In some areas of Bangladesh and West Bengal, concentrations of As in groundwater exceed guide concentrations, set internationally and nationally at 10 to 50 ?g l?1 and may reach levels in the mg l?1 range. The As derives from reductive dissolution of Fe oxyhydroxide and release of its sorbed As.

The natural contamination of drinking water by arsenic needs to be urgently addressed.

It is a crime. Numerous factories deliberately inject untreated effluents directly into the ground, contaminating underground aquifers. Down To Earth got samples

In Bangladesh, arsenic in groundwater above 0.05 mg/1, the maximum permissible limit laid down by WHO, was found in 41 out of 64 districts. People suffering from arsenicosis have been identified in 20 districts out of 21 districts we have surveyed so far.

The arsenic affected areas of West Bengal are lying on a sediment of Younger Deltaic Deposition (YDD). The same sediment extends eastwards towards Bangladesh, covering the approximate area of 34 districts out of a total of 64 districts in Bangladesh. We suspect that the groundwater of these 34 districts of Bangladesh may be arsenic contaminated.

Arsenic has been found in groundwater in seven districts of West Bengal covering an area 37,493 km having about 34 million population. Our survey indicates that 560 villages are arsenic-affected and more than a million people are drinking arsenic contaminated water and more than 200,000 people are suffering from arsenic-related diseases.

The effect on the charring temperature of arsenic in blood with wall and platform atomisations of a number of matrix modifiers, such as cobalt, copper, nickel and palladium, has been studied. Based on this study, a nitric acid de-proteinisation-nickel matrix modification-graphite platform-in-furnace atomic absorption spectrometric method was developed for the determination of nanogram per millilitre levels of arsenic in whole blood samples after a systematic evaluation of the temperature programme of the atomiser. The method of standard additions is mandatory.