EXPOSURE TO HEXAVALENT CHROMIUM FROM TANNERY WASTES AND HEALTH RISKS FOR URBAN POPULATION IN BANGLADESH

About 277 small, medium and large size tanneries in the outskirt of Dhaka city in Bangladesh produce 2-3% of world’s lather. These tanning industries process approximately 180 million square foot or 74,000 tons of raw hide annually and export about $400 million worth of lather and footwear. In the tanning process of raw hides these industries use a variety of chemicals and chromium salts. On a daily basis approximately 22,000 cubic meter of untreated liquid wastes are dumped in nearby canals and river Buriganga). In addition to population at work place in these industries, general population is exposed to chromium and hexavalent chromium through river water. Although Cr(III) is essential trace element, hexavalent chromium Cr(VI) is a known carcinogen. In addition to liquid wastes about 170 tons of solid wastes including discarded hides, shaving of lather, hair are dumped daily in the nearby river causing a potential health risk for neighboring population. Residents in nearby slum often use discarded hides and shaving of hides as fuel for cooking causing indoor air pollution. In addition to water, the ambient and indoor air are polluted with Cr(VI). In the current investigation, water samples near the industrial discharge areas and in the downstream areas were analyzed for total chromium (Cr) and Cr(VI). Total Cr in the downstream areas of discharge ranged from 96 to 403 ppb. In the distant rivers approximately 50-100 km away from the city without direct discharge from tanning industries the level of Cr is observed to be 2-5 ppb. In addition, we have carried out Cr speciation in particulate matters collected in air filters through the technique of ion chromatography and inductively coupled plasma mass spectrometry (IC-ICP-MS). The air sampling in ambient air and household indoor air in the neighborhood of tanning industries were carried out using a low volume air sampler (Minivol, Airmetrics Co, Oregon, USA). The Cr in air samples collected in the Hazaribagh tanning areas exhibited significantly (p < 0.050) higher level of Cr than the Cr level in air samples collected from control areas. All the data for total Cr and Cr(VI) in water, air in the urban areas near tanning industries and their potential health risks will be discussed in the paper.