I've gotten many automotive fluids into open wounds over the years working on my car. Why haven't my extremities fallen off?

Working on my car, I've busted knuckles open, cut my hands and arms up, etc. I've gotten motor oil, antifreeze, gasoline, transmission fluid etc into these open wounds on numerous occasions. Why haven't my arms fallen off from gangrene or something from all these toxic chemicals getting into my bloodstream?