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CAUSES OF MORTALITY IN AN ARSENIC-AFFECTED AREAS OF INNER MONGOLIA, CHINA
Citation:
WADE, T. J., Y. XIA, K. WU, Y. LI, Z. NING, AND J. S. MUMFORD. CAUSES OF MORTALITY IN AN ARSENIC-AFFECTED AREAS OF INNER MONGOLIA, CHINA. Presented at International Society for Environmental Epidemiology Annual Meeting, Paris, FRANCE, September 02 - 06, 2006.
Description:
Introduction
Shahai is a village in Inner Mongolia, China. In the early 1980s, the primary source of drinking water shifted away from large shallow wells to deeper artesian wells, which were often contaminated by naturally occurring arsenic. Characteristic arsenic-induced skin lesions were noticed in the region in the early 1990s.
Methods
We conducted a retrospective mortality study in Shahai to ascertain the overall mortality rate, and to classify causes of death. There is no systematic method for recording cause of death in the village. We conducted a complete census of the village. For each household member who died in the past five years, we collected information from the closest living relative about the cause of death including: symptoms leading up to death, medical records, medications, and hospital records. We visited hospitals and physicians to collect additional information about the deceased. A panel of physicians, epidemiologists, and nosologists determined the most likely cause of death, which was classified according to the International Classification of Disease, version 10 (ICD-10). Water samples from the household's primary source of water, usually an artesian well, were also collected.
Results
We interviewed 3,263 households. No household refused to participate. In the five-year period, households reported 576 deaths. Diseases of the heart were the leading cause of mortality (207 deaths, 36%), followed by cerebrovascular diseases (26%), malignant neoplasms (13%), accidents and intentional self-harm (8%), and influenza, pneumonia and tuberculosis (4%).
Discussion and Conclusions
Previous studies in arsenic-affected areas observed excess cancer and cardiovascular mortality. The proportion of deaths due to heart conditions recently published from a representative cohort in China was lower compared to our arsenic affected cohort (22.5% vs. 36%) although the proportion of deaths due to malignant neoplasms was higher (21.3% vs. 13%). Our results may reflect the relatively short period of time residents of Shahai have been exposed to arsenic. Studies have suggested that the latency period for some arsenic related cancers may be longer than 30 years. Some underlying cancers may also have been misdiagnosed due to the lack of appropriate diagnostic tools.
This work demonstrates the feasibility of collecting retrospective mortality information in a rural Chinese village and highlights the increasing importance of chronic diseases in China. Further work will include analyses of well-water arsenic and mortality rates and geographic patterns of mortality and exposure.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.