title: Promotion of well-switching to mitigate the current arsenic crisis in Bangladesh.
abstract: OBJECTIVE
  To survey tube wells and households in Araihazar upazila, Bangladesh, to set the stage for a long-term epidemiological study of the consequences of chronic arsenic exposure.
  
  
  METHODS
  Water samples and household data were collected over a period of 4 months in 2000 from 4997 contiguous tube wells serving a population of 55000, the position of each well being determined to within +/- 30 m using Global Positioning System receivers. Arsenic concentrations were determined by graphite-furnace atomic-absorption spectrometry. In addition, groundwater samples collected every 2 weeks for an entire year from six tube wells were analysed for arsenic by high-resolution inductively coupled plasma-mass spectrometry.
  
  
  RESULTS
  Half of the wells surveyed in Araihazar had been installed in the previous 5 years; 94% were privately owned. Only about 48% of the surveyed wells supplied water with an arsenic content below 50 micro g/l, the current Bangladesh standard for drinking-water. Similar to other regions of Bangladesh and West Bengal, India, the distribution of arsenic in Araihazar is spatially highly variable (range: 5-860 micro g/l) and therefore difficult to predict. Because of this variability, however, close to 90% of the inhabitants live within 100 m of a safe well. Monitoring of six tube wells currently meeting the 50 micro g/l standard showed no indication of a seasonal cycle in arsenic concentrations coupled to the hydrological cycle. This suggests that well-switching is a viable option in Araihazar, at least for the short term.
  
  
  CONCLUSIONS
  Well-switching should be more systematically encouraged in Araihazar and many other parts of Bangladesh and West Bengal, India. Social barriers to well-switching need to be better understood and, if possible, overcome.
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA. avangeen@ldeo.columbia.edu
authors.forename: Alexander
authors.initials: A
authors.lastname: Van Geen
authors.forename: Habibul
authors.initials: H
authors.lastname: Ahsan
authors.forename: Allan H
authors.initials: AH
authors.lastname: Horneman
authors.forename: Ratan K
authors.initials: RK
authors.lastname: Dhar
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Iftikhhar
authors.initials: I
authors.lastname: Hussain
authors.forename: Kazi Matin
authors.initials: KM
authors.lastname: Ahmed
authors.forename: Andrew
authors.initials: A
authors.lastname: Gelman
authors.forename: Martin
authors.initials: M
authors.lastname: Stute
authors.forename: H James
authors.initials: HJ
authors.lastname: Simpson
authors.forename: Sean
authors.initials: S
authors.lastname: Wallace
authors.forename: Christopher
authors.initials: C
authors.lastname: Small
authors.forename: Faruque
authors.initials: F
authors.lastname: Parvez
authors.forename: Vesna
authors.initials: V
authors.lastname: Slavkovich
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Loiacono
authors.forename: Marck
authors.initials: M
authors.lastname: Becker
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: Cheng
authors.forename: Hassina
authors.initials: H
authors.lastname: Momotaj
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shahnewaz
authors.forename: Ashraf Ali
authors.initials: AA
authors.lastname: Seddique
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Graziano
mesh_terms: D001151:Arsenic / Q000032:analysis*; D020261:Arsenic Poisoning / Q000453:epidemiology / Q000517:prevention & control; D001459:Bangladesh / Q000453:epidemiology; D004781:Environmental Exposure / Q000032:analysis*; D006801:Humans; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic