Zinc phosphide is an acute (single-dose) rodenticide that kills within hours. When ingested, stomach acid converts it to phosphine gas, which is lethal. It's the preferred rodenticide for outdoor/agricultural use because it poses minimal secondary poisoning risk — predators that eat poisoned rodents are unlikely to be harmed.
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Classification
Inorganic Rodenticide (Acute Toxin)
Signal Word
Danger
Mode of Action
Phosphine gas generation: stomach acid reacts with zinc phosphide → releases phosphine gas → cellular suffocation
Rats, mice, voles, gophers, ground squirrels, prairie dogs, moles (with proper baiting). Used extensively in agriculture for field rodent control. Not commonly used indoors due to odor and formulation type.
🏷️ Products & Brand Names
ZP Rodent Bait (Bell Labs), ZP Gopher Bait, Prozap Zinc Phosphide, Eraze (mouse bait), many agricultural formulations. Restricted Use Pesticide in some formulations — check state regulations.
⚠️ Safety & Precautions
HIGHLY TOXIC — signal word is "Danger." Toxic to all mammals if ingested. No antidote — treatment is supportive care only.
⚠️ DANGER: Zinc phosphide is acutely toxic to humans, pets, and all mammals. Store securely. Use tamper-resistant bait stations when possible. If a pet ingests zinc phosphide bait, seek emergency veterinary care IMMEDIATELY — time is critical. Do not induce vomiting (phosphine gas release in stomach is the killing mechanism).
✅ Reduced secondary poisoning: The key advantage of zinc phosphide over anticoagulant rodenticides is minimal secondary poisoning risk. The compound is metabolized quickly, so predators (hawks, owls, cats) that eat a poisoned rodent receive a much lower dose. This is why it's preferred in areas with raptor populations.
Example
0.5 oz
per gallon
⚗️ Mixing Calculator
Enter your sprayer size and target rate — get the exact amount to pour. Backpack, hand sprayer, hose-end, or skid unit.
For gophers: Zinc phosphide gopher bait placed directly in active burrow systems is one of the most effective gopher control methods. Probe for the main tunnel, drop bait in, and close the hole. Check in 48 hours.
Bait shyness: Zinc phosphide has a strong garlic-like odor and taste. Rodents can develop "bait shyness" — if they eat a sublethal dose and survive, they'll avoid it forever. This means proper placement and fresh bait are critical. One shot is all you get.
Pre-baiting: For rats and mice, pre-baiting with untreated grain for 2-3 days before switching to zinc phosphide bait dramatically improves acceptance. The rodents become accustomed to feeding at the location.
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💡 Acute rodenticide — releases phosphine gas in stomach. Low secondary poisoning risk. Restricted Use Pesticide.
❓ Frequently Asked Questions
Q: Is zinc phosphide safe for pets?
Follow the product label. Keep pets out of treated areas until completely dried (2–4 hours for sprays). Once dry, treated surfaces pose minimal risk to dogs and cats.
Q: Can I use zinc phosphide indoors?
Check the specific product label — formulations vary. Baits and dusts often have indoor labeling; concentrates and granulars are typically outdoor.
Q: How long does zinc phosphide last after application?
Residual varies by formulation, surface type, weather, and UV exposure. Indoor applications last longer than outdoor. Check the product label for re-application intervals.
Q: What should I do if exposed?
Remove contaminated clothing, wash skin with soap and water. For eye contact, rinse 15–20 minutes. For ingestion or severe symptoms, call Poison Control (1-800-222-1222). Have the product label available.
📋 Safety Data Sheet (SDS)
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Zinc Phosphide Rodenticide — Safety Data Sheet
View the official SDS document for this product directly on the CDMS label database.
💡 Did you know? Zinc phosphide has been used as a rodenticide since the 1930s. During WWII, it was the primary rodent control agent used by the US military to protect food supplies. Its minimal secondary poisoning risk makes it the rodenticide of choice in wildlife-sensitive areas.
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Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional. Last reviewed: April 2026.
