Pollution

污染

A poison Pill

一颗毒药

Feb 21st 2008 | BOSTON
From The Economist print edition

Human contraceptives are bad for fish

人类避孕药有害鱼类

ONEthing Canada is not short of is lakes. It has so many that it can affordto set some aside to experiment on. And that is what Karen Kidd, anecotoxicologist at the University of New Brunswick, has just done to asmall lake in north-west Ontario. She has poisoned it in the nameof science.

加拿大的湖非常多，这一点无庸置疑。它有太多的湖以至于可以提供一些进行科学实验。来自新巴恩兹维克大学的毒药学家克伦·基德就刚刚完成了一个在西北安大略湖的实验。她以科学研究的方式对该湖释毒。

Herchosen poison was oestrogen, one of the hormones that make women womenand help to control the menstrual cycle. People flush a lot of oestrogendown the toilet. Some is natural. Some is the synthetic stuff used inoral contraceptives. There is a strong suspicion that if thisoestrogenis not removed during sewage treatment (some works do, some donot), it causes serious damage to rivers and lakes. Until now, however,proof has been lacking.Dr Kidd wanted to find out if the suspicion wascorrect. As she told a session of the American Association for theAdvancement of Science meeting in Boston,it is.

她选择的毒素是一种可以促进女性发育并且控制月经周期的雌激素。人们经常把很多雌激素冲进厕所。有这样一种猜测，即如果这种雌激素在下水道污水处理过程中没有被清除，它将对湖河环境造成严重的破坏。但直到现在还没有足够的证据证明这一点。而据克伦·基德在波士顿召开的美国科学进步协会的会议上所说，现在有了。

Thelake's algae, bacteria and invertebrates appeared unfazed by the extrahormone which she dumped in the lake at regular intervals.Presumably,its chemistry was not similar enough to their own biochemicals for themto notice. But the population plunged in the smallest fish species,the fathead minnow. Male minnows became feminised: their spermproduction was delayed and they started producing eggs. After two yearsof treatment, the fathead minnow population collapsed.

她定期的向湖中倒入一些激素，而湖中的藻类、菌类以及无脊椎动物看起来并未被打扰。推测可能是倒入激素的化学成分与它们本身含有的不太相同所以无法引起它们的注意。然而最小的鱼种，黑头呆鱼的数量却发生了变化。雄性黑头呆鱼变的雌性化了：它们的精子生产被延迟，而且开始产卵。在进行两年的实验后，黑头呆鱼的数量大减。

Otherchanges took longer. Pearl dace mature more slowly than minnows and canoutlive them by several years. The dace therefore managed to hold outfor three years before the lack of male potency brought about apopulation crash.

其他一些变化则经历了较长的时间。珍珠鱼的成长期比黑头呆鱼要久并且寿命更长。在由于缺乏雄性交配而造成总量锐减之前，珍珠鱼数量三年保持不变。

Therewas damage even to the lake's largest fish, its trout. Here the causewas less that boys were turning into girls than that the trout were onshort rations—since the minnows had disappeared. But the upshot was thesame: fewer trout, and confirmation that oestrogens are very badnews for fish, even at low concentrations.

甚至对湖中最大的鱼，鲑鱼，也受到了破坏。这里，由于男孩变女孩而造成配给不足的情况没有已经消失的黑头呆鱼那么严重。但结果是一样的：鲑鱼数量减少了，并且更加确定雌激素对鱼类有害，哪怕只是微量。

Thebetter news was that things quickly returned to normal once the hormonetreatment stopped. Fixing sewage works to prevent them from spewing outoestrogen should therefore help fairly rapidly. Controlling the sale ofcontraceptive pills will not be necessary, and fishermen will once againbe able to use their rods and tackle with impunity.