The Dread Pirate Roberts may have built up an immunity to the most deadly poisons, but we can't all be the hero from The Princess Bride. We're better off avoiding poisons, whether in games of chance or out in the wild. Unfortunately, the designers of Jurassic Park didn't read Mother Nature's warning label: this is one toxic playground.
When poison appears in Jurassic Park, it's a sign not only of danger, but also of ignorance. When showing off the park's swimming pool, for example, P.R. chief Ed Regis points out the authentic Jurassic ferns planted in the area. Ellie Sattler recognizes them immediately, and she knows something Regis doesn't: the spores of the ferns are deadly. Nobody noticed this before?
It's as if the designers thought, hey, let's plant a toxic jungle like the one in Nausicaä of the Valley of the Wind. Only they didn't think: "Even touching the attractive green fronds could make you sick, and if a child were to take a mouthful, he would most certainly die—the toxin was fifty times more poisonous than oleander" (3.17.26). Great greenery for swimming pools—if you want lawsuits galore.
And the park designers aren't just ignorant about the plant life; they're ignorant about the dinosaurs, too. No one knew that the Dilophosaurs were poisonous and could spit their poison at people until workers at the park found out the hard way. Nobody at the park has been planning ahead: all they care about is profit, not the actual long-term viability of the park.
At Jurassic Park, poison is a sign of deadly ignorance.