The groundwater in Bhojpur, Khagaria and Begusarai districts is not fit for drinking, says a latest report of the state's public health and engineering department.

The groundwater in these three districts is highly polluted with heavy presence of arsenic/iron content.

The groundwater in 33 out of Bihar's 38 districts is also polluted, according to the report. The department officials had examined water samples taken from across the state to test for quality.

Altogether, 6,54,000 groundwater samples were taken from across the state.

Out of these, 1,54,000 samples were found to be polluted, which comes to around 23.48 per cent of the total samples taken, as per the report.

The report said in the polluted water, arsenic, iron and fluoride contents were found to be much higher than the permissible limits.

According to the World Health Organisation (WHO) guidelines, the maximum acceptable level of concentration of arsenic in safe drinking water is 0.01mg per litre.

In many districts of the state, the level of arsenic is as high as 3mg/l - way above WHO's acceptable safe level and even the safe level of 0.05 mg/l set by the Bureau of Indian Standards.

A.K. Ghosh, a Patna-based arsenic expert, said a large number of cases of arsenic poisoning had been reported from the districts along the Ganga.

"It's a matter of serious concern," said Ghosh, a professor at the department of environment and water management at AN College, Patna. He has conducted several arsenic field surveys in the past 10 years.

Experts feel the high level of arsenic in groundwater is one of the reasons behind increase in cases of cancer.

Scientists at the Mahavir Cancer Sansthan in Patna, in their recent research studies, have said that arsenic had been found in tissues of patients suffering from cancer.

The source of the chemical was drinking water, the scientists stated.

The scientists concluded that the probability of two types of cancer (skin and gall bladder) was because of ingestion of drinking water in which arsenic presence was more than 300 parts per billion (ppb). WHO recommends a provisional guideline of 10ppb of arsenic in drinking water. The Indian standard is 50 ppb.

The Sansthan's research also said arsenic increases the possibility of DNA damage. The study was based on 200 cancer patients from Bhojpur, Vaishali and Buxar.

Public health and engineering minister Krishnanandan Prasad Verma had informed the Assembly last year that 13 districts in the Gangetic plain had more arsenic content than the Indian permissible limit.

The source of arsenic, according to experts, was silt from the Himalayas, which gets deposited downstream through the Ganga. In its natural form of arsenopyrite (iron arsenic sulphide), it is insoluble in water.

The possibility of more groundwater arsenic contamination sources, particularly in the Ganga basin, might be found in the future, arsenic expert Ghosh said.