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Rodenticide formulations

Quick answerVerified September 26, 2026

What is rodenticide formulations?

Rodent baits built on anticoagulants, which block vitamin K recycling so clotting fails and signs are delayed by days; cholecalciferol (vitamin D3), which overwhelms calcium regulation; or bromethalin, which stops nerve cells producing energy. Second-generation anticoagulants can kill from one feeding and persist in tissue, so EPA keeps them out of consumer products.

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Where it fits

First-generation anticoagulants where rodents will feed on the bait over several days. EPA describes warfarin-type compounds as much more toxic when feeding occurs on several successive days than on one day only. Second-generation compounds tend to stay in animal tissue longer than first-generation ones, so a multiple-feed active is the lower-residue choice where the programme can wait.
Second-generation anticoagulants in professional programmes only. Brodifacoum, bromadiolone, difenacoum and difethialone are registered only for the commercial and structural pest control markets, in containers of at least 16 pounds of bait (8 pounds for agricultural buildings). EPA describes them as more likely to kill after a single night's feeding. That potency is also the reason for the restriction.
Tamper-resistant stations as a label requirement, not an upgrade. Labels require tamper-resistant bait stations for outdoor above-ground placements and where children under six or pets may reach the bait. UC IPM adds nontarget mammals and birds to that list. Consumer products since the 2008 decision must be block or paste bait sold in a station. Loose pellets are not permitted.
Accounts where accidental human exposure is the main worry. Anticoagulant poisoning has a specific antidote, phytonadione (vitamin K1). EPA's clinical manual warns that vitamin K3 and K4 do not work, and that large second-generation ingestions may need treatment for as long as three or four months. Bromethalin has no known antidote and treatment is supportive only.

Where it does not

This is the part the brochure leaves out, so it is the part worth reading.

Treating secondary poisoning as theoretical. In liver samples from 43 red-tailed hawks admitted to a Massachusetts wildlife clinic from 2017 to 2019, every bird was positive for anticoagulant rodenticides, 91% carried two to four different compounds, and 14 were diagnosed with anticoagulant toxicosis. Brodifacoum, bromadiolone and difethialone were the compounds found most often. A predator that eats many poisoned rodents can build up a toxic dose over time.
Bromethalin as the automatically "safer" swap in homes with pets and children. It is one of only three actives allowed in consumer bait stations, but it has no antidote. In people and animals it causes cerebral oedema, and EPA's manual lists stupor, coma and possible seizures. Pick the active for the exposure risk at that site, not for how it is marketed.
Anywhere state law is stricter than the federal label. California now prohibits most uses of brodifacoum, bromadiolone and difethialone, and of the first-generation compounds diphacinone, chlorophacinone and warfarin. Almost all bait used in and around structures there must be in stations within 50 feet of a structure. A national protocol is not compliant in California.
Assuming the federal rules are settled. EPA's November 2024 final biological evaluation covered 11 rodenticides. It found currently labelled uses likely to adversely affect 1-8% of listed species. Its mitigation is geographically specific and tied to application method (bait station, in-burrow or broadcast). It will reach you through label language, terms of registration or Bulletins Live! Two. Carcass searches are held back for sites where other measures are not practical. Check the bulletin for the county before you bait.
Leaving dead and dying rodents on site. EPA's own reasoning for its mitigation is that some rodenticides stay in target animals long enough to affect the predators and scavengers that eat them. A baiting programme with no carcass pickup is a secondary exposure programme.

Sources

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