Posted By Keith Archer. David, Not very well up on this but I seem to think it is something to do with the way that controlled drugs are used and stored for manufacture in Switzerland much the same as the Home office (could possibly be the MCA) do in the UK and the Federal Drugs Agency (FDA) in the US. Hope this helps Keith

Posted By David Allan David I was intrigued by your posting and decided to do my own bit of digging. Our own Occ Health specialist had never heard of this, but guessed it might be toxicity values. emailed the experts in Switzerland and recieved the following reply. Dear Mr. Allan In Switzerland the Swiss Federal Office of Public Health classifies toxic substances in 5 poison classes. The most dangerous poisons are classified in class 1, while the class 5 products contain only weak poisons. This classification is primarily based on the LD 50 values, however different other factors are important too. For more detailed information you can search on http://www.bag.admin.ch/ where you can place questions too. Yours sincerely Monika Guirguis, MD Senior resident Swiss Toxicological Information Centre Freiestrasse 16 CH-8028 Zurich Don't know why the swiss class has been singled out for mention but hope this clarifies your query. David