PAN Pesticides Database - Chemicals

Metribuzin - Identification, toxicity, use, water pollution potential, ecological toxicity and regulatory information

Note: See Working with the Information on this Page section below for important notes about this data.

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Identifying information, including synonyms, ID numbers, use type, chemical classification, a link to a list of all products containing this chemical and a list of the top crops this pesticide is used on in California.
Signs and symptoms of poisoning, first aid, and links to treatment information for this chemical.
Link to information on toxicity to humans, including carcinogenicity, reproductive and developmental toxicity, neurotoxicity, and acute toxicity.
Links to world-wide registration status as well as regulatory information for the U.S. and California.
Water quality standards and physical properties affecting water contamination potential.
Toxicity to aquatic organisms.
List of chemicals in the same family, including breakdown products, salts, esters, isomers, and other derivatives.

Chemical Identification and Use for Metribuzin

Basic Identification Information About This Chemical
Chemical Name: Metribuzin
CAS Number: 21087-64-9
U.S. EPA PC Code: 101101
CA DPR Chem Code: 1692
Molecular Weight: 214.3
Molecular Structure:
Use Type: Herbicide
Chem Class: Triazinone
View Related Chemicals
Additional Resources About This Chemical Class and Use Type
Historical Use of this Chemical
Top five crops and sites for this pesticide in California
Alfalfa for Forage   Tomatoes for Processing   Potatoes   Asparagus   Soil Preplant  
View All Crops and Sites
Other Names for this Chemical
About Chemical Synonyms
(US EPA PC Code ) , 1,2,4-Triazin-5(4H)-one, 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)- , 101101 (US EPA PC Code Text ) , 1692 (CA DPR Chem Code) ) , 181 (PDP Code) , 21087-64-9 (CAS number) , 21087649 , 21087649 (CAS number without hyphens) , 4-Amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one , 4-Amino-6-(1,1-dimethylethyl)-3-methylthio)-1,2,4-triazin-5(4H)-one , 4-Amino-6-tert-butyl-3-(methylthio)-s-triazin-5(4H)-one , 4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one , as-Triazin-5(4H)-one, 4-amino-6-tert-butyl-3-(methylthio)- , as-Triazin-5(4H)-one, 4-amino-6-tert-butyl-3-(methylthio)- (8CI) , Bay 94337 , Canopy, component of (with 128901) , Canopy, component of (with 128901) , DPX G2504 , Lexone , Matribuzin , Metribuzim , Metribuzin , METRIBUZIN (CA DPR Chem Code Text ) , Metribuzin (Sencor) , Metribuzina , metribuzine , Sencor
Products Containing This Chemical
Current and historic U.S. registered products
View U.S. Products All Products Currently Registered Products

Signs and Symptoms of Metribuzin Poisoning

NOTE! There may be other diseases and chemicals that have similar symptoms.

If you have a poisoning emergency in the United States call 1-800-222-1222.
If the victim has collapsed or is unconscious, call 911.

Symptoms of Metribuzin Exposure from the International Chemical Safety Cards (ICSC)

Report a Poisoning

View full ICSC Cards: English   Español   Française   Chinese   Dutch   Finnish   German   Hungarian   Japanese   Swahili   Thai   Urdu  

Route of Exposure


First Aid

Inhalation Fresh air rest. Refer for medical attention.
Skin Rinse and then wash skin with water and soap.
Eyes First rinse with plenty of water for several minutes (remove contact lenses if easily possible) then take to a doctor.
Ingestion Rinse mouth. Rest. Refer for medical attention.
Notes for ICSC Information
Bay 61597 Bay DIC 1468 Bayer 94337 Bayer 6159H Bayer 6443H DIC 1468 Lexone Sencor Sencoral Sencorer and Sencorex are trade names.

Toxicity Information for Metribuzin

  Note: Information for many chemicals is incomplete and may not be fully representative of effects on humans. Why?

Summary Toxicity Information

PAN Bad Actor
Carcinogen Cholinesterase
Water Contaminant
Developmental or
Reproductive Toxin
Moderate Unclassifiable No Potential
Indicates high toxicity in the given toxicological category. Indicates no available weight-of-the-evidence summary assessment. For additional information on toxicity from scientific journals or registration documents, see the "Additional Resources for Toxicity " section of the chemical detail page.
1. PAN Bad Actors are chemicals that are one or more of the following: highly acutely toxic, cholinesterase inhibitor, known/probable carcinogen, known groundwater pollutant or known reproductive or developmental toxicant. NOTE! Because there are no authoritative lists of Endocrine Disrupting (ED) chemicals, EDs are not yet considered PAN Bad Actor chemicals.
2. The acute toxicity reported on this page is of the pure chemical ingredient only and may not reflect the acute toxicity of individual pesticide products. To view acute toxicity of individual products, click on 'View Products' link in the 'Chemical Identification' section above.

Detailed Toxicity Information

Acute Toxicity 2
WHO Acute Hazard
TRI Acute Hazard
Material Safety Data Sheets
Acute rating from U.S. EPA product label
U.S. NTP Acute Toxicity Studies
      View Studies
Cholinesterase Inhibitor
II, Moderately Hazardous
Not Listed
Not Available
Moderately Toxic
No NTP Studies

