"Highly toxic" metals like lead accumulate in our bones, research suggests.
Although often associated with pipes and paint, lead production began 2,500 years ago with the onset of coins, peaking in ancient Rome. Production then ebbed and flowed over the centuries, spiking again to meet the demands of the Industrial Revolution.
To better understand how lead exposure influences our health, scientists from the Hebrew University of Jerusalem (HU) analysed the bone fragments of 130 Rome residents, from the ancient period up until the 17th Century.
Results, published in the journal Environmental Science and Technology, reveal the amount of lead that accumulated in the skeletons mimicked the metal's production over time.
Swallowing, absorbing or even inhaling lead particles has been linked to high blood pressure, kidney disease, heart complications and infertility.
Lead production is set to increase alongside manufacturing demands for batteries, solar panels, wind turbines and electronic devices, like the universally popular iPhone.
"This documentation of lead pollution throughout human history indicates that, remarkably, much of the estimated dynamics in lead production is replicated in human exposure," said lead author Professor Yigal Erel.
"Thus, lead pollution in humans has closely followed their rates of lead production.
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"Simply put: the more lead we produce, the more people are likely to be absorbing it into their bodies. This has a highly toxic effect."
Lead gets stored in our bones, blood and tissues, acting as "a source of continual internal exposure". As we age, our bones demineralise, potentially increasing our internal exposure.
Fleeting exposure to very high levels of the metal can cause lead poisoning – triggering abdominal pain, constipation, fatigue and headaches. In extreme cases, lead poisoning can cause kidney problems, brain damage or even death.
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Prolonged lead exposure has been linked to depression, nausea, vomiting, forgetfulness and irritability. It may also raise the risk of heart and kidney complications, among other conditions.
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Increased amounts of lead have been measured in glaciers and lake sediments. To better understand whether concentrations have risen in our bodies, the HU scientists analysed the bones of people who lived before and after the onset of the metal's production.
Lead concentrations were found to rise alongside coin production in ancient Rome, silver mining in Germany and the "New World", and finally during the Industrial Revolution.
"The close relationship between lead production rates and lead concentrations in humans in the past suggests that, without proper regulation, we will continue to experience the damaging health impacts of toxic metals contamination," said Professor Erel.
People who are regularly exposed to lead, like miners and recycling facility workers, are known to be more at risk. Nevertheless, members of the public still encounter the metal every day. This may worsen as batteries and solar panels deteriorate over time, releasing lead particles into the air and soil.
"Any expanded use of metals should go hand in hand with industrial hygiene, ideally safe metal recycling and increased environmental and toxicological consideration in the selection of metals for industrial use," said Professor Erel.
Speaking to Yahoo News UK, Professor Erel added: "As long as the cellphone is working and is well maintained, the danger is minimal, but when we discard it, and if it is not properly recycled, then its components, including lead, might be leached to the soil and to the groundwater.
"Other elements such as cobalt, gallium, arsenic and others should [also] be of concern. For example, cellphones contain approximately 60 different elements, including lead, cobalt, and other toxic (and non-toxic) metals."
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