Chronic Arsenic Toxicity: Clinical Features, Epidemiology, and Treatment: Experience in West Bengal

Abstract

Chronic arsenic toxicity due to drinking arsenic-contaminated water has been one of the worst environmental health hazards affecting eight districts of West Bengal since the early eighties. Detailed clinical examination and investigation of 248 such patients revealed protean clinical manifestations of such toxicity. Over and above hyperpigmentation and keratosis, weakness, anaemia, burning sensation of eyes, solid swelling of legs, liver fibrosis, chronic lung disease, gangrene of toes, neuropathy, and skin cancer are some of the other manifestations. A cross-sectional survey involving 7683 participants of all ages was conducted in an arsenic-affected region between 04 1995 and 03 1996. Out of a population of 7683 surveyed, 3467 and 4216 people consumed water containing As below and above 0.05 mg/L, respectively. Except pain abdomen the prevalence of all other clinical manifestations tested (e.g., pigmentation, keratosis, Hepatomegaly, weakness, nausea, lung disease and neuropathy) were found to be significantly higher in As exposed people (water As>0.05 mg/L) compared to control population (water As level<0.05 mg/L). The prevalence of pigmentation and keratosis, hepatomegaly, chronic respiratory disease and weakness rose significantly with increasing arsenic concentrations in drinking water. The respiratory effects were most pronounced in individuals with high arsenic water concentrations who also had skin lesion. Therapy with chelating agent DMSA was not found to be superior to placebo effect. However, therapy with DMPS caused significant improvement of clinical condition of chronic arsenicosis patients as evidenced by significant reduction of total clinical scores from 8.90 ± 2.84 to 3.27 ± 1.73; p<0.0001. Efficacy of specific chelation therapy for patients suffering from chronic As toxicity has further need to be fully substantiated. However, supportive treatment could help in reducing many symptoms of the patients. Treatment in hospital with good nutritious diet has been found to reduce symptom score in a subset of placebo treated patients in West Bengal during the course of DMSA and DMPS trial. People should be advised to stop drinking As contaminated water or exposure to As from any other source. The various clinical manifestations should be treated symptomatically.

Keywords:

• Arsenicosis
• Non cirrhotic portal fibrosis
• Pulmonary fibrosis
• Arsenic epidemiology
• Dimercapto succinic acid
• Dimercapto propane succinate

Acknowledgments

The materials presented in the communication are based on studies carried out at Institute of Post Graduate Medical Education & Research, Kolkata, India, with the assitance of the following co-investigators : Mrs N. Ghosh, A. Santra, J. Dasgupta, A. Pal, A. Ghosh, S. Sarkar, N. Chattopadhaya, B. K. De, B. K. Roy, U. C. Ghoshal, J. Saha, A. Chatterjee, S. Dutta, S. Lahiri, S. Das, T. Das, D. Chakraborti, R. Haque, A. H. Smith, C. R. Angle & J. H. Centeno. The author expresses thanks to the Director of the Institute and Director of Medical Education, Govt. of West Bengal for allowing him to carry on the studies. The epidemiological study was funded by the Rajiv Gandhi National Drinking Water Mission, Ministry of Rural Development, Government of India, research grants W-11046/2/496-TM II (R & D). Support for analysis and preparation for publication was also received from the US Environmental Protection Agency National Center for Environmental Assessment and from research grants P30-ES01896 and P42-ES04705 from the National Institute of Environmental Health Sciences, NIH. The author thanks Mr. Biswajit Debnath, Computer Programmer, IPGME & R, for assistance in preparation of the manuscript.