The heavy metal threat lurking in your diet

Agricultural findings expose alarming levels of metal in staple crops and vegetables

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August 6, 2024

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Here’s a story: you’ve been eating too much junk and soon your clothes start feeling a bit tighter, each step you take down the road makes you puff and pant a little bit more, and finally your doctor reminds you of all the negative impacts these foods might have on your health. You decide to act, stick to a plan to cut down on junk, start cooking on your own, very careful of the calories you’re taking in. Two months down the lane, you see that you are starting to fit back in your clothes.

A story with a happy climax, ain’t it? Well, not so much.

While switching to veggies, cooking on your own, and keeping a check on the calories you consume are all good, most people tend to overlook some crucial questions: how are these so-called ‘healthy’ vegetables farmed? What are the inputs that are used to cultivate these veggies? And what are the impacts on consuming these ‘healthy’ foods?

In pursuit of answers to these pressing questions, numerous studies were undertaken. Their discoveries shed light on the presence of heavy metals in food production.

In a study conducted by the Environment Management and Policy Research Institute (EMPRI) by visiting 20 spots including high-end supermarkets, local markets, organic stores, and Hopcoms, it was found that the levels of cadmium, iron, and lead in our veggies are far above the permissible limit.

In a different study, a group of agriculture scientists from Odisha University of Agriculture and Technology (OUAT), SOA University, and Birsa Agricultural University discovered that rice, pulses, and veggies around Narasinghpur block in Cuttack were packing higher levels of cadmium, lead, mercury, and arsenic than recommended.

Similar results were also observed in a study by National Environmental Engineering Research Institute (NEERI), which showed that the vegetables sold in Delhi and grown along the Yamuna floodplains had high doses of lead.

This calls for a deeper understanding of what goes into our foods and how they are farmed.

A study in Bengaluru

For the EMPRI study, the researchers took a close look at 10 veggies including brinjal, tomato, capsicum, etc. to see if they were carrying any heavy metals.

Turns out, some of these veggies were breaking the iron limit, pegged at 425.5 mg/kg. For example, beans from the organic shops had 810.20 mg/kg of iron! Coriander and spinach weren't far behind. Even the onions from Hopcoms had more iron than expected, with 592.18 mg/kg.

And it wasn't just iron causing trouble. Cadmium levels were supposed to be low, like 0.2 mg/kg. But brinjal from a supermarket in BTM Layout in Bengaluru had a whopping 52.30 mg/kg of cadmium! Coriander, spinach, and carrot weren't far off either.

The study also revealed a higher concentration of heavy metals in leafy vegetables. This appears to be linked to the increased transpiration rate of leafy greens. Transpiration is the process by which plants release water vapor through their leaves.

Given that the majority of Bengaluru's vegetables originate from neighboring districts such as Kolar, Chikkaballapur, and Bengaluru Rural, there has been a heightened focus on the project that pumps secondary-treated sewage water to these areas.

When farmers use wastewater, they're inadvertently loading up their crops with heavy metals. It's like the veggies are soaking up all the toxins from that water, leading to higher concentrations of heavy metals.

The NGT had also registered a suo motu case after news reports came out regarding heavy metal contaminated food in Bengaluru.

Harmful effects

Before we discuss the harmful effects of these heavy metals, let us understand what they are.

Heavy metals are dense metals with high atomic weights or numbers. They include common elements like iron, copper, gold, and aluminum. While some heavy metals are essential for life, others can be harmful when they enter the environment through industrial activities.

Cadmium, notorious for its adverse effects on the liver and lungs, can also compromise the immune system. While the body typically eliminates cadmium ingested through food, elevated levels can accumulate in the kidneys, leading to impaired function.

Excessive consumption of lead can result in severe health issues, including neurological damage.

Although iron is essential in moderate amounts, excessive intake can lead to complications such as anemia. Furthermore, high doses of iron may interfere with the absorption of other vital nutrients like zinc and increase the risk of liver cancer and heart disease.

Prevention strategies

Cleaning vegetables thoroughly with portable water removes external metal contamination. Soaking them in a 2% salt solution and washing again aids in eliminating contaminants.

Cooking vegetables with ample water helps leach out internal metal traces. Consuming antioxidant-rich fruits and vegetables like gooseberries, oranges, lemons, strawberries, tomatoes, and blueberries counteracts metal contamination effects by reducing free radicals.

Blanching fruits before juicing and vegetables before adding to salads reduces heavy metal presence.

And beyond all, knowing more about your food, what goes into cultivating them, where it was cultivated, and switching to trustable organic brands could hold the key to a healthier future.