Paules said Tox21 is organized into a series of cross partner projects, which have clear goals, a limited period of 3 years, and designated benchmarks for deciding whether they should continue. (Photo courtesy of Steve McCaw)

Federal partners gathered at NIEHS May 15-16 to discuss the implementation of the new Toxicology in the 21st Century (Tox21) strategic plan.

“Most of the chemicals we use have undergone limited, if any, traditional testing for toxicity. Tox21 is working to fill that gap,” said Rick Paules, Ph.D., chief of the National Toxicology Program (NTP) Biomolecular Screening Branch and meeting chairperson. “This meeting is about implementation of our strategic plan and a check in on how we’re doing.”

For more than a decade (see sidebar), Tox21 has used automation and cell-based tests to rapidly measure the toxicity of chemicals with a mechanized, high-throughput approach. Paules celebrated Tox21 as a successful interagency collaboration between NTP, the National Center for Advancing Translational Sciences, the U.S. Environmental Protection Agency, and the Food and Drug Administration (FDA), as did Suzanne Fitzpatrick, Ph.D., who represents FDA on the Tox21 management team.

“We are pretty excited that the Tox21 strategic plan is incorporating many of the new emerging methods in addition to high-throughput methods,” Fitzpatrick said.

Emerging methods added, existing methods evolve

Elizabeth Maull, Ph.D., from NTP, provided an update from the Tox21 communications group. She highlighted the new interagency Tox21 website. (Photo courtesy of Steve McCaw)

Under the new strategic plan, NTP Tox21 activities will continue to refine prediction of chemical toxicity to humans.

• Enhanced methods for testing genetic toxicity will assess whether chemicals are toxic to thousands of genes in specific types of cells.
• Increased use of stem cells will support study of the effects of chemicals on developmental processes.
• New computational models will help to better predict the relationship between external chemical doses and resulting chemical concentrations in tissues.
• The Tox21 consortium will test toxicity in biological systems more complex than single cell types.
• Some testing will be done in alternative species like zebrafish.
• Tox21 is exploring the use of 3-D cellular models or tissue chip systems that model the structure and function of different organs, or even how these organs interact. Such approaches will not be as fast as current Tox21 assays, so testing thousands of compounds will have to be carefully strategized. 

The Tox21 consortium will continue to refine its high-throughput methods and is also developing performance standards to establish confidence in new approaches.

(Virginia Guidry, Ph.D., is a technical writer and public information specialist in the NIEHS Office of Communications and Public Liaison and a regular contributor to the Environmental Factor.)