Why is Jack's entire neighborhood forced to evacuate after the train accident in the novel, White Noise?

Nyodene Derivative is the synthetic gas that is released from a train accident, terrorizing Jack's neighborhood and making them evacuate. It is a man made gas that has caused a number of malicious side effects in rats and is responsible for sweating palms, vomiting, comas, miscarriages and severe cases of deja vu in humans.