A intervention study for improvement of decreased nitric oxide levels and oxidative stress in arsenosis patients in China

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Arsenic is a naturally occurring element that is ubiquitously present in the environment. The main source of human environmental exposure is through consumption of water containing high levels of arsenic, primarily from natural contamination. In Asia, millions of people are chronically exposed to a high level of arsenic from their drinking water, obtained from wells drilled into arsenic-rich geologic strata. Nitric oxide (NO) is a messenger molecule that plays an important role in neurotransmission, vasodilation, and immune response. In a field study in an endemic area of chronic arsenic poisoning in Inner Mongolia, China, we found that prolonged exposure of humans to arsenic results in reduction of systemic NO levels and oxidative stress. Such phenomena were also seen with rabbits chronically exposed to arsenic (18 weeks, 5μg/ml), supporting the notion that arsenic is a metalloid that causes impairment of systemic NO production and increased oxidative stress through reactive oxygen species (ROS) generation and decreased antioxidant enzyme activities.Replacement of heavily arsenic-contaminated drinking water with low-arsenic water is thought to be a potential intervention strategy for arsenosis, although the reversibility of arsenic intoxication has not been established. However, our current intervention study in the endemic area of chronic arsenic poisoning in Inner Mongolia indicated that decreased NO levels and peripheral vascular disease in arsenosis patients can be reversed by exposure cessation. These results have important implications in the public health approach to arsenic exposure. From these observations, we thought that clearance of arsenic at the cellular level is critical for decreased arsenic poisoning.