Outdoor & Yard / Compounds / Mercury (methylmercury)

Mercury (methylmercury) in the yard and garden

Elevated risk for your yard

IARC Group 1; primary neurotoxicant; tuna/swordfish main sources; >80% of US adults exceed EPA reference dose with high fish consumption.

What is mercury (methylmercury)?

The IUPAC name is methylmercury(1+).

Also known as: methylmercury(1+), Methylmercury ion, CH3Hg+, METHYLMERCURY(II) CATION.

IUPAC name
methylmercury(1+)
CAS number
22967-92-6
Molecular formula
CH3Hg+
Molecular weight
215.63 g/mol
SMILES
C[Hg+]
PubChem CID
6860

Risk for people, pets,

Elevated risk

IARC Group 1; primary neurotoxicant; tuna/swordfish main sources; >80% of US adults exceed EPA reference dose with high fish consumption.

Regulatory consensus

4 regulatory and scientific bodies have classified Mercury (methylmercury). The classifications differ — that's the data.

AgencyYearClassificationNotes
IARC2017Group 1 (carcinogenic to humans)Methylmercury compounds; colon cancer; Monograph 115; also potent neurotoxicant
US EPA1995Likely to be carcinogenic to humansFish consumption advisory; fetal neurotoxicity primary concern; RfD 0.1 μg/kg/day
EPA CTX / IRIS—C (Possible human carcinogen)
EPA CTX / Health Canada—Group 2B: IARC (possibly carcinogenic to humans)

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 mercury (methylmercury)

  • 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 Mercury (methylmercury):

  • Low-mercury fish species
    Trade-offs: Dietary substitution: salmon, sardines, anchovies, pollock vs tuna/swordfish/shark. Same omega-3 benefits with 5-10x lower mercury. No performance tradeoff for nutrition.
    Relative cost: 1.2-2×
  • Algal DHA/EPA supplements
    Trade-offs: Plant-based omega-3 with zero mercury. Bioavailability 85-95% of fish oil. Higher cost per gram omega-3. Suitable for pregnant/nursing populations.
    Relative cost: 1.2-2×
  • LED/fluorescent alternatives (for mercury-containing lighting)
    Trade-offs: LED eliminates mercury entirely. Higher upfront cost, lower lifetime cost. Superior energy efficiency. Mercury-containing CFLs being phased out globally.
    Relative cost: 1.2-2×

Frequently asked questions

Is mercury (methylmercury) safe for your yard?

IARC Group 1; primary neurotoxicant; tuna/swordfish main sources; >80% of US adults exceed EPA reference dose with high fish consumption.

What products contain mercury (methylmercury)?

Mercury (methylmercury) 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 mercury (methylmercury)?

Mercury (methylmercury) has been classified by 4 agencies including IARC, US EPA, EPA CTX / IRIS, EPA CTX / Health Canada, 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 Mercury (methylmercury) in the outdoor app

Look up products containing mercury (methylmercury), compare to alternatives, and explore the full data record.

Open in outdoor View raw API data

Sources (2)
  1. IARC Monographs Volume 115: Methylmercury Compounds (2017) — regulatory
  2. US EPA: Mercury Study Report to Congress and Fish Consumption Advisory (1995) — 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 →