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Zero Animal Testing Proposed in Tier 0 Toxicology Testing

Little is known about the toxicity of many of the estimated 70,000 chemicals in commerce in the United States. To address this growing public health dilemma, chemicals of greatest concern need to receive priority. At a recent conference, PCRM advocated for greater use of “tiered” testing approaches that reduce the number of animal-based toxicity tests, which often have questionable value for predicting human health effects.

MouseAt the Society for Risk Analysis conference in Boston, Nancy Beck, Ph.D., PCRM scientific adviser, presented “Tiered Testing: The Animal Welfare Perspective” to an audience of scientists, government regulators, and chemical manufacturers. Dr. Beck stressed that, although it is impossible to test all of these chemicals using existing methods—because of cost, time, and most importantly, the number of animals required—“tiered” approaches allow regulators to eliminate low-risk chemicals that need not be tested further.

Tiered testing programs, used by federal regulatory agencies such as the Environmental Protection Agency (EPA), begin with quick and simple first-tier tests and then progress to more specialized, higher-tiered tests when early tests reveal reason for concern.

This system limits the number of chemicals tested and the amount of testing performed for each, effectively reducing the amount of animal testing conducted. To further reduce the number of animal-based toxicity tests performed, testing programs should implement a nonanimal “tier 0” as the first step in a testing strategy, Dr. Beck recommended.

Use of a tier 0—based on computer modeling and quick and inexpensive in vitro methods—would allow regulators to narrow their focus to chemicals of concern even earlier. Ultimately, this would reduce the cost, time, and animal deaths associated with higher-tiered testing—benefiting animals, public health, regulators, and manufacturers.

Dr. Beck also argued that the nonanimal methods proposed for tier 0 are more predictive of toxic effects in humans. These methods are based on an understanding of the molecular pathways that lead to toxicity in humans, allowing scientists to better define how a chemical exerts its toxic effects. This means more accurate predictions for human health without the standard toxicity tests that often result in the painful deaths of hundreds or thousands of animals per chemical.

PCRM is working diligently to ensure that these new nonanimal methods will completely replace the animal methods used in the higher tiers. And PCRM is not alone in requesting that cutting-edge nonanimal technology replace cruel, antiquated, and inappropriate animal testing.

The ToxCast Program at the EPA’s National Center for Computational Toxicology has been outlining a similar approach. By using computer modeling and in vitro methods to identify key toxicity pathways, these scientists hope to gain a better understanding of a broad range of chemicals’ mechanisms of action and molecular affects to better predict hazard and prioritize chemicals for testing.

The prestigious National Research Council (NRC) has recommended that the chemical industry and government make similar nonanimal approaches a priority. In the NRC report “Toxicity Testing in the 21st Century: A Vision and a Strategy,” the organization outlined the following goals for the future of toxicity testing:

  • Broader coverage of chemicals, mixtures, outcomes, and life stages
  • Reductions in cost and duration of testing
  • Use of fewer animals and reduction of suffering in those used
  • Development of a more robust scientific strategy for assessing health effects, based on human cells and tissues.

And as Europe’s Regulation on Registration, Evaluation, Authorisation, and Restriction of Chemicals, and the United States’ Toxic Substances Control Act demand quicker assessment of a wider range of chemicals, the only way to meet this demand is through new, nonanimal approaches.

For more information on PCRM’s work to stop animal testing of industrial chemicals, visit the Testing of Industrial Chemicals: Strategies that Save Animals section.

Nancy Beck, Ph.D.
Nancy Beck, Ph.D.

PCRM Online, January 2009

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