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Advancing the next generation of chemical safety evaluation

Human Disease Outcome

How ToxCast Fits Into CompTox Research

Status of ToxCast Development
  • Phase I: The "Proof of Concept" completed in 2009 profiled roughly 300 well studied chemicals (primarily pesticides). The chemicals included in Phase I have over 30 years of existing toxicity data since they have already been tested using traditional toxicology methods (primarily animal studies). This animal study data can be searched and queried using EPA's Toxicity Reference Database (ToxRefDB) that stores nearly $2 billion worth of studies.
  • Phase II: Screened 1,800 chemicals from a broad range of sources including: industrial and consumer products, food additives, touted "green" products, nanomaterials and drugs that never made it to the market. The chemicals were screened in more than 800 in vitro high-throughput screening assays.

A major part of EPA’s CompTox research is the Toxicity Forecaster (ToxCast™). ToxCast is a multi-year effort launched in 2007 that uses automated chemical screening technologies (called "high-throughput screening assays") to expose living cells or isolated proteins to chemicals. The cells or proteins are then screened for changes in biological activity that may suggest potential toxic effects and eventually potential adverse health effects. These innovative methods have the potential to limit the number of required laboratory animal-based toxicity tests while quickly and efficiently screening large numbers of chemicals.

Chemical Prioritization

ToxCast data is starting to help inform chemical prioritization.

  • EPA's Endocrine Disruption Screening Program has already started the scientific review process needed to begin using ToxCast data to prioritize the thousands of chemicals that need to be tested for potential endocrine-related activity.
  • Other potential uses include prioritizing chemicals that need testing under the Toxic Substance Control Act and informing the Safe Drinking Water Act’s candidate contaminant lists.
Research Overview
  • ToxCast has evaluated over 2,000 chemicals from a broad range of sources including: industrial and consumer products, food additives, and potentially "green" chemicals that could be safer alternatives to existing chemicals. Chemicals were evaluated in over 700 high-throughput assays that cover a range of high-level cell responses and approximately 300 signaling pathways.
  • Research is ongoing to determine which assays under what conditions may lead to toxicological responses. The results of this research can then be used to inform the context in which decision makers can use the data.
  • ToxCast results are contributed to the federal agency collaboration called Toxicity Testing in the 21st Century (Tox21). Tox21 pools chemical research, data and screening tools from multiple federal agencies including the National Toxicology Program/ National Institute of Environmental Health Science, National Center for Advancing Translational Sciences and the Food and Drug Administration. So far, Tox21 has compiled high-throughput screening data on nearly ten thousand chemicals.
  • As part of EPA’s commitment to gather and share its chemical data in open and transparent ways, all ToxCast chemical data is publicly available for anyone to access and use through user-friendly web applications called "interactive Chemical Safety for Sustainability Dashboards or iCSS for short.

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