Hypertension Incidence and Its Relation to Arsenic Ingestion: A 13-year Follow-up Study in Arseniasis Endemic Area of Southwestern Taiwan:

TAA2-O-04 Introduction: It is of interest and public health concern that cardiovascular disease risk may be increased due to previous arsenic exposure even after a tap water supply system was implemented. The aim of the present study was to evaluate the incidence of hypertension 2 decades after cessation of high arsenic exposure (1920 to1970), and to assess the importance of arsenic compared with conventional risk factors for hypertension occurrence in a prospective cohort from the arseniasis-endemic area of southwestern Taiwan. Method: In 1990, we recruited 513 residents, aged over 30 years and without hypertension, from 3 villages where the prevalence of black foot disease used to be the highest in Taiwan. We used arsenic concentrations in artesian well water consumed by the local residents. Well-trained nurses or clinicians measured blood pressure using an arm mercury sphygmomanometer at baseline and at follow-up in 2003. We defined hypertension according to the Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC-7). Results: Eighty-nine subjects developed hypertension among 238 nonhypertensives in 1990. The incidence was 27.7 (95% CI, 14.5–40.9), 53.5 (95% CI, 34.0–73.0), and 53.9 (95% CI, 34.9–72.9) per 1000 person-years for accumulative arsenic tertiles of <12.6 (mg/L × years of drinking), 12.6 to 19.9, and >19.9, respectively. The incidence doubled (RR = 2.17, 95% CI, 1.00–4.68) in those with 20 years of artesian well water drinking, after the adjustment for age, gender, and obesity. Diastolic and systolic blood pressures increased linearly and significantly (r = 0.22, P = 0.004; r = 0.15, P = 0.047, respectively) with increasing arsenic concentrations. We found a synergistic effect between arsenic exposure and obesity on hypertension incidence. Conclusion: Arsenic exposure was related to increased incidence of hypertension even after 20 years of tap water use. These results suggest that cardiovascular disease risk needs to be monitored despite cessation of high arsenic exposure from drinking water.