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Road rage? Gas fumes may heighten aggression

Nov. 24, 2009
Courtesy BioMed Central
and World Science staff

Mount­ing prices may not be the only thing caus­ing an­ger at the gas pumps. A new study has found that rats ex­posed to fumes from leaded and un­leaded gas­o­line be­come more ag­gres­sive. Wheth­er that ap­plies to peo­ple too re­mains to be tested.

A new study has found that rats ex­posed to fumes from leaded and un­leaded gas­o­line be­come more ag­gres­sive.

Amal Ki­nawy of Cai­ro Un­ivers­ity in Egypt ex­am­ined the ef­fects of gas­o­line fumes in three groups of male rats, each ex­posed to ei­ther leaded-gas fumes, un­leaded-gas fumes or clean air. She ob­served the ro­dents’ be­hav­ior and stud­ied any re­sult­ing brain changes. 

The re­search found that rats ex­posed to ei­ther kind of fu­el va­por showed in­creased time spent in bel­lig­er­ent pos­tures, and high­er num­bers of ac­tu­al at­tacks, com­pared to the clean-air group. 

But did this re­sult from an ac­tu­al phys­i­o­logi­cal change? Or could the rats have just been an­gry about be­ing forced to smell some­thing un­pleas­ant?

Ex­amina­t­ion of the an­i­mals’ brains af­ter the ex­pe­ri­ment sug­gested the first fac­tor was at least partly in­volved, ac­cord­ing to Ki­nawy. “Rats ex­posed to un­leaded gas­o­line showed in­dica­t­ions of in­creased dam­age caused by free rad­i­cals,” or high­ly reac­tive mo­le­cules, she not­ed. She al­so found al­tered lev­els of neu­ro­trans­mit­ters, or sig­nal­ing mo­le­cules, in the brain cor­tex re­gion, in com­par­i­son with the clean-a­ir or leaded gas­o­line groups. 

Fur­ther­more, “in­hala­t­ion of both fu­els in­duced sig­nif­i­cant fluctua­t­ions in neu­ro­trans­mit­ters in the hy­po­thal­a­mus, hip­po­cam­pus and cere­bel­lum,” sec­tions of the brain, she added.

“Mil­lions of peo­ple eve­ry day are ex­posed to gas­o­line fumes while refu­elling their cars. Ex­po­sure can al­so come from ex­haust fumes and, par­tic­u­larly in the de­vel­op­ing world, de­lib­er­ate gas­o­line sniff­ing as a means of get­ting high,” she said. “Height­ened ag­gres­sion may be yet an­oth­er risk for the hu­man popula­t­ion chron­ic­ally ex­posed to ur­ban air pol­lut­ed by au­to­mo­bile smoke.” The study is pub­lished in the on­line re­search jour­nal BMC Phys­i­ol­o­gy.

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Mounting prices may not be the only thing causing anger at the gas pumps. A new study has found that rats exposed to fumes from leaded and unleaded gasoline become more aggressive. Whether that applies to people too remains to be tested. Amal Kinawy of Cairo University in Egypt examined the effects of gasoline fumes in three groups of male rats, each exposed to either leaded-gas fumes, unleaded-gas fumes or clean air. She observed the rodents’ behavior and studied any resulting brain changes. The research found that rats exposed to either kind of fuel vapor showed increased aggressive behavior, such as more time spent in belligerent postures and increased numbers of actual attacks, in comparison to the clean air group. But did this result from actual physiological change? Or could the rats have just been angry about being forced to experience an unpleasant smell? Examination of the animals’ brains after the experiment indicated the first factor was at least partly involved, according to Kinawy. “Rats exposed to unleaded gasoline showed indications of increased damage caused by free radicals,” or oxygen-containing molecules, she noted. She also found altered levels of neurotransmitters, or signaling molecules, in the brain cortex region, in comparison with the clean-air or leaded gasoline groups. Furthermore, “inhalation of both fuels induced significant fluctuations in neurotransmitters in the hypothalamus, hippocampus and cerebellum,” sections of the brain, she added. “Millions of people every day are exposed to gasoline fumes while refuelling their cars. Exposure can also come from exhaust fumes and, particularly in the developing world, deliberate gasoline sniffing as a means of getting high,” she said. Kinawy concludes, “Heightened aggression may be yet another risk for the human population chronically exposed to urban air polluted by automobile smoke.” The study is published in the online research journal BMC Physiology.