dietary intake; renal tubular deposition; acute poisoning treatment; industrial uses; calcium oxalate crystals; pediatric rhubarb exposure (2020) (2020) — regulatory
  3. OSHA PEL — Oxalic acid (29 CFR 1910.1000 Table Z-1) skin notation (2020) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for medical, legal, or regulatory advice. Why we built ALETHEIA →