Evidence for decreasing quality of semen during past 50 years

In a 1981 study, 80% of the DES-exposed males qualified as infertile

1992 Study Abstract

To investigate whether semen quality has changed during the past 50 years.

Review of publications on semen quality in men without a history of infertility selected by means of Cumulated Index Medicus and Current List (1930-1965) and MEDLINE Silver Platter database (1966-August 1991).

14,947 men included in a total of 61 papers published between 1938 and 1991.

Mean sperm density and mean seminal volume.

Linear regression of data weighted by number of men in each study showed a significant decrease in mean sperm count from 113 x 10(6)/ml in 1940 to 66 x 10(6)/ml in 1990 (p < 0.0001) and in seminal volume from 3.40 ml to 2.75 ml (p = 0.027), indicating an even more pronounced decrease in sperm production than expressed by the decline in sperm density.

There has been a genuine decline in semen quality over the past 50 years. As male fertility is to some extent correlated with sperm count the results may reflect an overall reduction in male fertility. The biological significance of these changes is emphasised by a concomitant increase in the incidence of genitourinary abnormalities such as testicular cancer and possibly also cryptorchidism and hypospadias, suggesting a growing impact of factors with serious effects on male gonadal function.

Such remarkable changes in semen quality and the occurrence of genitourinary abnormalities over a relatively short period is more probably due to environmental rather than genetic factors. Some common prenatal influences could be responsible both for the decline in sperm density and for the increase in cancer of the testis, hypospadias, and cryptorchidism. Whether oestrogens or compounds with oestrogen-like activity or other environmental or endogenous factors damage testicular function remains to be determined.


  • Full text (free access) : Evidence for decreasing quality of semen during past 50 years, The International journal of risk & safety in medicine, The BMJ, bmj00091-0019, PMCID: PMC1883354, 1992 Sep 12.
  • Featured image credit freemalaysiatoday.

The Role of Parental and Grandparental Epigenetic Alterations in Familial Cancer Risk

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Some epigenetic alterations that influence cancer risk are inherited through the germline from the DES-exposed to offspring and are observed in multiple DES generations of victims

2008 Study Abstract

Epigenetic alterations of the genome such as DNA promoter methylation and chromatin remodeling play an important role in tumorigenesis. These modifications take place throughout development with subsequent events occurring later in adulthood. Recent studies, however, suggest that some epigenetic alterations that influence cancer risk are inherited through the germline from parent to child and are observed in multiple generations. Epigenetic changes may be inherited as Mendelian, non-Mendelian, or environmentally induced traits. Here, we will discuss Mendelian, non-Mendelian, and environmentally induced patterns of multigenerational epigenetic alterations as well as some possible mechanisms for how these events may be occurring.


One example of multiple generations in families showing effects of an environmental agent are daughters of mothers who were exposed to diethylstilbestrol (DES) during the first trimester.

The daughters show developmental abnormalities and an increased risk of developing a rare type of clear-cell adenocarcinoma. DES daughters also show a 2.5-fold increase in breast cancer risk after 40 years of age. To prove that this indeed is an inherited transgenerational effect, granddaughters and great granddaughters of the exposed mothers will need to show a DES phenotype. This analysis has not yet been completed.

Mouse studies have shown that the F2 generation from a DES-exposed pregnant female had strikingly similar effects as the F1 generation, including abnormal uterine development and uterine cancer. The proposed mechanism of action of DES is aberrant CpG methylation of key uterine cancer genes. The changes in CpG methylation may be stable throughout gametogenesis, providing insight into the transgenerational effects of DES.

Sources and more information
  • Full study (free access) : The Role of Parental and Grandparental Epigenetic Alterations in Familial Cancer Risk, Perspectives in Cancer Research, NCBI PubMed PMC4423451, 2008 Nov.
  • Epigenetics featured image credit NestleNutritionInstitute.

DES and Nuclear Receptors

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Nuclear receptors and endocrine disruptors in fetal and neonatal testes: a gapped landscape

2014 Study Abstract

During the last decades, many studies reported that male reproductive disorders are increasing among humans. It is currently acknowledged that these abnormalities can result from fetal exposure to environmental chemicals that are progressively becoming more concentrated and widespread in our environment.

