I am familiar with this type of advertising MP, mostly produced by a company in Denmark. Sold these when I was in the promotional advertising business but never had a client with potentially lethal contents. You have an interesting piece of history, a peek at who's who in the chemical business and their by-products they have to dump in a safe manner.

Even though you have a very small amount of this material, take precautions that it never breaks to release the contents.

Thanks for sharing this interesting piece of history with us.