The Independent reported that new research shows that Egyptian pyramids' builders were exposed to incredibly high levels of heavy metals such as copper and asen, marking the earliest example of metal pollution - archaeologists said.
A new analysis of soil samples from the Giza Plateau shows that copper and asen pollution is over 5,000 years old due to the use of metal tools, especially those used to build the pyramid complex.
The study published in the journal Geology assessed the sedimentary core drilled under the foot of pyramids near the ancient port of Khufu, near the Nile River.
Archaeologists suspect that this now-disappeared river branch helped transport materials to build the pyramids more than 5,000 years ago.
According to the new study, a huge workforce of about 7,000 to 20,000 people, including historical craftsmen, bricklayers, metal workers, carpenters and managers, worked on site to complete the pyramid construction project.
Research shows that the copper tools used by workers have been mixed with asen to increase the durability of the blade, the cutter and the drill.
They said the port played an important role in transporting materials to build ancient Egyptian cemeteries and was also a place to produce large bronze tools.
The latest findings show that the origin of metal pollution at this site is around 3265 BC, much earlier than initially predicted.
metal pollution seems to have peaked about 750 years later, around 2,500 BC, when the construction of the pyramid was in its final stages, lasting until about 1000 BC.
"We found that significant local pollution occurred during the reign of the Egyptian kings Khufu, Khafre and Menkaure, coinciding with the metal processing during the preparation and construction of works," the scientists wrote.
Researchers say the level of metal pollution appears to be about five to six times higher than the amount of natural metals detected in the environment.
The discovery also shows that the construction of the pyramid complex in Giza may have begun earlier than previously thought, coinciding with the start of the Nile River's water level.
Even as the Nile River recedes and the port of Khufu continues to narrow, metal processing continues.
copper pollution remains high even during the civil instability period around 2200 B.C. when the Nile River dropped to its lowest level, showing a very resilient workforce.
Although copper in limited quantity is necessary for human life, exposure to a higher level, as discovered at this location, can cause negative effects on both humans and wild animals such as vomiting and diarrhea.
It is unclear whether the ancient Egyptians faced these symptoms due to metal pollution or how they handled them.
"Although the pyramid complex has created an outstanding cultural heritage for humanity, it also marks the beginning of a significant amount of human-caused metal pollution in Giza," the researchers concluded.
