Hirakud, 7 other Odisha wetlands show high levels of toxic heavy metals

High carcinogenic risk at Hirakud for adults and children; Heavy metals can enter crops through soil, get consumed by humans, warns study  

By Rohini Krishnamurthy
Published: Tuesday 03 October 2023
The ecological risk index of Hirakud was the highest among the wetlands. Photo: iStock_

High levels of cancer-causing heavy metals such as lead and chromium have been found in eight wetlands in Odisha, including Hirakud. The Hirakud reservoir is one of the largest human-made reservoirs in India. 

The findings were recorded in a new study published in the journal Scientific Reports on September 28, 2023.

In the modern world, anthropogenic activities such as urbanisation, industrialisation and agricultural practices deposit heavy metals in wetlands, which act as heavy metal sinks, the researchers wrote in their study. 

Read more: Heavy metals emerging as potential threat to public health on urban beaches: Study

Heavy metal pollutants that commonly accumulate in wetlands as a result of human activity include lead, chromium, cadmium, copper, mercury, nickel, zinc, manganese and arsenic. These metals can enter crops through the soil, which are then consumed by humans.

The heavy metals can also enter the environment indirectly through the food chain.

“Since the water from these wetlands is not being drawn directly for human consumption, the only way for people in the surrounding community to indirectly consume it is by consuming various foods from that wetland, such as fish, rice, some vegetables and spinach,” read the paper.

Very little was known about wetland pollution in the study area, the researchers noted. So they aimed to do three things: Study the wetland soils for the accumulation of heavy metals such as lead, chromium, copper and zinc. 

The second was to assess the ecological risk of wetlands inside agricultural landscapes and the third was to study the human health risk potential of lead and chromium.

Read more: New method for efficient removal of heavy metals from water

They selected eight wetlands: Natural ones such as Chandaneswar, Chilika, Daringbadi and Koraput as well as constructed ones like Bhadrak, Hirakud, Talcher and Titlagarh. Next, the researchers collected 144 samples from the eight identified wetlands. 

They recorded the highest concentrations of lead (51.25 micrograms per gram) and chromium (266 micrograms per gram) in Hirakud.

They found the highest concentration of copper at the Bhadrak site, with 34.27 micrograms per gram. Koraput showed a higher abundance of zinc. All the sites, according to the findings, had a higher concentration of chromium than other studies had previously shown. 

The researchers also calculated the ecological risk posed by heavy metal accumulation. The ecological risk index measures the potential ecological risk (RI) factor of all metals tested together.

The highest RI was found in Hirakud, followed by Talcher, Bhadrak, Titlagarh, Chilika, Chandaneswar, Koraput and Daringbadi.

As for carcinogenic risk, Hirakud topped the list among adults and children. “Industrial development in the study area poses carcinogenic effects due to the addition of heavy metals in soil from the effluents,” the study highlighted. 

Read more: The pesky problem of offshoring pollution

Besides, the western part of the study area is a hub for rice production. The contamination either happens through contaminated soils or the use of pesticides.

Previous studies have shown that the health of the local community is at risk if they consume rice contaminated with heavy metals.

“This could be one of the reasons for the increasingly higher number of cancer patients in the particular region of the study area, which is supported by previous studies,” the researchers wrote. 

The findings of the paper could help frame successful policies and raise awareness, they added.

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