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Request for Information (NOT-ES-11-007): Needs and Approaches for Assessing the Human Health Impacts of Exposure to Mixtures

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National Institutes of Health (NIH), HHS.


Request for information.


The National Institute of Environmental Health Sciences (NIEHs), the Division of Extramural Research and Training (DERT) and the National Toxicology Program (NTP) seek input for identification of key research areas in mixtures. Information provided will be used in planning a workshop for late summer 2011 to help inform the development of intramural and extramural research efforts that address the combined health effects of multiple environmental exposures (“mixtures”). This request for information (RFI) is for planning purposes only and should not be construed as a funding opportunity or grant program. Input from all interested parties is welcome including the lay public, environmental health researchers, health professionals, educators, policy makers, industry, and others. Please respond on-line at the Mixtures Request for Information Web page (​go/​rfimix) by April 15, 2011.


Please respond online at the Mixtures Request for Information Web page (​go/​rfimix) by April 15, 2011.

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Other correspondence regarding this RFI should be directed to either (1) Dr. Danielle Carlin, DERT Program Administrator, NIEHS, P.O. Box 12233, MD K3-04, Research Triangle Park, NC 27709, (telephone) 919-541-1409, (e-mail) or (2) Dr. Cynthia Rider, NTP Toxicologist, NIEHS, P.O. Box 12233, MD K2-12, Research Triangle Park, NC 27709, (telephone) 919-541-7638, (e-mail)

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The NIEHS mission is to reduce the burden of human illness and disability by understanding how the environment influences the development and progression of human disease. To accomplish this, the NIEHS supports research and professional development in environmental health sciences, clinical research, and public health.

DERT plans, directs and evaluates the NIEHS grant program, which supports research and research training in environmental health. It develops program priorities and recommends funding levels to assure maximum utilization of available resources in attainment of NIEHS objectives. Through cooperative relationships with NIH and with public and private institutions and organizations, DERT maintains an awareness of national research efforts and assesses the need for research and research training in environmental health.

The NTP is an interagency program whose mission is to evaluate agents of public health concern by developing and applying tools of modern toxicology and molecular biology. The NTP designs and conducts laboratory studies and testing programs and analyzes its findings to assess potential hazards to human health from exposure to environmental substances. The NTP also carries out formal review and literature analysis activities.

The evaluation of human health effects from multiple environmental exposures represents a special challenge to the research community due to the Start Printed Page 12964inherent complexity of the topic. The term “mixture” can be broadly interpreted and can refer to a substance with variable composition or to mixtures resulting from combined exposures. For the purposes of this RFI, “mixtures” pertains to any set of multiple environmental exposures (chemical or non-chemical) that may contribute jointly to adverse human health outcomes, irrespective of whether people are exposed to the substances at the same/different times or through similar/distinct sources or routes.

Continuous human exposure to complex and dynamic mixtures precludes directly testing the toxicity of each possible exposure combination. Therefore, predictive models of mixture toxicity must be developed and validated in order to characterize the hazard associated with complex exposures. In order to develop these models, a better understanding is required of both the composition of real-world exposures and the fundamental principles of chemical interactions. Combinatorial or statistical approaches are needed to address the potential interactions of complex exposures. Moreover, these approaches should be used to move beyond assessment of individual chemicals and further our understanding of the impacts of realistic exposures.

Information gathered through this RFI will be used in planning a workshop on mixtures to be held in late summer 2011. The date and location have not yet been determined, but when set, will be announced in the Federal Register. The overarching goals of this workshop are to foster discussion on the approaches, infrastructure, and resources needed to make progress and to identify new scientific opportunities by applying innovative tools to the field of mixtures research. Additionally, the workshop should provide opportunities for development of collaborations and foster multidisciplinary interactions among the mixtures scientific community. The workshop will bring together experts from multiple disciplines including, but not limited to, exposure assessment, risk assessment, biostatistics, toxicology, biology, regulatory science, and epidemiology.

Information Requested

DERT and the NTP request information on the challenges and potential solutions in mixtures research. Responses to any or all of the questions below are invited from interested individuals/groups, including, but not limited to, the environmental health research community, health professionals, educators, policy makers, industry, and the public.

  • What are the underlying scientific knowledge gaps for assessing the effects of mixtures on human health?
  • What are the scientific issues encountered in performing risk assessments of mixtures that can be addressed by new research?
  • What types of scientific data (e.g., mechanistic, epidemiological) are needed to address these underlying knowledge gaps?
  • What are the new technologies and innovative approaches that could be leveraged to address these underlying knowledge gaps?

All responses to information requested in this RFI are optional. The information collected will be analyzed and considered for use in the further development of the workshop. The summarized data (without identifiers) may appear in future reports. Although the NIH will provide safeguards to prevent the release of identifying information, there is no guarantee of confidentiality. This RFI is for planning purposes only and shall not be construed as a solicitation for applications or as an obligation on the part of the Government. The Government will not pay for the preparation of any information submitted or for the Government's use of that information. Acknowledgement of receipt of responses will be provided through the Web site (​go/​rfimix), but respondents will not be notified of the Government's assessment of the information received. No basis for claims against the Government shall arise as a result of responses to this RFI, or in the Government's use of such information as part of its evaluation process.

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Dated: February 28, 2011.

Linda S. Birnbaum,

Director, National Institute of Environmental Health Sciences and National Toxicology Program.

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[FR Doc. 2011-5352 Filed 3-8-11; 8:45 am]