THE FIRST SIGN of poisoning, which may appear as long as 10 years after someone starts drinking arsenic-laden water, is black spots on the upper chest, back and arms, known as melanosis.

• 中毒的症状可能在开始饮用含砷水10年之后才出现，首先是胸部上方、背部及手臂出现黑斑，就是所谓的黑变症；