title: Associations between arsenic in drinking water and pterygium in southwestern Taiwan.
abstract: BACKGROUND
  Pterygium is a fibrovascular growth of the bulbar conjunctiva and underlying subconjunctival tissue that may cause blindness. The mechanism of pterygium formation is not yet fully understood, but pterygium has some tumorlike features.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the association between arsenic exposure through drinking water and the occurrence of pterygium in southwestern Taiwan.
  
  
  METHODS
  We recruited participants > 40 years of age from three villages in the arseniasis-endemic area in southwestern Taiwan (exposure villages) and four neighboring nonendemic villages (comparison villages). Each participant received an eye examination and a questionnaire interview. Photographs taken of both eyes were later graded by an ophthalmologist to determine pterygium status.
  
  
  RESULTS
  We included 223 participants from the exposure villages and 160 from the comparison villages. The prevalence of pterygium was higher in the exposure villages across all age groups in both sexes and increased with cumulative arsenic exposure. We found a significant association between cumulative arsenic exposure and the prevalence of pterygium. After adjusting for age, sex, working under sunlight, and working in sandy environments, we found that cumulative arsenic exposure of 0.1-15.0 mg/L-year and > or = 15.1 mg/L-year were associated with increased risks of developing pterygium. The adjusted odds ratios were 2.04 [95% confidence interval (CI), 1.04-3.99] and 2.88 (95% CI, 1.42-5.83), respectively.
  
  
  CONCLUSIONS
  Chronic exposure to arsenic in drinking water was related to the occurrence of pterygium, and the association was still observed after adjusting for exposures to sunlight and sandy environments.
authors.affiliation: Department of Environmental and Occupational Health, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.forename: Shu-Li
authors.initials: SL
authors.lastname: Wang
authors.forename: Horng-Jiun
authors.initials: HJ
authors.lastname: Wu
authors.forename: Kuang-Hsi
authors.initials: KH
authors.lastname: Chang
authors.forename: Peter
authors.initials: P
authors.lastname: Yeh
authors.forename: Chien-Jen
authors.initials: CJ
authors.lastname: Chen
authors.forename: How-Ran
authors.initials: HR
authors.lastname: Guo
mesh_terms: D000328:Adult; D000368:Aged; D001151:Arsenic / Q000633:toxicity*; D004781:Environmental Exposure / Q000009:adverse effects*; D005124:Eye Abnormalities / Q000139:chemically induced*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011625:Pterygium / Q000139:chemically induced*; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014881:Water Supply
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic