The contaminated soda is mentioned briefly in the beginning of the film, when Bruce Banner is working on a project with General Ross. We learn that the soda was contaminated with a gamma ray-induced chemical compound that was accidentally released into the public. This leads to Bruce being exposed and transforming into the Hulk.
However, the film doesn't show the actual soda or its effects on anyone else.
The focus is on Bruce Banner's struggle and the impact of the gamma radiation on him. The contaminated soda is simply a plot device to set the story in motion.