VOA标准英语2009年-Lead Poisoning Study Shows Damage Grea

Brain scans of men and women exposed to lead during childhood shows residual¹ damage less severe in females

Rose Hoban | Washington, DC 18 December 2009

Ever since the ancient Roman era, people have known that lead, a heavy metal long used in paints, ceramics² and construction, is very bad for you.  Acute lead exposure, particularly in children, leads to neurological and behavioral problems. Nonetheless, young people continue to be exposed to lead, and new research shows the serious long-term effects of this childhood lead exposure.

In the past, many common household items contained lead, everything from water pipes, to drinking vessels³, to eating utensils⁴. Most people had lead in their blood, but it was believed that some amount of lead was acceptable. Over the past few decades, however, scientists have determined⁵ that even trace amounts of lead in children's bodies leads to long-term neurological and behavioral problems.

Study followed toddlers into adulthood⁶

Kim Cecil, from the University of Cincinnati is one of those scientists.  She was part of a team of researchers who took annual blood samples from several hundred lead-exposed children for more than 20 years. The children lived in a Cincinnati neighborhood located near a busy highway.

"The neighborhood that [these kids] were recruited from is adjacent to an interstate.  So their playgrounds are contaminated, outside the homes," Cecil says.  Inside the older rental⁷ housing where many live, she adds, "the lead would chip off and eventually become dust that settles on the floors in the windowsills.  And then as they become toddlers as they started crawling around, they get that lead dust on their hands from the windowsills in the floors, they put it in their mouth."

Lead poisoning damages thinking and concentration

Now these toddlers are young adults in their 20s, and Cecil and her colleagues brought them into the hospital for brain scans.  While they were in the brain-scanning machine, they were asked to do tasks that required concentration and attention. The researchers were able to see which parts of their brains were most active.

"When we plotted the circuits in the brain against their childhood lead blood lead levels, we found that those with a higher blood lead measurement had less activity in the part of the brain normally left to do the attention tasks," Cecil notes.

These problems existed years after the lead exposure, long after their blood lead levels had decreased.
   
Hormones⁸ may shield women from some damage

What Cecil found most interesting was that there were differences in the brains of the males and the females exposed to lead as children.  The male brains, especially nerve cell rich parts of the brain associated with thinking and remembering, seemed to have sustained more long term damage from high lead levels than the brains of the young women.

"We see that men have greater volume loss, the men have greater changes in their white matter," she says.

Cecil also saw that the brains of the young women did a better job of compensating⁹ for the damage.  She says this will be her next line of inquiry¹⁰ – whether female hormones, such as estrogen, somehow protect young women from the neurological damage created by exposure to lead.

Cecil presented her findings at the annual meeting of the Radiological Society of North America.
 

1 residual   

adj.复播复映追加时间；存留下来的，剩余的

参考例句：

• There are still a few residual problems with the computer program.电脑程序还有一些残留问题。
• The resulting residual chromatism is known as secondary spectrum.所得到的剩余色差叫做二次光谱。

2 ceramics   

n.制陶业；陶器

参考例句：

• an exhibition of ceramics by Picasso 毕加索陶瓷作品展
• The ceramics bore the imprint of Luca della Robbia. 陶器上印有卢卡·德拉·罗比亚的字样。

3 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》

4 utensils   

器具，用具，器皿( utensil的名词复数 )； 器物

参考例句：

• Formerly most of our household utensils were made of brass. 以前我们家庭用的器皿多数是用黄铜做的。
• Some utensils were in a state of decay when they were unearthed. 有些器皿在出土时已经残破。

5 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

6 adulthood   

n.成年，成人期

参考例句：

• Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
• Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。

7 rental   

n.租赁，出租，出租业

参考例句：

• The yearly rental of her house is 2400 yuan.她这房子年租金是2400元。
• We can organise car rental from Chicago O'Hare Airport.我们可以安排提供从芝加哥奥黑尔机场出发的租车服务。

8 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

9 compensating   

补偿，补助，修正

参考例句：

• I am able to set up compensating networks of nerve connections. 我能建立起补偿性的神经联系网。
• It is desirable that compensating cables be run in earthed conduit. 补偿导线最好在地下管道中穿过。

10 inquiry   

n.打听，询问，调查，查问

参考例句：

• Many parents have been pressing for an inquiry into the problem.许多家长迫切要求调查这个问题。
• The field of inquiry has narrowed down to five persons.调查的范围已经缩小到只剩5个人了。