Arsenic in ground water has been found above the maximum permissible limit in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present 37 blocks of these six districts by the side of the River Ganga are affected and about 800 000 people from 312 villagedwards are drinking arsenic contaminated water and amongst them at least 175 000 people are showing arsenical skin lesions. The source of arsenic is geological. We have analysed thousands of tube-well water samples from these six districts for four arsenic species namely, arsenite, arsenate, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). We could detect no MMAA or DMAA in any of these samples. In urine, DMAA and MMAA are the predominant species along with arsenite and arsenate. The techniques we used for the determination and speciation of arsenic are: (i) separation of arsenite and arsenate from water by sodium diethyldithiocarbamate in chloroform followed by FI-HGAAS; (ii) spectrophotometry using Ag-DDTC in chloroform with hexamethylenetetramine as absorbing solution; (iiz) ion-exchange separation of arsenite and arsenate from water followed by FI-HGAAS; and (iv) for analysis of inorganic arsenic and its metabolites in urine, FI-HGAAS was used after separation of the species by a , I combined cation-anion-exchange column. Total arsenic, in urine was determined by FI-HGAAS after acid decomposition. The most toxic species, arsenite, is present in ground water at about 50% of the total arsenic level, and more than 90% of the total arsenic in urine is inorganic arsenic and its metabolites.

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In six districts of West Bengal arsenic has been found in ground water above the maximum permissible limit recommended by the WHO of 0.05 mg l-1. This water is used by the villagers for drinking, cooking and other household purposes. These six districts have an area of 34,000 km2 and hold a population of 30 million. Over the last five years we have surveyed only a few small areas of these six affected districts and our survey revealed that, at present, at least 800,000 people from 312 villages in 37 blocks are drinking contaminated water and more than 175,000 people are showing arsenical skin lesions that are the late stages of manifestation of arsenic toxicity. Most of the three stages of arsenic-related clinical manifestations are observed amongst the affected people. The common symptoms are conjunctivitis, melanosis, depigmentation, keratosis and hyperkeratosis; cases of gangrene and malignant neoplasms are also observed. The source of arsenic is geological. We have analysed thousands of arsenic contaminated water samples. Most of the water samples contain a mixture of arsenite and arsenate and in none of them could we detect methylarsonic or dimethylarsenic acid. We have also analysed a large number of urine, hair and nail samples, several skin-scales and some liver tissues (biopsy samples) of the people drinking the arsenic contaminated water and showing arsenical skin lesions. Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for the analysis of hair, nails, urine and skin-scale after decomposition by various techniques. The liver tissues were analysed by Zeeman corrected-ETAAS using a few milligrams of the biopsy samples.

TiO 2 nanofillers (5 nm, 0-15% weight) have been introduced in the PMMA matrix using a twin screw extruder to increase the performance of PMMA. The twin screw extrusion process is optimized to disperse the particles into PMMA. Nanofiller infusion improves the thermal, mechanical, and UV absorption properties of PMMA. TiO 2 -PMMA nanocomposites exhibit the increase in tensile modulus (90%), decomposition temperature (31%), dimension stability ($ 60%) and UV absorption ($ 410%). Properties of the nanoTiO 2 -PMMA composites are depending on the dispersion of TiO 2 in the PMMA matrix. It is interrelated with loading. Formation and disappearance of the peaks in FTIR confirm the chemical interaction of PMMA with TiO 2 .