I stumbled across some amusing history in Why nitrate?, an article that explains why Kodak used something as explosive as nitrocellulose for filmstock:
It was created to replace ivory, which was expensive, and becoming scare since the Elephants were being killed at a faster rate than they were reproducing. Initially, nitrocellulose was used for billiard balls, cufflinks, combs and other toiletry items, as a replacement for ivory since the cost of making it was so cheap. Even then, it was highly flammable. If you hit a pool ball hard enough it would explode. In fact, there’s a gag in a Buster Keaton film when he uses pool balls like grenades while being chased. Nitrocellulose combs and cufflinks used to start on fire when people smoked near them. Despite it’s danger, it was so cheap to make many people liked it and it allowed middle class people to afford the luxury items reserved for the wealthy in the ivory days.
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It was when the French and later Americans actually started projecting the nitrate film onto large screens with brighter Carbon Arc illumination that the problems started. The film shrank in the exchanges and if it jammed in the projector you had a major fire on your hands. An early screening in France at the turn of the century started a nitrate fire that killed a hundred patrons and there were nitrate fires in vaults, labs and theaters throughout its history. Di-acetate safety film was developed in the twenties by Kodak and Pathe but only used for the amateur and non-commercial markets because it shrank more rapidly than Nitrate. It wasn’t until 1948 that slow shrinking, slow burning tri-acetate safety film was adopted by the industry and the nitrate phased out.