Edible vegetables are hyperaccumulators of heavy metals
Vegetables with Heavy Metals, HEAVY TOXIC TO HEALTH
Excessive amounts of heavy metals; Toxicity to Human Body – Empri Report Waste water for growing vegetables
The higher concentration of the heavy metals in vegetables is due to the use of untreated sanitary and industrial wastewater by the farmers for the irrigation of vegetables.
Kere Manjunath ಕೆರೆ ಮಂಜುನಾಥ್
BENGALURU: The concentration of heavy metals in vegetables grown using sewage water has increased, increasing the risk of toxic elements being added to the human body, according to a study by the Forest Department's Environmental Management and Policy Research Institute (EMPRI).
The study was conducted by collecting 400 samples of 10 vegetables from markets, super market stores, hopcoms, organic stores in different parts of the city. In this, heavy metals were found in vegetables in excess of the limits allowed by the Food and Agriculture Organization (FAO).
In November 2022, MPRI published a report titled 'Study of Heavy Metals Concentration in Vegetables Available in Bangalore City Markets'. Dr. N. Hema, P.B. Aishwarya, D.R. Divya led the study.
Vegetables are supplied to Bengaluru city from Kolar, Chikkaballapur, Ramnagar and Bangalore rural districts. 70 tons of vegetables are being distributed from Hopcoms alone. Apart from this, vegetables are also being sold in private stores and super markets.
Local markets like Malleswar, Yeshavantpur, Banashankari, Gandhibazar, K.R. the market; Different super market outlets on Bannerghatta Road, Jayanagar, Rajajinagar, Kanakapura Roads; Organic stores at Vasantnagar, ISRO Layout, Rajajinagar, Indiranagar, Vajarahalli; Samples of vegetables were collected from Hopcoms located at Lalbagh, Yalahanka, Shantinagar, Hebbala, Rajarajeshwarinagar.
Eggplant, tomato, capsicum, beans, carrot, green chilli, onion, potato, spinach and coriander were collected from the markets. Heavy metals were detected by a pre-programmed program in the Nuvao-Ultra Microwave Digestion Extraction System.
The permissible limit of iron content in beans is 425.5 mg per kg. In beans bought from a well-known organic store, this amount is 810.20 mg per kg. Coriander has 945 mg/kg and spinach has 554.58 mg/kg. 592.18 mg/kg of iron was found in Hopcoms onion.
Heavy metal content in vegetables in big super markets or small retailers is higher than the permissible limit. FAO has set a cadmium limit of 0.2 mg/kg. However, cadmium was found to be 52.30 mg/kg in eggplant collected from super market of BTM layout. Coriander contains 53.30 mg/kg, spinach 53.50 mg/kg, carrot 54.60 mg/kg. This metal is highly toxic which weakens the liver, lungs and immune system.
Lead is said to be highly toxic and the permissible limit for this metal is 0.3 mg/kg. But in many vegetables stored in super markets, this amount is 12.20 mg/kg.
The permissible limit of nickel metal in vegetables is 67.9 mg/kg, and green chillies, carrots, potatoes, tomatoes and beans have excessive concentrations of this metal.
The content of these heavy metals is very high in vegetables and consuming them will have a very bad effect on health. Thus, vegetable growing in sewage water should be restricted. Sewage water and industrial waste water should not be used for vegetable cultivation. The report suggested that vegetable growing in the outskirts of the city should be banned.
The report highlighted that spinach available in the city should not be consumed, as the amount of heavy metals in leafy vegetables is higher than other vegetables.
Research team scientist N. Hema said, 'The method of tracing the origin of vegetables should be further enhanced and guaranteed. The maximum amount of metals in vegetables and their duration of use should be reviewed. The extent to which these metals adversely affect children, adults and the elderly should be disclosed. The effect of consuming these vegetables on people's health should be comprehensively explained,' he said.
How much metal is in which vegetable? *As reported by MP
Iron (permissible limit 425.5 mg/kg)
Amount in vegetables
- Beans 810.20 mg/kg
- Coriander greens 945.70 mg/kg
- Spinach 554.58 mg/kg
Cadmium (permissible limit 0.2 mg/kg)
- Brinjal 52.30 mg/kg
- Coriander greens 53.30 mg/kg
- Spinach 53.50 mg/kg
- Carrot 54.60 mg/kg
Due to rapid increase in population and industrialization, the natural water resources are under enormous pressure. Industrial and municipal wastewater production has been increasing over a period of time. Industrial effluents contain large numbers of toxic pollutants like heavy metals and these pollutant rich effluents are drained in water bodies without any treatment. This heavy metal rich waste water is frequently used for irrigation purposes by the peri-urban farmers due to its free and continuous availability throughout the year. These farmers tend to grow the crops with a short cultivation period and the vegetables are grown to cater to the needs of the nearby markets. The heavy metals are non-biodegradable, persistent, carcinogenic and mutagenic in nature.
