The exposome refers to an emergent research field, the aim of which is to develop an integrative science of the totality of exposures to which an individual is subjected over the course of their life and which influence their health. This contribution offers a critical analysis of the promises and realisations of this emerging field as regards the holistic integration of exposures and the goal of delivering a more precise explanation of the disease-exposure associations. First, two research orientations are distinguished in the field: one more reductionistic, mainly relying on the biomarker approach and omics technologies; the other more comprehensive as regards the scope of the data and the disciplines integrated. I then show that various meanings are given to “integration” and to “holism”, before arguing that the biomarker approach and the mechanistic view of causation, central to the more reductionistic orientation, is not necessarily the most suitable to achieve the goal of a holistic integration of exposures. The evidence surrounding the health benefits to the population and individuals of adopting the aim of a strong explanative integration is also discussed. I conclude by affirming the need for more reflection on the type and nature, relevance and value, of integration itself, before the exposome field develops any further.