1. Section for Toxicology and Biological Work Environment, Department of Chemical and Biological Work Environment, National Institute of Occupational Health, N-0304 Oslo, Norway
2. Department of Chemistry and Toxicology, Veterinary Research Institute, 621 00 Brno, Czech Republic
3. Department of Genetic Toxicology and Nanotoxicology, Institute of Experimental Medicine of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
4. Division of Infection Control, Environment and Health, Department of Air and Noise
5. Division of Infection Control, Department of Molecular Biology, Norwegian Institute of Public Health, N-0304 Oslo, Norway
6. Department of Occupational Medicine and Epidemiology, National Institute of Occupational Health, N-0304 Oslo, Norway