Heavy metals in food may lead to health risks, experts warn and urge caution

When present at high levels and consumed over a long period, heavy metals can cause health complications, researchers say

Moinul Hoque Chowdhurybdnews24.com
Published : 15 Nov 2022, 09:45 PM
Updated : 15 Nov 2022, 09:45 PM

Are the vegetables, rice, poultry or fish you eat every day safe to consume?

Recent research shows that Bangladesh’s food production is tainted with the negative impact of pollution. Some food products were found to contain heavy metals at a level higher than the human body can tolerate.

A group of researchers at Bangladesh Agricultural University recently found heavy metals in eggplants were at higher than tolerable levels, raising a red flag about public health hazards.

Their research showed that several such metals including lead, nickel, copper, cadmium, iron, manganese and zinc were present in eggplants.

The eggplant research was not the first of its kind to find the presence of heavy metals in food, said Prof Quazi Forhad Quadir at the Department of Agricultural Chemistry at BAU. The department has conducted similar research for the past ten years on rice from Chattogram and Mymensingh, and many other foodstuffs, including eggplant, spinach, chicken, beef, and tilapia fish to identify heavy metals in them.

“We found that [consumers] were exposed to the highest levels [of heavy metals] in rice, followed by spinach and eggplants.”

Arsenic, mercury and lead can be harmful to human health when found in the food cycle, said Asst Prof Palash Kumar Dhar of Khulna University’s chemistry discipline. When present at higher levels, they can mutate human cells and then gradually cause complications.

He, however, said that it was not confirmed that heavy metals’ presence in food would definitely pose a health risk for humans. “We assume that it may happen. The effect of heavy metal consumption on human health may manifest after 10 to 20 years. There could be some physical changes.”

Other researchers said that heavy metals were found in vegetables, rice, fish and poultry or meat from different parts of the country beyond the tolerable level. There is a risk for people when those foods are consumed for a long period, but this should not be cause for alarm, they said. There should be effective initiatives to ensure that only approved pesticides, fungicides and fertilisers are used in the fields.

Harmful chemicals produced as by-products in factories should be prevented from polluting the water and waste management must be monitored, they said.

Proper monitoring by the government and awareness of the people would ensure food safety for the people, they added.

“We do a review when any research yields such information. We’re aware of it and are continually monitoring it,” said Bipul Chandra Das, joint secretary in the Ministry of Agriculture. 

He said there was nothing to worry about and the ministry was vigilant on the issue.

Sometimes the farmers use a few more chemicals than is necessary, said Dr HM Moniruzzaman, deputy director of the Department of Agricultural Extension (DAE). The DAE provides trade licenses from one of its wings for those chemicals that are safe to use. 

“We give directives on which chemicals are good to use. Some vegetables can be consumed in a week after using certain chemicals. For some chemicals, people must refrain from eating the vegetable it was used on for 15 days. That’s why we ask the farmers to use those chemicals with limited after-effects,” he said.

Overall environmental damage has affected farmland as well. Safe farming, prevention of pollution and using organic fertiliser will ensure safe food for the people, he said. Pesticides and other chemicals to remove weeds should be used according to the safety rules.

Citing research, the DAE official said that soaking food items [fruits, vegetables and grains] in water for 20 minutes removes all impurities from the chemicals. The chemicals used in paddy farming are not harmful. Besides, lead and cadmium, the chemicals that come from the environment are 90 percent removed from the food items when soaked, according to other research he added. There was nothing to worry about, he said. 

“We always encourage farmers to prioritise safety in farming. We arrange training and monitor the agricultural process in every upazila while employing officers at the root levels. The department and its officers are all vigilant about food safety,” said Dr Moniruzzaman.

HEAVY METALS IN JAMALPUR’S EGGPLANTS: A RECENT ISSUE

A group of researchers led by Dr Md Zakir Hossain of the agricultural chemistry department of BAU conducted research to identify heavy metals in the soil at Islampur and Melandaha upazilas in Jamalpur and eggplants produced there and to evaluate the possible health risks to human health.

Results of the research were published in the ‘Scientific Reports’ journal, based in the UK, US and the Netherlands, this year.

Prof Quazi Forhad Quadir was the co-supervisor of the research paper done by postgraduate student Anika Bushra. Shaila Sharmin, MH Rashid, MS Rahman and Supti Mallick were the co-writers of the paper.

The paper focused on soil pollution due to heavy metals, acquiring micro-nutrients and health hazards for people after consuming eggplants containing heavy metals.

At least 60 topsoil samples and 80 eggplant samples from 20 spots in Jamalpur were evaluated and the presence of heavy metals was identified.

The metals found in the eggplants were lead, nickel, copper, cadmium, iron, manganese and zinc. In 75 percent of samples, lead was found beyond the tolerable level fixed by the FAO and WHO, while excess cadmium was found in 10 percent of samples.

A review of the qualities of the heavy metal identified in the eggplants following the US-based USEPA’s cancer and non-cancer health hazard model showed all samples had lead and nickel beyond the safe level while 40 percent of samples had cadmium above the safe level.

