The White House. Photo: BBC

(VOVworld)- The US Secret Service said Tuesday that an envelope posted to the White House early this week has tested positive for cyanide.  Spokesperson for the US Secret Service, Bryan Leary, said that a letter sent to the White House on Monday containing a milky white substance and the initial biological test showed a negative result. However, a chemical test gave a positive result. A sample from the letter is being sent to another facility for further testing. The US Secret Service affirmed that no White House staff was contaminated or exposed to cyanide in this case.