Reconceptualizing and Defining Exposomics within Environmental Health: Expanding the Scope of Health Research.

BACKGROUND Exposomics, the study of the exposome, is flourishing, but the field is not well defined. The term "exposome" refers to all environmental influences and associated biological responses throughout the lifespan. However, this definition is very similar to that of the term "environment"-the external elements and conditions that surround and affect the life and development of an organism. Consequently, the exposome seems to be nothing more than a synonym for the environment, and exposomics a synonym for environmental research. As a result, some have rebranded their "standard" environmental health research with the neologistic exposome term, whereas others ignore or seek to abandon the seemingly redundant concept of the exposome. OBJECTIVES We argue that exposomics needs to sharpen its mission focus to counteract this apparent redundancy. Exposomics should be defined as a research program in environmental health aimed at enabling a comprehensive and discovery-driven approach to identifying environmental determinants of human health. Similar to the aim of the Human Genome Project, exposomics aims to analyze the complete complexity of exposures and their corresponding biological responses. Exposomics' primary premise is that the existence of undiscovered, potentially interconnected, nongenetic (environmental) risk factors for health necessitates a comprehensive discovery-driven analysis approach. DISCUSSION We argue that exposomics researchers should adopt our reconceptualization of exposomics and focus on the productiveness and integrity of their research program: its purpose and principles. We suggest that exposomics researchers should coordinate the writing of reviews that assess the program's productiveness and integrity, as well as provide a platform for exposomics researchers to define their vision for the field. https://doi.org/10.1289/EHP14509.