title: Arsenic in drinking-water and risk for cancer in Denmark.
abstract: BACKGROUND
  Arsenic is a well-known carcinogen, which is often found in drinking-water. Epidemiologic studies have shown increased cancer risks among individuals exposed to high concentrations of arsenic in drinking-water, whereas studies of the carcinogenic effect of low doses have had inconsistent results.
  
  
  OBJECTIVE
  Our aim was to determine if exposure to low levels of arsenic in drinking-water in Denmark is associated with an increased risk for cancer.
  
  
  METHODS
  The study was based on a prospective Danish cohort of 57,053 persons in the Copenhagen and Aarhus areas. Cancer cases were identified in the Danish Cancer Registry, and the Danish civil registration system was used to trace and geocode residential addresses of the cohort members. We used a geographic information system to link addresses with water supply areas, then estimated individual exposure to arsenic using residential addresses back to 1970. Average exposure for the cohort ranged between 0.05 and 25.3 microg/L (mean = 1.2 microg/L). Cox's regression models were used to analyze possible relationships between arsenic and cancer.
  
  
  RESULTS
  We found no significant association between exposure to arsenic and risk for cancers of the lung, bladder, liver, kidney, prostate, or colorectum, or melanoma skin cancer; however, the risk for non-melanoma skin cancer decreased with increasing exposure (incidence rate ratio = 0.88/microg/L average exposure; 95% confidence interval, 0.84-0.94). Results adjusted for enrollment area showed no association with non-melanoma skin cancer.
  
  
  CONCLUSIONS
  The results indicate that exposure to low doses of arsenic might be associated with a reduced risk for skin cancer.
authors.affiliation: Danish Cancer Society, Institute of Cancer Epidemiology, Strandboulevarden 49, Copenhagen, Denmark. baastrup@cancer.dk
authors.forename: Rikke
authors.initials: R
authors.lastname: Baastrup
authors.forename: Mette
authors.initials: M
authors.lastname: Sørensen
authors.forename: Thomas
authors.initials: T
authors.lastname: Balstrøm
authors.forename: Kirsten
authors.initials: K
authors.lastname: Frederiksen
authors.forename: Carsten Langtofte
authors.initials: CL
authors.lastname: Larsen
authors.forename: Anne
authors.initials: A
authors.lastname: Tjønneland
authors.forename: Kim
authors.initials: K
authors.lastname: Overvad
authors.forename: Ole
authors.initials: O
authors.lastname: Raaschou-Nielsen
mesh_terms: D001151:Arsenic / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity*; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D014881:Water Supply
chemical_list: D002273:Carcinogens; D001151:Arsenic