1. Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA), 53757 Sankt Augustin, Germany
2. Institution for the Building Trade, German Social Accident Insurance, 71032 Boeblingen, Germany
3. Institution for the Woodworking and Metalworking Industries, German Social Accident Insurance, 40472 Dusseldorf, Germany
4. Institution for the Raw Materials and Chemical Industry, German Social Accident Insurance, 44789 Bochum, Germany