There was never green poison, it was a clinical engineering smallpox virus, called the dollar flue. It made people sick, infect people roamed the streets of d1. Amherst escaped with the dollar flue, we were under the impression he went to Washington DC and set the plot for d2
they changed it to green poison, which is stored in barrels all over DC, which is a gas that kills you almost instantly, this explains why there are no sick civilians roaming the streets. There is no mention of Amherst, kenner, or the Russian in d2. I still do not see any relationship between d1 and d2, other than your a division agent.
Green poison was another name for it... probably because it was on money. And money is green.
The stuff stored in barrels is DC62, and it's yellow. It was an experimental chemical that was supposed to kill the remaining green poison/dollar flu/smallpox varicola chimera on non-organic surfaces. Unfortunately, as it was completely untested it became deadly when exposed to cold. Then the True Sons found a way to weaponize it as a chemical weapon. The Black Tusk were looking at making it even more effective as a weapon.
You do see some mention of Kenner, mostly in comms and echos around the city. Nobody knows where he went.
You don't see sick people running around (other than maybe some of the Outcasts) because almost everyone infected would have died off in the 6 months since the infection. And almost all sources of infection have cleared... other than a few small pockets as Roy Benitez states in one of the comms you come across.