An Arsenic Forecast for China

About 140 million people worldwide drink groundwater containing unsafe levels of arsenic (1). Chronic exposure to this tasteless, odorless poison leads to health effects such as skin lesions and cancer. In China, pollution is pervasive and anthropogenic groundwater contamination has attracted attention (2). Naturally-occurring arsenic is perhaps less widespread, yet equally dangerous to those exposed. Though the problem has been known for decades (3) and mitigation is ongoing (4), estimates of the exposed population differ widely (5, 6). On page 866 of this issue, Rodriguez-Lado et al. (7) assess the probability of the occurrence of unsafe arsenic levels in China's groundwater and identify at-risk areas where data are sparse. They suggest that more than 19 million Chinese may be drinking water above the World Health Organization guideline of 10 mu g/liter. Such predictive models could guide action toward minimizing the impact of this widespread threat to human health.