toxin

As we all know, the United States is a big country in the research of biological and chemical weapons, and has been conducting research on biological and chemical weapons in secret. Although the US government has always denied it, there are general signs and evidence that its biological research...

A few members of Congress received threatening letters with a white powdery substance that was later found to be harmless. Apparently there has been a threat that 100 such letters will be sent out and 10 will have lethal powders. source...