Camels living near a petroleum plant in Saudi Arabia are susceptible to ingesting a range of heavy metals, potentially putting at risk people who consume their meat or milk, according to a new study.
The research found increased levels of lead and other heavy metals in camels that lived close to an oil-extraction depot in the east of Saudi Arabia. Similar contamination was detected in the area’s soil.
The study, by academics at King Saud University in Riyadh, Taif University and Cairo University, also showed that the camels experienced tissue damage, inflammation, and liver and kidney abnormalities.
“Heavy metals were increased in the blood, milk, and meat of the camel samples collected from the site of the oil industry,” the researchers wrote in the journal Animals.
“Therefore, the consumption of camel milk and meat could be a route of transmitting these heavy metals to the body of people living near the oil industry site, particularly children who consume a large amount of milk.”
Titled “Heavy metal accumulation, tissue injury, oxidative stress, and inflammation in dromedary camels living near petroleum industry sites in Saudi Arabia,” the study looked at camels living near Al Jubail. This city on the Arabian Gulf is, the researchers said, home to the Middle East’s largest petrochemical company.
Material was also collected from camels at a site several hundred kilometres inland from Al Jubail, and from camels living roughly halfway between the two.
The researchers, based in Saudi Arabia, Egypt and the UK, measured levels of heavy metals in the milk, blood, muscle, liver, and kidney of camels from the three sites.
Some samples were from living camels, while others were collected from animals slaughtered for human consumption.
As well as finding elevated levels of lead in the camels and in the soil near the petroleum plant, the researchers detected larger amounts of cadmium, nickel and vanadium, all of which are heavy metals. Lead has been associated with kidney and brain damage, anaemia and weakness when ingested by humans.
A type of chemical imbalance called oxidative stress and a form of cell death named apoptosis were also more common in camels living close to the plant.
Liver and kidney tissue samples were examined under the microscope and greatest abnormalities were found in camels closest to the facility, with their liver tissue containing fat droplets and evidence of fibrosis or scarring.
“These findings may be of public interest and call attention to the assessment of the impact of the petroleum industry on the environment and the health of nearby communities,” the researchers wrote.
Dr Ulrich Wernery, scientific director of the Central Veterinary Research Laboratory (CVRL) in Dubai, who was not connected to the study, said that effects the camels suffered were probably because of the food or water they ate, rather than because of pollutants in the air.
He said he had some reservations about the research, such as a lack of detail about exactly how far from the plant the camels lived, and whether they roamed the nearby desert — where they potentially could have ingested heavy metals while browsing vegetation. However, despite his misgivings, Dr Wernery described the findings as a “nice” study.
“A plant will have emissions and it goes into the soil, that’s for sure,” Dr Wernery said.
“It can affect animals, wildlife and goats and sheep.
“I’m sure there’s an effect from the plant, there’s no doubt about it, and for other animals.”
Prof Rajiv Chowdhury, chair of the Department of Global Health at Florida International University, who has researched the effects of heavy metals, said that exposure to heavy metals, such as lead and cadmium, could increase the risk of cardiovascular disease. The risk of cancer is also increased.
“Exposure to lead, particularly in occupational cohort studies in humans, showed higher risks of brain cancer, Hodgkin’s lymphoma, lung and rectal cancers,” he said.
“Childhood lead exposure in humans has also been associated with lower cognitive function in later life.”
He said there is also evidence linking occupational exposure to cadmium to increased risk of lung cancer, while nickel compounds may be carcinogenic too.
For both lead and cadmium, Prof Chowdhury said industrial activities are a source of exposure. This is because the metals could contaminate the air and the surrounding environment, although there are numerous other sources of exposure, including water supplies.
According to Dr Wernery, the absence of large-scale petroleum plants on land in Dubai means that the issues highlighted in the paper are much less likely to affect camels in the emirate.
He said feed given to camels and other animals at the CVRL was regularly checked for heavy metals, such as lead and cadmium, but was never found to be contaminated. Much of the feed is imported from Canada or Australia, but fresh alfalfa (a flowering plant) is sourced locally.
The CVRL also tests locally made honey, which was likewise found to be free of heavy metals.