Among the chemicals present in the environment (air, water, food, and many consumer products), several can act as endocrine disrupting compounds (EDCs), thus interfering with the endocrine system. Phthalates, bisphenol A (BPA), and diethylstilbestrol (DES) have been largely incriminated, particularly during the fetal and neonatal period, due to their estrogenic and/or anti-androgenic properties. Indeed, many epidemiological and experimental studies have highlighted their deleterious impact on fetal and neonatal testis development.

As EDCs can affect many different genomic and non-genomic pathways, the mechanisms underlying the adverse effects of EDC exposure are difficult to elucidate. Using literature data and results from our laboratory, in the present review, we discuss the role of classical nuclear receptors (genomic pathway) in the fetal and neonatal testis response to EDC exposure, particularly to phthalates, BPA, and DES.

Among the nuclear receptors, we focused on some of the most likely candidates, such as peroxisome-proliferator activated receptor (PPAR), androgen receptor (AR), estrogen receptors (ERα and β), liver X receptors (LXR), and small heterodimer partner (SHP).

First, we describe the expression and potential functions (based on data from studies using receptor agonists and mouse knockout models) of these nuclear receptors in the developing testis. Then, for each EDC studied, we summarize the main evidences indicating that the reprotoxic effect of each EDC under study is mediated through a specific nuclear receptor(s). We also point-out the involvement of other receptors and nuclear receptor-independent pathways.

DES and Nuclear Receptors

DES and ERs

Diethylstilbestrol exerts its anti-androgen effects mainly through classical ER signaling, particularly via ERα. In an organ culture system of mouse fetal testes, the reduction in testosterone production observed following DES exposure in wild type testes does not occur in ERα-deficient mice. Similarly, INSL3 gene expression and testis descent are not affected by in utero exposure to DES in ERαKO mice, whereas ERβ invalidation does not protect from DES effect.

DES and ARs and PPARs

To our knowledge, there is no data showing the direct involvement of AR or PPARs in DES testis effects. However, an indirect action of DES cannot be excluded in relation with the reduction of testosterone secretion observed in vitro in rodent testes incubated with DES.

DES and LXRs

Some studies have linked estrogens and LXRs in breast and in mouse adipose tissue. In the testis, LXRs could partially interfere with DES effects. Daily treatment with DES from day 1 to day 5 after birth induces an important increase in cell apoptosis in LXR-deficient mice at day 10 compared to wild type animals. Likewise, LXRs modify the neonatal effects of DES on the expression of Leydig and Sertoli cell markers. However, whether LXRs have a protective effect against or contribute to DES effects remains unclear.


Treatment with DES promotes SHP mRNA accumulation in the testes of wild type SHP male mice (NR0B2+/+) at postnatal day 10 (P10). Moreover, neonatal DES exposure induces apoptosis, in P10 NR0B2+/+ mice, without any effect on cell proliferation. Conversely, DES does not have any effect on apoptosis in the testes of NR0B2L−/L− males, suggesting that SHP inactivation protects against DES effects. This seems to be germ cell-specific because DES treatment drastically decreases intratesticular testosterone in both NR0B2L−/L− and NR0B2L−/L− males. Interestingly, SHP, mediating the deleterious effects of DES in mice, is not detectable in human fetal testes, and incubation with DES does not modify testosterone production by human fetal testes in culture. SHP absence in human fetal testes could be an additional explanation for their lack of sensitivity to DES.

Sources and more information
  • Full study (free access) : Nuclear receptors and endocrine disruptors in fetal and neonatal testes: a gapped landscape, Frontiers in endocrinology, NCBI PubMed PMC4423451, 2014 Apr.
  • Structural Organization of Nuclear Receptors featured image credit wikipedia.

The ‘oestrogen hypothesis’- where do we stand now ?

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In utero, rodents exposed to DES during development have abnormal testicular histology and altered adult male fertility

2003 Study Abstract

The original ‘oestrogen hypothesis‘ postulated that the apparent increase in human male reproductive developmental disorders (testis cancer, cryptorchidism, hypospadias, low sperm counts) might have occurred because of increased oestrogen exposure of the human foetus/neonate; five potential routes of exposure were considered.

This review revisits this hypothesis in the light of the data to have emerged since 1993. It addresses whether there is a secular increasing trend in the listed disorders and highlights the limitations of available data and how these are being addressed. It considers whether new data has emerged to support the suggestion that increased oestrogen exposure could cause these abnormalities and reviews new data on potential routes via which such increased exposure could have occurred.

