Ecological study
An ecological study is a special epidemiological study that examines one or more risk factors in an area and relates them, for example, to the disease frequency of the population group in that area. Individual individuals are not examined, but collected data from the area or from the population group to be examined is used.
Other epidemiological methods such as cross-sectional studies , cohort studies and case-control studies are used to investigate the relationship between individual exposures and diseases (e.g. smoking and cancer) .
The prerequisite for ecological studies are corresponding data (noise, air pollutants, chemical pollution of drinking water and food, ionizing / non-ionizing radiation, etc.), which often come from measurements over long periods of time. The problem is to determine the actual individual exposure within the population. In some cases it is possible to examine disease frequencies and stress indicators at regional level (e.g. district). Various authors point out the particular problems of such approaches.
The German Federal Office for Radiation Protection (BfS) criticizes the method as follows: "Ecological studies are prone to error because it is assumed that the groups examined differ only with regard to the risk factor of interest (such as radiation), but not with regard to other risk factors (such as Example smoking). Although they can give indications of possible causes, they are fundamentally unsuitable for risk assessments. ”However, some recent studies examine several factors in order to differentiate the risks (for example in the case of existing diseases). The NORAH research project on the effects of noise also recorded previous illnesses and excluded the relevant population group in a case-control study in order to ensure that the illnesses were not triggered by other factors.
The aim of analytical ecological studies is to create a gradient between sufficiently clearly graded exposures and correspondingly graded disease frequencies on ecological - i.e. H. to be demonstrated at regional level (ecological dose-effect relationship).
literature
- ^ KJ Rothman, S. Greenland: Modern Epidemiology. 2nd Edition. Lippincott Williams & Wilkins, Philadelphia 1998.
- ↑ FJ Mather, LE White, EC Langlois, CF Shorter, CM Swalm, JG Shaffer, WR Hartley: Statistical methods for linking health, exposure, and hazards. In: Environ Health Perspect . 112 (14), Oct 2004, pp. 1440-1445.
- ↑ BfS: Epidemiology of Radiation-Related Diseases - Ecological Study , accessed on April 25, 2016.
- ^ H. Scherb, K. Voigt: Analytical ecological epidemiology: exposure-response relations in spatially stratified time series. Environmetrics Special Issue: The 18th TIES Conference: Computational Environmetrics: Protection of Renewable Environment and Human and Ecosystem Health. Volume 20, No. 6, September 2009, pp. 596-606.