Food & Drink / Compounds / Chromic acid (chromium trioxide)

Chromic acid (chromium trioxide) in food: ingestion safety

High risk

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

Cr(VI) drinking-water contamination — the Erin Brockovich/Hinkley California case, plus the broader EPA NPDWR review. NTP rodent cancer bioassay supports the oral-route classification; EPA MCL revision under review.

What is chromic acid (chromium trioxide)?

The IUPAC name is trioxochromium.

Also known as: trioxochromium, Chromium trioxide, Chromium(VI) oxide, CrO3.

IUPAC name
trioxochromium
CAS number
1333-82-0
Molecular formula
CrO3
Molecular weight
99.994 g/mol
SMILES
O=[Cr](=O)=O
PubChem CID
14915

Risk for people

High risk

Cr(VI) drinking-water contamination — the Erin Brockovich/Hinkley California case, plus the broader EPA NPDWR review. NTP rodent cancer bioassay supports the oral-route classification; EPA MCL revision under review.

Regulatory consensus

4 regulatory and scientific bodies have classified Chromic acid (chromium trioxide). The classifications differ — that's the data.

AgencyYearClassificationNotes
IARC2012Group 1 — Chromium(VI) compounds are carcinogenic to humans (IARC Monograph Volume 49, 1990; Volume 100C, 2012); chromic acid (CrO3) is one of the primary Cr(VI) sources evaluated; lung cancer causation in chromate production, chrome plating, and pigment manufacturing workers is established
EPA CTX / NTP RoC—Known Human Carcinogen
EPA CTX / Genetox—Genotoxicity: positive (Ames: positive, 7 positive / 0 negative reports)
EPA CTX / Genetox—Genotoxicity: positive (Ames: positive, 7 positive / 0 negative reports)

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 you encounter chromic acid (chromium trioxide)

  • Contaminated Water — Mining site runoff, Industrial discharge areas, Drinking water from old infrastructure
  • Soil Contamination — Industrial sites, Smelter areas, Battery recycling facilities
  • Food Chain — Fish from contaminated waters, Shellfish from polluted areas, Crops grown in contaminated soil

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Chromic acid (chromium trioxide):

  • Enzyme or biocatalysts where applicable
    Trade-offs: Temperature/pH sensitivity. Higher cost for some applications.
    Relative cost: 2-5×

Frequently asked questions

Is chromic acid (chromium trioxide) safe for you?

Cr(VI) drinking-water contamination — the Erin Brockovich/Hinkley California case, plus the broader EPA NPDWR review. NTP rodent cancer bioassay supports the oral-route classification; EPA MCL revision under review.

What products contain chromic acid (chromium trioxide)?

Chromic acid (chromium trioxide) appears in: Mining site runoff (Contaminated water); Industrial discharge areas (Contaminated water); Industrial sites (Soil contamination); Smelter areas (Soil contamination); Fish from contaminated waters (Food chain).

Why do regulators disagree about chromic acid (chromium trioxide)?

Chromic acid (chromium trioxide) has been classified by 4 agencies including IARC, EPA CTX / NTP RoC, EPA CTX / Genetox, EPA CTX / Genetox, 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 Chromic acid (chromium trioxide) in the food app

Look up products containing chromic acid (chromium trioxide), compare to alternatives, and explore the full data record.

Open in food View raw API data

Sources (4)
  1. IARC Group 1 Chromium VI Compounds Vol 49 1990 Vol 100C 2012; Chromic Acid CrO3 Hard Chrome Electroplating Lung Cancer; Nasal Septum Perforation Chrome Holes; Cr-DNA Adducts ROS Cr(V) Reductive Activation; EU CLP Carc 1A H350i SVHC REACH Authorisation List; OSHA Cr(VI) Standard 5 μg/m3 2006; Hinkley California Erin Brockovich Groundwater; EU WFD Priority Substance; Aquatic Acute 1 H400 (2012) — regulatory
  2. OSHA Hexavalent Chromium Standard (29 CFR 1910.1026) — PEL 5 µg/m³ (2006) — regulatory
  3. ATSDR Toxicological Profile for Chromium (2012) — regulatory
  4. EPA IRIS — Hexavalent chromium inhalation unit risk (1998) — 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 →