In December 2017, the U.S. National Academy of Sciences (NAS) published a report which addressed the influence of the human microbiome on the body’s response to environmental chemicals, along with a shorter document emphasizing the report’s highlights.

NAS scientists from the Committee on Advancing Understanding of the Implications of Environmental-Chemical Interactions with the Human Microbiome drew attention to studies showing “associations between perturbations in the human microbiome and human disease.” While there may be a need to consider the chemical-microbiome interactions during human health risk assessment, the authors noted that “such considerations would add substantial complexity to an already complex analysis.”

As a first step for tackling this issue, the scientists outlined a research strategy focused “on addressing questions about the interactions of environmental chemicals with the human microbiome and the implications for human health risk.” Future research should focus on the two types of possible interactions, namely the effect of environmental chemicals on the microbiome, and the microbiome’s ability to “modulate exposure to environmental chemicals.”

In addition, the third proposed research direction should investigate the importance of microbiome variation, answering the questions of “whether knowledge of population variation in the human microbiome improves understanding of individual health risks and susceptibility to effects of environmental chemicals;” “whether the differences [between species] are so great that effects are being missed or mischaracterized by using animal models to predict human health risks associated with environmental-chemical exposure;” and “whether the factors that are used to extrapolate effects in animals to humans account adequately for the microbiome variation.”

Among the barriers that need to be overcome to successfully carry out the research proposed, the committee identified the need for “substantial investments of time and resources” along with “multidisciplinary expertise not found within a single laboratory.” Further, adequate in vitro model systems faithfully representing the host environment (e.g. gut) have not been developed yet. There is also a pressing need to collect and maintain “microbial reference communities” that “accurately represent the variation in the human microbiome,” and “reference information” on these communities should be made available by populating databases and libraries. Lastly, a “lack of standardization in experimental approaches” should be tackled in order to ensure the reproducibility.

To adequately address the challenges outlined, the committee called for “interdisciplinary collaborations . . . to make the best use of available knowledge and resources in each agency or organization.” By the authors’ estimation, already in “2-4 years . . . the proposed research should allow judgements to be made about whether explicit consideration of microbiome interactions in the study of environmental-chemical toxicity yields information that is not available from traditional studies that do not explicitly consider microbiomes.” This will allow assessing “the importance of the human microbiome as a contributor to human health risks associated with exposures to environmental chemicals.”

Read more

NAS (2017). “Environmental chemicals, the human microbiome, and health risk: A research strategy.” DOI 10.17226/24960

NAS (2017). “Environmental chemicals, the human microbiome, and health risk: A research strategy. Highlights.(pdf)

Emma Davis (January 11, 2018). “Microorganisms in humans could change chemical risk assessment results, says NAS.Chemical Watch