Groundwater in 44 districts of Nepal is contaminated with arsenic, according to the country's Public Health Engineering Department. In some areas, the arsenic content is 10 times higher than the acceptable level. Out of the 60 districts where groundwater tests were carried out, only 16 were found free from harmful substance. The department could not pinpoint the cause of contamination. However, some experts speculate that the cause may be depletion of groundwater table, leakage of industrial effluents in the soil and excessive use of chemical fertiliser and pesticides.