Egyptian Workers Who Built Pyramids of Giza Exposed to Dangerous Toxins

While there are still uncertainties about how exactly the three gigantic pyramids on Egypt’s Giza Plateau were built, no one doubts that the work involved was intensive and difficult. But as revealed by a new study of the local environment at the time of the pyramids’ construction, this work was also, quite literally, toxic. It seems the laborers who built these astonishing structures were exposed to dangerous concentrations of poisonous heavy metals, primarily copper and arsenic, on a daily basis.

This unexpected discovery resulted from excavations that started in the urban streets of Cairo. It was necessary to dig there to reach the bottom of the now-dry floor of Khufu Harbor, which several thousand years ago was a thriving and active port located on a long-dead branch of the Nile very near where the Giza pyramids were erected.

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Researchers drill a sediment core in Giza, once the Khufu Harbor. (Nick Marriner/Geology)

Toxic Soil

When sediment samples were taken from the site of the old harbor, they revealed the presence of unsafe levels of copper and arsenic. These heavy metals can be hazardous to human health and exposure to them can cause many different kinds of health problems, some of which could be fatal.

According to the international team of scientists responsible for discovering the toxins in Khufu Harbor sediment, this toxic pollution was a byproduct of intensive metalworking activity. Copper and arsenic contaminants in the water, soil, and air would have posed a serious health risk to the workers responsible for the metalworking, for the laborers assigned to use the copper tools that were produced, and for anyone else spending a lot of time in that environment for any reason.

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The Giza-pyramids and Giza Necropolis, Egypt, seen from above. Photo taken on 12 December 2008. (Robster1983/CC0)

In Ancient Egypt, Pyramid Building Could be Hazardous to Your Health

Notably, the scientists have dated the contamination problem back to the 26th century BC, which is when three kings of the Fourth Dynasty of ancient Egypt’s Old Kingdom ordered the construction of the three pyramids of Giza.

“We found that significant local contamination occurred during the regnal years of Kings Khufu, Khafre, and Menkaure, consistent with metalworking during the preparation and construction of the edifices,” the scientists wrote in a paper about their work published in the journal Geology.

“While the pyramid complex led to the creation of an outstanding cultural legacy for humanity, it also marked the onset of significant human-caused metal contamination at Giza.”

The research team analyzed the samples they obtained from the bottom of Khufu Harbor using a technology known as plasma-mass spectrometry (ICP-MS), which allowed them to test for the presence of copper, arsenic, aluminum, iron, and titanium. They also carried out a half-dozen carbon-14 dating tests on the samples, to pin down the dates when any contaminants would have been deposited.

"We found the oldest regional metal contamination ever recorded in the world," said study co-author Alain Véron, a geochemist from France's Aix-Marseille Université, in an interview with the science magazine Eos. He stated that his team had found levels of copper that were "5 to 6 times higher than the natural background" during the latter stages of the 26th century, with these extreme levels of contamination continuing on for another 1,500 years after that.

Interestingly, the earliest traces of copper and arsenic found at the bottom of Khufu Harbor dated back to 3,265 BC. This shows that metalworking began at Giza at least 200 years earlier than previously believed, and several centuries before the construction of the world-famous pyramids began. That puts the origins of the practice back into the Predynastic era, which contradicts the previous belief that Giza had not been populated this long ago.

It seems the area around Khufu Harbor was a major metalworking center for as long as 2,000 years. Tools would have been made out of copper, with arsenic added to the metallic mixture to make them stronger and more durable. The ancient Egyptian metalworkers produced chisels, drills, blades, knives, and other sharpened tools suitable for working with a variety of materials, including limestone, wood, and textiles.

The site of the metalworking facilities was located right at the foot of the pyramids, as that is where the extinct Nile branch that hosted the harbor ran. Estimates are that between 5,000 and 20,000 laborers were involved in the construction of the pyramids, and a significant number were undoubtedly exposed to hazardous levels of copper and arsenic, which likely spread out and poisoned the soil, water and air all around the metalworking facilities.

Ancient Egypt Was More than Just its Elites

Surprisingly, metalworking at the site did not stop when the Nile River began to lose volume around 2,200 BC, which caused Khufu Harbor to shrink. By this time the pyramid-building days had long passed, yet metalworking activity continued at a brisk pace, as revealed by the continued contamination of the harbor at this time.

What experts on ancient Egyptian society and history believe is that the receding of the Nile opened up fertile floodplains that were ideal for agriculture, causing an increase in farming activity that would have required metal tools to carry out. And so the metalworking at the site continued, as did the poisoning of the people who lived or worked there, whether out of choice or necessity.

In fact, one of the purposes of the new study was to find out more about how non-elite ancient Egyptians with limited options actually lived. In the past much of the focus has been on the pharaohs and aristocrats who ordered the construction of grand and elaborate monuments, but did none of the real work required to build them.

"We'd like to know more about 95% of the people rather than the elite," Véron declared, expressing his team’s populist sentiments.

From this perspective, it is easy to see why this new study of heavy metal pollution in ancient Egypt is so groundbreaking. It reveals that the lives of the workers who constructed the pyramids of Giza were even more fraught with danger than previously believed, as they likely experienced many troubling health issues as a result of their exposure to some highly toxic substances. Whether Egyptian elites knew about what was going on, or cared, is unknown.

Top image: Ai generated image of builders on the Giza plateau.              Source: Roman/Adobe Stock

By Nathan Falde