Clean drinking water: a double-edged sword?
来源：未知 作者：冉谕驯 时间：2019-03-02 01:05:01
By Bryant Furlow THE spring thaw came late to Wisconsin in 1993. Then towards the end of March, as water levels in Lake Michigan were rising, Milwaukee’s drinking water treatment plant failed – with disastrous consequences. Over 400,000 people fell victim to cryptosporidiosis, a debilitating attack of diarrhoea that can last several days and is caused by a nasty little protozoan called cryptosporidium. The final death toll was 54. The Milwaukee incident was particularly shocking for a rich country, but it is by no means isolated. In recent decades, outbreaks of cryptosporidiosis have been reported elsewhere in the US, Canada, Australia and Europe. In fact, it is now widely considered an “emerging disease” in much of the developed world. And it is not alone. Other water-borne pathogens such as Giardia, noroviruses and harmful strains of E. coli all seem to be on the increase. A century ago, the diseases caused by such microbes were major killers worldwide, and contaminated drinking water still kills 2 million each year in developing countries. But in the industrialised world, where the mass production of purified water was one of the great engineering achievements of the 20th century, we thought we had these diseases licked. It seems we were wrong. This isn’t just an issue of public health; it is also a financial one. The Milwaukee outbreak ran up a tab of $32 million in medical costs and an additional $65 million in lost productivity,