Secular trends
The disorders listed above are now considered to represent a syndrome of disorders (testicular dysgenesis syndrome, TDS) with a common origin in foetal life. Testicular cancer has increased in incidence in Caucasian men worldwide and lifetime risk is 0.3-0.8%. Secular trends in cryptorchidism are unclear but it is by far the commonest (2-4% at birth) congenital abnormality in either sex. Secular trends for hypospadias are not robust, although most studies suggest a progressive increase; registry data probably under-estimates incidence, but based on this data hypospadias is the second most common (0.3-0.7% at birth) congenital malformation. Retrospective analyses of sperm count data show a global downward trend but this is inconclusive – prospective studies using standardized methodology show significant differences between countries and very low sperm counts in the youngest cohort of men. For all disorders, other then testis cancer, standardized prospective studies are the best way forward and are in progress across Europe.

Oestrogen effects
Evidence that foetal exposure to oestrogens can induce the above disorders has strengthened. New pathways via which such changes could be induced have been identified, including suppression of testosterone production by the foetal testis, suppression of androgen receptor expression and suppression of insulin-like factor-3 (InsL3) production by foetal Leydig cells. Other evidence suggests that the balance between androgen and oestrogen action may be important in induction of reproductive tract abnormalities.

Oestrogen exposure
Although many new environmental oestrogens have been identified, their uniformly weak oestrogenicity excludes the possibility that they could induce the above disorders. However, emerging data implicates various environmental chemicals in being able to alter endogenous levels of androgens (certain phthalates) and oestrogens (polychlorinated biphenyls, polyhalogenated hydrocarbons), and the former have been shown to induce a similar collection of disorders to TDS.

Other mechanisms via which increased fetal exposure to pregnancy oestrogens might occur (increasing trend in obesity, dietary changes) are also discussed.

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Was DES involved in falling sperm counts and disorders of the male reproductive tract ?

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Male sexual development in “a sea of oestrogen” during in-utero DES exposure

1993 Study Abstract

The incidence of disorders of development of the male reproductive tract has more than doubled in the past 30-50 years while sperm counts have declined by about half.

Similar abnormalities occur in the sons of women exposed to diethylstilbestrol (DES) during pregnancy and can be induced in animals by brief exposure to exogenous oestrogen/DES during pregnancy.

We argue that the increasing incidence of reproductive abnormalities in the human male may be related to increased oestrogen exposure in utero, and identify mechanisms by which this exposure could occur.

Sources and more information
  • Are oestrogens involved in falling sperm counts and disorders of the male reproductive tract?, The Lancet, NCBI PubMed PMID: 8098802, 1993.

Neonatal DES exposure results in immunodeficiency that persists into adulthood

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Effect of immunosuppression on neonatally diethylstilbestrol-induced genital tract lesion and tumor development in female mice

1984 Study Abstract

Neonatal treatment of female rodents with the synthetic estrogen diethylstilbestrol [(DES) CAS: 56-53-1; alpha, alpha’-diethyl-4,4′-dimethoxystilbene] results in immunodeficiency that persists into adulthood, along with progressive development of genital tract lesions.

DES-induced immunosuppression was examined as a possible promoter of genital tract lesion and tumor development in BALB/cCrgl female mice. Secondary suppression of T-cell immunity after neonatal DES treatment failed to increase lesion incidence or to promote genital tract tumor development in 8-month-old mice. Although hyperplastic lesions were present in 70% of the genital tracts from DES-treated mice at 8 months of age, apparently few neoplastic cells are present at this time, since transplantation of genital tracts from these animals into syngeneic hosts did not yield tumors. To reduce the possibility that potential tumors were too immunogenic to survive in the syngeneic hosts, genital tract pieces from 12-month-old DES-treated female mice were transplanted into immunosuppressed hosts; only 1 tumor resulted. The tumor was a mixed adenocarcinoma, squamous cell carcinoma, and sarcoma and was immunogenic.

These results suggest that immunosurveillance by T-cells is relatively unimportant in DES-induced genital tract lesion development.

Sources and more information
  • Effect of immunosuppression on neonatally diethylstilbestrol-induced genital tract lesion and tumor development in female mice, Journal of the National Cancer Institute, NCBI PubMed PMID: 6592383, 1984 Oct.
  • Immunodeficiency featured image credit olamed.

