六间房直播大厅3090:环境化学成分可能导致夫妻不孕

最新的研究成果已经提供证据表明环境中的化学品干扰内分泌，从而造成无法怀孕。

By Lindsey Konkel and Environmental Health News  | October 12, 2011 | 1 

作者：环境健康新闻/Lindsey Konkel/2011年10月12日

Kira Testin knew that something was wrong before she and her husband ever saw the fertility specialist. “We had been trying for a year to get pregnant,” recalls Testin, who was 27 at the time. “We weren’t na?ve, but it still was devastating to hear that we would be unable to conceive naturally.”

在Kira Testin和丈夫见到生殖专家以前，她就觉得有些不对劲。“为了怀孕，我们努力了一年”Testin回忆道，她当时27岁。“我们不是并不幼稚，但是一听到可能无法自然怀孕时，还是觉得天像是要塌下来一样”

For the Testins, in vitro fertilization (IVF) – when a woman’s eggs are retrieved, fertilized and grown to embryo-stage in a petri dish, then implanted back in her uterus – was their only chance at pregnancy.

对Testins夫妻来说,他们怀孕的唯一机会就是体外受精——从女性子宫内取出卵，在培养皿受精，长到胚胎阶段后再重新植入她的子宫。

And their chances were low at that. More often than not, IVF takes repeated, costly and heart-wrenching attempts.

他们那样做的成功率很低。试管婴儿往往需要经过反复的、昂贵的而且是心痛的尝试。

Now scientists have found another potential obstacle for would-be parents. New research has turned up evidence of a link between endocrine-disrupting chemicals in the environment and poor IVF outcomes.

现在科学家们发现了导致准父母们无法怀孕的另外一个可能。新的研究结果已经证明环境中扰乱内分泌的化学品和不良的体外受精是有关系的。

Some chemicals in food and consumer products may disrupt a woman’s estrogen, which interferes with her ability to get pregnant. Higher blood levels of pollutants such as bisphenol A (BPA), polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) have been found in mothers with failed IVF attempts, according to a handful of recent studies.

食品和消费品中有一些化学成分可能扰乱女性的雌性激素，并干扰了她怀孕的能力。根据最近的许多研究报告表明，在体外受精失败的母亲里发现了较高的血浓度污染物，例如：血双酚A（BPA），多氯联苯（PCBs）和六氯苯（HCB）。

The Testins, from a small town near Milwaukee, Wis., are among an estimated 9 million U.S. couples – one out of every eight – who are infertile, according to the American Fertility Association.

根据美国生育协会统计，Testins夫妻来自威斯康星州的一个叫密尔沃基的小镇，他们是美国九百万对夫妻中的一对——其中每八对夫妻就有一对夫妻不能怀孕。

Causes of infertility are numerous, ranging from hormonal imbalances, to defects of the uterus, to misshapen sperm, low sperm count or low sperm motility in men.

导致不孕的原因有很多，从女性方面的原因，如：荷尔蒙失调、子宫问题；到男性方面的原因，如：精子畸形、数量少或者是不活跃。

Some scientists now theorize that endocrine-disrupting chemicals in the environment also can reduce fertility. Endocrine disruptors are a class of more than 1,200 chemicals that can mimic or block hormones, including estrogen, the primary female sex hormone involved in pregnancy.

现在一些科学家用系统的理论说明，环境中存在的化学成分扰乱内分泌，从而降低怀孕的机率。扰乱内分泌的化学成分大概有1200类，它们可以复制或者阻碍荷尔蒙，包括雌性激素，它是女性致孕的主要激素。

“These chemicals may affect the way hormones regulate many aspects of our bodies, potentially even the ability to get pregnant,” said Laura Vandenberg, a reproductive scientist at Tufts University.

“这些化学成分可以影响荷尔蒙调整身体的多种方面的方法，尤其是怀孕的能力，”Laura Vandenberg说，她是塔夫茨大学的生殖科学家。

In one study of 765 women who underwent a total of 827 IVF cycles at Boston area clinics, researchers found an association between blood PCB concentrations and the rate at which embryos successfully attached or implanted to the uterine wall. The study was published in July in the journal Environmental Health Perspectives.

在对波士顿地区诊所765名女性的827个体外受精周期的学习中，研究人员发现血多氯联苯混合浓度和胚胎成功的附着或者植入子宫壁比率的关联。该研究成果已经于7月在环境健康展望类期刊中出版。

The odds of failed implantation doubled among women with the highest blood level of PCB-153 (the form of the chemical, on average, present in the highest concentration) compared to women with the lowest levels. Women with the highest levels were also 41 percent less likely to give birth to a live infant than women with the lowest blood levels.

PCB-153血浓度（一般指高浓度中存在的化学成分的形式）较高的女性胚胎植入的失败机率是浓度较低者的两倍。浓度较高的女性带来一个健康宝宝的比率比较低者少41%。

Perhaps the most surprising finding – even low levels of PCBs, the same as those found in the general U.S. population, were associated with adverse early pregnancy outcomes in IVF, said Dr. Russ Hauser, professor of environmental and occupational epidemiology at Harvard School of Public Health and co-author of the study.

也许最令人震惊的发现是—即使是含量不多的多氯联苯，和在美国多数人口中发现的一样，和试管婴儿的早期不良妊娠有关，Russ Hauser博士指出，他是哈佛大学公共卫生系的环境和职业流行病学教授，也是本次研究的作者之一。

The same researchers also reported a link between another long-banned pollutant, hexachlorobenzene (HCB), and implantation failure, in a paper published online in Environmental Health Perspectives in August.

研究人员还指出另外一个被长期禁止的污染物—六氯苯可能导致胚胎植入的失败，这一份文件于八月份在环境健康展望的网站上出版。

PCBs and HCB are both long-lived pollutants that accumulate in food chains and take decades to break down. Animal studies have shown that both types of compounds can mimic or block hormones. Hauser said there is evidence that HCB suppresses a hormone called luteal progesterone, which is important for egg implantation.

多氯联苯和六氯苯都是长期存在，并积累在食物链中的污染物，取缔这些物质需要长达数十年的时间。在对动物的实验研究结果表明，这两种成分的化合物可以模仿或阻碍荷尔蒙。Hauser说，有证据表明，六氯苯对一种叫黄体酮的激素有抑制作用，这种激素对卵的植入有很重要的作用。

PCBs – a class of industrial chemicals used mostly as insulating fluids for electrical equipment – have been banned in the United States as well as in most other developed countries for more than 30 years. However, because of their extensive use and long half-life, human exposure remains widespread. In fact, studies have shown that more than 95 percent of Americans older than 12 still have detectable levels of PCBs in their blood. Humans are exposed mainly through food.

多氯联苯——电气设备中经常被用于绝缘液体的一种工业化学品—已经被美国及大多数发达国家禁止使用超过30年。然而，因为其被广泛使用及教长的半衰期，人类经常与其接触。事实上，研究表明超过95%的12岁以上的美国人血液中仍然检测出含有多氯联苯。人类主要是通过食物接触到这些化学成分。