The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Bromadiolone (CAS 28772-56-7)
- Chemical class
- Hydroxycoumarin anticoagulant; a single-dose (second-generation) anticoagulant.[2][3]
- Mode of action
- Anticoagulant: blocks the liver enzyme that recycles vitamin K, which blood clotting depends on; insecticide resistance groups do not apply to rodenticides[2]
- Signal word
- Contrac All-Weather Blox: Caution[1]
How it works
Anticoagulants stop the liver enzyme that recycles vitamin K, which the body needs to make clotting factors; once stored clotting factors run out, uncontrolled bleeding follows. That is why signs can be delayed for days.[2]
Single-dose anticoagulants are more toxic than older multiple-feeding ones because they bind the enzyme more tightly, and they are stored in the liver rather than quickly excreted.[2]
What homeowners can use instead
Products sold to homeowners must be ready-to-use bait stations; EPA allows only bait stations containing bromethalin, chlorophacinone or diphacinone to be sold to consumers.[3]
Where it is used
Second-generation anticoagulants like bromadiolone are for professional and agricultural users and are not to be sold in consumer stores.[3]
Labeled for house mice, Norway rats and roof rats in and within 100 feet of buildings. Tamper-resistant bait stations are mandatory outdoors above ground and wherever children, pets or non-target animals could reach the bait.[1]
For rats the label calls for 3 to 16 one-ounce blocks per placement, 15 to 30 feet apart, kept supplied for 10 days or until feeding stops; for mice, 1 block per placement every 8 to 12 feet for 15 days.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Contrac All-Weather Blox[1] | Bell Laboratories, Inc. | 12455-79 | 0.005% | bait block | Caution |
Safety and environmental hazards
People
Signal word CAUTION: harmful if swallowed or absorbed through the skin. Swallowing it can reduce the blood's ability to clot and cause bleeding; the label tells physicians to give vitamin K1 and repeat it as needed based on clotting tests.[1]
Pets
If a pet eats the bait, call a veterinarian at once. Vets give vitamin K1 and may check clotting times every three days for up to 30 days. NPIC rates bromadiolone a high secondary-poisoning risk to mammals, so dogs and cats can be poisoned by eating poisoned rodents.[1][2]
Bees and pollinators
The label lists no bee hazard; its warnings are about fish, birds and mammals.[1]
Fish and water
The label says it is extremely toxic to fish, birds and other wildlife, and that predatory and scavenging animals may be poisoned by eating rodents that ate the bait; NPIC rates its secondary risk to birds as moderate.[1][2]
Common questions
Sources
- U.S. EPA Pesticide Product Label System, “Contrac All-Weather Blox label, EPA Reg. No. 12455-79 (EPA-stamped, Feb. 13, 2020).” www3.epa.gov/pesticides/chem_search/ppls/012455-00079-20200213.pdf (accessed 2026-10-06)
- National Pesticide Information Center, “Rodenticides Topic Fact Sheet.” npic.orst.edu/factsheets/rodenticides.html (accessed 2026-10-06)
- U.S. Environmental Protection Agency, “Restrictions on Rodenticide Products.” www.epa.gov/rodenticides/restrictions-rodenticide-products (accessed 2026-10-06)