oa Recent Findings from the Health Effects of Arsenic Longitudinal Study in Bangladesh

The Health Effects of Arsenic Longitudinal Study (HEALS), a large multidisciplinary prospective cohort study in Araihazar, Bangladesh, was established in 2000 to evaluate the effects of a wide range of arsenic (As) exposures on various health outcomes, including premalignant and malignant skin lesions, total mortality, and children’s neuropsychological development (1). In this presentation, some important recent findings will be presented. Approximately 12,000 adults, aged 18-75, were recruited for the study; their well water As concentrations ranged from 0.1 to 864 ug/L. Since 2000, each participant has been evaluated roughly every other year. A total of 7.31, 9.95 and 2.03% of the participants completing 4 years of active follow-up reported having a chronic cough, breathing problem or blood in their sputum, respectively, as assessed by trained physicians. We found a dose-response relationship between As exposure and clinical symptoms of respiratory diseases (2). The mechanism of this effect, also reported in other countries, is not known. In particular, these adverse respiratory effects of As were clearly evident in the low to moderate dose range. We have also studied the association between As exposure and total mortality. 407 deaths were ascertained between October 2000 and February 2009. Multivariate adjusted hazard ratios for all-cause mortality in a comparison of arsenic at concentrations of 10•1–50•0 μg/L, 50•1–150•0 μg/L, and 150•1–864•0 μg/L with at least 10•0 μg/L in well water were 1•34 (95% CI 0•99–1•82), 1•09 (0•81–1•47), and 1•68 (1•26–2•23), respectively (3). Deaths due to diseases of circulatory system accounted for 43% of total mortality in the population. The mortality rate for cardiovascular disease was 214.3 per 100 000 person years in people drinking water containing <12.0 μg/L arsenic, compared with 271.1 per 100 000 person years in people drinking water with ≥12.0 μg/L arsenic. There was a dose-response relation between exposure to arsenic in well water assessed at baseline and mortality from ischaemic heart disease and other heart disease (4). The children of HEALS participants have been involved in several cross-sectional studies that examined the relationships between As exposure and several neuropsychological outcomes. We have observed dose-dependent deficits in intelligence in 8- to 11-year-old children (5, 6) and in 6-year-old children (7). More recently, we have also investigated the associations of water As and water manganese (Mn) with motor function in 304 children in Bangladesh, aged 8 to 11 years. In addition to water, we measured As and Mn concentrations in blood, urine and toenails. We assessed motor function with the Bruininks-Oseretsky Test (BOT-2), which can be summarized with a total score of overall motor proficiency (TMC) or in four subscales: fine manual control (FMC), manual co-ordination (MC), body co-ordination (BC) and strength and agility (SA). After adjustment for covariates, water As (but not Mn) levels were associated with decreases in FMC, BC and TMC; similar findings were observed when we used urinary or blood As as the exposure measure (8). Collectively, the findings from the HEALS study and a growing body of basic science and population-based evidence indicate the urgent need to provide As-free drinking water to the many affected populations around the world.