An overview on chronic arsenism via drinking water in PR China.

Chronic endemic arsenism via drinking water was first found in Taiwan in 1968, and reported in Xinjiang Province in mainland China in the 1980s. Arsenism has become one of the most serious endemic diseases in China in the last two decades. Up to now, the disease has been found in Inner Mongolia, Shanxi, Ningxia, Jilin and Qinghai provinces. According to the Chinese maximum limit standard of arsenic (As) in drinking water, over 2 millions people have been exposed to high arsenic and about 10,000 persons were diagnosed as arsenism patients. There are different As concentrations in the water of different sites, even in the same area. Most of the As concentrations range from 0.05 to 2.0mg/l. The incidence of arsenism increases as As concentrations in drinking water and the drinking time increase. The age distribution of patients with arsenism ranged from 3 to 80 years old with peak prevalence in adults. A dose-effect relationship between the status of arsenism and arsenic level and drinking time has been shown. New high-arsenic areas in China have been discovered during recent investigations. In order to reduce the adverse health effects of arsenism, the central and local governments of China have provided significant funds to change water levels of As and at the same time take general measures to "reduce arsenic intake, remove arsenic from the body and treat the patients". After the implementation of these control measures in certain regions, the clinical symptoms and signs of 30% of the patients were improved. There was no change in 52% of patients and only 18% of patients got worse. It is suggested that future work in the research and control of arsenism in China should include: (1) identify all the high arsenic areas in China, (2) study the association of arsenism with fluorosis, (3) determine individual susceptibility, (4) select biomarkers for diagnosis in the early stage of a arsenism, and (5) investigate the molecular mechanisms of carcinogenesis.