20th century lead pollution in South America was worst in two millennia

By The Guardian

Mankind’s increasing potential to damage and then partially remediate the environment has been underlined by a new study of lead pollution found in Bolivian ice cores.

Swiss researchers found that less than half a century of leaded gasoline use in South America caused more Pb pollution (lead in the periodic table) than anything else in the previous two millennia, despite the long, precolonial history of mining and metal work in the region.

While this confirms one of the enormous negative impact of motor traffic and increased fossil fuel use, the study also showed that intervention by policymakers can make a significant difference because Pb levels dropped rapidly following the introduction of unleaded petrol.

The study - Pb pollution from leaded gasoline in South America in the context of a 2000-year metallurgical history, which is published on Friday in the journal Science Advances - was carried out by researchers from the Paul Scherrer Institute of the University of Berne .

They used a mass spectrometer to measure lead concentrations and isotopes in a 138-meter-long ice core sample taken from the Illimani glacier. Different ratios of isotopes allowed them to distinguish between those from leaded petrol and those from mining.

They found that Pb pollution - a neurotoxin - tripled after the 1960s, when leaded petrol was introduced, compared to the historical average of two thousand years when most of the contamination was from silver mines and other types of metallurgy.

Previous studies, elsewhere in the world, have already shown a spike in lead levels in the second half of the 20th century. Last year, Nasa revealed that industrial lead pollution - which is carried by precipitation - beat human explorers to the South Pole by more than two decades.

The latest research is the first to confirm this trend South America, which is home to some of the world’s oldest mining activities.

“Our study reveals a significant drop in lead pollution levels after the ban on leaded gasoline in the region of the Bolivian Andes, although it has still not fallen to natural levels,” says Anja Eichler, one of the authors of the study. “This once again highlights the importance of the ban of leaded gasoline for the environment and human health.”