Last Update: July 4, 2015
Once crude oil is refined to oil products (gasoline, diesel, jet fuel, and other products), it is delivered to its end use. Typically this is gasoline delivered through a gasoline pump. The other non-liquid-fuel crude oil products are delivered through other means, such as becoming a constituent of asphalt.
The liquid fuels are delivered to refueling stations by a combination of pipelines, ships, trains, and trucks. They're dispensed to customers through pumps into on-board fuel tanks. Eventually the fuel will be combusted in an internal combustion engine to produce motion.
That's what happens when all goes well. Of course problems occur along the way from refinery to consumer.
Every step of the way, liquid fuels leak during delivery, or accidents occur causing spills. In either case gasoline, diesel, etc, are released into the environment.
While gasoline, diesel, etc, are probably not as toxic as crude oil (see What’s in Crude Oil? A lotta toxic stuff, Benzene, Tuolene, etc), they are still carcinogenic. In most jurisdictions, gasoline pumps are required to carry warning signs that cancerous chemicals are dispensed through the fueling station. Meaning any gasoline, diesel, etc spill exposes everyone to cancerous chemicals.
Oh, and lead was commonly used in the past as a gasoline additive. Lead toxicity is known to wide ranging problems, especially in the brain. [Wikipedia]
Lead toxicity from gasoline occurs through normal use, since the lead is part of the exhaust. The air in any locale still using leaded gasoline, therefore, has lead, which is easily inhaled poisoning everyone who breaths.