The Bombay Stock Exchange benchmark Sensex that opened higher by over 42 points in opening trade later dropped 119 points in the afternoon to trade at 18, 289 points. Similarly, the wide-based National stock Exchange Nifty was also trading 48 points down at 5494 pionts a shortwhile ago. Shares of Vedanta Group company Sterlite Industries today plunged over 4 per cent after the government rejected environment clearance to the group's 1.7 billion US Dollar bauxite mining project in Orissa.The scrip, which was creeping in the negative zone in morning trade, sank 4.22 per cent to hit a low of Rs 152 soon after the reports of rejection of environment clearance flashed.