Outdoor & Yard / Compounds / Metribuzin

Metribuzin in the yard and garden

Moderate risk for your yard

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

Safety profile for Metribuzin relevant to people, pets, and pollinators.

What is metribuzin?

The IUPAC name is 4-amino-6-methyl-4H-1,2,4-triazin-5-one 3-tert-butyl.

Also known as: 4-amino-6-methyl-4H-1,2,4-triazin-5-one 3-tert-butyl, Lexone, Sencor, Metribuzine.

IUPAC name
4-amino-6-methyl-4H-1,2,4-triazin-5-one 3-tert-butyl
CAS number
21087-64-9
Molecular formula
C8H14N4OS
Molecular weight
214.28 g/mol
SMILES
CC(C)(C)C1=NN=C(N(C1=O)N)SC
PubChem CID
30479

Risk for people, pets,

Moderate risk

Regulatory consensus

2 regulatory and scientific bodies have classified Metribuzin. The classifications differ — that's the data.

AgencyYearClassificationNotes
EPA—General use herbicide for potatoes, soybeansapproved
IARC—No classificationinsufficient evidence

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 metribuzin

  • agricultural herbicide (potatoes, soybeans)
  • crop residues
  • groundwater

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Metribuzin:

  • S-metolachlor + metribuzin reduced-rate program
    Trade-offs: Reduced (not eliminated) metribuzin use. Better groundwater profile than full-rate.
    Relative cost: Similar
  • Cover crop suppression + mechanical cultivation
    Trade-offs: Labor-intensive. Less consistent than chemical control. Requires timing expertise.
    Relative cost: Variable; potential savings on herbicide

Frequently asked questions

What products contain metribuzin?

Metribuzin appears in: agricultural herbicide (potatoes, soybeans); crop residues; groundwater.

Why do regulators disagree about metribuzin?

Metribuzin has been classified by 2 agencies including EPA, IARC, 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 Metribuzin in the outdoor app

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

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Sources (1)
  1. ATSDR Toxicological Profile — CAS 21087-64-9 — reference

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 →