Mixtures research at NIEHS: an evolving program

Our plain-English summary of Mixtures research at NIEHS: an evolving program, by C.V. Rider, D.J. Carlin, M.J. Devito, et al (Toxicology, 2013).

The study

• Authors: C.V. Rider, D.J. Carlin, M.J. Devito, C.L. Thompson, N.J. Walker
• Journal: Toxicology
• Published: 2013;313(2-3):94-102
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The National Institute of Environmental Health Sciences (NIEHS) has a rich history in evaluating the toxicity of mixtures. The types of mixtures assessed by the Division of the National Toxicology Program (DNTP) and the extramural community (through the Division of Extramural Research and Training, DERT) have included a broad range of chemicals and toxicants, with each study having a unique set of questions and design considerations. Some examples of the types of mixtures studied include: groundwater contaminants, pesticides/fertilizers, dioxin-like chemicals (assessing the toxic equivalency approach), drug combinations, air pollution, metals, polycyclic aromatic hydrocarbons, technical mixtures (e.g., pentachlorophenol, flame retardants), and mixed entities (e.g., herbals, asbestos). These endeavors have provided excellent data on the toxicity of specific mixtures and have been informative to the human health risk assessment process in general (e.g., providing data on low dose exposures to environmental chemicals). However, the mixtures research effort at NIEHS, to date, has been driven by test article nominations to the DNTP or by investigator-initiated research through DERT. Recently, the NIEHS has embarked upon an effort to coordinate mixtures research across both intramural and extramural divisions in order to maximize mixtures research results. A path forward for NIEHS mixtures research will be based on feedback from a Request for Information (RFI) designed to gather up-to-date views on the knowledge gaps and roadblocks to evaluating mixtures and performing cumulative risk assessment, and a workshop organized to bring together mixtures experts from risk assessment, exposure science, biology, epidemiology, and statistics. The future of mixtures research at NIEHS will include projects from nominations to DNTP, studies by extramural investigators, and collaborations across government agencies that address high-priority questions in the field of mixtures research.

Published by Elsevier Ireland Ltd.

In plain English

This article was not a research study and reported no new data on asbestos. It was an overview, written by staff of the US National Institute of Environmental Health Sciences (NIEHS), of the institute's past, current and planned research on mixtures, meaning combined exposures to several chemicals or other stressors. The authors described earlier National Toxicology Program work on mixtures such as groundwater contaminants, pesticide and fertilizer mixtures, herbal extracts, AIDS drug combinations and flame retardants. They also listed grants funded through the institute's extramural division. Asbestos was named only as an example of a "mixed entity" in the abstract and as the title of one past grant, "Asbestos and NO2 in Environmental Lung Disease" (University of Vermont, 1998 to 2002). The article gave no results from that grant. The authors reported that NIEHS issued a Request for Information in spring 2011 and held a workshop in Chapel Hill, North Carolina, on September 26 and 27, 2011. Workshop themes included combining in vitro and in vivo approaches and better coordination between epidemiology and toxicology. The authors concluded that mixtures research is a priority at NIEHS and will continue to be.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative overview (review) of NIEHS mixtures research programs; not an original study
• Who was studied: No study population. The article describes NIEHS intramural (National Toxicology Program) and extramural mixtures research projects, grants, a 2011 Request for Information and a 2011 workshop.
• Exposure: Chemical mixtures in general. Asbestos appears in two places. The abstract names it as an example of a "mixed entity" among the mixtures studied. It is also the title of one past extramural grant (with nitrogen dioxide, NO2), led at the University of Vermont, 1998 to 2002. The article gives no asbestos fiber type, data or findings.
• Main results:
  • NIEHS held a multidisciplinary mixtures workshop on September 26 and 27, 2011, in Chapel Hill, NC. It produced cross-cutting themes, including the need to combine in vitro and in vivo approaches.
  • Workshop themes also included better coordination between epidemiology and toxicology.
  • A Tox21 mixtures pilot project was planned to evaluate interactions of up to 80 chemicals in over 130 mixing ratios.
• The authors' conclusion: The authors concluded that mixtures research is a priority at NIEHS and will continue to be in the future.

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology.

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