Skip to main content icon/video/no-internet
icon backReturn to Entries

Toxicity Testing

Toxicity testing is a system of different forms of scientific research to establish the toxic dose of a substance either in humans or other living organisms in the environment. In terms of food, the most important toxicity testing is performed for the U.S. Food and Drug Administration (FDA): testing the safety of food additives. These include food color additives, food ingredients, and substances used in food packaging. If a company wants to use a new additive, it must petition for FDA approval after performing extensive research into the chemical, physical, and biological properties of the new additive. No testing is required if a substance falls under the category known as Generally Recognized as Safe (GRAS). Testing the safety or toxicity of a substance is performed based on biological models, testing on tissue in petri dishes, animal testing, and epidemiological studies. This entry describes the FDA classifications, the methods for testing toxicity, and the various types of additives requiring testing.

Classifications

Under the 1938 Federal Food, Drug, and Cosmetic Act (FD&C), any substance that is intentionally added to food (a food additive) is subject to pre-market review and approval by the FDA, unless the substance is generally recognized as having been adequately shown to be safe under the conditions of its intended use. “Generally recognized” means that it is acknowledged as safe by professionals in the field, has been established as safe through scientific procedure, or has been in use since before 1958 and is common enough that experience suggests that it is safe. By using food additives from the GRAS list, manufacturers can avoid the costly process of testing a new chemical and petitioning for FDA approval.

In addition to the lists of GRAS additives and certified food colors, there is a list of more than 3,000 substances in an inventory known as Everything Added to Food in the United States. This inventory is a list of FDA-evaluated substances, not all of substances that are found in food. Foods that are not GRAS must pass FDA regulations for toxicity testing. The necessary testing methods depend on the predicted human exposure levels and the toxicity of the chemical.

Methods

There are many methods for testing the toxicity of a chemical. The gold standard in toxicology continues to be animal testing, also known as in vivo testing. For ingestible chemicals, such as food additives, the most common animal subjects are rats and dogs. The first tests that are run are acute toxicity tests to determine the short-term lethal dose and to establish a dose–response curve. A group of animals, typically rats or mice, are matched by sex and age for control purposes. They are then treated with a specific dose of the chemical (e.g., 10 mg). The surviving animals are then killed, and all animals are necropsied for tissue examination. This process will then be repeated at increasing doses, such as a series testing of 10, 20, 40, and 80 mg concentrations. The level at which half of the animals die is known as lethal dose 50%, or LD50. Chronic exposure testing will typically take a year of exposure at a series of lower doses than acute toxicity because rodents are sometimes more or less sensitive to certain chemicals than other animals or humans. If subsequent testing is required, it will often occur in a nonrodent, such as a dog or monkey. Testing performed on a tissue culture, cellular components, or molecules (like DNA) is known as in vitro testing. Because of the costs and ethical concerns surrounding animal testing, in vitro testing and chemical modeling have become increasingly important in determining whether animal testing is considered necessary.

...

  • Loading...
locked icon

Sign in to access this content

Get a 30 day FREE TRIAL

  • Watch videos from a variety of sources bringing classroom topics to life
  • Read modern, diverse business cases
  • Explore hundreds of books and reference titles

Read next

More like this

Sage Recommends

We found other relevant content for you on other Sage platforms.

close

Have you created a personal profile? Login or create a profile so that you can save clips, playlists and searches

close
close
close Signed In to profile You are signed in as:
close
Logged in Institution Institution