A study performed by BHU researchers revealed that that vegetables and grains irrigated with mixed effluent from industrial and residential districts of Bhadohi had higher concentrations of heavy metals than those irrigated with groundwater. The study was published in the journal of Toxicology Reports.

Under the supervision of Botany assistant professor Rajesh Kumar Sharma, 84 composite samples of vegetables were collected during a seasonal period. All of the samples were washed with running tap water, sliced into little pieces, and dried in the oven. The dried samples were then ground into powder and cooked with di-acid (nitric acid and perchloric acid) for 6-8 hours at a steady temperature. The Atomic Absorption Spectrophotometer was used to measure heavy metal contamination levels (cadmium, nickel, chromium, copper, and zinc) in vegetable and grain filtrates. 

Copper and chromium were found to be below the Indian Standard safety level in all vegetables and grains tested, whereas zinc exceeded the safety limit only in palak. Nickel and cadmium levels in all tested vegetables and grains exceeded both Indian and WHO/FAO safety guidelines.

The largest daily consumption of heavy metals by local populations was determined to be nickel through wheat grains and chromium through radish and garlic. Copper, nickel, and cadmium health indices were more than one unit for children and adults who consumed wheat and paddy grains.

Consumption of heavy metal contaminated vegetables and other food items on a regular basis can result in mental and behavioural disorders, asthma, cancer, nervous system-related diseases, cardiovascular diseases, kidney or renal-related diseases, endocrine system irregularities, obesity, and breast cancer. Excessive sewerage can be linked to a lack of sanitation facilities, poor septage management, and a lack of sewage and sanitation policies.

Groundwater is becoming increasingly contaminated as a result of industrial waste and unsustainable farming practices. Such problems can be solved by using groundwater instead of wastewater for irrigation, minimizing monoculture, and employing a variety of scientific methodologies.

(Source: https://timesofindia.indiatimes.com/city/varanasi/crops-irrigated-with-wastewater-threat-to-human-health-bhu-study/articleshowprint/99104808.cms?val=3728)