VOA标准英语2013--Common Chemical May Damage Teeth

 

Common Chemical May Damage Teeth

 

A chemical compound that’s been linked to a number of health problems in animal studies may also damage tooth enamel¹ in humans. BPA is found in many resins² and plastics that people use everyday, such as water and baby bottles and food containers.

BPA, or Bisphenol A, can leach³ from the plastic and into food, water or snacks – and from there into us. A U.S. Centers for Disease Control survey in 2003/2004 found detectable⁴ levels of the chemical in 93 percent of more than 2,500 urine samples tested. It can also contaminate the environment, with countless⁵ plastic bottles littering many landscapes and waterways.

The NIH, the National Institutes of Health, says, “Animal studies indicate BPA may cause adverse⁶ effects, such as obesity⁷, behavioral changes, diabetes⁸, early onset⁹ puberty, asthma¹⁰, cardiovascular diseases, reproductive disorders¹¹ and development of prostate, breast and uterine cancer.”

It adds there is “reason for concern, especially for parents, because some animal studies report effects in fetuses¹² and newborns exposed to BPA.” There’s ongoing¹³ research on whether BPA does indeed affect people the way it can animals.

French researcher Sylvie Babajko is the lead author of an article on BPA appearing in the American Journal of Pathology. She said that BPA is an endocrine disruptor.

“An endocrine disruptor is a substance that disturbs the endocrine system. That means hormones¹⁴ in humans, as well as in progeny¹⁵.”

The endocrine system is a series of glands¹⁶, such as the thyroid pituitary and adrenal, which release hormones affecting sexual development, growth and metabolism¹⁷. And these hormones go everywhere in the body. Some chemicals can make their levels go up and down.

Babajko and fellow researchers are now trying to confirm that BPA can damage tooth enamel. She said they were notified about the possible link by others studying the effects of endocrine disruptors on lab animals’ reproductive systems.

“They found that the rats exposed to low doses of endocrine disruptors presented white spots on incisors. They called us and we studied these white spots and found that there was an enamel hypomineralization due to endocrine disruptors exposure,” she said.

In other words, BPA, circulating in the body, can adversely¹⁸ affect cells that produce tooth enamel, making it fragile or brittle¹⁹. The question is: Are those white marks now showing up on human teeth as well?

“It is probably a problem,” she said, “because things and food contain BPA and we are probably all exposed to BPA. And it has been shown, at least with experiments on animals, that BPA can cause a lot of defects and teeth are one additional target of BPA.”

Analysis of the rats’ teeth show similar characteristics found in about 18 percent of children between the ages six and eight. These kids may have teeth that are extra sensitive to pain or more liable to get cavities. It’s believed humans are most sensitive to BPA in the first years of life. Further study is needed, but those white streaks²⁰ may be an indication of early exposure to the chemical.

Since BPA can disrupt estrogen levels in animals, there’s concern that could affect men’s reproductive health. Men do produce estrogen, but usually in much lower levels than women. However, Babajko said that’s not been confirmed and is difficult to prove.

“It is possible, but not demonstrated in humans, of course, because we are all subjected to many endocrine disruptors. And it is difficult to be sure that BPA is the only one that is responsible for the reproductive defects. It is difficult to know precisely²¹ if BPA is the only one or if it is acting²² in combination with other molecules,” she said.

Concerns about BPA have led to the production of BPA-free plastic products. Europe banned baby bottles containing the chemical in January 2011. The U.S. took similar action in July of last year. While the Food and Drug Administration began voicing concerns about BPA in 2010, it has not officially reversed its 2008 decision declaring BPA safe.

France intends to extend the BPA ban to all food containers in July 2015.

