Toxicants & Fumigants

A toxicant is a poisonous substance – it causes harm  and even death of an organism. A fumigant is a a type of toxicant. It is a pesticide that volatilizes, forming a toxic vapor or gas that kills in the gaseous state. Regulations regarding the use of toxicants change over time as new products are developed and research has new findings. In particular, due to the risk and number of poisonings from rodenticides, consumer use of some products is being reconsidered. Read labels before purchasing any toxicant to make sure that you can legally use it as the label directs. Some require training and state certification as a pesticide applicator prior to use.

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Definitions – See Glossary

Toxicant – substance used to poison a problem animal, typically through ingestion, although it can be inhaled as a gas.

Fumigant – gas used to poison a nuisance animal as it breathes.

General Use Pesticides (GUP) – may be purchased over-the-counter.

Restricted Use Pesticides (RUP) – require a pesticide applicator’s license to purchase and use.

Secondary poisoning – Injury to an organism that ate the animal that was poisoned originally.

Facts about Pesticides

  • No one can guarantee where a poisoned animal will die.
  • No pesticide can be called “SAFE”. You can only use pesticides more safely or less safely.
  • Most negative incidents with toxicants, including fumigants, occur because the applicator failed to follow the instructions on the label.


1. Phosphine Gas

  • Phostoxin– Degesch America
    • Fumigation Management Plan (FMP) is required when using this product.

2. Charcoal-Potassium Nitrate

Used as a rodent fumigant in burrows, carbon (charcoal) formulated with several other pesticide active ingredients (sodium and potassium nitrates and sulfur), is used in pyrotechnic fumigant gas cartridge products. When a cartridge is ignited and placed in a pest burrow, it produces carbon monoxide and other gases that kill target pests.

Toxicants in Rodenticides


First Generation Active Ingredient Feeding
  Warfarin Multi-feed
  Chlorophacinone Multi-feed
  Diphacinone Multi-feed
Second Generation    
  Brodifacoum Single Feed
  Bromadiolone Single Feed
  Difenacoum Single Feed
  Difethialone Single Feed


Active Ingredient Feeding Mode of Action
Bromethalin Single Feed Interferes with the animal’s nervous system
Cholecalciferol Single Feed Causes internal bleeding and kidney injury by increasing calcium levels to  a lethal level
Zinc Phosphide Single Feed Blocks cells from making energy, and the cells die


Bait Station Use – 2012. Univ. of Nebraska-Lincoln

Restrictions on Rodenticide Products – 2021. US EPA 

Rodenticides – National Pesticide Information Center (NPIC)

Rodenticide Fact Sheet – National Pesticide Information Center (NPIC)