Print version ISSN 0042-9686
Bull World Health Organ vol.80 n.2 Genebra Jan. 2002
Arsenic and hypertension in Bangladesh
Editor The prevalence, awareness, treatment and control of hypertension among the elderly in Bangladesh and India were discussed recently in the Bulletin (1). I should like to draw attention to the role of arsenic poisoning in this respect. My colleagues and I previously reported in the Bulletin that the contamination of groundwater by arsenic in Bangladesh can be described as "the largest poisoning of a population in history, with millions of people exposed" (2). Tube-wells were installed to provide safe drinking-water and prevent diarrhoeal diseases, but were not tested for arsenic.
We have recently described a link between arsenic in drinking-water and the occurrence of diabetes mellitus and hypertension in Bangladesh (3). From a public health point of view, arsenic exposure has attracted great interest in the past few decades, especially regarding the risk of lung cancer among copper-smelting workers, but also the risk of skin and bladder cancer seen in connection with exposure through drinking-water. Studies in other countries with long-term exposure indicate that 1 in 10 persons who drink water containing 500 mg of arsenic per litre may ultimately die from arsenic-related cancers of the lung, bladder and skin.
Epidemiological data (4) indicate the doseeffect relationship between levels of arsenic in drinking-water and the pre-valence of hypertension. For a 50 mg/l concentration, the risk of hypertension was doubled compared with non- exposure. These results confirm findings reported from Taiwan, China (5). Considering time-weighted mean arsenic exposure (500 mg/l, 5001000 mg/l, and >1000 mg/l), the adjusted prevalence ratios for hypertension among the subjects without skin lesions were 0.8 (95% confidence interval (CI) = 0.41.8), 1.7 (95% CI = 0.83.3), and 2.2 (95% CI = 1.14.3), respectively (4). With the same reference and exposure categories, subjects with skin lesions had adjusted prevalence ratios of 1.4 (95% CI = 0.63.2), 2.5 (95% CI = 1.25.1), and 2.9 (95% CI = 1.36.1), respectively (4). The doseresponse trend was significant both for subjects with and without skin lesions (P<0.001). Currently, at least 20 out of 120 million population in Bangladesh are exposed to arsenic in drinking-water at concentrations of >50 mg/l (6). Given this frequency of exposure and the indicated excess risk for hypertension, a non-negligible proportion of the future hypertension burden in Bangladesh could be attributed to arsenic poisoning.
The epidemiological evidence supporting a causal association between well water containing inorganic arsenic and occurrence of hypertension points to the need to take arsenic exposure into account in further studies on hypertension.
Conflicts of interest: none declared.
1. Hypertension Study Group. Prevalence, awareness, treatment and control of hypertension among the elderly in Bangladesh and India: a multicentre study. Bulletin of the World Health Organization 2001;79:490-500.
2. Smith AH, Lingas EO, Rahman M. Contamination of drinking-water by arsenic in Bangladesh: a public health emergency. Bulletin of the World Health Organization 2000;78:1093-103.
3. Rahman M. Nonmalignant health effects of arsenic exposure. Linköping: Linköping University; 1999. Medical Dissertation No. 612.
4. Rahman M, Tondel M, Ahmad SA, Chowdhury IA, Faruquee MH, Axelson O. Hypertension and arsenic exposure in Bangladesh. Hypertension 1999;33:74-8.
5. Chen CJ, Hsueh YM, Lai MS, Shyu MP, Chen SY, Wu MM, et al. Increased prevalence of hypertension and long-term arsenic exposure. Hypertension 1995;25:53-60.
6. British Geological Survey. Phase 2 groundwater studies of arsenic contamination in Bangladesh. Nottingham: British Geological Survey; 2001. Available at URL: www.bgs.ac.uk/arsenic