Nearly 200 million people in the world, including ~57 million in Bangladesh and ~17 million in the United States, are chronically exposed to inorganic arsenic, a class I human carcinogen, and are at increased risk of mortality, cancers, cardiovascular, pulmonary and other non-malignant diseases. As part of the Columbia University SRP, we established the Health Effects of Arsenic Longitudinal Study (HEALS)—a large prospective cohort study based on individual-level data from a population exposed to a wide range of inorganic arsenic from drinking water in Araihazar, Bangladesh. Over the past 14 years, using a population-based sampling frame, we recruited >30,000 men and women (with >95% response rate) and collected detailed questionnaire and clinical data, as well as biological samples at baseline and biennially thereafter.
Approximately 80% of cohort participants are exposed to water arsenic at low-to-moderate doses (0-150 µg/L) with nearly 75% exposed at <100 µg/L. Through a dedicated medical clinic established by Columbia University and The University of Chicago that exclusively serves the HEALS participants, we have also developed an effective mechanism of following the cohort, especially for detecting incidence of respiratory and cardiovascular disorders.
The association between individual-level arsenic exposure and dermatological, pulmonary, and cardiovascular health outcomes has not been well established in the scientific literature, particularly at low-to-moderate exposure levels. Our overall goal is to prospectively evaluate the effects of various measures of arsenic exposure and metabolism on: i) incidence of skin lesions and skin cancer, ii) incidence and mortality from chronic lung disorders and mortality from lung cancers, iii) incidence and mortality from cardiovascular disease (CVD), and iv) a number of biological and preclinical markers potentially involved in skin and lung disorders/cancers and CVD. The information derived from this study will have direct public health impact on arsenic-exposed populations and can be readily incorporated in future prevention and mitigation measures for reducing arsenic-induced health effects in this population.
Over the past year, analysis of data collected by the HEALS study has contributed to a wide variety of health-related fields, including cardiovascular disease, pulmonary health, and cancer. Three papers by Chen et al. in 2013 established that cardiovascular disease and its precursors were found to be associated with higher levels of arsenic exposure, and a lower ability to excrete arsenic from the body. Results from Parvez et al. (2013) suggested that even low-levels of arsenic exposure may impair lung function. Melkonian et al. (2013) established that steamed rice consumption is associated with higher levels of urinary arsenic, as well as higher levels of the skin lesions that often precede other arsenic-related morbidity and mortality. Analysis of the HEALS study data also provided evidence that the levels of selenium in a person’s blood may help reduce the levels of arsenic (George et al., 2013). In a recently accepted publication, Argos et al. (2014) showed that arsenic exposure is associated with increased non-malignant lung disease mortality and arsenical skin lesion status is associated with increased lung cancer mortality. The cohort data was also utilized in several secondary analyses, leading to several notable publications. Analysis by Wu et al. (2013) reported an association between tobacco smoking and mortality for the first time in a Bangladeshi population. An analysis by Argos et al. (2013) found an association between high protein diet and cancer mortality. Variability in blood pressure was linked with the risk of death for the first time in a population-based cohort (Yinon et al., 2013). Quality of life and mental health were lower in HEALS participants with high levels of arsenic exposure (Syed et al, 2012). Several other manuscripts in preparation and under review will be reporting results of a number of additional analyses from the HEALS data.
We will continue to actively follow-up participants biennially as well as through our chronic disease surveillance mechanism between follow-up visits for the successful achievement of this project's aims.