2. The acute toxicity reported on this page is of the pure chemical ingredient only and may not reflect the acute toxicity of individual pesticide products. To view acute toxicity of individual products, click on 'View Products' link in the 'Chemical Identification' section above.
Cancer Information
IARC Carcinogens
U.S. NTP Carcinogens
California Prop 65 Known Carcinogens
U.S. EPA Carcinogens
TRI Carcinogen
Not Listed
Not Listed
Not Listed
D, Unclassifiable, ambiguous data
Not Listed
Endocrine Disruption
Illinois EPA list
Keith list
Colborn list
Benbrook list
Danish Inert list
EU list
Not listed
Reproductive and Developmental Toxicity
CA Prop 65 Developmental Toxin
U.S. TRI Developmental Toxin
CA Prop 65 Female Reproductive Toxin
CA Prop 65 Male Reproductive Toxin
U.S. TRI Reproductive Toxin
Not Listed
Not Listed
Not Listed
Chemicals of Special Concern
PAN Bad Actors
PAN Dirty Dozen list
Not Listed

Water Pollution Potential and Criteria for Metribuzin

Water Pollution Potential

PAN Ground Water Contaminant Rating Potential
Physical Property Data Related to Water Contamination Potential
Water Solubility (Avg, mg/L)
Adsorption Coefficient (Koc)
Hydrolysis Half-life (Avg, Days)
Aerobic Soil Half-life (Avg, Days)
Anaerobic Soil Half-life (Avg, Days)

Water Standards and Criteria

U.S. National Drinking Water Standards and Health Criteria
g/L unless noted  
Maximum Contaminant Level (MCL) 0  
Maximum Contaminant Level Goal (MCLG)  
One Day Exposure Health Advisory Level 5,000  
Ten Day Exposure Health Advisory Level 5,000  
Lifetime Exposure Health Advisory Level 70.0  
Reference Dose 10.0 (g/kg/day)  
U.S. Drinking Water Equivalent Level 350.0  
Concentration with Lifetime Cancer Risk of 1 in 10,000  
Canada Drinking Water Standards and Criteria
g/L unless noted  
Maximum Acceptable Concentration (MAC) 80.0
Interim Maximum Acceptable Concentration (IMAC)
Aesthetic Objectives
Canadian Water Quality Guidelines for the Protection of Aquatic Life
g/L unless noted  
Fresh Water Guidelines 1.0 Notes: c
Salt Water Guidelines
Canadian Water Quality Guidelines for the Protection of Agricultural Water Uses
g/L unless noted  
Irrigation Water Guidelines .5
Livestock Water Guidelines 80

Regulatory Information for Metribuzin

International Regulatory Status

UNEP Persistent Organic Pollutant (POP)
UNEP Prior Informed Consent Chemical (PIC)
WHO Obsolete Pesticide
Not Listed
Not Listed
Not Listed

U.S. and California Regulatory Status

U.S. EPA Registered
U.S. EPA Hazardous Air Pollutant
U.S. EPA Minimum Risk Pesticide (25b list)

CA Registered
CA Groundwater Contaminant
CA Toxic Air Contaminant
Not Listed

Not Listed

Maximum Tolerance and Residue Levels

Codex Alimentarius
   (UN FAO Maximum Residue Limits)
U.S. Maximum Tolerance Levels
European Union Maximum Residue Levels
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Ecotoxicity for Metribuzin

Note! Information for many chemicals is incomplete and may not be fully representative of effects on the environment. Why? Click on underlined terms for definitions and additional information.

Aquatic Ecotoxicity

All Toxic Effects for Organism Group
Organism Group Effects Noted
Amphibians Genetics, Growth, Mortality
AquaticPlants Ecosystem Process, Growth, Population
Crustaceans Mortality
Fish Accumulation, Mortality
Insects Intoxication
Molluscs Intoxication
Phytoplankton Accumulation, Biochemistry, Enzyme(s), Growth, Physiology, Population, Reproduction
Zooplankton Growth, Intoxication, Mortality, Population, Reproduction
~ Un-Assigned Biochemistry, Physiology, Population
View All Aquatic Ecotoxicity Studies and References
Summary of Acute Toxicity for Organism Group
Organism Group Average Acute Toxicity Acute Toxicity Range
Crustaceans Slightly Toxic Slight Toxicity
Fish Slightly Toxic Not Acutely Toxic to Slightly Toxic
Zooplankton Slightly Toxic Slight Toxicity
~ Un-Assigned Moderately Toxic Moderate Toxicity
View All Acute Summaries

Terrestrial Ecotoxicity

Summary of Acute Toxicity for Organism Group
Organism Group Average Acute Toxicity Acute Toxicity Range
HoneybeesSlightly ToxicSlightly Toxic
Note: Population-level effects on honeybees may occur even if a pesticide has low acute toxicity. For example, certain pesticides interfere with honeybee reproduction, ability to navigate, or temperature regulation, any of which can have an effect on long-term survival of honeybee colonies. The neonicotinoids, pyrethroids and keto-enol pesticides are some types of pesticides causing one or more of these effects.
Honeybee Chronic Toxicity

Sorry, no honeybee chronic toxicity data available for this chemical. Try related chemicals.

Related Chemicals for Metribuzin

CAS Number Relation Reason Chemical Name Chem Detail Symptoms California Use Chem Use Type U.S. EPA Reg PAN Bad Actor
21087-64-9 Parent P Metribuzin View View View Herbicide Yes Yes
Related 5a Desamino-metribuzin View View View Breakdown product No Not Listed
52236-30-3 Related 5a Diketo-desamino-metribuzin View View View Breakdown product No Not Listed
56507-37-0 Related 5a Diketo-metribuzin View View View Breakdown product No Not Listed
Related 5a Metribuzin-DA View View View Breakdown product No Not Listed
Working with the Information on this Page

Click on underlined terms for definitions or go to the Pesticide Tutorial overview page.

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* Data marked with an asterisk indicates that this chemical is not explicitly listed on the corresponding list. Instead, it belongs to a group of chemicals that IS designated on the list. For example, if an agency assigns a classification of reproductive toxicant to "mercury compounds", that classification is applied to all mercury compounds in the PAN Pesticide database, which are then marked with an asterisk.

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