Outdoor & Yard / Compounds / Hexavalent chromium [Cr(VI)]

Hexavalent chromium [Cr(VI)] in the yard and garden

High risk for your yard

IARC Group 1; EPA known carcinogen. Lung cancer risk elevated 10–40× in occupationally exposed chromate workers. Cr(VI) crosses cell membranes via sulfate transporters, is reduced intracellularly to Cr(III), and generates DNA strand breaks, Cr-DNA adducts, and oxidative damage. Drinking water exposure (Erin Brockovich contamination; Hinkley, CA) linked to elevated community cancer rates. EPA has not set a federal MCL specifically for Cr(VI); California MCL 0.01 mg/L.

What is hexavalent chromium [cr(vi)]?

Molecular formula
CrO3
Molecular weight
99.994 g/mol
SMILES
O=[Cr](=O)=O
PubChem CID
14915

Risk for people, pets,

High risk

IARC Group 1; EPA known carcinogen. Lung cancer risk elevated 10–40× in occupationally exposed chromate workers. Cr(VI) crosses cell membranes via sulfate transporters, is reduced intracellularly to Cr(III), and generates DNA strand breaks, Cr-DNA adducts, and oxidative damage. Drinking water exposure (Erin Brockovich contamination; Hinkley, CA) linked to elevated community cancer rates. EPA has not set a federal MCL specifically for Cr(VI); California MCL 0.01 mg/L.

Regulatory consensus

2 regulatory and scientific bodies have classified Hexavalent chromium [Cr(VI)]. The classifications differ — that's the data.

AgencyYearClassificationNotes
IARC2012Group 1 (carcinogenic to humans)Chromium(VI) compounds; lung cancer (dominant), nasal/sinus cancer; confirmed in chromate production, chromium plating, and stainless steel welding workers; Monograph 100C
US EPA2010known to be carcinogenic to humansEPA IRIS inhalation assessment (2010) and oral assessment (1998); lung cancer via inhalation; genotoxic via Cr(VI) reduction to Cr(III) inside cells generating reactive oxygen species and DNA adducts; inhalation unit risk 1.2 × 10⁻² per μg/m³

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 yard encounter hexavalent chromium [cr(vi)]

  • 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 Hexavalent chromium [Cr(VI)]:

  • Trivalent chromium (Cr(III)) conversion coatings
    Trade-offs: Drop-in replacement for Cr(VI) passivation. Slight color difference. 90-95% equivalent corrosion protection. Lower toxicity profile. Widely adopted in EU post-REACH.
    Relative cost: 1.2-2×
  • Zinc flake coatings (Geomet, Delta-Protekt)
    Trade-offs: Chrome-free corrosion protection for fasteners and automotive parts. Excellent salt spray performance (720-1500 hrs). Dip/spin application. Cost: 2-3x zinc plating but eliminates Cr(VI) entirely.
    Relative cost: 1.2-2×

Frequently asked questions

Is hexavalent chromium [cr(vi)] safe for your yard?

IARC Group 1; EPA known carcinogen. Lung cancer risk elevated 10–40× in occupationally exposed chromate workers. Cr(VI) crosses cell membranes via sulfate transporters, is reduced intracellularly to Cr(III), and generates DNA strand breaks, Cr-DNA adducts, and oxidative damage. Drinking water exposure (Erin Brockovich contamination; Hinkley, CA) linked to elevated community cancer rates. EPA has not set a federal MCL specifically for Cr(VI); California MCL 0.01 mg/L.

What products contain hexavalent chromium [cr(vi)]?

Hexavalent chromium [Cr(VI)] 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).

See Hexavalent chromium [Cr(VI)] in the outdoor app

Look up products containing hexavalent chromium [cr(vi)], compare to alternatives, and explore the full data record.

Open in outdoor View raw API data

Sources (3)
  1. IARC Monographs Volume 100C: Chromium (VI) Compounds — Arsenic, Metals, Fibres, and Dusts (2012) — regulatory
  2. US EPA IRIS: Chromium VI — Toxicological Review (Inhalation, Final) (2010) — regulatory
  3. OSHA Standard 29 CFR 1910.1026: Occupational Exposure to Hexavalent Chromium (2006) — regulatory

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