Article From News From Bangladesh archives
Arsenic In The Food Chain
A study on "Arsenic in Groundwater of Bangladesh: Contamination in the Food Chain" jointly conducted by the Department of Soil, Water and Environment of Dhaka University and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) examined a thousand samples of crops, cereals and vegetables, a thousand samples of soils and 400 samples of water from 50 upazilas in 15 most affected regions. These samples were analysed in laboratories within the country and in Australia. The samples were collected from Rangpur, Dinajpur, Kushtia, Jessore, Faridpur, Laxmipur, Narayanganj, Rajshahi, Pabna, Munshiganj, Meherpur and Dhaka.
The Australian Centre is funding the on-going study, the first of its kind in the country, for International Agricultural Research. Dr Ravi Naidu from Australia, the team leader and Prof S M Imamul Huq of the Department of Soil, Water and Environment, DU, jointly carried out the research. But to our mind the probability of detecting arsenic in the food chain is one that should have been dealt with long ago, as this was a factor that was constantly ignored. Of course arsenic in the groundwater was possibly more challenging but ignoring the possibility of arsenic in the food chain also may have cost us a lot and not only time.
As we recall we wrote a leader on this possibility as far back as 1997 and last year we wrote that scientists should focus not only on the problem of finding safe sources of water but also how to avoid arsenic getting into the food chain. Now it seems we couldn’t have been more right as today researchers are saying about one-fifth of the population in most of the arsenic affected areas in the country are at risk of consuming arsenic in rice, wheat and vegetables and the only question left to answer is, are people affected by consuming the contaminated food? No doubt the answer to this will be yes as any long-time consumption of arsenic-contaminated food may damage kidneys, liver, lungs, bladder and other major organs of the body.
That this is a matter of great concern goes without saying as just by looking at the plants one cannot tell if they are contaminated or not. This is disconcerting as one is also unable to tell if the water used for irrigation purposes or cooking is contaminated. In the study, the researchers found that food cooked with arsenic- contaminated tubewell water contained a high level of arsenic. But they said that intake of arsenic by plants from soil varies from region to region.
Some types of soil have a capacity for very strong bonding while others do not. So, arsenic released from soil to the plants is quite different. "We have detected significant amount of arsenic transferred from groundwater to crops, says Dr Ravi Naidu, although many crops are still safe. The researchers also studied samples of cooked food collected from the affected areas and found the level of arsenic in rice was 0.35 mg/kg, 0.81 mg/kg in vegetable curry, 0.33 mg/kg in spinach, 0.39 mg/kg in fish curry and 0.27 mg/kg in pumpkin. However as arsenic was not found in cooked lentil, brinjal and egg we can be grateful for small mercies. We now need to find out whether arsenic travels from the cooked vegetables into the human body and if it does, does it remain there or is it eliminated.
The highest concentration of arsenic was found in arum, which was 150 mg per kg. The level was 5.1 mg/kg in bean, 20.1 mg/kg in gourd leaf, 93.3 mg/kg in onion, 7.2 mg/kg in tomato, 0.83 mg/kg to 1.1 mg/kg in papaya, 1.8 to 2.7 mg/kg in cauliflower, 0.05 to 7.2 mg/kg in cabbage, 1.9 to 4.5 mg/kg in leafy vegetables, red spinach and stalks of spinach, 1 mg/kg in wheat and 5.3 mg/kg of rice in the affected areas. The maximum allowable limit of consumption of arsenic through food by a person is 0.2 mg/kg per day.
However, the study showed that potato, bitter gourd, brinjal, snake gourd (chichinga), bitter gourd, Kakrol, ladies finger, palwal, large leafy spinach, pumpkin, sweet potato, turmeric, ginger and green chili are safe as presence of arsenic in them are insignificant and does not pose a threat. But with many farmers and villagers filling their ponds with groundwater, its use for irrigation is suspect as the toxic effects of arsenic are very complex and can range from gangrene of the peripheral organs to skin cancer and cancer of the internal organs such as the liver, kidney and bladder.
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