Metal mining pollution threatens 23 million people worldwide: study

Researchers just published a study in the journal Science, which provides new evidence on the strong impact caused by metal mining pollution in rivers and floodplains around the world. They estimate that concentrations of dangerous toxic waste potentially affect 23 million people.

Led by Professors Mark Macklin and Chris Thomas, from the University of Lincoln, United Kingdom, the study provides a global view of the environmental problems and health threats involved in metal mining activities.

The research team used a new georeferenced global database of 185,000 metal mines and employed a combination of process-based modelling and empirical testing to assess the global scale of metal mining pollution in river systems and its implications for human populations and the environment.

The study modeled contamination from all known active and inactive metal mining sites, including tailings storage facilities (used to store mining waste), and analyzed potentially harmful contaminants like lead, zinc, copper, and arsenic. These contaminants are carried in waters down from mining facilities and are often deposited along river channels and floodplains over extended periods of time.

23 million people affected

The new results highlight the widespread extent of the pollution, which affects approximately 479,200 kilometers of river channels and spans 164,000 square kilometers of floodplains across the country. The pollution has been released at a time of increasing demand for metals and minerals to meet the demands of the green energy transition.

The results obtained indicate that approximately 23.48 million people reside in these affected floodplains, support 5.72 million livestock and cover more than 65,000 square kilometers of irrigated land. The team behind the study believes these figures are a conservative estimate due to the lack of available data for several countries.

Humans can encounter these metal contaminants through skin contact, unintentional ingestion, inhaling contaminated dust, and consuming food and water grown in soil contaminated with them.

This additional danger poses a threat to the health of urban and rural communities in low-income countries and communities that rely on these rivers and floodplains, especially in regions already afflicted by water-related diseases.

The researchers say that this contamination constitutes a significant and growing constraint on water and food security, compromises vital ecosystem services, and contributes to antimicrobial resistance in the environment in the industrialized nations of Western Europe, as well as the United Kingdom and the United States.

Professor Chris Thomas, one of those responsible for the study, said that the world must transition to green energy and the rapid growth of global metal mining is crucial.

He added, "Much of the estimated global pollution we have mapped is a legacy of the industrial age, so they are encouraging modern mining to prioritize environmental sustainability."

A tool to act

"Our new method for predicting the dispersion of mining waste in river systems around the world provides governments, environmental regulators, the mining industry and local communities with a tool that, for the first time, will allow them to assess the impacts of the off-site and downstream mining on ecosystems and human health," said Professor Mark Macklin, who led the international team of researchers told Ground Report.

"We hope this will facilitate mitigation of the environmental effects of historic and current mining and, more importantly, help minimize the impacts of future mining development on communities, while protecting food and water security," Macklin added.

Professor Deanna Kemp from the University of Queensland's Sustainable Minerals Institute, who was part of the team behind the study, called the results "sobering".

"These findings remind us that mining can cause extensive damage downstream over long periods of time," Kemp said. "Many people benefit from mining and metals, but we must do more to understand and prevent the negative effects on people who live and work in affected areas."

Prof. Paul Brewer, Aberystwyth Univ., highlights the significant global threat from metal mining. This study reveals that people exposed to contaminant metals from long-term waste discharge into rivers are nearly 50 times more numerous than those affected by acute tailings dam failures. The new model aids in assessing downstream impacts and guides better strategies for land contaminated by metal mining.

New set of tools and datasets 

Researchers used a new georeferenced global database of 185,000 metal mines compiled by the team to quantify the magnitude of the well-known problem. A combination of process-based modelling and empirical testing was employed by the team.

VU Amsterdam researchers Paolo Scussolini and Dirk Eilander played a specific role in the research, using models to create unique global maps of river floods that mimicked pre-industrial conditions in climate and human influences. This provided the ideal basis for their colleagues, who in turn simulated the dispersion of the contamination that has taken place along centuries of mining activities. The research aims to improve the management of mining.

Our productive system provides a sobering picture of the unintended, long-term consequences. Metal mining will not disappear; on the contrary, it will grow to enable development and the energy transition. Therefore, it is essential to know the extent and location of mining contamination in order to prioritize areas for remediation and containment of pollution, and to improve management of mining.

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