Tag Archives: computational toxicology

Building scientific bridges to support EPA’s new chemical testing programs

Jennifer McPartland, Ph.D., is a Health Scientist.

Readers of this blog are acutely aware of the dearth of data available for tens of thousands of chemicals in U.S. commerce today.  This state of ignorance reflects legal and resource constraints as well as the “challenge” of continuously integrating advancements in our scientific understanding of human health and disease into the way we assess chemical toxicity.

Fortunately, federal efforts to develop new chemical testing approaches, such as the high-throughput screening programs ToxCast and Tox21, offer a great opportunity to narrow the data gap while also helping to shine light on how environmental chemicals can impact our health.  But realizing the full potential of these new approaches will take a village.

Today in Environmental Health Perspectives we have published a commentary  that calls for greater and more diverse engagement of the basic research community in developing and using the new federal chemical testing data. We also provide recommendations that we believe would help facilitate and improve such engagement.  Read on to learn more.   Read More »

Posted in Emerging Testing Methods, Health Policy, Health Science| Also tagged | Comments closed

EDF comments at EPA workshop on applying systematic review methodology to IRIS assessments

Rachel Shaffer is a research assistant.

Lately, much of the attention of the environmental health community has been focused on Capitol Hill and the Lautenberg-Vitter chemical safety reform bill that would amend the antiquated Toxic Substances Control Act (TSCA). Yet significant – if somewhat esoteric – developments are underway at EPA that will also have major impacts on how the safety of chemicals is assessed.  EPA has been implementing improvements to its Integrated Risk Information System, commonly known as “IRIS.” The purpose of the IRIS program is to evaluate information on the effects of potential exposures to environmental substances and provide health hazard assessments, which are then used to support regulatory decisions across the agency.  And while it isn’t directly affected by TSCA or its reform, IRIS provides both indirect and direct support to the office at EPA that does administer TSCA.  

In other words, what happens in IRIS doesn’t stay in IRIS.

So… what’s IRIS up to? Read More »

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21st Century on the horizon for endocrine disruptor screening?

Rachel Shaffer is a research assistant. Jennifer McPartland, Ph.D., is a Health Scientist.

BPA, DDT, PCBs, PBDEs, phthalates, PFOA … Forgive the alphabet soup, but chances are you’ve heard of at least some of these endocrine-disrupting chemicals (EDCs), which have been the subject of a lot of public and media attention in the last several years. Research has begun to uncover the ways in which these chemicals can interact with the body’s hormone – or endocrine – system to disrupt various natural biological processes, including metabolism, the reproductive system, and development of the brain and nervous systems.

While the endocrine-disrupting properties of the chemicals named above have been confirmed, scientists suspect there may be many more such chemicals in our environment, in the products we use, and in our bodies.  How can we identify them?

Legislation enacted in 1996 required the U.S. Environmental Protection Agency (EPA) to develop a screening program to identify potential EDCs.  More than 10 years later, EPA finally launched the Endocrine Disruptor Screening Program (EDSP).  Testing is being conducted in two phases, or “tiers.”  In “Tier 1,” a screening battery of validated in vivo and in vitro assays is used to identify chemicals with potential to interfere with the endocrine system. Chemicals flagged in the first tier of testing are then subject to “Tier 2” testing intended to determine the specific effect and the lowest dose at which it occurs. (We should note this program is very controversial and the subject of ongoing debate, but that is not the subject of this post.)

EPA has identified an estimated 9,700 chemicals to be screened – a very daunting task given the time- and resource-intensive nature of the testing battery EPA has established.  Might there be a way to expedite the identification and testing of the more problematic chemicals? A study published earlier this year in Environmental Health Perspectives (EHP) investigates a possible approach: using in vitro high-throughput (HT) assays developed through EPA’s ToxCast and Tox21 programs to target and prioritize chemicals for further testing under the EDSP. While use of these assays poses its own challenges, might it at least help in determining an appropriate testing sequence?  Read More »

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Variety is the spice of … accurate chemical testing

Rachel Shaffer is a research assistant.  Jennifer McPartland, Ph.D., is a Health Scientist.

There has been a lot of buzz in recent years about the federal government’s new chemical testing initiatives, ToxCast and Tox21 (see, for example, these articles in Scientific American and the New York Times).  These programs are developing high-throughput (HT) in-vitro testing to evaluate—and ultimately predict—the biological effects of chemicals.  In contrast to the relatively slow pace of traditional animal testing, ToxCast and Tox21 use sophisticated robots to rapidly test thousands of chemicals at a time. As a result, they hold the potential to more efficiently fill enormous gaps in available health data, predict adverse effects, and shed light on exactly how chemicals interact and interfere with our biology. (For more on these potential benefits, see Section 5 of EDF’s Chemical Testing Primer).

Yet, among the key challenges that these new methods must address is one that traditional, animal-based methods have faced for decades: how can laboratory testing adequately account for the high degree of variability in the human population? The latest research suggests the exciting possibility that genetic diversity, at least, may be able to be incorporated into emerging HT in vitro approaches.   Read More »

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EDF launches website on EPA’s emerging chemical testing programs

Jennifer McPartland, Ph.D., is a Health Scientist.

New approaches for evaluating chemical hazard and risk are needed to help address substantial data gaps that exist for the thousands of chemicals currently in the marketplace as well as those yet to be introduced.   EPA has been investing significant resources to create research programs dedicated to advancing new types of chemical testing and assessment approaches.  But what exactly are these approaches?  How might they improve the practice of risk assessment?  Are they appropriate for decision-making, and if so, what kinds of decision making?  What role does the public interest community have to play? 

To explore these and other important issues, EDF’s Health Program has launched a website, “Chemical Testing in the 21st Century,” that provides an  introduction to these new approaches and the programs the EPA has built around them—including their potential uses, benefits and limitations.  The website includes the following informational resources: 

  1. Chemical Testing in the 21st Century: A Primer – An introduction to EPA’s Computational Toxicology (CompTox) research initiative and its component programs, such as ToxCast; a discussion of the opportunities and challenges of these new testing programs; and a discussion of issues and needs for greater engagement by the public interest community.  
  2. Chemical Testing in the 21st Century: Webinar Series – Linked audio and video recordings of each of EDF’s three webinars (held in October) featuring EDF and EPA scientists exploring the basics of EPA’s new testing programs and the promises and challenges they present. 

We will soon be adding a page with descriptions of and links to additional resources.

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Exposing our ignorance: EPA study reveals barren exposure data landscape

Jennifer McPartland, Ph.D., is a Health Scientist.

This past November, EPA scientists published a sobering paper, “The exposure data landscape for manufactured chemicals,” in the journal Science of the Total Environment.  The paper reveals how little systematic information we have about human and environmental exposures to the thousands of chemicals in use today.

The aim of the study was “to define important aspects of the [chemical] exposure space and to catalog the available exposure information for chemicals being considered for analysis as part of the U.S. EPA ToxCast screening and prioritization program.”  Its conclusion:  “The results suggest that currently available exposure data are insufficient to provide the evidence base required to inform risk assessment and public health decision making.”  Not good, but not surprising.  Read on for more detail. Read More »

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