Human Exposure to Endocrine Disrupters and Semen Quality

Abstract

Reproductive pathology in the male represents about 20% of infertility cases. Male infertility may be attributed to a number of causes, including genetic and congenital abnormalities, infection, multisystemic diseases, varicocele, and others; however, a significant number of cases are idiopathic. Global declines in semen quality were suggested to be associated with enhanced exposure to environmental chemicals that act as endocrine disrupters as a result of our increased use of pesticides, plastics, and other anthropogenic materials. A significant body of toxicology data based upon laboratory and wildlife animals studies suggests that exposure to certain endocrine disrupters is associated with reproductive toxicity, including (1) abnormalities of the male reproductive tract (cryptorchidism, hypospadias), (2) reduced semen quality, and (3) impaired fertility in the adult. There is, however, a relative paucity of studies designed to measure exposure to endocrine disrupters on semen quality parameters (sperm concentration, motility, morphology). An overview of the human semen quality literature is presented that examines the role of endocrine disrupters including organochlorines (OC), dioxins, phthalates, phytoestrogens, and chemical mixtures (pesticides and tobacco smoke).

Teasing out the role of aromatase in the healthy and diseased testis

“…However, when aromatase exceeds normal levels, as in the case of some patients with PJS, aromatase turns into a potent proliferative agent and aids in the development and progression of Sertoli cell tumors. Whether or not too much aromatase has an influence on fertility in PJS patients remains unknown, however given the recorded effects of exogenous estrogens on sperm parameters, 7,51 it is likely their fertilizing capacity would be compromised. Suffice to say, deciphering the specific roles of aromatase and estrogens and their underlying cellular and molecular mechanisms in the healthy testis, would be extremely valuable in advancing our understanding of how these mechanisms become compromised in the diseased testis, to ultimately reveal potential therapies for aromatase driven testicular disease.…”

“…50 Moreover, clinical studies suggest that excess estrogens can also have detrimental effects on sperm quality parameters, including sperm concentration, motility and morphology, as evidenced by the exposure to bisphenol A (BPA), an estrogen-like chemical found in plastics 7 and other endocrine disruptors (reviewed in ref. 51). It is important to note, endocrine disruptors may impact sperm quality via non-estrogenic actions.…”

Phytoestrogen Content of Foods of Animal Origin: Dairy Products, Eggs, Meat, Fish, and Seafood

“…Their possible effects have been implicated in the etiology of hormone-dependent cancers (2)(3)(4)(5), cardiovascular disease (4,6), osteoporosis (4, 7) menopausal symptoms (4,8), male infertility (9), obesity, and type-2 diabetes (10). Evidence that these compounds are biologically active even at low levels in humans comes from interactions between phytoestrogens and gene variants of the estrogen receptor (ESR1 and NR1I2) (11,12), sex-hormone binding globulin (SHBG) (13), and probably aromatase (CYP19) (14).…”

Reproductive Toxicity of Metals in Men

“…Several studies established an increasing incidence of various abnormalities of the human reproductive system, including a decreased sperm count and an increased incidence of testicular and prostate cancer (2-7), but also great differences among countries and different locations within a country. This has triggered an increasing interest in the possible causes of these abnormalities and factors that contribute to this deterioration and the geographical differences, including environmental and lifestyle factors (8)(9)(10)(11)(12)(13).…”