Studies in migrant populations and other investigations clearly show that the ‘environment’ plays a much bigger role than genetics in producing chronic disease. However, characterizing the environmental risk factors is currently far more challenging than identifying the genetic factors. The “exposome”, representing the totality of environmental exposures from conception onwards, offers a novel approach to understanding the environmental causes of disease through unbiased studies of the internal chemical environment. It replaces the chemical-by-chemical approach to finding causes of disease and includes endogenous and exogenous exposures. Several ‘omic’ technologies can be applied to characterize the exposome of specific diseases and can thereby promote discovery of the key exposures responsible for chronic diseases.
Recognizing that environmental factors were poorly characterized in epidemiologic studies, Christopher Wild in 2005 defined the ‘exposome’ as a key determinant of chronic diseases (Cancer Epi Biomarkers Prev 14: 1847-50, 2005). Recently, Rappaport and Smith proposed that the human exposome should be characterized by measuring important constituents of the body’s internal chemical environment arising from both exogenous and endogenous sources (Science 330(6003): 460-1, 2010). That is, Rappaport and Smith argued for use of biomonitoring to characterize what we define here as the ‘internal exposome’. In contrast, the traditional view of ‘environmental exposures’, is essentially confined to pollutants from air, soil and water.
Characterizing the human exposome represents a challengesimilar to the human genome project (HGP), which began when DNAsequencing was in its infancy. Lessons can be learned from the HGP as to how to begin a human exposome project. For example, the process must be science driven and the best teams must be built to meet technological challenges. Thus, to start an ambitious research program leading to Environment-Wide Association Studies and possibly a human exposome project, with the same breadth and vision that motivated GWAS and the HGP, the Exposome Alliance has been formed that currently involves founding members from Berkeley, Imperial and Kings Colleges London, IARC and NIEHS. We invite all interested parties to join the Alliance and thereby to promote investment in a human exposome project.
The human exposome project would attempt to characterize the internal exposomes of individuals of multiple ethnicities who live in different environments and have widely differing risk factors for disease. In this way we would hope to understand the diversity and patterns of human exposures in a manner similar to the HapMap project, which aims to describe the common patterns of human DNA sequence variation. We should not be discouraged by the fact that efficient technologies do not currently exist, as the history of DNA sequencing clearly illustrates. We should instead forge ahead together as there is no alternative if we wish to really find the causes of the current obesity epidemic, harvest the findings from GWAS in gene-environment interaction studies and prevent major chronic diseases.
Please join us by subscribing to this site.
Dr. Jim Lenhart discusses the Exposome and disease on Healthline Today.