Published on August 5, 2022
Ahmedabad: The healthy serving of green, leafy vegetables like spinach and cabbage considered central for good health might be laced with harmful heavy metals from the soil in which it’s grown and the water it’s fed.
A doctoral study ‘Heavy Metals in Soil, Agricultural Product and in Groundwater from Industrially Contaminated Sites of Gujarat’ by Bibhabasu Mohanty at School of Technology, Pandit Deendayal Energy University (PDEU), highlighted higher than permissible levels of metals such as lead and nickel in vegetable samples from Ahmedabad city. The study was conducted under guidance of Dr Anirban Das, associate professor at PDEU.
The study mentioned that the soil and groundwater should also be checked as sources of heavy metals in vegetables. The study by extension mentioned that the soil and groundwater should also be checked as the sources of the heavy metals in vegetables such as brinjal, tomato, cabbage, cauliflower and spinach. The study took samples from Gyaspur, Visalpur, Kasindra, Saroda, Chandisar, Kaloli, Asmalli, and Khada villages around Vasna sewage plant.
The study highlights the concentration of heavy metals such as copper, manganese, nickel, lead and zinc in wastewater exceeding permissible values by Indian and World Health Organization (WHO) standards. Zinc concentration was found to be the most prevalent heavy metal followed by manganese and copper.
Due to the use of wastewater for irrigation, concentration of metals was found to be high – especially of nickel and lead. For example, against the permissible limit of 1.5 micrograms of nickel per gram of vegetable, samples in Brinjal showed a maximum value of 4.1, tomato and cabbage 4.2 and cauliflower 3.8. For lead, against a permissible limit of 2.5 micrograms per gram of vegetable, researchers found highest 8.4 in spinach at one spot while highest 6.9 was found in brinjals from one of the villages.
“It’s one of the first studies analysing all three aspects – groundwater, soil and final produce (vegetables) – in context of heavy metals around Ahmedabad. Earlier studies indicated presence of cadmium, lead and chromium in cabbage, beans, chili and brinjal in Rajkot, and arsenic in soil and arsenic, lead and nickel were found in spinach, radish, tomato, chili and cabbage in Vadodara,” said Dr Mohanty, now a faculty at a city-based university.
The study suggested soil washing technology by using chelating agents and surfactants for the removal of heavy metals. More efficient treatment of the wastewater – which is sometimes used for irrigation in farms – is also suggested as a possible remedy to reduce the heavy metal content.
“The human body cannot process heavy metals effectively due to its high molecular weight. Kidneys can’t eliminate it through normal processes and thus it starts accumulating in the body,” said Dr Tejas Prajapati, a city-based toxicologist. “It spreads in parts of the body such as the liver, bones and brains and hampers its normal functioning.”
The study indicated harmful effects of nickel and lead as insomnia, hypertension, reduction in fertility and damage to neural and renal systems.