男性暴露在砷环境下或影响精子质量
近日，中国科学院城市环境研究所暴露科学与健康效应研究组发现：普通男性人群暴露于日常生活环境中的砷，其精子质量也可能会受到影响。相关研究成果日前发表于《环境健康》（Environmental Health）。
砷是一种非金属元素，是灰白色、有金属光泽的结晶块，质脆且有毒。该课题组研究员申河清告诉《中国科学报》记者，之前对于砷的毒性研究，主要集中于其致癌性等方面。最新的研究则显示，该物质还具有内分泌干扰作用，如大鼠或小鼠经过砷刺激会产生内分泌功能障碍，进而导致雄性不育。相关流行病学调查也表明，慢性砷暴露可能会影响男性勃起功能，但目前尚不清楚砷对于男性生殖系统其他方面的影响。
为此，通过与临床医生合作，该课题组收集了100名育龄男性不育症患者的尿样和精子样品。对尿样5种形态砷的含量进行了检测，并检测了患者的精子质量（精液量、精子活率、精子浓度及精子形态等）。随后用统计学分析研究了砷暴露和男性精子质量的相关性以及吸烟、饮酒等习惯对于人体内砷代谢的影响。
结果显示，砷的代谢物二甲基砷（DMA）与精子浓度呈负相关，表明环境剂量下的砷暴露，也就是非刻意地接触砷，也可能会导致男性精子浓度下降。另外，吸烟人群与非吸烟人群的尿样中一甲基砷（MMA）的含量存在显著性差异，表明吸烟可能会加速砷的代谢过程。
申河清表示，该研究只是初步结果，下一步他们将通过扩大人群的样本量等手段来进一步证实以上结论。
据悉，该研究得到中科院“百人计划”项目环境污染物的人群暴露与健康、国家自然科学基金、科技部国际合作项目城市群环境复合污染与生态健康研究以及中科院重要方向项目城市环境质量与健康效应创新团队的资助。
Environmental exposure to arsenic may reduce human semen quality: associations derived from a Chinese cross-sectional study
Weipan Xu, Huaqiong Bao, Feng Liu, Liangpo Liu, Yong-Guan Zhu, Jianwen She, Sijun Dong, Min Cai, Lianbing Li, Chuanhai Li and Heqing Shen
Background Recent observations in in vitro and in vivo models suggest that arsenic (As) is an endocrine disruptor at environmentally-relevant levels. When exposed to As, male rats and mice show steroidogenic dysfunction that can lead to infertility. However, the possible effects of As on human male semen quality remain obscure.
Methods We monitored the profile of As species in the urine of a reproductive-age human cohort and assessed its association with semen quality. Men (n = 96) were recruited in an infertility clinic from July 2009 to August 2010 in the Affiliated Hospital of Chongqing Institute for Population and Family Planning. Five urinary As species were analyzed by high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Clinical information on the semen volume, sperm concentration and motility was employed to catalogue and evaluate semen quality according to WHO guidelines. As species concentrations in addition to other continuous variables were dichotomized by the medians and modelled as categorical variables in order to explore using the binary logistic regression possible associations between As exposure and semen quality.
Results Urinary concentrations (geometric mean ± SD, μg g-1 creatinine) of different As species were 7.49 (±24.8) for AsB, 20.9 (±13.7) for DMA, 2.77 (±3.33) for MMA, and 4.03 (±3.67) for Asi (AsiIII and AsiV). DMA concentrations above the median were significantly associated with below-reference sperm concentrations (P =0.02) after adjusting for age, body mass index (BMI), abstinence, smoking and drinking habits. In addition, smoking was positively associated with MMA.
Conclusion Reduced parameters in human semen quality are positively associated with As exposure in a reproductive-age Chinese cohort.
