EPA Communities of Practice
Exposure Science for Toxicity Testing, Screening, and Prioritization

Community of Practice

The primary purpose of the EPA Exposure Science Community of Practice (ExpoCoP) is to provide a forum for promoting the advancement and utilization of exposure science to address Agency needs for chemical screening, prioritization and toxicity testing. We look forward to sharing experience and broadening outreach, as we continue this dialogue with our many EPA, academic, stakeholder and international colleagues.

ExpoCoP meetings are held monthly, typically at EPA’s RTP campus, on the second Tuesday of the month, from 11am-Noon EST/EDT. Teleconferencing is available. For more information on the ExpoCoP, or to be added to the meeting email list, contact either Elaine Cohen Hubal (hubal.elaine@epa.gov; 919-541-4077) or Linda Sheldon (sheldon.linda@epa.gov; 919-541-2205).

Background

The EPA Exposure Science Community of Practice (ExpoCoP) formed in May 2008 to advance application of exposure science to inform and support research being conducted at EPA using advancements in the field of computational toxicology. The goal of the ExpoCoP is to advise on development of a research program in exposure science to address EPA needs for chemical prioritization, screening, and toxicity testing.
Globally there is a need to characterize potential risk to human health and the environment that arises from the manufacture and use of tens of thousands of chemicals. Currently, a significant research effort is underway to apply new technologies to screen and prioritize chemicals for toxicity testing as well as to improve understanding of toxicity pathways. The 2007 National Research Council report, Toxicity Testing in the 21st Century: A Vision and a Strategy, calls for a collaborative effort across the toxicology community to rely less on animal studies and more on in vitro tests using human cells and cellular components to identify chemicals with toxic effects. A framework for implementing this long-range vision is provided by the recently formalized collaboration between two NIH institutes and the EPA to use high-speed, automated screening methods to efficiently test compounds for potential toxicity (Science Feb 15, 2008). More immediately, the US EPA is completing the Phase I pilot for a chemical prioritization research program, called ToxCastTM. Here EPA is developing methods for using computational chemistry, high-throughput screening, and toxicogenomic technologies to predict potential toxicity and prioritize limited testing resources.

These high visibility efforts in toxicity testing and computational toxicology raise important research questions and opportunities for exposure scientists. The National Academies report authors (NRC, 2007) emphasize that, population-based data and human exposure information are required at each step of their vision for toxicity testing; that these data will continue to play a critical role in both guiding development and use of the toxicity information. Exposure research questions posed in this report include how to: (1) use information on host susceptibility and background exposures to interpret and extrapolate in vitro test results; (2) use human exposure data to select doses for toxicity testing so information on biological effects is developed at environmentally relevant exposures; and (3) relate human exposure data from biomonitoring surveys to concentrations that perturb toxicity pathways to identify potentially important exposures. The NCCT Computational Toxicology program has identified the need to include exposure information for chemical prioritization, modeling system response to chemical exposures across multiple levels of biological organization, and linking information on potential toxicity of environmental contaminants to real-world health outcomes (e.g., complex disease).

The ExpoCoP will focus initially on issues associated with classifying chemicals based on potential for human exposure and linking results with the ToxCast™ chemical prioritization activity. An important component will be to consider how best to consolidate and link human exposure data for this purpose.

The Community includes individuals from the Office of Research and Development (ORD) Labs and Centers, from Program Offices, and from organizations outside of EPA currently involved in screening and prioritizing based on potential for human exposure or with applicable expertise in this area. The ExpoCoP is co-chaired by a member of the NCCT and a member of the National Exposure Research Laboratory (NERL), but draws on the expertise of scientists across ORD and the Agency as needed for specific issues.

The charter of the ExpoCoP includes the following functions:

Organize periodic meetings or conference calls (at least quarterly) around specific issues or projects, with goal of identifying state of the science, research needs, and consensus positions.
Organize outreach to broader scientific community to demonstrate EPA's interest in exposure science for toxicity testing and to obtain input and participation.
Report regularly to the Director of the NCCT and the ORD CTISC on issues, progress, and outputs.

Specific goals of the ExpoCoP is to provide input on the following:

Development of key partnerships and collaborations with external groups that can facilitate development of exposure information and computational tools required to inform chemical prioritization.
Identification of research needs to improve Agency computational resources for addressing exposure screening and prioritization.
Creation of a consolidated EPA exposure database focused on measured concentrations in exposure and biological media.
Standards for exposure data representation.
Approaches for improving accessibility to EPA human exposure data and for facilitating links between exposure and toxicity data.
Development of a curated human exposure knowledge base.
Novel approaches for characterizing exposure to prioritize chemicals.

ExpoCoP membership

As of July 2008, the ExpoCoP has a membership of approximately 40 individuals from over 15 public and private sector organizations. Membership will be modified throughout the working life of Community as appropriate; to be added to the meeting email list, contact either Elaine Cohen Hubal (hubal.elaine@epa.gov; 919-541-4077) or Linda Sheldon (sheldon.linda@epa.gov; 919-541-2205).