Urh. 1.1987 - 10.1992: Institute for Water, Soil and Hygiene of the Federal Health Office, Langen Laboratories; 11.1993 - 13.1994: Institute for Water, Soil and Hygiene of the Federal Health Office; 14.1999 - 19.1997: Institute for Water, Soil and Hygiene, Federal Environmental Agency; 20.1997 - 23.1999: Institute for Water, Soil and Hygiene, Federal Environmental Agency Germany