An analysis of the soil showed that it was the source of the metals, particularly cadmium, lead, nickel and copper. Poisonous insecticides, fertiliser, and polluted irrigation water are the reasons for heavy metals infusing farming lands, according to researchers.

But they said further research is required to confirm the findings so that initiatives can be taken at the policy level to prevent the entry of heavy metals into the food chain.

PREVENTION AT SOURCE, AWARENESS AND INITIATIVES NEEDED

Asst Prof Palash Kumar Dhar of Khulna University’s chemistry discipline has also conducted some research work on the presence of heavy metals in foods.

Citing one study in Jashore about the presence of heavy metals in vegetables and its risks to human health, Prof Dhar said that anything over a standard level is harmful to health. The presence of heavy metals at an excessive level may damage health in the long term.

He recommended that such metals should be properly recycled so they go through treatment instead of seeping into the soil, he said.

“You won’t see the result right away when you eat food [containing heavy metals]. There can be different complications if you eat it for a long time, like 30-35 years. I am not saying that it will definitely happen, but assuming that it will is the best bet for probability.”

Research in both Bangladesh and abroad has found the presence of natural heavy metals is spread to different places through mining, industrial work, farming or any other man-made activity. The metals can spread through water or become airborne as well. 

The first task is to ensure that heavy metal-laden products are dumped at designated places in the environment, said Palash Kumar Dhar. These waste metals should undergo treatment. Electronic goods are not recycled and they are often dumped indiscriminately. The metals will leave a negative impact once they stay in the soil for 10 to 20 years, he said.

"It's not an overnight issue."

“The damage we see today has been caused by such waste dumped at locations 10 or 20 years ago. Their effect has reached this level today. Be it crops, soil or water, some heavy metals are found. The damage may seem limited today, but it will only strengthen." 

HAZARDS AND RISKS: A DATABASE RECOMMENDED

Research has never specifically mentioned the source of heavy metals found in foods. They only mention the quantity or level of the metals, said Palash Kumar Dhar.

He said that it was not confirmed that heavy metals’ presence in food would definitely pose a health risk for humans. The effect of heavy metal consumption on human health may manifest after 10 to 20 years. “Human bodies are designed in a way that a little [quantity of metals] will enter and remain. They may not necessarily cause a problem but there’s a chance. It depends on the body’s condition. We must be careful against any harmful matter.”

Electronic goods should be discarded carefully, he said. They should be processed before they enter the soil. “Otherwise you can’t prevent it. Even after ten years, the metals will remain present there.”

“Authorities should ensure the industries are dumping [metal waste] properly. Sources of metals and heavy metals should be monitored and properly recycled. Strict monitoring and the formation of a database should be initiated.”

When asked how the database could be set up, the expert said the entire country can be divided into different zones under a single project and the government can do it if they want to.

“Authorities should think twice before starting farming in areas where heavy metals are found [in the soil] in large quantities. They must see what the risks of farming in those red zones are. Proper management and monitoring are necessary.”

“The government should prioritise monitoring areas where more heavy metals are found. If they can prevent the problem at the source, it will be resolved to a large extent. It’s not an easy task. The main areas should be identified and the data should be prepared,” said Palash Kumar Dhar.

MORE RESEARCH, GOOD AGRICULTURE PRACTICES AND MONITORING NEEDED

Prof Quazi Forhad Quaadir has been researching the presence of heavy metals in food for ten years.

His research projects focus on the comparative difference between the samples from two places and how harmful they were for human health, he said.

“It’s not the fault of the rice or eggplant. The metal is coming from the soil. We’re

researching on minimising the amount at the source.”

Use of e-devices has increased. Battery-operated rickshaws are running everywhere, he said. “There should be a policy for the disposal [of e-devices and batteries]. Many legal, as well as illegal factories, are popping up on farmland. They must be brought under a system for monitoring.”

Further research can be done on reducing the existence of heavy metals in foods, the expert said. He recommended regulatory control and monitoring at the policy level to prevent the infusion of excessive metals in the food cycle.

It isn’t ‘alternative farming’ but rather ‘good agricultural practices’ that will reduce the risk, the professor said. “In that case, the financial loss faced by the farmers must be addressed in addition to creating awareness.”

“Pesticide use should be fixed by the policies just as fertiliser use is controlled by the policy. Also, the implementation of fertiliser management must be ensured. Irrigation systems should be monitored as well. Irrigation supply, especially in the industrial areas in Savar, Chattogram and farming land beside the Buriganga and Shitalakkhya rivers should be monitored.”

The eggplant research was conducted only on a single product in a specific district, said Prof Forhad. “The other foods on our menu are not unpolluted. We need to monitor the quantity of fertiliser used in farming. Also, the authorities should control the quality of pesticides and monitor if any toxic elements are being imported besides the approved pesticides.”

[Writing in English by Sabrina Karim Murshed; editing by Shoumik Hassin]

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Editor-in-Chief and Publisher