正在迅速消失的精子

​​​​​​Sperm Count Dropping in Western World

西方世界的精子数量不断下降

The trend has occurred over 40 years
这一趋势已经出现了40多年

​LONDON (Reuters) – Sperm counts in men from America, Europe, Australia and New Zealand have dropped by more than 50 percent in less than 40 years, researchers said on Tuesday.

伦敦（路透社）- 周二，研究者声称，美国，欧洲，澳大利亚和新西兰的男性精子数量在过去不到40年中已经下降了50％以上。

They also said the rate of decline is not slowing. Both findings — in a meta-analysis bringing together various studies — pointed to a potential decline in male health and fertility.

他们还说这个下降速率迄今并未放缓。一项综合了不同研究的荟萃分析得出以上两个发现，表明了男性在健康和生育能力方面的潜在衰退。

“This study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of the sharp ongoing drop in sperm count,” said Hagai Levine, who co-led the work at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Jerusalem.

“这项研究为全世界研究者和医疗主管机构敲了警钟，提醒他们探究精子数量持续急剧下降的原因”，Hagai Levine说道，他在耶路撒冷Hebrew大学Hadassah Braun公共健康和社区医疗学院共同领导了本次研究。

The analysis did not explore reasons for the decline, but researchers said falling sperm counts have previously been linked to various factors such as exposure to certain chemicals and pesticides, smoking, stress and obesity.

这项分析没有探索衰退的原因，但是研究者们提到精子数量的下降曾与许多因素有关，包括接触化学品和农药，吸烟，压力和肥胖。

This suggests measures of sperm quality may reflect the impact of modern living on male health and act as a “canary in the coal mine” signaling broader health risks, they said.

这暗示了精子质量的度量可能反映出现代生活方式对于男性健康的影响，以及作为其他健康风险的前兆。研究者这样说道。

Studies have reported declines in sperm count since the early 1990s, but many of those have been questioned because they did not account for potentially major confounding factors such as age, sexual activity and the types of men involved.

在1990年代早期就有研究报告了精子数量的下降，但是大多数都因没有计入诸如年龄，性行为和被统计男性的类型这样的潜在混淆性因素而被质疑。

Working with a team of researchers in the United States, Brazil, Denmark, Israel and Spain, Levine screened and brought together the findings of 185 sperm count studies from 1973 to 2011 and then conducted a so-called meta-regression analysis.

Levine和来自美国，巴西，丹麦，以色列和西班牙的研究者筛选了从1973年到2011年的185项精子数量研究，进行所谓的元回归分析。

The results, published in the journal Human Reproduction Update, showed a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm count among North American, European, Australian and New Zealand men. The former measures the concentration of semen in a man’s ejaculation, while the latter is semen concentration multiplied by volume.

研究结果发表在《人类生育力调查》（Human Reproduction Update）期刊上，显示北美，欧洲，澳大利亚和新西兰男性精子浓度下降了52.4％，而精子总数下降了59.3％。前者测量的是男性一次射精量的精子浓度，而后者则是精子浓度乘以体积。

In contrast, no significant decline was seen in South America, Asia and Africa. The researchers noted, however, that far fewer studies have been conducted in these regions.

与此相反的是，南美洲，亚洲和非洲的数据并没有出现明显滑落。然而研究者们也注意到这些区域的相关研究数量相对少得多。

Experts asked to comment on the work said it was a comprehensive and well-conducted analysis and did a good job of adjusting for confounders that could have skewed its findings.

应邀对此研究发表评论的专家表示，这是一个全面且优秀的分析，而且在控制混淆因素方面做得很好。

Daniel Brison, a specialist in embryology and stem cell biology at Britain’s Manchester University, said the findings had “major implications not just for fertility but for male health and wider public health”.

英国曼彻斯特大学的胚胎学和干细胞生物学专家Daniel Brison说，这些发现“不仅在生育能力，而且在男性健康和更广泛的公共卫生领域有重要意义。”

“An unanswered question is whether the impact of whatever is causing declining sperm counts will be seen in future generations of children via epigenetic (gene modifications) or other mechanisms operating in sperm,” he said in an emailed comment.

“一个悬而未决的问题是，不管是何种原因造成了精子数量的下降，其影响是否会通过表观遗传（基因改变）或精子内部的其它某种机制作用于未来的几代孩子，从而被观察到。”Daniel Brison在一份通过电邮发来的评论中说到。

Richard Sharpe at Edinburgh University added: “Given that we still do not know what lifestyle, dietary or chemical exposures might have caused this decrease, research efforts to identify (them) need to be redoubled and to be non-presumptive as to cause.”

而来自Edinburgh大学的Richard Sharpe补充说：“既然我们仍然不知道究竟是生活方式，饮食还是化学暴露造成了这个衰退，那么寻找原因的研究需要加强，并且对原因不预设假定”。