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  1. Biological, Chemical, and Physical Contaminants in Animal Food

Chemical Hazards

Chemical contaminants cover a broad range of contaminants, including naturally occurring components of certain food ingredients (e.g., glucosinolates), toxins produced by microorganisms found in the environment (e.g., mycotoxins), pesticides, and industrial chemicals. CVM routinely monitors many chemical contaminants under its Animal Food Contaminants program, like mycotoxins, pesticides, heavy metals, and dioxins.

On this page:

Mycotoxins

  • Aflatoxins
  • Deoxynivalenol
  • Fumonisin
  • Ochratoxin A
  • Zearalenone

Pesticides

Industrial Chemicals

Heavy Metals

Miscellaneous Contaminants


Mycotoxins

Mycotoxins are toxic metabolites of certain fungi (molds) that can grow on agricultural commodities in the field and during storage. The occurrence of these toxins on grains, seeds, and complete animal food is influenced by various environmental factors, such as temperature, humidity, and rainfall during growing, harvesting, and storage. When fungal growth occurs, mycotoxins are produced in commodities; some of which are used in animal food. The mycotoxins will then remain in the food throughout every phase of food production. Mycotoxins are difficult to eliminate because they are not destroyed by most of the processes used in animal food production. When consumed by animals or humans, the results can be detrimental, resulting in illness or even death. The effects of mycotoxins can manifest in a variety of ways, including neurologic impairment, liver, kidney, or heart failure. 

To prevent mycotoxins from becoming an animal health hazard, animal food manufacturers are required to conduct a hazard analysis that identifies potential hazards within the manufacturing process and provide evidence of consistent monitoring and preventive controls for mycotoxins in animal food.

Aflatoxins

Aflatoxins are produced by molds of the Aspergillus species. Aflatoxins are among the most well-known mycotoxins due to their high level of toxicity in many animals and people. Aspergillus can grow on grains and seeds during growing season as well as after harvest during storage. The amount of fungal growth and the resulting aflatoxin level in food ingredients is influenced by the temperature and humidity and can vary from year to year. 

Aflatoxins are potent toxins and known carcinogens, so their levels in food should be limited to the lowest practical level. Aflatoxins are also known to cause liver damage and liver failure in animals. Animals that consume aflatoxin-contaminated food can also transfer the toxins to meat, milk, and eggs, potentially exposing humans to a health hazard.

Deoxynivalenol

Deoxynivalenol (DON, or vomitoxin), is produced by Fusarium graminearum, a mold commonly associated with grains such as wheat, barley, oats, and corn.

Its most notorious disease commonly affects wheat and is known as Fusarium Head Blight (FHB). Infestation can occur throughout the cultivation process and generally initiate decomposition. If wheat infested with fusarium mold makes its way into the diets of humans, it may cause symptoms such as vomiting, diarrhea, abdominal pain, headaches, dizziness, fever, and it may cause immunological issues. Animals, too, will suffer from vomiting and abdominal pain. In animals, swine are the most susceptible.

Fumonisin

Fumonisins are toxins produced by various molds of the Fusarium genus (e.g., F. moniliforme, F. verticillioides, and F. proliferatum) that are common, natural contaminants of corn. Fumonisins can cause leukoencephalomalacia in horses and pulmonary edema in pigs. They have been linked to a variety of significant adverse health effects in other livestock and experimental animals. Fumonisin B1 is known to induce kidney tumors in male rats and liver tumors in female mice when they consume food containing 50 ppm fumonisin and above. A wide variety of significant adverse animal health effects such as neurological symptoms, cardiopulmonary failures, and kidney failure have been associated with fumonisins. Horses are extremely susceptible to the harmful effects of fumonisins.

Ochratoxin A

Ochratoxin A is a fungal toxin produced regularly by Aspergillus and Penicillium molds. The contaminant, ochratoxin A, can be found in cereals. It is acknowledged as a carcinogen in mice.

Although the FDA has placed limitations on the quantity allowed in animal food, there are still complications because of its heat tolerance. Most fungi would be destroyed when the food is properly cooked, avoiding the adverse effects in animals and humans upon consumption, but Ochratoxin A is resistant to heat.

Zearalenone

Zearalenone (ZEA) is produced by the growth of the fungus Fusarium graminearum on food commodities. This mold grows best on foods during periods of low temperatures coupled with high humidity, although it can grow during other weather conditions as well. When animals or humans are exposed to zearalenone at low levels for brief periods there may not be any visible symptoms, as ZEA has a low toxicity. However, when the toxin is present in food at high levels or when there is long term exposure at low levels, it can cause reproductive disorders.

