The exposome encompasses the totality of human environmental (i.e. non-genetic) exposures from conception onwards, complementing the genome, first proposed in 2005 by a cancer epidemiologist. As of 2016, it may not be possible to measure or model.
The exposome was first proposed in 2005 by cancer epidemiologist Christopher Paul Wild in an article entitled "Complementing the genome with an "exposome": the outstanding challenge of environmental exposure measurement in molecular epidemiology". The concept of the exposome and how to assess it has led to lively discussions with varied views in 2010, 2012, and 2014,
In his 2005 article, Wild stated, "At its most complete, the exposome encompasses life-course environmental exposures (including lifestyle factors), from the prenatal period onwards." The concept was first proposed to draw attention to the need for better and more complete environmental exposure data for causal research, in order to balance the investment in genetics. According to Wild, even incomplete versions of the exposome could be useful to epidemiology. In 2012, Wild outlined methods, including personal sensors, biomarkers, and 'omics' technologies, to better define the exposome. He described three overlapping domains within the exposome:
- a general external environment including the urban environment, education, climate factors, social capital, stress,
- a specific external environment with specific contaminants, radiation, infections, lifestyle factors (e.g. tobacco, alcohol), diet, physical activity, etc.
- an internal environment to include internal biological factors such as metabolic factors, hormones, gut microflora, inflammation, oxidative stress.
In late 2013, this definition was explained in greater depth in the first book on the exposome. In 2014, the same author revised the definition to include the body's response with its endogenous metabolic processes which alter the processing of chemicals.
For complex disorders, specific genetic causes appear to account for only 10-30% of the disease incidence, but there has been no standard or systematic way to measure the influence of environmental exposures. Some studies into the interaction of genetic and environmental factors in the incidence of diabetes have demonstrated that "environment-wide association studies" (EWAS, or exposome-wide association studies) may be feasible. However, it is not clear what data sets are most appropriate to represent the value of "E".
As of 2016, it may not be possible to measure or model the full exposome, but several European projects have started to make first attempts. In 2012, the European Commission awarded two large grants to pursue exposome-related research.
The HELIX project at the Barcelona-based Centre for Research in Environmental Epidemiology was launched around 2014, and aimed to develop an early-life exposome.
A second project, Exposomics, based at Imperial College London, launched in 2012, aimed to use smartphones utilising GPS and environmental sensors to assess exposures.
In late 2013, a major initiative called the "Health and Environment-Wide Associations based on Large Scale population Surveys" or HEALS, began. Touted as the largest environmental health-related study in Europe, HEALS proposes to adopt a paradigm defined by interactions between DNA sequence, epigenetic DNA modifications, gene expression, and environmental factors.
In December 2011, the US National Academy of Sciences hosted a meeting entitled "Emerging Technologies for Measuring Individual Exposomes." A Centers for Disease Control and Prevention overview, "Exposome and Exposomics", outlines the three priority areas for researching the occupational exposome as identified by the National Institute for Occupational Safety and Health. The National Institutes of Health (NIH) has invested in technologies supporting exposome-related research including biosensors, and supports research on gene-environment interactions.
Proposed Human Exposome Project (HEP)
The idea of a Human Exposome Project, analogous to the Human Genome Project, has been proposed and discussed in numerous scientific meetings, but as of 2017, no such project exists. Given the lack of clarity on how science would go about pursuing such a project, support has been lacking. Reports on the issue include:
- a 2011 review on the exposome and exposure science by Paul Lioy and Stephen Rappaport, "Exposure science and the exposome: an opportunity for coherence in the environmental health sciences" in the journal Environmental Health Perspectives.
- a 2012 report from the United States National Research Council "Exposure Science in the 21st Century: A Vision and A Strategy", outlining the challenges in systematic evaluations of the exposome.
The concept of the exposome has contributed to the 2010 proposal of a new paradigm in disease phenotype, "the unique disease principle": Every individual has a unique disease process different from any other individual, considering uniqueness of the exposome and its unique influence on molecular pathologic processes including alterations in the interactome. This principle was first described in neoplastic diseases as "the unique tumor principle". Based on this unique disease principle, the interdisciplinary field of molecular pathological epidemiology (MPE) integrates molecular pathology and epidemiology.
- Wild, CP (Aug 2005). "Complementing the genome with an "exposome": the outstanding challenge of environmental exposure measurement in molecular epidemiology". Cancer Epidemiology, Biomarkers & Prevention. 14 (8): 1847–50. doi:10.1158/1055-9965.EPI-05-0456. PMID 16103423.
- Rappaport SM, Smith MT (2010). "Epidemiology. Environment and disease risks". Science. 330 (6003): 460–461. doi:10.1126/science.1192603. PMC 4841276. PMID 20966241.
- Rappaport SM (2011). "Implications of the exposome for exposure science". J Expo Sci Environ Epidemiol. 21 (1): 5–9. doi:10.1038/jes.2010.50. PMID 21081972.
- Wild, CP (Feb 2012). "The exposome: from concept to utility". International Journal of Epidemiology. 41 (1): 24–32. doi:10.1093/ije/dyr236. PMID 22296988.
- Peters A, Hoek G, Katsouyanni K (2012). "Understanding the link between environmental exposures and health: does the exposome promise too much?". Epidemiol Community Health. 66 (2): 103–105. doi:10.1136/jech-2011-200643. PMID 22080817.
- Buck Louis GM, Sundaram R (2012). "Exposome: time for transformative research". Stat Med. 31 (22): 2569–75. doi:10.1002/sim.5496. PMC 3842164. PMID 22969025.
- Centers for Disease Control and Prevention (2012). "Exposome and Exposomics". Retrieved 5 March 2013.
