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Technical Fact Sheet

As of 2011, NPIC stopped creating technical pesticide fact sheets. The old collection of technical fact sheets will remain available in this archive, but they may contain out-of-date material. NPIC no longer has the capacity to consistently update them. To visit our general fact sheets, click here. For up-to-date technical fact sheets, please visit the Environmental Protection Agency’s webpage.

Molecular Structure -

Laboratory Testing: Before pesticides are registered by the U.S. EPA, they must undergo laboratory testing for short-term (acute) and long-term (chronic) health effects. Laboratory animals are purposely given high enough doses to cause toxic effects. These tests help scientists judge how these chemicals might affect humans, domestic animals, and wildlife in cases of overexposure.

Chemical Class and Type:

Physical / Chemical Properties:


Mode of Action:

Target and Non-target Organisms

Acute Toxicity:



High Toxicity Moderate Toxicity Low Toxicity Very Low Toxicity
Acute Oral LD50 Up to and including 50 mg/kg
(≤ 50 mg/kg)
Greater than 50 through 500 mg/kg
(>50-500 mg/kg)
Greater than 500 through 5000 mg/kg
(>500-5000 mg/kg)
Greater than 5000 mg/kg
(>5000 mg/kg)
Inhalation LC50 Up to and including 0.05 mg/L
(≤0.05 mg/L)
Greater than 0.05 through 0.5 mg/L
(>0.05-0.5 mg/L)
Greater than 0.5 through 2.0 mg/L
(>0.5-2.0 mg/L)
Greater than 2.0 mg/L
(>2.0 mg/L)
Dermal LD50 Up to and including 200 mg/kg
(≤200 mg/kg)
Greater than 200 through 2000 mg/kg
(>200-2000 mg/kg)
Greater than 2000 through 5000 mg/kg
(>2000-5000 mg/kg)
Greater than 5000 mg/kg
(>5000 mg/kg)
Primary Eye Irritation Corrosive (irreversible destruction of ocular tissue) or corneal involvement or irritation persisting for more than 21 days Corneal involvement or other eye irritation clearing in 8 - 21 days Corneal involvement or other eye irritation clearing in 7 days or less Minimal effects clearing in less than 24 hours
Primary Skin Irritation Corrosive (tissue destruction into the dermis and/or scarring) Severe irritation at 72 hours (severe erythema or edema) Moderate irritation at 72 hours (moderate erythema) Mild or slight irritation at 72 hours (no irritation or erythema)
The highlighted boxes reflect the values in the "Acute Toxicity" section of this fact sheet. Modeled after the U.S. Environmental Protection Agency, Office of Pesticide Programs, Label Review Manual, Chapter 7: Precautionary Labeling. https://www.epa.gov/sites/default/files/2018-04/documents/chap-07-mar-2018.pdf


Signs of Toxicity - Animals

Signs of Toxicity - Humans

Chronic Toxicity:



Exposure: Effects of fipronil on human health and the environment depend on how much fipronil is present and the length and frequency of exposure. Effects also depend on the health of a person and/or certain environmental factors.

Endocrine Disruption:



Cancer: Government agencies in the United States and abroad have developed programs to evaluate the potential for a chemical to cause cancer. Testing guidelines and classification systems vary. To learn more about the meaning of various cancer classification descriptors listed in this fact sheet, please visit the appropriate reference, or call NPIC.


Reproductive or Teratogenic Effects:



Fate in the Body:





Medical Tests and Monitoring:

The "half-life" is the time required for half of the compound to break down in the environment.

1 half-life = 50% remaining
2 half-lives = 25% remaining
3 half-lives = 12% remaining
4 half-lives = 6% remaining
5 half-lives = 3% remaining

Half-lives can vary widely based on environmental factors. The amount of chemical remaining after a half-life will always depend on the amount of the chemical originally applied. It should be noted that some chemicals may degrade into compounds of toxicological significance.

Environmental Fate:






Food Residue

Ecotoxicity Studies:


Fish and Aquatic Life

Terrestrial Invertebrates

Regulatory Guidelines:

Date Reviewed: January 2009

Please cite as: Jackson, D.; Cornell, C. B.; Luukinen, B.; Buhl, K.; Stone, D. 2009. Fipronil Technical Fact Sheet; National Pesticide Information Center, Oregon State University Extension Services. http://npic.orst.edu/factsheets/archive/fiptech.html.


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  3. Ying, G. G.; Kookana, R. S. Sorption of Fipronil and Its Metabolites on Soils From South Australia. J. Environ. Sci. Health 2001, B36 (5), 545-558.
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  17. Mohamed, F.; Senarathna, L.; Percy, A.; Abeyewardene, M.; Eaglesham, G.; Cheng, R.; Azher, S.; Hittarage, A.; Dissanayake, W.; Sheriff, M. H. R.; Davies, W.; Buckley, N. A.; Eddleston, M. Acute Human Self-poisoning with the N-Phenylpyrazole Insecticide Fipronil--a GABAA-Gated Chloride Channel Blocker. J. Toxicol. Clin. Toxicol. 2004, 42 (7), 955-963.
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