To consider lead in relation to paints and pipes is somewhat reductive if we consider that the production of this heavy metal has a rich and long history that began thousands of years ago, as documented by numerous geochemical and archaeo-metallurgical studies conducted in recent decades: the production of coins gave a significant boost to lead production 2,500 years ago, reaching its peak in Roman times, and then declining in the Middle Ages. From 1,000 years ago, lead production increased in conjunction with silver mining in Germany and then in the New World, and then again to meet the needs of the industrial revolution. However, what is the impact of industrialisation and metal pollution on the human body?

To answer this question, a study published in the journal Environmental Science and Technology, in which Alfredo Coppa of the Department of Environmental Biology, among others, took part, analysed the human remains of 132 individuals who lived in prehistoric times in various necropolises in central Italy in order to detect changes over time in lead production rates and the risk of human exposure to this metal. 

Specifically, the researchers analysed the concentration of 24 elements, including lead, in bone fragments belonging to individuals who lived in Rome and neighbouring areas (five, in Sardinia), from 12,000 years ago until the 17th century, demonstrating how the concentration of lead in bones and teeth reflects historical changes in the production of this metal: a higher concentration, found in recent millennia, corresponds to a general increase in its production. 

"This documentation of lead pollution over time indicates that much of the estimated dynamic in production is replicated in humans living in the area," says Alfredo Coppa of Sapienza. "Lead pollution in humans has therefore closely followed the rates of its production. The more lead is produced, the more likely it is that human bodies will absorb it, with a highly toxic effect."

While the people most at risk are those with the greatest occupational exposure to lead, such as miners and employees of recycling plants, this metal can actually be found in other forms in everyone's daily life. "Any expanded use of metals," Coppa adds, "should go hand in hand with industrial hygiene, ideally with safe metal recycling and greater attention to environmental and toxicological aspects when selecting  metals for industrial use.

It has been shown that as the world production of lead increased, so did its absorption rates in people living during those historical periods, even if they were not directly involved in the production of this metal but simply breathed the contaminated air.

Several studies have shown that exposure to toxic lead in people, especially children, occurs through diet, air pollution and urban soil resuspension, among others. There is also a growing demand for metals in batteries, solar panels, wind turbines and other electronic devices.

The close relationship between lead production rates and lead concentrations in humans in the past suggests that we will continue to experience the harmful health impacts of toxic metal contamination without appropriate regulation.

References:

Lead in Archeological Human Bones Reflecting Historical Changes in Lead Production - Yigal Erel, Ron Pinhasi, Alfredo Coppa, Adi Ticher, Ofir Tirosh, and Liran Carmel -Environmental Science and Technology 2021. DOI: https://doi.org/10.1021/acs.est.1c00614

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