What fuel does a truck use that transports chemical toxins?

Answer 1

There is nothing special about a cargo that makes a truck use a different fuel source. If you have a truck that runs on hydrogen, or a truck that runs on sunlight, or a truck that runs on propane, you can carry "chemical toxins" with either or none of them. Most trucks run on diesel fuel, (which can be just about any oil, but usually is made from crude oil), and so that is the "answer" to your question.