Impaired immune function (infectious illness, allergic, autoimmune conditions) in the DES-exposed

Long-term Effects of Exposure to Diethylstilbestrol

1988 Study Abstract

The present survey represents a preliminary look at possible health effects of prenatal exposure to DES in humans beyond those already known. As such, it should be considered as a guide to areas needing further investigation in less biased samples. The findings, however, are consistent with those of experimental studies in animals and indicate a need for follow-up in the human cohort. Of particular note are conditions that suggest impaired immune function, such as infectious illness, allergic and autoimmune conditions, and malignant tumors.

Studies of certain genetic strains of mice with exposure to DES during the critical neonatal period of immune system ontogeny-analogous to the first trimester of human pregnancy-show persistent, lifelong immunosuppression. The main DES effect is a reduced number of Thelper cells, important for the induction and regulation of many immune responses. B-cell response is impaired in assays requiring T-cell mediation but is normal if corrected for T-helper numbers. Experiments with varying combinations of B and T cells in vitro show that the defect is in T-cell number but not function.

Mice with neonatal exposure also have a reduced number of natural killer cells thought to recognize and kill certain tumor cells. Following injection with a classic carcinogen (3-methylcholanthrene [MCA]), DES-exposed mice show a reduced ability to resist tumors; MCA-induced sarcomas appear in greater numbers and at a faster rate.

Our findings regarding asthma, arthritis, and lupus are also consistent with those of a small study of human peripheral blood lymphocytes suggesting a hyperreactive immune response in women with in utero exposure to DES. Another small study of the daughters suggested possible functional alterations of natural killer cells. Even more suggestive, our findings are consistent with those of a recent preliminary report from the largest ongoing follow-up of DES daughters, the federally funded Diethylstilbestrol Adenosis Project. This report indicates about a twofold increase in autoimmune conditions in women with prenatal exposure compared with controls. One small study of daughters who had had DES associated cancer or reproductive problems showed no consistent increase in the rates of infectious disease but a suggestive increase in the rates of autoimmune disease compared with controls.

Evaluating immunologic consequences in women and men with DES exposure will be complicated by possible genetic contributions and by varying dosage and timing of the prenatal exposure. Furthermore, health consequences might become detectable only as the population ages, when the immune system generally declines in competence.

Possible pathologic disorders of the prostate, as noted in our survey, were also noted in experimental models of DES effects in rodents.In preliminary studies of mice with neonatal DES exposure, evidence of cytologic malignancy in the area of the prostate appeared only in the experimentally treated animals. Recent experiments in which human fetal prostate tissue was grafted into DES-treated and untreated athymic nude mice and then allowed to continue growing revealed ductal dilation and persistent distortion of ductal architecture; these conditions could contribute to early or increased development of prostatic neoplasms (S. Mee, G.R. Cunha, C.V. Yonemura, et al, “The Effects of Diethylstilbestrol on Human Prostate Development,” unpublished data, 1987).

Further inquiry should also focus on a possible increased prevalence of elevated prolactin levels among DES daughters. Substantial endocrine alterations occur in rodents; more specifically, experimental studies show that perinatal DES exposure results in a disruption of hypothalamic-pituitary feedback systems, including the regulation and production of prolactin. While endocrine effects of a similar magnitude are not apparent within the human cohort, there could be an increase of more subtle functional alterations in daughters or sons (or both) with exposure to DES. Although difficult to measure, abnormal endocrine function could be contributing to a diminished reproductive capacity in ways beyond the more apparent and well-documented structural anomalies. Two small studies of plasma hormones in the daughters suggest abnormalities that may reflect a disturbance of hypothalamic-pituitary-ovarian function. An additional study suggests that hyperprolactinemia may be a significant factor in infertility in daughters with DES exposure.

Comprehensive follow-up of DES-exposed daughters and sons is required to answer questions about the long-term consequences of prenatal exposure. As the cohort ages and reaches new “milestones” of increased health risks, such follow-up can contribute to a more adequate assessment of this population’s risks and to the early detection of various health conditions that may be affected by prenatal DES exposure and be responsive to treatment. In addition, an increased knowledge of the health consequences associatedwith DES exposure addresses a broader scientific need to examine fully the results of this reproductive exposure. Women and men with in utero exposure to DES constitute a unique, identified cohort from which much can be learned about the hormonal effects on both normal and abnormal human development. This cohort can provide a greater understanding of developmental biology, sex differentiation, and pathologic processes in humans. Beyond the basic knowledge to be gained are implications for therapeutic substances in use currently or considered for the future.

