1. ^aDepartment of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
2. ^bDepartment of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
3. ^cNational Institute of Preventive and Social Medicine, Dhaka, Bangladesh
4. ^dDepartment of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY, USA
5. ^eLamont Doherty Earth Observatory, Columbia University, New York, NY, USA
6. ^fHerbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA

Correspondence: Dr. H. Ahsan, Department of Epidemiology, Mailman School of Public Health, Columbia University Medical Center, 722 West 168th Street, Room 720-G, New York, NY 10032, USA. Tel.: +1 212 305 7636; Fax: +1 212 342 2129. E-mail: habibul.ahsan@columbia.edu

Received 2 March 2005; Accepted 27 June 2005; Published online 14 September 2005.

Abstract

Health Effects of Arsenic Longitudinal Study (HEALS), a multidisciplinary and large prospective cohort study in Araihazar, Bangladesh, was established to evaluate the effects of full-dose range arsenic (As) exposure on various health outcomes, including premalignant and malignant skin tumors, total mortality, pregnancy outcomes, and children's cognitive development. In this paper, we provide descriptions of the study methods including study design, study population, data collection, response rates, and exposure and outcome assessments. We also present characteristics of the study participants including the distribution of exposure and the prevalence of skin lesion at baseline recruitment. A total of 11,746 married men and women between 18 and 75 years of age participated in the study at baseline (a response rate of 98%) and completed a full questionnaire interview that included a food frequency questionnaire, with a response rate of 98%. Among the 98% of the participants who completed the clinical evaluation, over 90% provided blood samples and spot urine samples. Higher educational status, male gender, and presence of premalignant skin lesions were associated with an increased likelihood of providing blood and urine samples. Older participants were less likely to donate a blood sample. About one-third of the participants consumed water from a well with As concentration in each of three groups: >100 g/l, 25–100 g/l, and <25 g/l. Average urinary As concentrations were 140 and 136 g/l for males and females, respectively. HEALS has several unique features, including a prospective study design, comprehensive assessments of both past and future changes in As exposure at the individual level, a large repository of biological samples, and a full dose range of As exposures in the study population. HEALS is a valuable resource for examining novel research questions on the health effects of As exposure.