toxicity forecaster

Advancing Chemical Testing by the Thousands

Reposted from EPA Connect, the official blog of EPA leadership.

By Bob Kavlock

Bob Kavlock PortraitStudying thousands of chemicals at a time with the use of high-tech computer screening models and automated, often robot-assisted processes sounds like science fiction. But it’s not. EPA scientists are doing just that, leading the advancement of “high-throughput screening,” fast, efficient processes used to expose hundreds of living cells or isolated proteins to chemicals and then screen them for changes in biological activity—clues to potential adverse health effects related to chemical exposure.

This scientific advance is positioned to transform how we understand the safety of chemicals going forward. Twenty years ago, using high-throughput screening to test chemicals for potential human health risks seemed like technology that belonged in a science fiction television series rather than in real life.

Back then there were several large data gaps that would not allow us to extrapolate from the isolated biological changes we observe on a cellular level to adverse human health effects. However, through our computational toxicology (CompTox) research, which integrates, biology,

Robotic arm moving samples for screening

Robotic arm moves samples for automated chemical screening.

biotechnology, chemistry, and computer science, that is changing. We are helping to transform the paradigm of chemical testing from one that relies almost solely on expensive and time-consuming animal testing methods to one that uses the full power of modern molecular biology and robotics.

A significant part of this effort is the Toxicity Forecaster (ToxCast), launched in 2007. ToxCast allows us to prioritize potentially toxic chemicals for more extensive testing as well as giving us the opportunity to test newer, possibly safer alternatives to existing chemicals. By 2013, we evaluated more than 2,000 chemicals from industrial and consumer products to food additives using more than 500 high-throughput screening assays.

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Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Release the Data! New Chemical Data, Workshops, and Challenges

By Matthew T. Martin

Scientist prepares a well-plate for high-throughput screening.

Scientist preparing a well-plate for high-throughput screening.

Ever open that cabinet under the kitchen sink, grab that bright blue bottle of window cleaner and wonder exactly what sort of chemicals are floating around in it? Many of you have at one time or another, and for those of you who have never given it a second thought rest assured that my colleagues and I at EPA are dedicated to identifying and categorizing all of the chemicals we might be exposed to on any given day. However, due the expensive, time-consuming process of traditional testing, which assesses one chemical at a time, only a small fraction of the tens of thousands of chemicals currently in commerce have been adequately assessed for potential human and environmental health risks.

To close this data gap and better evaluate potential health risks, we have worked hard in recent years to accelerate the pace of chemical testing. I am proud to say that we have now completed phase two of the multi-year Toxicity Forecaster (ToxCast) project and are publically releasing ToxCast data on 1,800 chemicals evaluated in over 700 high-throughput screening assays. This is a significant accomplishment that we want to share with the scientific community.

The new data is accessible through the new interactive Chemical Safety for Sustainability (iCSS) Dashboard, a web-based application for users to access and interact with the data freely at their own discretion. Users can select the chemicals and data of interest and then score the information to help inform chemical safety decisions.

As part of the data release, I hope the scientific community will take advantage of this new windfall of data and become involved in the ToxCast project by participating in the Predictive Toxicology Challenges. The first two challenges of the series, available through TopCoder and InnoCentive crowd sourcing technology, will ask the scientific and technology community to develop new algorithms to predict lowest effect levels (LELs) of chemicals using the new ToxCast data. Winners will receive monetary prizes to help fund their own planned research, and their solutions will help us determine innovative ways to use ToxCast data to inform decisions made about the chemical safety.

Also, beginning January 14,we are also hosting several stakeholder outreach workshops and webinars to address potential challenges with data translation, accessibility, and any other troubleshooting issues that might arise during the initial data launch. This is an opportunity for the scientific community to provide input on data usage and offer immediate feedback about the new data and the iCSS dashboard.

About the author: Matthew T. Martin is a research biologist within EPA’s National Center for Computational Toxicology, where he is part of the ToxCast team and leads the CSS task for developing predictive models of toxicity using high-throughput screening data. He also serves as the project lead for developing the new CSS Dashboard Web Application.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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EPA Scientists Presented Open Science at White House

By Tina Bahadori

From weather forecasts, air quality advisories, and portable GPS navigation devices, to waterfowl migration, and the mapping of the human genome, the use of government and government-supported science and data have vastly improved our lives. They have also sparked countless new private businesses and industries leading to economic growth and opportunity for innovators and entrepreneurs in every region of the country.

Recognizing the power and potential of such Open Science, on June 20, 2013 the White House invited four EPA scientists—Drs. Richard Judson, Keith Houck, Matt Martin, and Ann Richard—to present research posters describing their efforts to provide public access to massive amounts of data from chemical safety studies. The scientists presented their posters after the White House’s “Champions of Change” award ceremony. The award ceremony recognized 13 Champions of Change for their efforts to provide the public access to innovative science.

