Q. Why do we need a toxic bait for feral swine?

A. Feral swine (also called wild pigs, Eurasian boar, or feral hogs) are a harmful

and destructive invasive species causing damage and disease threats to crops,

public property, native ecosystems, livestock health, and human health. More

than 6 million feral swine are located in at least 35 states across the United

States. Their damages to agricultural crops alone are estimated at $190 million

each year.

Although trapping, aerial operations, and recreational hunting of feral swine have 

effectively reduced damage in some areas, studies show that at least 70 percent 

of feral swine must be removed each year in order to prevent population growth. 

A toxic bait for use with feral swine is another tool in the toolbox for integrated 

feral swine damage management. Since 2013, Wildlife Services' National Wildlife 

Research Center (NWRC) scientists and collaborators have been evaluating the 

potential use of a bait containing sodium nitrite as a feral swine toxicant.

Q. What is sodium nitrite?

A. Sodium nitrite (NaNO2) is a meat preservative commonly used to cure meats

such as sausage and bacon. When eaten in high doses over a short period of

time, it is toxic to feral swine.

Q. How does it work?

A. An overdose of sodium nitrite reduces the ability of blood to transfer oxygen to

tissues, a condition known as methemoglobinemia. The mode of death is similar

to carbon monoxide poisoning. Once enough sodium nitrite bait is eaten, the feral

swine gets faint, is rendered unconscious, and quickly dies. In most cases, feral

swine die within 2.5 to 3 hours after eating a lethal dose.

Q. How is the toxicant delivered?

A. A micro-encapsulation coating is placed around sodium nitrite prior to

manufacturing the feral swine bait. This helps to protect sodium nitrite from

breaking down, and hides its odor and salty flavor. The micro-encapsulated

Protecting People

Protecting Agriculture

Protecting Wildlife

Wildlife Services Factsheet

January 2018

Questions and Answers: 

Sodium Nitrite Toxic Bait for Feral Swine

Wildlife Services (WS), a 

program within the U.S. 

Department of Agriculture’s 

(USDA) Animal and Plant 

Health Inspection Service 

(APHIS), provides Federal 

leadership and expertise 

to resolve wildlife conflicts

that threaten the Nation’s 

agricultural and natural 

resources, human health and 

safety, and property.

Created in 2014, the APHIS 

National Feral Swine Damage 

Management Program is a 

nationally-coordinated effort 

among Federal, State, Tribal 

and local entities to manage 

feral swine damage and stop 

their spread.

Wildlife Services is 

developing and testing 

swine-specific bait delivery 

systems and baiting 

strategies.
sodium nitrite is mixed with an oil-based bait (peanut paste) to 

attract feral swine and improve stability. The microencapsulation coating rapidly dissolves once eaten by feral 

swine, allowing the active ingredient (nitrite) to enter the 

bloodstream. Studies using bait with 10% sodium nitrite have 

resulted in feral swine mortality rates as high as 95%. 

Approximately 1/3 lb. of bait of this concentration is lethal to a 

70 lb. feral swine.

Q. What are the risks to non-target species, scavengers

and the environment?

A. Many factors are considered when developing a toxic bait.

Not only must it be effective and humane in eliminating feral

swine, but also low risk for those handling it, the environment,

and wildlife. Other wildlife, such as raccoons, bears and deer,

may be attracted to the bait. Sodium nitrite can be toxic to other

animals if eaten at high amounts over a short time period. To

prevent other species from accessing the bait, NWRC

scientists are developing and testing swine-specific delivery

systems and baiting strategies.

The majority of sodium nitrite eaten by feral swine is 

metabolized prior to death. Any remaining sodium nitrite in the 

carcass continues to break down, limiting the risk of hazards 

to scavenging animals. The compound also degrades quickly 

when exposed to environmental elements, such as 

microorganisms, sunlight, heat, and moisture.

Q. How will hunters know if a feral swine has eaten

sodium nitrite bait and what are human health impacts?

A. It is unlikely that a hunter will shoot a feral swine exposed

to a lethal dose of sodium nitrite because animals die within a

few hours of eating the bait. If a swine does not eat enough

bait to become sick, it simply metabolizes the remaining

sodium nitrite. If a treated feral swine is killed by a hunter

before it succumbs to the toxicant, its blood would be

unusually thick and chocolate brown in color.

Preliminary data show low levels of nitrite in the meat of feral 

swine killed with sodium nitrite. However, the EPA 

assessment of human health impacts is ongoing. The

stomach and digestive tract of treated feral swine will contain 

sodium nitrite residues and residual bait. These organs 

should be discarded. Skin contact with sodium nitrite bait is 

not considered harmful under normal circumstances.

However, persons with a peanut allergy should avoid all

contact with the bait or digestive tract contents. Pesticide

labels typically require the use of gloves when handling

products and health experts recommend hunters wear gloves 

and other protective equipment when processing feral swine

to protect against diseases the animals may carry.

Federal and state regulations concerning the use of a sodium 

nitrite toxicant have not yet been developed. The U.S. 

Environmental Protection Agency (EPA) will evaluate any 

potential risks to human health during the registration 

process.

Q. Is the toxic bait available for use?

A. No. The goal is to register the sodium nitrite bait for use

with feral swine with the EPA by 2020-2021. In 2016, an

application was submitted to the EPA by APHIS Wildlife

Services for an experimental use permit to conduct field trials

starting in 2018.

Q. Who will be allowed to use the toxic bait?

A. If registered by the EPA, the toxic bait will be available for

use by APHIS Wildlife Services certified applicators or those

working under their authority.

Q. How can I learn more?

A. For more information, please go to www.aphis.usda.gov/

wildlife-damage/feral-swine or www.aphis.usda.gov/

wildlifedamage/nwrc on the Web.

United States Department of Agriculture

Animal and Plant Health Inspection Service

The U.S. Department of Agriculture is an equal opportunity provider and employer.

Mention of companies or commercial products does not imply recommendation or endorsement by the USDA over others not mentioned. The USDA neither guarantees 

nor warrants the standard of any product mentioned. Product names are mentioned solely to report factually on available data and to provide specifi c information.