Niels E. Skakkebæk

TL;DR: There has been a genuine decline in semen quality over the past 50 years, and as male fertility is to some extent correlated with sperm count the results may reflect an overall reduction in male fertility.

TL;DR: Existing evidence supporting a new concept that poor semen quality, testis cancer, undescended testis and hypospadias are symptoms of one underlying entity, the testicular dysgenesis syndrome (TDS), which may be increasingly common due to adverse environmental influences is summarized.

TL;DR: It is argued that the increasing incidence of reproductive abnormalities in the human male may be related to increased oestrogen exposure in utero, and mechanisms by which this exposure could occur are identified.

TL;DR: These observations urge further study of the onset of puberty as a possible sensitive and early marker of the interactions between environmental conditions and genetic susceptibility that can influence physiological and pathological processes.

TL;DR: The growing number of reports demonstrating that common environmental contaminants and natural factors possess estrogenic activity presents the working hypothesis that the adverse trends in male reproductive health may be, at least in part, associated with exposure to estrogenic or other hormonally active environmental chemicals during fetal and childhood development.