Dichlorodiphenyltrichloroethane (DDT) was mainly used in the former GDR and in US properties as a wood preservative and for pest control. Sometimes DDT was also added to wall paints. Due to the long years of use, massive contamination of the building fabric often occurred. It accumulates in the food chain and in the human body. Carcinogenic and mutagenic effects have been shown in animal experiments. In 1972 the use of DDT was banned in the FRG and in 1990 in the former GDR.