Cocuzza Marcello, Esteves Sandro C
Department of Urology, University of São Paulo (USP), Rua Dr. Enéas de Carvalho Aguiar 255, 7o. Andar, Sala 710F, 05403-000 São Paulo, SP, Brazil.
ANDROFERT, Andrology and Human Reproduction Clinic, Referral Center for Male Reproduction, Avenue Dr. Heitor Penteado 1464, 13075-460 Campinas, SP, Brazil.
ScientificWorldJournal. 2014 Feb 2;2014:365691. doi: 10.1155/2014/365691. eCollection 2014.
We systematically examined the evidence of declining sperm counts and the hypothesis that an increased exposure to environmental pollutants is responsible for such decline. Search engines, including PUBMED, MEDLINE, EMBASE, BIOSIS, and Cochrane library, were used to identify epidemiologic studies published from 1985 to 2013. We concluded that there is no enough evidence to confirm a worldwide decline in sperm counts. Also, there seems to be no scientific truth of a causative role for endocrine disruptors in the temporal decline of sperm production. Such assumptions are based on few meta-analyses and retrospective studies, while other well-conducted researches could not confirm these findings. We acknowledge that difficult-to-control confounding factors in the highly variable nature of semen, selection criteria, and comparability of populations from different time periods in secular-trend studies, the quality of laboratory methods for counting sperm, and apparently geographic variations in semen quality are the main issues that complicate the interpretation of the available evidence. Owing to the importance of this subject and the uncertainties still prevailing, there is a need not only for continuing monitoring of semen quality, reproductive hormones, and xenobiotics, but also for a better definition of fecundity.
我们系统地研究了精子数量下降的证据，以及环境污染物暴露增加导致这种下降的假说。利用包括PUBMED、MEDLINE、EMBASE、BIOSIS和Cochrane图书馆在内的搜索引擎，识别1985年至2013年发表的流行病学研究。我们得出结论，没有足够的证据证实全球范围内精子数量的下降。此外，内分泌干扰物在精子生成的时间性下降中起因果作用这一说法似乎也没有科学依据。此类假设基于少数荟萃分析和回顾性研究，而其他精心开展的研究无法证实这些发现。我们认识到，在长期趋势研究中，精液高度可变的性质、选择标准以及不同时期人群的可比性、精子计数实验室方法的质量，以及精液质量明显的地理差异等难以控制的混杂因素，是使现有证据解释复杂化的主要问题。鉴于该主题的重要性以及仍然存在的不确定性，不仅需要持续监测精液质量、生殖激素和外源性物质，还需要更好地定义生育力。
