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