Guidance

Additional Information

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Pesticides

Section 408 of the Federal Food, Drug, and Cosmetic Act (FD&C Act) authorizes the U.S. Environmental Protection Agency (EPA) to set tolerances, or maximum residue limits, for pesticide residues on foods. Under the FD&C Act, FDA has the responsibility to enforce EPA-established pesticide tolerances in foods imported into the United States and domestic foods shipped in interstate commerce (with the exception of meat, poultry, and certain egg products, regulated by the Food Safety Inspection Service of the U.S. Department of Agriculture). To accomplish this task, both the Center for Food Safety and Applied Nutrition and CVM manage a Pesticide Residue Monitoring Program. Each year, FDA investigators collect a variety of animal food samples as part of CVM’s Feed Contaminants Compliance Program and sends them to the Office of Regulatory Affair’s laboratories for pesticide analysis. This program allows FDA to gather information on pesticide residues in animal foods and food ingredients, thereby protecting both human and animal health.

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Industrial Chemicals

Dioxins/PCBs

Dioxins and polychlorinated biphenyls (PCBs) are persistent environmental pollutants resulting from industrial processes. Their toxicity varies, but some of the dioxin and PCB congeners may be carcinogens at low levels of exposure over extended periods of time.

  • There are no tolerances or other administrative levels established by the FDA for dioxins in animal food.
  • Temporary tolerances for PCBs in animal food can be found in 21 CFR 509.30.

FDA, in conjunction with the European Union, the U.S. EPA, and USDA, is addressing both international and domestic dioxin and PCB concerns in animal food. One example of each is provided below.

Domestic Dioxin Concern

In July 1997, FDA found contamination of animal food with dioxin, which resulted in elevated levels of dioxin in chickens, eggs and catfish. Dioxin contamination was found in animal food distributed to over 3,400 consignees throughout the country.

FDA's Response

  • The source of the dioxin contamination was traced to a mined clay product called "ball clay," which is used as an anti-caking agent in soybean meal, in other feed components, and in complete animal food.
  • CVM worked cooperatively with the affected industries to halt any further distribution and use of the animal food known to be contaminated with dioxin. This was carried out across the country.
  • In 1999, ball clay was not accepted for use as an ingredient by the Association of American Feed Control Officials.
  • In FY 1998, FDA initiated steps to determine whether other mined clay products and naturally derived anticaking agents were contaminated with dioxin.
  • Industry associations met with CVM to determine the type of information needed, which resulted in a compilation of industry sampling of anticaking agents for dioxins.

FDA, with analytical assistance from EPA, surveyed mined animal food ingredients for the presence of dioxins, as a supplement to industry sampling.

International PCB Concern

FDA received information that fat from a rendering company in Belgium was contaminated with PCBs and dioxin in January of 1999. This product was shipped to animal food manufacturers and incorporated into animal food distributed to poultry, hog, and cattle farms in Belgium, France, and the Netherlands, with the majority of the product going to Belgium. Analysis of chickens and eggs in Belgium revealed elevated PCBs levels and low levels of dioxins.

FDA's Response

  • On June 4,1999, FDA issued an Import Bulletin to the field directing animal food and animal by-products for animal food from France, Belgium, and Netherlands, and egg-containing products, from Belgium offered for entry into the U.S. to be held at the port of entry.
  • On June 11, 1999, FDA issued Import Alert 99-24, "Detention Without Physical Examination of Human Food Products and Animal Feeds Contaminated with Dioxin and/or PCB Compounds".

On August 23, 1999, FDA issued a guidance representing the Agency's current thinking on possible dioxin/PCB contamination of animal source material in EU countries: Guidance for Industry: Possible Dioxin/PCB Contamination of Drug and Biological Products.

Melamine

Melamine has been approved by the FDA for use in packaging, adhesives, filters, and use in other food contact surfaces. Thus, there may be low levels of melamine in domestic food as a result of these approved uses in the United States. In other countries, melamine is a frequent component of fertilizers. When feed or food become contaminated with both melamine and cyanuric acid, the combination can be hazardous to both animals and humans because the combination can form crystals that block the kidney.

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Heavy Metals

Heavy metals are inherent to the environment and can be both helpful and harmful, nonetheless, they are frequently present in animal food. The difficulty to eliminate these metals from diets is irrefutable as they are naturally absorbed by florae used in animal food production. Under the Feed Contaminant program, the FDA routinely tests animal food, including pet food, for heavy metals.

There are two types of metals that are regulated.

  • The first are imperative to the animals’ health. They might help with growth, weight, or be required by the body in its rebuttal of diseases. If the animal is not provided with enough of this type of metal, there may be weight loss or other symptoms that could be fatal.
  • The second are non-essential and these consist of metals that neither help nor harm the organisms. These also might be metals that could be tolerated by the animal, but lethal to humans when passed on through their byproducts.

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Miscellaneous Contaminants

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