About one fifth of the population in most of the arsenic affected areas in the country are at risk of consuming arsenic-contaminated rice, wheat and vegetables, researchers told the Daily Star yesterday.

But whether they are affected by consuming the arsenic-contaminated food is yet to be studied, they said.

However, there is a wide variety of crops in those areas which are safe, said the researchers who are working in this field in the country for over two years.

Long-time consumption of such foodstuff may damage the kidney,

liver, lungs, bladder and other major organs of the body.

The highest concentration of arsenic was found in arum, which was 150 mg per kg.

The level was 5.1 mg per kg in bean, 20.1 mg in gourd leaf, 93.3 mg in onion, 7.2 mg in tomato, 0.83 to 1.1 mg in papaya, 1.8 to 2.7 mg in cauliflower, 0.05 to 7.2 mg in cabbage, 1.9 to 4.5 mg in leafy vegetables like lal shakh and data shakh, 1 mg in wheat and 5.3 mg per kg of rice in the affected areas.

The maximum allowable limit of consumption of arsenic through food by a person is 0.2 mg per day.

However, the study showed that potato, bitter gourd, brinjal, snake

gourd (chichinga), gourd, Kakrol, ladies finger, palwal (potal), puishak, pumpkin, sweet potato, turmeric, ginger and green chili are safe as presence of arsenic in them are insignificant and does not pose any threat.

These were was found in a study titled ''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).

A total of 1000 samples of crops, cereals and vegetables, 1000 of soil

and 400 of water collected from 50 upazilas in 15 most affected regions were analysed in laboratories in the country and in Australia.

The samples were collected from Ranpur, Dinajpur, Kushtia, Jessore, Faridpur, Laxmipur, Narayanganj, Rajshahi, Pabna, Munshiganj, Meherpur and Dhaka.

The on-going study, the first of its kind in the country, is being funded by the Australian Centre 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.

"We have detected significant amount of arsenic transferred from groundwater to crops although many crops are still safe," said Dr Ravi Naidu.

He said, "Intake of arsenic by plants from soil varies from region to region. Some types of soil have capacity for very strong bonding while others do not. So, arsenic released from soil to the plants is quite different."

Apparently, by looking at the plants, one can not understand whether those are contaminated or not.

In the study, the researchers also found that food cooked with arsenic-contaminated tubewell water contains high level of arsenic.

They also studied samples of cooked food collected from the affected areas. The level of arsenic was found at 0.35 mg/kg in rice, 0.81 in vegetable curry, 0.33 in spinach, 0.39 in fish curry and 0.27 mg/kg in pumpkin. However, arsenic was not found in cooked lentil, brinjal and egg.

"When a crop is irrigated with arsenic contaminated water, there is evidence of arsenic entering into the crop. In the study, arsenic in irrigation water was found at between 0.136 and 0.555 parts per million (ppm)," said Prof S M Imamul Huq

He said, "We have to do further studies to find out whether arsenic travels from cooked vegetables to human body or it is simply eliminated from the body."