新理念综合教程BOOk4单元测试1.docxVIP

The soaring number of gender-bending chemicals in the environment has disturbing fertility implications for humans and wildlife, scientists are warning. They say wild animals are being feminised by a host of common man-made pollutants which mimic the female sex hormone oestrogen and escape into seas, rivers, the earth and air when waste is disposed of. The chemicals--found in food packaging, cleaning products, plastics, sewage and paint--cause genital deformities, reduce sperm count and even turn males into females. Dozens of species--including polar bears, fish, whales and otters--are suffering, according to the environmental group ChemTrust. Fish have been badly hit by man-made gender-bending chemicals. In one study, half the male fish in British lowland rivers had signs of being feminised. But all vertebrates--or creatures with backbones--have similar sex hormone receptors in their bodies. Therefore, observations in one species may serve to highlight pollution issues of concern for other vertebrates, including humans, the report says. Its author, Gywnne Lyons, a former government adviser on chemical-pollution, said: some Urgent action is needed to control gender-bending chemicals and more resources are needed for monitoring wildlife. If wildlife populations crash, it will be too late. Unless enough males contribute to the next generation there is a real threat to animal populations in the long term. Some studies have shown that sperm counts in the West have fallen over the past 30 years. Others have shown a rise in boys born with genital deformities. Communities heavily polluted with hormone-disrupting chemicals in Russia, Canada and Italy haveproduced twice as many girls as boys.Passage Two??????Biological diversity has become widely recognized as a critical conservation issue only since the past two decades. The rapid destruction of the tropical rain forests which are the ecosystems with the highest known species diversity on Earth ha