Honeycomb is mainly composed of wax, which is not broken down in human digestive systems.
This wax is usually not in any way harmful. Many candies are coated with
mineral oil, which is basically petroleum oil, similar to petroleum jelly, but shorter hydrocarbon chains.
I find this somewhat disturbing, and am reluctant to eat such candies, but apparently it is not harmful. Incidently, my lakrisal candies contain ammonium chloride for flavor.
Petrol seems to be poisonous mostly because it is so volatile.