In addition to the 13 Champions of Change, the White House selected 12 scientists (including the EPA researchers) to present posters describing their vision and commitment to Open Science.

EPA scientists at the White House poster session.

EPA scientists Ann Richard and Matt Martin at the White House poster session.

The select group of 25 was chosen from hundreds of nominations submitted to the White House’s request for innovative Open Science leaders. The White House event highlighted outstanding individuals, organizations, and research projects promoting and using open scientific data and publications to accelerate progress.

To exemplify Open Science work, the four EPA scientists presented how they are using advances in computational toxicology to provide open and accessible chemical safety data to help better protect human health and the environment. Each of the EPA scientists are working to harness the power of computer science and innovative new chemical safety assessment methods and tools to provide open, transparent public access to chemical information. For example:

  • Dr. Matt Martin leads a team of Agency scientists and partners who developed the Toxicity Reference database (ToxRefDB). ToxRefDB contains 30 years and $2 billion worth of pesticide registration studies. The database allows scientists and others to search and download thousands of toxicity testing results on hundreds of chemicals that were previously only available on paper or microfiche.
  • Dr. Ann Richard is the leader behind another open, accessible database, the Distributed Structure-Searchable Toxicity Database (DSSTox). DSSTox provides open-access to information on the physical and structural properties of chemicals and links this information to toxicity potential. This is key information for assessing the potential risk of chemicals to human health and the environment.
  • Dr. Richard Judson leads a team of scientists who developed the Aggregated Computational Toxicology online Resource (ACToR). ACToR is EPA’s online warehouse of all publicly available chemical data aggregated from more than 1,000 public sources on more than half a million chemicals. ACToR can be used to query a specific chemical and find available public hazard, exposure, and risk assessment data as well as previously unpublished studies related to cancer, reproductive, and developmental toxicity.
  • Dr. Keith Houck is the driving force behind EPA’s Toxicity Forecaster (ToxCast), a research program advancing the use of automated, rapid chemical tests (called “high-throughput screening assays”) to screen thousands of chemicals in more than 650 assays for toxicity potential. This includes the development of the ToxCast Database (ToxCastDB) which provides publicly accessible, searchable, and downloadable access to all the screening data generated by ToxCast.

These four scientists have led the effort to democratize access to knowledge and information and level the playing field for all those involved and interested in protecting public health and the environment. By doing so, they exemplify the spirit of Open Science celebrated by President Obama’s Champions of Change program.

About the Author: Tina Bahadori, Sc.D. is the National Program Director for EPA’s Chemical Safety for Sustainability research program.  Learn more about her on EPA’s Science Matters: Meet our Scientists web page.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Science Matters: Predicting the Future of Children’s Health

Children's Health MonthTo observe October as Children’s Health Month, we will periodically post Science Matters feature articles about EPA’s children’s health research here on the blog.  Learn more about EPA’s efforts to protect children’s health by going to

According to the Centers for Disease Control and Prevention, approximately one in every 33 babies born in the United States is born with a birth defect. Birth defects can heighten the risk of long-term disability as well as increase the risk of illness, potentially impacting a child for the rest of his or her life. Unfortunately, the causes of most birth defects are unknown.

EPA researchers are tapping powerful, high-tech computer systems and models to better determine how prenatal exposure to environmental factors might impact embryo and fetal development. Working on EPA’s Virtual Embryo (v-Embryo™) project, they create computer models of developing body systems and combine them with data from a number of EPA studies and toxicity databases to “virtually” examine the effects of a variety of prenatal exposures.

Virtual Embryo simulates how chemicals and pesticides, including those that disrupt the endocrine system, interact with important biological processes that could disrupt fetal development.  The chemicals used in simulations are identified by EPA’s Toxicity Forecaster as having the potential to affect development.

The predictions from the computer simulations need to be further tested against non-virtual observations. However, the models provide scientists with a powerful tool for screening and prioritizing the chemicals that need to be more closely examined, greatly reducing the cost and number of targeted studies needed.

“We’ve built small prototype systems, now what we want to do is move into complex systems models that will be more relevant to environmental predictions,” said Thomas B. Knudsen, Ph.D., an EPA systems biologist who is leading the project.

Virtual Embryo models have focused on blood vessel development and limb development, but are being expanded to include early development of the male reproductive system, which is known to be particularly sensitive to endocrine disrupting chemicals.

Knudsen says that having more models is important because different chemicals can affect biological systems in various ways. Luckily, the time it takes to develop new models decreases as researchers’ model-developing knowledge grows.

“The important challenge for us is to try to integrate some of this work with other issues of broad importance to children’s health,” said Knudsen. “We’re focused primarily on embryonic development, but a person doesn’t stop developing at birth. We have to take what we are learning from the embryo and extend that information into life stages beyond birth.”

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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