1 enamel   

n.珐琅，搪瓷，瓷釉；(牙齿的)珐琅质

参考例句：

• I chipped the enamel on my front tooth when I fell over.我跌倒时门牙的珐琅质碰碎了。
• He collected coloured enamel bowls from Yugoslavia.他藏有来自南斯拉夫的彩色搪瓷碗。

2 resins   

n.树脂，松香( resin的名词复数 )；合成树脂v.树脂，松香( resin的第三人称单数 )；合成树脂

参考例句：

• The resins were used to turn out millions of helmet liners. 用这类树脂生产了成百万只钢盔内衬。 来自辞典例句
• Cheapness is one of the main attractions of polyester resins. 廉价是聚酯树脂受到欢迎的主要原因之一。 来自辞典例句

3 leach   

v.分离，过滤掉；n.过滤；过滤器

参考例句：

• Liquid water can leach soluble materials from the interface.液态水能够从界面溶解出可溶性物质。
• They believe that the humic materials are leached from decaying plant materials.他们认为腐植物料是从腐烂的植物体浸沥而来。

4 detectable   

adj.可发觉的；可查明的

参考例句：

• The noise is barely detectable by the human ear.人的耳朵几乎是察觉不到这种噪音的。
• The inflection point at this PH is barely detectable.在此PH值下，拐点不易发现。

5 countless   

adj.无数的，多得不计其数的

参考例句：

• In the war countless innocent people lost their lives.在这场战争中无数无辜的人丧失了性命。
• I've told you countless times.我已经告诉你无数遍了。

6 adverse   

adj.不利的；有害的；敌对的，不友好的

参考例句：

• He is adverse to going abroad.他反对出国。
• The improper use of medicine could lead to severe adverse reactions.用药不当会产生严重的不良反应。

7 obesity   

n.肥胖，肥大

参考例句：

• One effect of overeating may be obesity.吃得过多能导致肥胖。
• Sugar and fat can more easily lead to obesity than some other foods.糖和脂肪比其他食物更容易导致肥胖。

8 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

9 onset   

n.进攻，袭击，开始，突然开始

参考例句：

• The drug must be taken from the onset of the infection.这种药必须在感染的最初期就开始服用。
• Our troops withstood the onset of the enemy.我们的部队抵挡住了敌人的进攻。

10 asthma   

n.气喘病，哮喘病

参考例句：

• I think he's having an asthma attack.我想他现在是哮喘病发作了。
• Its presence in allergic asthma is well known.它在过敏性气喘中的存在是大家很熟悉的。

11 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》

12 fetuses   

n.胎，胎儿( fetus的名词复数 )

参考例句：

• DNA was extracted from fetuses at mid-gestation, about 10 days past conception. DNA从受孕大约10天后的中期妊娠胚胎中提取。 来自互联网
• Brucellosis is a disease that causes fetuses to abort in cattle. 普鲁士菌病是一种可以导致牲畜胎儿夭折的疾病。 来自互联网

13 ongoing   

adj.进行中的，前进的

参考例句：

• The problem is ongoing.这个问题尚未解决。
• The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。

14 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。

15 progeny   

n.后代，子孙；结果

参考例句：

• His numerous progeny are scattered all over the country.他为数众多的后代散布在全国各地。
• He was surrounded by his numerous progeny.众多的子孙簇拥着他。

16 glands   

n.腺( gland的名词复数 )

参考例句：

• a snake's poison glands 蛇的毒腺
• the sebaceous glands in the skin 皮脂腺

17 metabolism   

n.新陈代谢

参考例句：

• After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食，卡罗尔的新陈代谢完全紊乱了。
• All living matter undergoes a process of metabolism.生物都有新陈代谢。

18 adversely   

ad.有害地

参考例句：

• We commented adversely upon the imbecility of that message of telegraphic style. 我们对着这条电报式的愚蠢的留言发泄了一通不满。
• Widely fluctuating exchange rates may adversely affect international trade. 浮动幅度很大的汇率可能会对国际贸易产生有害的影响。

19 brittle   

adj.易碎的；脆弱的；冷淡的；(声音)尖利的

参考例句：

• The pond was covered in a brittle layer of ice.池塘覆盖了一层易碎的冰。
• She gave a brittle laugh.她冷淡地笑了笑。

20 streaks   

n.（与周围有所不同的）条纹( streak的名词复数 )；（通常指不好的）特征（倾向）；（不断经历成功或失败的）一段时期v.快速移动( streak的第三人称单数 )；使布满条纹

参考例句：

• streaks of grey in her hair 她头上的绺绺白发
• Bacon has streaks of fat and streaks of lean. 咸肉中有几层肥的和几层瘦的。 来自《现代英汉综合大词典》

21 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

22 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。