- Buck Louis G. M.; Yeung E.; Sundaram R.; et al. (2013). "The Exposome – Exciting Opportunities for Discoveries in Reproductive and Perinatal Epidemiology". Paediatric and Perinatal Epidemiology. 27 (3): 229–236. doi:10.1111/ppe.12040. PMC 3625972. PMID 23574410.
- Vrijheid M, Slama R, Robinson O, Chatzi L, Coen M, et al. (2014). "The Human Early-Life Exposome (HELIX): Project Rationale and Design". Environ Health Perspect. 122 (6): 535–544. doi:10.1289/ehp.1307204. PMC 4048258. PMID 24610234.
- Miller Gary W.; Jones Dean P (2014). "The Nature of Nurture: Refining the Definition of the Exposome". Toxicological Sciences. 137 (1): 1–2. doi:10.1093/toxsci/kft251. PMC 3871934. PMID 24213143.
- Porta M, editor. Greenland S, Hernán M, dos Santos Silva I, Last JM, associate editors (2014). A dictionary of epidemiology, 6th. edition. New York: Oxford University Press. ISBN 9780199976737
- Gary Miller (2 December 2013). The Exposome: A Primer. Elsevier. p. 118. ISBN 978-0124172173. Retrieved 16 January 2014.
- Gary Miller (20 November 2013). "G x E = ?". Sci Connect. Elsevier. Retrieved 16 January 2014.
- Miller Gary W.; Jones Dean P. (January 2014). "The Nature of Nurture: Refining the Definition of the Exposome". Toxicological Sciences. 137 (1): 1–2. doi:10.1093/toxsci/kft251. PMC 3871934. PMID 24213143.
- Patel, CJ; Bhattacharya, J; Butte, AJ (May 20, 2010). "An Environment-Wide Association Study (EWAS) on type 2 diabetes mellitus". PLoS ONE. 5 (5): e10746. Bibcode:2010PLoSO...510746P. doi:10.1371/journal.pone.0010746. PMC 2873978. PMID 20505766.
- Patel, CJ; Chen, R; Kodama, K; Ioannidis, JP; Butte, AJ (20 January 2013). "Systematic identification of interaction effects between genome- and environment-wide associations in type 2 diabetes mellitus". Human Genetics. 132 (5): 495–508. doi:10.1007/s00439-012-1258-z. PMC 3625410. PMID 23334806.
- Smith Martyn T.; Rappaport Stephen M. (August 2009). "Building Exposure Biology Centers to Put the E into "G × E" Interaction Studies". Environmental Health Perspectives. 117 (8): A334–A335. doi:10.1289/ehp.12812. PMC 2721881. PMID 19672377.
- Callaway, Ewen (27 November 2012). "Daily dose of toxics to be tracked". Nature. 491 (7426): 647. Bibcode:2012Natur.491..647C. doi:10.1038/491647a. PMID 23192121.
- Vrijheid, M; Slama, R; Robinson, O; Chatzi, L; Coen, M; van den Hazel, P; Thomsen, C; Wright, J; Athersuch, TJ; Avellana, N; Basagaña, X; Brochot, C; Bucchini, L; Bustamante, M; Carracedo, A; Casas, M; Estivill, X; Fairley, L; van Gent, D; Gonzalez, JR; Granum, B; Gražulevičienė, R; Gutzkow, KB; Julvez, J; Keun, HC; Kogevinas, M; McEachan, RR; Meltzer, HM; Sabidó, E; Schwarze, PE; Siroux, V; Sunyer, J; Want, EJ; Zeman, F; Nieuwenhuijsen, MJ (June 2014). "The human early-life exposome (HELIX): project rationale and design". Environmental Health Perspectives. 122 (6): 535–44. doi:10.1289/ehp.1307204. PMC 4048258. PMID 24610234.
- About Exposomics EU
- "HEALS-EU". Retrieved 16 January 2014.
- "National Academy of Sciences meeting". Retrieved 21 January 2013.
- "NIEHS Gene-Environment studies". Retrieved 21 January 2013.
- "Genes and Environment Initiative". Retrieved 21 January 2013.
- Arnaud, Celia Henry (16 August 2010). "Exposing The Exposome". Chemical & Engineering News, Vol. 88, No. 33, pp. 42–44. American Chemical Society. Retrieved 5 March 2013.
- Lioy, PJ; Rappaport, SM (Nov 2011). "Exposure science and the exposome: an opportunity for coherence in the environmental health sciences". Environmental Health Perspectives. 119 (11): A466–7. doi:10.1289/ehp.1104387. PMC 3226514. PMID 22171373.
- "NRC report supports NIEHS vision of the exposome". Retrieved 21 January 2013.
- Council, National Research; Studies, Division on Earth Life; Toxicology, Board on Environmental Studies and; Century, Committee on Human Environmental Exposure Science in the 21st (2012-09-07). Exposure Science in the 21st Century: A Vision and a Strategy. ISBN 9780309264686. Retrieved 21 January 2013.
- Ogino S, Lochhead P, Chan AT, et al. (2013). "Molecular pathological epidemiology of epigenetics: emerging integrative science to analyze environment, host, and disease". Mod Pathol. 26 (4): 465–484. doi:10.1038/modpathol.2012.214. PMC 3637979. PMID 23307060.
- Ogino S, Fuchs CS, Giovannucci E (2012). "How many molecular subtypes? Implications of the unique tumor principle in personalized medicine". Expert Rev Mol Diagn. 12 (6): 621–628. doi:10.1586/erm.12.46. PMC 3492839. PMID 22845482.
- Ogino S, Stampfer M (2010). "Lifestyle factors and microsatellite instability in colorectal cancer: the evolving field of molecular pathological epidemiology". J Natl Cancer Inst. 102 (6): 365–367. doi:10.1093/jnci/djq031. PMC 2841039. PMID 20208016.