363 lecture 24-2008, predation

363 lecture 24-2008, predation - Mom's beef puts son's...

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Mom's beef puts son's sperm count at stake By Thomas H. Maugh II, Times Staff Writer March 28, 2007 Men whose mothers ate a lot of beef during their pregnancy have a sperm count about 25% below normal and three times the normal risk of fertility problems, researchers reported Tuesday. The problem may be due to anabolic steroids used in the United States to fatten the cattle, Dr. Shanna H. Swan of the University of Rochester Medical Center reported in the journal Human Reproduction. It could also be due to pesticides and other environmental contaminants, she added. If the sperm deficit is related to the hormones in beef, Swan's findings may be "just the tip of the iceberg," wrote biologist Frederick vom Saal of the University of Missouri- Columbia in an editorial accompanying the paper. In daughters of the beef-eaters, those same hormones could alter the incidence of polycystic ovarian syndrome, the age of puberty and the postnatal growth rate, he said. "It's a small effect, but it is a significant effect," said Dr. Ted Schettler, an environmental health specialist at the Institute for Global Communications in San Francisco. "It's not surprising. The more you look at dietary factors, the more you turn up interesting information about how diet during pregnancy affects lots of aspects of human health."
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Six growth-promoting hormones are routinely used in cattle production in the United States and Canada: the natural steroids estradiol, testosterone and progesterone, and the synthetic hormones zeranol, trenbolone acetate and melengestrol acetate. At slaughter, not all of these hormones have been metabolized. Diethyl stilbestrol was also used in this country from 1954 to 1979, when it was banned after tests showed that minks fed chicken waste containing DES became infertile. The Food and Drug Administration limits how much hormone residue is permissible in beef. Those limits may need to be reexamined if Swan's findings can be confirmed, Vom Saal said. The use of these hormones in beef was banned in Europe in 1988, and the United States has disputed the EU's attempts to ban imports of U.S. beef containing hormones. Studies in rodents have shown that even a trace of estrogen in the uterus from food can affect an offspring's sperm count, but no one has previously tried to study the question in humans. …… They found that, in general, the more beef a woman ate, the lower her son's sperm count. For women who ate beef at least seven times a week, the son's sperm averaged 24.3% below normal. And even though those sons produced a pregnancy, they were three times as likely to have consulted a fertility doctor.
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Bush Appointee Said to Reject Advice on Endangered Species A senior Bush political appointee at the Interior Department has rejected staff scientists' recommendations to protect imperiled animals and plants under the Endangered Species Act at least six times in the past three years, documents show. In addition, staff complaints that their scientific findings were frequently overruled or
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This note was uploaded on 10/22/2008 for the course BSCI 363 taught by Professor Staff during the Spring '08 term at Maryland.

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363 lecture 24-2008, predation - Mom's beef puts son's...

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