The German Environmental Survey (GerES): Response Rates and Compliance

Abstract

P-786 Abstract: It is now 20 years that the surveillance program of the German Environmental Survey (GerES) was started. The present paper summarizes the experience gained with regard to response rates and compliance. GerESs are nationwide cross-sectional studies to determine the exposure to environmental pollutants of the general population and to explore exposure pathways. Furthermore, trends can be evaluated by comparing data from two or more GerESs. GerES is now being carried out for the fourth time (GerES IV). While in GerES I to III adults were studied – only in GerES II additionally children aged 6 to 14 years –, the aim of GerES IV is solely the study of 3- to 14-year-old children. All GerESs have been performed in cooperation with the corresponding German National Health and Examination Surveys conducted by another federal institution, the Robert Koch Institute. A random subsample of the Health Survey participants took part in each GerES. Consequently, the response rate of GerES has always been lower than that of the corresponding Health Survey. A comparison of the three GerESs for adults earlier shows a continuous decline of the response rate from 73% in 1985/86 (GerES I, West-Germany only) and about 63% and 70% in 1990/92 (GerES II, West- and East-Germany, respectively) to 55% in 1998 (GerES III). Preliminary response rates of GerES IV for children, the field phase of which is still running, are almost identical to those of GerES III. Reasons for this trend will be discussed. As only participants of the Health Survey take part in GerES, GerES “inherits” any response bias from the Health Survey. In all GerESs the proportion of subjects of low socioeconomic status has been higher in the group of the non-responders than in the group of the participants. Compliance of the participants has always been high. In the following, the percentages are given for GerES III (study population: 18–69 years) and GerES IV (3–14 years; preliminary data), respectively. Most subjects provide blood samples (96%/87%), morning urine samples (98%, 97%) and tap water samples (99%/99%) as well as vacuum cleaner bags (95%/90%). Reasons for non-compliance will be discussed. The financial support of the Federal Ministries for the Environment, Nature Conservation and Nuclear Safety, and of Education and Research is gratefully acknowledged. Field work for GerES IV was carried out by the Robert Koch Institute, Berlin.