The definition of region that I propose is developed from the UN University course discussion. The course definition states that a region is defined as the territory controlled by a regent and his regiment. This can be simply changed for clinical trials to state that the region is the territory controlled (covered) by the drug, pollutant, environmental factor, race etc., etc., and other sub-factors being investigated by the researcher. This further fits the UN University course outline example “that regions are not out there waiting to be discovered but are constructed, deconstructed and reconstructed through interactions between various actors [ ] on the basis of what is most appropriate for their commonly held goals.” I further agree that regions can overlap and must have a physical reality and some kind of boundary or limit. The examples I will use to demonstrate region are familiar to me and I am not trying to make a political statement by using them. Example 1. Major trade corridors in the Mekong region Avian influenza poses a significant risk to both avian and human health. It has been commonplace in the media for wild birds, free-range and backyard poultry to be blamed for spreading the virus. However an investigation by the NGO GRAIN indicates that the development of industrial poultry farms in Asia and the global poultry trade should be investigated for helping to spread the virus. (GRAIN, 2006. Fowl play: The poultry industry's central role in the bird flu crisis. http://www.grain.org/go/birdflu ) The first map by WHO shows Avian influenza (H5N1) in Asia as of 29 September 2005. The second map shows the region that could be used in a research study – the region is major trade corridors in the Mekong. Another region in this example could be dispersion of industrial poultry farms in Asia by year. http://www.pbs.org/wnet/wideangle/shows/vietnam/map3.html Example 2. Electromagnetic fields The World Health Organization (WHO), the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and the German and Austrian Governments held a jointly sponsored seminar in November 1996 on the biological effects of low-level radiofrequency (RF) electromagnetic fields. RF fields were defined as having frequencies in the range of 10 MHz to 300 GHz (Repacholi, 1998). Repacholi MH. 1998. Low-level exposure to radiofrequency electromagnetic fields: health effects and research needs. Bioelectromagnetics 19(1):1-19. The definition of region that could be used to identify any health hazards from Electromagnetic field exposure would be the specific technology that was used. For example if an Italian company was contracted to install power grids in an Eastern European country and an African country and they installed the same technology in both countries that specific technology is the region to be studied in a clinical trial and the temperature difference and differences in quality of medical care in the two countries would be sub-factors. So for example the health endpoints associated with ELF and/or RF include childhood leukaemia, brain tumours, genotoxic effects, neurological effects and neurodegenerative diseases, immune system deregulation, allergic and inflammatory responses, breast cancer, miscarriage and some cardiovascular effects (Hardell and Sage, 2008; Maslanyi et al., 2007) and these endpoints might not be reported to the health care system in the African country. Hardell L, Sage C. 2008. Biological effects from electromagnetic field exposure and public exposure standards. Biomed Pharmacother.62(2):104-9. Maslanyj MP, Mee TJ, Renew DC, Simpson J, Ansell P, Allen SG, Roman E. 2007. Investigation of the sources of residential power frequency magnetic field exposure in the UK Childhood Cancer Study. J Radiol Prot. 27(1):41-58. Erratum in: J Radiol Prot. 2007 Jun;27(2):207. Example 3. Industrial pollutants and fertility A clinical trial to establish the relationship between industrial pollutants and fertility could define region as the pollutant being investigated. For example a heavy metal like cadmium (Thompson and Bannigan, 2008) or lead (Whitfield et al., 2007), or a pesticide like atrazine (Bakke et al., 2009). Some studies are based on a geographical region (Bakke et al., 2009) but do not always take into account that a person might have been exposed on a farm during childhood but then moved to an urban area. This would be important in the studies conducted by Swan. Whitfield et al. (2007) claim that a sub-factor to be added to the region definition is genetic variation. Thompson J, Bannigan J.2008. Cadmium: toxic effects on the reproductive system and the embryo. Reprod Toxicol. 25(3):304-15. Whitfield JB, Dy V, McQuilty R, Zhu G, Montgomery GW, Ferreira MA, Duffy DL, Neale MC, Heijmans BT, Heath AC, Martin NG. Evidence of genetic effects on blood lead concentration. Environ Health Perspect. 2007 Aug;115(8):1224-30. Bakke B, De Roos AJ, Barr DB, Stewart PA, Blair A, Freeman LB, Lynch CF, Allen RH, Alavanja MC, Vermeulen R. 2009. Exposure to atrazine and selected non-persistent pesticides among corn farmers during a growing season. J Expo Sci Environ Epidemiol.19(6):544-54. Swan SH. 2006. Semen quality in fertile US men in relation to geographical area and pesticide exposure. Int J Androl. 29(1):62-8; discussion 105-8. Swan SH, Kruse RL, Liu F, Barr DB, Drobnis EZ, Redmon JB, Wang C, Brazil C, Overstreet JW. 2003. Study for Future Families Research Group. Semen quality in relation to biomarkers of pesticide exposure. Environ Health Perspect. 111(12):1478-84. Comment in: Environ Health Perspect. 2005 Oct;113(10):A652; author reply A652-3. Swan SH, Brazil C, Drobnis EZ, Liu F, Kruse RL, Hatch M, Redmon JB, Wang C, Overstreet JW. 2003. Study For Future Families Research Group. Geographic differences in semen quality of fertile U.S. males. Environ Health Perspect. 111(4):414-20.