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Updated: Jul 28, 2019 17:52 IST

Rice grain, wheat flour and a variety of vegetables being sold in Kolkata have tested positive for arsenic levels dangerously above permissible limits, warns a research by Jadavpur University’s School of Environmental Sciences (SOES).

What’s more and since produce sold in Kolkata doesn’t originate only from areas known to be afflicted with arsenic in the soil, like some Bengal districts and neighbouring states like Bihar and Uttar Pradesh, the finding may hold alarming nation-wide implications.

“All these food items are transported to states across the country, so a study in other metros will yield similar results,” said environmental scientist, Prof Tarit Roychowdhury, chief researcher of the year-long study during which he and his seven-man team collected 232 samples of staples and vegetables from 30 households in Kolkata suburbs and nine markets across Kolkata. The research paper was published on May 27.

In 2011, the World Health Organisation (WHO) announced that maximum permissible level of arsenic in drinking water is 0.01 milligram per litre or 10 µg /litre (microgram per litre). According to the Indian Standards for Drinking Water, the permissible level in absence of alternative source of water is 0.05 mg/litre (50 µg /litre). The WHO also withdrew the earlier provisional tolerable daily intake (PTDI) of inorganic arsenic found in food of 2.1 µg per kg of total bodyweight per day (µg/ kg bodyweight/day), as it was no longer found to protect health.

“The arsenic content found in the samples we surveyed, ranged from 24 to 324 µg /kilo (microgram per kilo). Inorganic arsenic (arsenite and arsenate) is toxic and carcinogenic and exposes people to the risk of cancer,” said Prof Roychowdhury.

The finding was worrisome for another reason. Doctors who studied the findings told HT that finding arsenic in produce from states and districts with no history of ground water contamination indicated that the grains and vegetables may have been poisoned by arsenic in pesticides or other sources.

Also read: High level of arsenic found in Punjab groundwater

West Bengal figures among seven states, including Bihar, Uttar Pradesh and Jharkhand that are known for a high concentration of arsenic in ground water at several places.

This is the first research by any reputable institution that has come up with definitive figures on arsenic contamination in farm-grown food consumed by millions in Kolkata. In March 2019, Jadavpur University came sixth among the top 10 universities in the country in the Union human resource development ministry’s National Institutional Ranking Framework.

Set up in 1989 by environmental scientist Prof Dipankar Chakraborty, who died last year, SOES has done pioneering research on arsenic contamination in Bengal and the Gangetic basin.

Kolkata’s deputy mayor Atin Ghosh, who is also in charge of the health department of Kolkata Municipal Corporation, said, “It is extremely difficult for a civic body to check every food item entering a metro. We do not have that infrastructure. Since chemical contamination has become a worldwide problem we are setting up a modern laboratory. It will be operational in another year. We are giving equal importance to public awareness.”

Prominent doctors reacted to SOES’s findings.

“Though there may be no specific symptoms in the initial stage, arsenic contamination in food can cause the malfunction of multiple organs, hepatitis, lung infection, etc. Even problems relating to physical and mental growth of a child can be related to toxins in food,” said Dr Mahua Bhattacharya, a specialist in internal medicine at a renowned private hospital in south Kolkata. Though the physician has sent some of her patients for arsenic tests, she warns that there is no clear methodology to identify arsenic as the root cause of a given disease.

Surgical oncologist Dr Sujoy Bala, too, said that though skin cancer is a known outcome of arsenic contamination, it is tough to draw a direct correlation between arsenic and cancer because of the rampant use in India of pesticides which also contains arsenic, and nitrogen compounds.

“Arsenic can even alter our genetic structure and affect our offspring. Prevention, and not treatment, should be the government’s priority,” Bala said.

A 2018 report of WHO noted that inorganic arsenic is naturally present at high levels in the groundwater of a number of countries, including Argentina, Bangladesh, Chile, China, India, Mexico and the United States of America. According to the study, drinking water, crops irrigated with contaminated water and food prepared with contaminated water are the sources of exposure.

Fish, shellfish, meat, poultry, dairy products and cereals can also be dietary sources of arsenic, although exposure from these foods is generally much lower compared to that through groundwater.

“It is now recognized that at least 140 million people in 50 countries have been drinking water containing arsenic at levels above the WHO provisional guideline value,” warns the study, which outlines the use of arsenic as an industrial alloying agent in the processing industry as well as in the hide tanning process.