Over the years arsenic is well known for its toxicity and arsenic contamination of tap water is becoming a worldwide problem . Excessive amounts of arsenic in drinking water may lead to chronic arsenic poisoning and is considered relevant to carcinogenesis and very harmful to human .

长期以来，砷以它的毒性而闻名， 饮用水中的砷污染成为一个世界问题，饮用水中含有过量的砷会 导致人体慢性砷中毒，医学上认为砷是一种癌症诱因，对人类危害极大。

In one study tap water accounted for up to20 percent of human exposure to lead .

一项研究表明， 自来水占人体所接触到的 铅的20%。

Captain Sellers introduced the tap of bell as a signal to heave the lead .

赛勒斯船长提出了以 敲铃为抛测 铅的办法。

For each child the researchers measured the concentration of manganese in tap water from their home as well as iron copper lead zinc arsenic magnesium and calcium .

对于每一个孩子，研究者检测了他们家里 自来水中锰、铁、铜、 铅、锌、砷、镁和钙的含量。

Furthermore lead is frequently used as a material for water supply pipes and tap water that has been in contact with a lead pipe for a long time ( e.g. overnight ) can contain relatively high amounts of lead .

而且铅经常用来作为供水管道的材料，因此 自来水 与 铅管有长时间的接触（比如说，一晚上），从而 自来水中含有较高量的铅。