Microplastics have been identified as one of the four major emerging global pollutants, with its associated health risks becoming a forefront scientific issue in the fields of public health and ecological safety. Large amounts of microplastics have been detected in various environmental media, food products, and daily-use commodities which are in frequent contact with humans. Three primary pathways of human exposure to microplastics are inhalation, ingestion, and dermal contact. Current available studies have revealed that microplastics with diverse morphologies and dimensions have been identified in many human biological samples, including blood, liver, and placenta by spectroscopic and mass spectrometric techniques. However, the potential implications of microplastics on human health remain largely undefined. This review summarized and compared the exposure levels, size distributions, morphological characteristics, and chemical compositions of microplastics in different human tissues and organs. It also summarized current common analytical techniques for detecting microplastics in human biological samples, and analyzed the potential adverse effects of microplastic deposition on human tissues and organs. Finally, the limitations of current research were discussed, and a prospective outlook was provided on how to scientifically and effectively conduct investigation of microplastics in human populations.

Objectlve To examine the metaphase Ⅱ spindle and chromosome configurations of human oocytes cultured for different times after thawing.MethodsUsing slow-cooling and raid-thawing protocol combined with 0.3 mol/L sucrose and 1.5 mol/L 1,2-propanedio 1(1,2-PROH)to cryoprotect human mature oocytes(n=102),the 64 survival oocytes without abnormal zona pellucida and cytoskeletal were randomly assigned to three groups after thawing:group A:culture 1 hour(n=20),group B:culture 3 hour(n=22),group C:culture 5 hours(n=22),the fresh oocytes served as control group(n=18).Immunocytochefifical staining and fluorescence microscopy were used to assess the morphology of the metaphase Ⅱ spindle and chromosome.Results(1)The normal spindle rates of groups A,B and C were 10％(2/20),46％(10/22)and 41％(9/22)respectively,significantly decreased compared with control group (83％,15/18;P＜0.05).The rates of absent spindle in group A(45％,9/20)was significantly higher than control group(6％,1/18;P＜0.01).Also,the rates of absent spindle in group A was higher than groups B (14％,3/20)and C(14％,3/20;P＜0.05).However,no significant differences were observed in groups B and C(P＞0.05).(2)A significant increase in abnormal chromosome rate was observed in group A(30％,6/20)compared to groups B(68％,15/22),C(64％,14/22)and control group(78％,14/18;P＜0.05).No differences in chromosome morphology were observed in groups B,C and control group(P＞0.05).Conclusions The cryoprotectant protocol leads to a deleterious effect on the organization of the meiotic spindle and chromosome at MⅡ stage.The 3-5 hours post-thawing incubation could permit restoration of the meiotic spindles and chromosome.