title: Estimating water supply arsenic levels in the New England Bladder Cancer Study.
abstract: BACKGROUND
  Ingestion of inorganic arsenic in drinking water is recognized as a cause of bladder cancer when levels are relatively high (≥ 150 µg/L). The epidemiologic evidence is less clear at the low-to-moderate concentrations typically observed in the United States. Accurate retrospective exposure assessment over a long time period is a major challenge in conducting epidemiologic studies of environmental factors and diseases with long latency, such as cancer.
  
  
  OBJECTIVE
  We estimated arsenic concentrations in the water supplies of 2,611 participants in a population-based case-control study in northern New England.
  
  
  METHODS
  Estimates covered the lifetimes of most study participants and were based on a combination of arsenic measurements at the homes of the participants and statistical modeling of arsenic concentrations in the water supply of both past and current homes. We assigned a residential water supply arsenic concentration for 165,138 (95%) of the total 173,361 lifetime exposure years (EYs) and a workplace water supply arsenic level for 85,195 EYs (86% of reported occupational years).
  
  
  RESULTS
  Three methods accounted for 93% of the residential estimates of arsenic concentration: direct measurement of water samples (27%; median, 0.3 µg/L; range, 0.1-11.5), statistical models of water utility measurement data (49%; median, 0.4 µg/L; range, 0.3-3.3), and statistical models of arsenic concentrations in wells using aquifers in New England (17%; median, 1.6 µg/L; range, 0.6-22.4).
  
  
  CONCLUSIONS
  We used a different validation procedure for each of the three methods, and found our estimated levels to be comparable with available measured concentrations. This methodology allowed us to calculate potential drinking water exposure over long periods.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA. jnuckols@colostate.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Nuckols
authors.forename: Laura E Beane
authors.initials: LE
authors.lastname: Freeman
authors.forename: Jay H
authors.initials: JH
authors.lastname: Lubin
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Airola
authors.forename: Dalsu
authors.initials: D
authors.lastname: Baris
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Ayotte
authors.forename: Anne
authors.initials: A
authors.lastname: Taylor
authors.forename: Chris
authors.initials: C
authors.lastname: Paulu
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Karagas
authors.forename: Joanne
authors.initials: J
authors.lastname: Colt
authors.forename: Mary H
authors.initials: MH
authors.lastname: Ward
authors.forename: An-Tsun
authors.initials: AT
authors.lastname: Huang
authors.forename: William
authors.initials: W
authors.lastname: Bress
authors.forename: Sai
authors.initials: S
authors.lastname: Cherala
authors.forename: Debra T
authors.initials: DT
authors.lastname: Silverman
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Cantor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001151:Arsenic / Q000032:analysis*; D016022:Case-Control Studies; D002648:Child; D060766:Drinking Water / Q000737:chemistry*; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008281:Maine / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009513:New Hampshire / Q000453:epidemiology; D012044:Regression Analysis; D012189:Retrospective Studies; D018570:Risk Assessment; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology*; D014707:Vermont / Q000453:epidemiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D055815:Young Adult
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D001151:Arsenic