Sources and more information
  • Full study (free download) : Long-term Effects of Exposure to Diethylstilbestrol, Clinical Medicine, NCBI PubMed PMC1026532, 1988 Nov.
  • Prevalence Rates (%) of Selected Conditions Among Adults With Diethylstilbestrol (DES) Exposure featured image credit ncbi.

Alterations in immune responsiveness in women exposed to DES in utero

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In utero DES exposure associated with a hyper-reactive immune response during the reproductive years

1987 Study Abstract

In order to study the effect of in utero diethylstilbestrol (DES) exposure on the immune system of adult women, the blastogenic response of peripheral blood lymphocytes to two mitogens was compared in eight DES-exposed patients and in eight age-matched controls with normal menstrual cycles and proven fertility.

As measured by the uptake of 3H-thymidine (mean [+/- standard error]), response to the T-cell mitogen phytohemagglutin (PHA) was significantly higher (P less than 0.002) in cells of DES-exposed women (88.6 +/- 5.7 X 10(3) cpm) than in controls (44.0 +/- 8.9 X 10(3) cpm) at the lowest dose of mitogen tested (0.125 microgram/ml). Moreover, lymphocytes of DES-exposed subjects showed maximal blastogenic response to PHA at a concentration (0.125 microgram/ml) two to four times lower (P less than 0.002) than controls (0.25 microgram/ml to 0.5 microgram/ml). Cells of both DES-exposed subjects and controls were maximally responsive to pokeweed mitogen (PWM) at the lowest dose tested (0.625 microgram/ml).

These findings suggest that in utero DES exposure is associated with a hyper-reactive immune response during the reproductive years.

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Natural killer cells in in utero diethylstilbesterol-exposed patients

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DES effect on stimulation of the reticuloendothelial system

1983 Study Abstract

The observations that limited neonatal diethylstilbesterol (DES) exposure in mice produces persistent natural killing defects and that natural killer (NK) cells have an origin early in gestation suggested the possibility that NK abnormalities may exist in in utero DES-exposed women.

However, when compared to controls, these women showed slightly higher NK activity with no evidence of stimulation by accessory mononuclear cells. Altered natural killing cannot be invoked in this population as a contributing factor to increased cancer risk.

Sources and more information
  • Natural killer cells in in utero diethylstilbesterol-exposed patients, Gynecologic oncology, NCBI PubMed PMID: 6654182, 1983 Dec.
  • Natural killer (NK) cells featured image credit selfhacked.com/blog.

Altered immune response in adult women exposed in utero to DES

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DES Daughters have alterations in T-cell-mediated immunity

2001 Study Abstract

Between 1940 and 1970, 1.5 million female fetuses were exposed to diethylstilbestrol in utero. Numerous deleterious effects on reproductive anatomic and physiologic characteristics have been documented in these women. However, the effects of this exposure on nonreproductive systems, which may have lifelong consequences as this cohort of women progresses beyond the childbearing years, have received little attention. On the basis of an earlier preliminary observation of altered immune reponse, we hypothesized that diethylstilbestrol-exposed women may show abnormalities in T-cell-mediated immune response.

Thirteen women exposed to diethylstilbestrol in utero were compared with 13 age- and menstrual cycle phase-matched control subjects with respect to the in vitro T-cell response to the mitogens phytohemagglutinin, concanavalin A, and interleukin 2.

As compared with controls, tritiated thymidine incorporation by T cells harvested from diethylstilbestrol-exposed women was increased 3-fold over a range of concentrations in response to concanavalin A (P <.001), increased by 50% over a range of concentrations in response to phytohemagglutinin (P <.001), and increased 2-fold in response to the endogenous mitogen interleukin 2 (P <.05).

In vitro evidence suggests that women exposed to diethylstilbestrol have alterations in T-cell-mediated immunity. These changes require further attention with regard to their characterization, their role in the pathogenesis of cancer and autoimmunity, and their presence in normal women exposed to diethylstilbestrol in utero.

Sources and more information
  • Altered immune response in adult women exposed to diethylstilbestrol in utero, American journal of obstetrics and gynecology, NCBI PubMed PMID: 11483908, 2001 Jul.
  • Study of Human Immune Response featured image credit niaid.