Chronic arsenic toxicity in west Bengal--the worst calamity in the world.

Since 1983 large number of people are being encountered with arsenic toxicity due to drinking of arsenic contaminated water (0.05-3.2 mg/l) in 6 districts of West Bengal. Clinical and various laboratory investigations were carried out on 156 patients to ascertain the nature and degree of morbidity and mortality that occurred due to chronic arsenic toxicity. All the patients studied had typical rain drop like skin pigmentation (being inclusion criteria) while thickening of palm and sole were found in 65.5% patients. Other features included weakness (70%), gastro-intestinal symptoms (58.6%), involvement of respiratory system (57.08%) and nervous system (50.6%). Lung function tests showed restrictive lung disease in 53% (9/17) and combined obstructive and restrictive lung disease in 41% (7/17) of patients. Abnormal electromyography was found in 34.8% (10/29) and altered nerve conduction velocity in 34.8% (10/29) of cases. Enlargement of liver was found in 120 cases (76.9%) while splenomegaly in 31.4% cases. Liver function test showed elevated globulin level in 15.8% and alkaline phosphatase in 51.3%, alanine amino transferase (ALT) in 11.8% and aspartate amino transferase (AST) in 27.6% of cases. Evidence of portal hypertension was found in 33.3% patients. Liver biopsy reports of 45 patients showed non-cirrhotic portal fibrosis in 41, cirrhosis in 2 and normal histology in 2 cases. There was no correlation between the quantity of arsenic taken through water and the level of arsenic in hair, nail, liver tissues and the degree of fibrosis. There were 5 deaths of which one had skin cancer. The various non-cancer manifestations which were observed in these patients were much severe than those reported in similar cases in other parts of the world.