Background: Pterygium is a fibrovascular growth of the bulbar conjunctiva and underlying sub-conjunctival tissue that may cause blindness. The mechanism of pterygium formation is not yet fully understood, but pterygium has some tumor-like features. To evaluate the association between arsenic exposure through drinking water and the occurrence of pterygium, we conducted a study in southwestern Taiwan. Methods: We recruited participants over 40 years of age from three villages in the endemic area of arseniasis in southwestern Taiwan(exposure villages) and four neighboring non-endemic villages(comparison villages). Each participant received an eye examination and aquestionnaire interview. Photographs of both eyes were taken, which were later graded by an ophthalmologist for the status of pterygium. A total of223 participants from the exposure villages and 160 from the comparison villages were included in the analyses. Results: The prevalence of pterygium was higher in the exposure villages across all age groups in both genders and increased with the cumulative arsenic exposure. There was a significant association between cumulative arsenic exposure and the prevalence of pterygium. We found that working under sunlight and working in sandy environments were also risk factors for developing pterygium. After adjusting for age, gender, working under sunlight, and working in sandy environments, we found cumulative arsenic exposure of 0.1 to 15.0 mg/L-year and $ 15.1 mg/L-year were associated with increased risks of developing pterygium, and the odds ratios were 2.04 (95% confidence interval @CI#: 1.04 to 3.99) and 2.88(95%CI: 1.42 to 5.83), respectively. Conclusion: We conclude that chronic exposure to arsenic in drinking water was related to the occurrence of pterygium, and the association wasstill observed after adjusting for exposures to sunlight and sandy environments.
