The Microbiome in Human Health Risk Assessment: Where Do We Go from Here?

It is recognized that the complex collection of microbes in our gut, the microbiome, plays a critical role in our health and well-being.  It influences our responses, e.g., immunological, and reacts to environmental exposures, such as from food, drugs, and environmental contaminants.  Regulatory agencies are putting a great deal of effort into understanding the sequence of mechanistic events that lead to disease.  However, they haven’t generally incorporated the importance of the microbiome to a great extent and how it can provide insight into human health risk assessment.  We will likely need to rethink some of the risk assessments to take into account the contribution of the microbiome.  Research will greatly help assessments by addressing the lack of understanding of how xenobiotic exposures can affect the composition and function of the microbiome as well as how the microbiome can affect bioavailability of contaminants and susceptibility to pathogens.  Also, the interplay between chemical exposures and pathogens with commensal gut flora and with each other need to be examined as potential risk factors.  While the microbiome raises the complexity of the research in disease etiology, it will help human health risk assessors to rethink how chemicals and pathogens interact with exposed people.