A new study found aggression in lab rats after they inhaled petol fumes which may also be a pointer to the deleterious effects of urban pollution on the population.
Cairo University researcher Amal Kinawy exposed three groups of rats to either clean air, vapour from leaded petrol or vapour from unleaded petrol.
Dissection of the rats showed that those exposed to petrol (US gasoline), had big fluctuations in a key group of neurotransmitters -- chemicals used for exchanging messages between neurons -- in three areas of the brain.
In addition, rats exposed to unleaded petrol showed indications of neurological change. Their brain cells looked like they had been damaged by rogue molecules called free radicals.
Just as striking was that the rats exposed to either kind of fuel were more aggressive, spending more time in belligerent postures and carrying out more attacks, compared to the clean-air group.
Kinawy speculates that people chronically exposed to urban air polluted by traffic emissions may also be at risk of heightened aggression, although further research is needed to confirm this parallel.
"Millions of people every day are exposed to gasoline fumes while refuelling their cars," she said in a press release.
"Exposure can also come from exhaust fumes and, particularly in the developing world, deliberate gasoline sniffing is a means of getting high."
Her study appears online in BMC Physiology, an open-access peer-reviewed journal published by the British-based BioMed Central.