Risk assessment of chromium and cadmium emissions from the consumption of premium motor spirit (PMS) and automotive gas oil (AGO) in Nigeria

This paper assessed the chromium and cadmium emissions from consumption of premium motor spirit (PMS) and automotive gas oil (AGO) across the states, regions and the nation, Nigeria as a whole. This was with a view to determining the levels of per capita and land exposures to the emissions and the associated risks to humans, plants and animals. Annual fuel consumption and toxic transition metals contents were combined to estimate the annual emission rates of chromium and cadmium emissions from combustion of the PMS and AGO for a period of ten years (2009–2018). Per capita and land distributions of emissions were then calculated by using population and land areas, respectively. The results showed that total emission rates from both PMS and AGO were lowest in 2012, with 1,102 million mg/yr of chromium and 3,253 million mg/yr of cadmium, and highest in 2018, with 14,454 million mg/yr of chromium and 39,580 million mg/yr of cadmium. Emission rates per capita were also lowest in 2012, with 7 mg/yr.person of chromium and 20 mg/yr.person of cadmium, and highest in 2018 with 74 mg/yr.person of chromium and 201 mg/yr.person of cadmium. Land distribution was lowest in 2012, with 1.19 mg/yr.km(2) of chromium and 3.52 mg/yr.km(2) of cadmium, and highest in 2018, with 15.63 mg/yr.km(2) of chromium and 42.81 mg/yr.km(2) of cadmium. Comparing to regulatory limits, the risks of humans, animals and plants be poisoned are very high. It is recommended that stiff regulations concerning the heavy metal contents of fuels imported and distributed in Nigeria should be created and implemented to mitigate the risks of poisoning to humans, animals and crops.