www射-国产免费一级-欧美福利-亚洲成人福利-成人一区在线观看-亚州成人

   

Lead linked to aging in older brains

(Agencies)
Updated: 2008-01-28 06:53

NEW YORK - Could it be that the "natural" mental decline that afflicts many older people is related to how much lead they absorbed decades before?

That's the provocative idea emerging from some recent studies, part of a broader area of new research that suggests some pollutants can cause harm that shows up only years after someone is exposed.

The new work suggests long-ago lead exposure can make an aging person's brain work as if it's five years older than it really is. If that's verified by more research, it means that sharp cuts in environmental lead levels more than 20 years ago didn't stop its widespread effects.

"We're trying to offer a caution that a portion of what has been called normal aging might in fact be due to ubiquitous environmental exposures like lead," says Dr. Brian Schwartz of Johns Hopkins University.

"The fact that it's happening with lead is the first proof of principle that it's possible," said Schwartz, a leader in the study of lead's delayed effects. Other pollutants like mercury and pesticides may do the same thing, he said.

In fact, some recent research does suggest that being exposed to pesticides raises the risk of getting Parkinson's disease a decade or more later. Experts say such studies in mercury are lacking.

The notion of long-delayed effects is familiar; tobacco and asbestos, for example, can lead to cancer. But in recent years, scientists are coming to appreciate that exposure to other pollutants in early life also may promote disease much later on.

"It's an emerging area" for research, said Dr. Philip Landrigan of the Mount Sinai School of Medicine in New York. It certainly makes sense that if a substance destroys brain cells in early life, the brain may cope by drawing on its reserve capacity until it loses still more cells with aging, he said. Only then would symptoms like forgetfulness or tremors appear.

Linda Birnbaum, director of experimental toxicology at the U.S. Environmental Protection Agency, said infant mice exposed to chemicals like PCBs show only very subtle effects in young adulthood. But more dramatic harm in areas like movement and learning appears when they reach old age.

Animal studies also show clear evidence that being exposed to harmful substances in the womb can harm health later on, she said. For example, rodents that encounter PCBs or dioxins before birth are more susceptible to cancer once they grow up.

Studying delayed effects in people is difficult because they generally must be followed for a long time. Research with lead is easier because scientists can measure the amount that has accumulated in the shinbone over decades and get a read on how much lead a person has been exposed to in the past.

   1 2   


Top World News  
Today's Top News  
Most Commented/Read Stories in 48 Hours
主站蜘蛛池模板: 国产精品亚洲精品爽爽 | 一级女毛片 | 欧美一区二区高清 | 国产精品亚洲一区二区三区 | 中文字幕在线播 | 亚洲天堂国产精品 | 欧美日韩在线播放一区二区三区 | 国产一区二区久久精品 | 窝窝午夜看片七次郎青草视频 | 国产欧美成人xxx视频 | 国产精品亚洲一区二区三区在线观看 | 亚洲成在人 | 乱子伦xxxx | 免费aa在线观看 男人的天堂 | 99成人国产精品视频 | 日本一区二区三区在线 视频观看免费 | 成人观看网站a | 欧美手机在线视频 | 欧美高清色视频在线播放 | 亚洲精品在线播放 | 免费国产成人高清在线观看不卡 | 久久99视频 | 97在线免费 | 亚洲天堂网在线观看 | 精品国产区 | 久久亚洲在线 | 久草在线新视觉 | 亚州人成网在线播放 | 老色99久久九九精品尤物 | a级高清观看视频在线看 | 免费国产成人高清在线观看视频 | 精品96在线观看影院 | 欧美一级片毛片 | 色樱桃影院亚洲精品影院 | 亚洲一二区 | 99久久99久久久精品久久 | 一区二区三区视频网站 | 久久99精品一级毛片 | 亚洲好视频 | 精品国产高清不卡毛片 | 欧美中文字幕一区二区三区 |