 To prevent the resulting lead oxides from fouling the engine, gasoline was treated with an organobromine compound that converted lead oxides into the more volatile lead bromide, which was then exhausted from the engine into the environment.Like other compounds containing lead, lead dibromide is categorized as "probably carcinogenic to humans" (Category 2A), by the International Agency for Research on Cancer (IARC).Its release into the environment as a product of leaded gasoline was highly controversial.