The present research work was carried out to determine the bioaccumulation of heavy metals in the vegetables sold in a variety of markets across Bengaluru city. Even though the source of procurement of these vegetables in the markets were not made in the study, based on the concentration of heavy metals in the sampled vegetables there is future scope of tracing the sources of vegetables.
Toxic impacts of heavy metals
According to scientific evidence, heavy metals are toxic. At a lower range, it plays a vital role in the metabolism of a cellular system, whereas at a higher range, it becomes toxic, and thus these elements are called trace elements. After interacting with water, soil, and air, heavy metals can become highly poisonous, and humans and other living organisms can be exposed to them through the food chain
- * Vegetables are a major portion of the human diet, providing micro and macronutrients, fibers, vitamins etc., In addition, a wide range of antioxidants such as ascorbic acid, carotenoids, tocopherols, glutathione, phenolic acids, and flavonoids are found in vegetables (Sara et al, 2005) that are known to have positive effects on human health as they play a crucial role in preventing a number of chronic diseases (Agarwal et al., 2007). Vegetables can grow on all types of land, which is commonly contaminated with heavy metals. Depending on the vegetables, some of them have a greater potential to accumulate higher concentrations of heavy metals than others. That may have an impact on human health by consuming contaminated food. Differential plant tolerance to heavy metals is the cause of the leafy vegetables' varying metal uptake rates (Itanna, 2002). Leafy greens have a higher accumulator of metal ions than root vegetables and legumes (Alexander et al., 2006). Some heavy metals, such as cobalt, chromium, copper, magnesium, iron, molybdenum, manganese, selenium, nickel, and zinc, are essential nutrients that are required for various physiological and biochemical functions in the body and may result in deficiency diseases or syndromes if inadequate amounts but then in large doses they can cause acute or chronic toxicities. Long term accumulation of heavy metals in the body may result in slowing the progression of physical, muscular and neurological degenerative processes that mimic certain diseases such as Parkinson’s disease and Alzheimer’s disease (Jaishankar et .al, 2014).
Recommendation
It is very clear from the present study that the edible vegetables are hyperaccumulators of heavy metals. So, taking into consideration the health risks associated with consumption of these vegetables, it is suggested that vegetable cultivation should not use waste water as a source.
• Farmers growing vegetables should use clean surface water for cultivation of the crops
• In case of non-availability of clean water, at least treated water should be used for the purpose of cultivation
• Few vegetables studied had higher amounts of heavy metals than the prescribed limits standardized by various health associations.
• In terms of the eight metals analyzed, the concentrations in vegetables were not very different in the four categories of markets
• Cultivation of root and leafy vegetables which are hyper-accumulators, should be restricted in such polluted areas such as peripherals of the city
• Waste water reuse is the need of the hour because it will help to conserve and replenish the depleting potable water resources. Hence, it should be properly treated to remove the harmful pollutants before its reuse for irrigation purposes
• Awareness campaigns about the cause and effect of such toxic pollutants is the need of the hour
• Combined efforts should be done by the government, industrialists, farmers, soil and water scientists and social organizations to tackle such problems
• Reuse and reduction of materialistic things can be the first step to reduce the amount of pollutants in the environment.
Farmers should be made aware of toxic metal accumulations in greens and vegetables and their imminent threat to consumers
✓ For the farmers those who grow food crops, testing of soils and water should be mandated by the concerned regional agricultural department or pollution control board. More particularly, farmers, who grow these crops on either side of highways, must go for soil testing
✓ Farmers should not resort to unethical farming practices such as irrigating the crops with drainage and effluent waters
✓ It is advised to avoid eating spinach bought from the vegetable markets of the Bangalore. Instead, these greens can be grown organically at home in rooftop gardens, window gardens and balcony gardens
✓ Farmers of the suburban areas should not be allowed by law to grow the greens and vegetables utilizing the drainage and effluent waters
✓ A continuous monitoring is recommended to rule out toxic metal contamination in these greens and vegetables
city-wide inspections; Legal action
A special movement has been launched across Bangalore to check the quality of metal and pesticide content in vegetables. Further legal action will be taken based on the analysis results, said the Commissioner of Food Safety and Standards Authority.
If heavy metals are found in food samples, including vegetables, in excess of the prescribed standards, those substances are considered unsafe. According to section 59 of the Food Safety and Quality Act, 2006, traders who sell such food items are liable to imprisonment for six months to six years and a fine of ₹ 1 lakh to ₹ 5 lakh.
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