EDCs: an Endocrine Society Scientific Statement

EDC-statement banner
The group of molecules identified as endocrine disruptors include synthetic estrogens used as pharmaceutical agents such as Diethylstilbestrol DES.

Abstract

Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement, The Endocrine Society, dx.doi.org/10.1210/er.2009-0002, April 17, 2009.

There is growing interest in the possible health threat posed by endocrine-disrupting chemicals (EDCs), which are substances in our environment, food, and consumer products that interfere with hormone biosynthesis, metabolism, or action resulting in a deviation from normal homeostatic control or reproduction.

In this first Scientific Statement of The Endocrine Society, we present the evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostate cancer, neuroendocrinology, thyroid, metabolism and obesity, and cardiovascular endocrinology.

Results from animal models, human clinical observations, and epidemiological studies converge to implicate EDCs as a significant concern to public health. The mechanisms of EDCs involve divergent pathways including (but not limited to) estrogenic, antiandrogenic, thyroid, peroxisome proliferator-activated receptor ?, retinoid, and actions through other nuclear receptors; steroidogenic enzymes; neurotransmitter receptors and systems; and many other pathways that are highly conserved in wildlife and humans, and which can be modeled in laboratory in vitro and in vivo models. Furthermore, EDCs represent a broad class of molecules such as organochlorinated pesticides and industrial chemicals, plastics and plasticizers, fuels, and many other chemicals that are present in the environment or are in widespread use.

We make a number of recommendations to increase understanding of effects of EDCs, including enhancing increased basic and clinical research, invoking the precautionary principle, and advocating involvement of individual and scientific society stakeholders in communicating and implementing changes in public policy and awareness.

Discussion (DES and Fertility-specific)

General Introduction: the group of molecules identified as endocrine disruptors is highly heterogeneous and includes synthetic chemicals used as industrial solvents/lubricants and their byproducts [polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), dioxins], plastics [bisphenol A (BPA)], plasticizers (phthalates), pesticides [methoxychlor, chlorpyrifos, dichlorodiphenyltrichloroethane (DDT)], fungicides (vinclozolin), and pharmaceutical agents [diethylstilbestrol (DES)].

Reproduction: in the adult female, the first evidence of endocrine disruption was provided almost 40 yr ago through observations of uncommon vaginal adenocarcinoma in daughters born 15–22 yr earlier to women treated with the potent synthetic estrogen DES during pregnancy. Subsequently, DES effects and mechanisms have been substantiated in animal models. Thus, robust clinical observations together with experimental data support the causal role of DES in female reproductive disorders. However, the link between disorders such as premature pubarche and EDCs is so far indirect and weak, based on epidemiological association with both IUGR and ovulatory disorders. The implications of EDCs have been proposed in other disorders of the female reproductive system, including disorders of ovulation and lactation, benign breast disease, breast cancer, endometriosis, and uterine fibroids.

In the case of DES, there are both human and experimental observations indicating heritability.

Premature ovarian failure, decreased ovarian reserve, aneuploidy, granulosa steroidogenesis: interestingly, mice exposed in utero to DES, between d 9–16 gestation, have a dose-dependent decrease in reproductive capacity, including decreased numbers of litters and litter size and decreased numbers of oocytes (30%) ovulated in response to gonadotropin stimulation with all oocytes degenerating in the DES-exposed group, as well as numerous reproductive tract anatomic abnormalities. In women with in utero exposure to DES, Hatch et al reported an earlier age of menopause between the 43–55 yr olds, and the average age of menopause was 52.2 yr in unexposed women and 51.5 yr in exposed women. The effect of DES increased with cumulative doses and was highest in a cohort of highest in utero exposure during the 1950s. These observations are consistent with a smaller follicle pool and fewer oocytes ovulated, as in DES-exposed mice after ovulation induction.

Reproductive tract anomalies: disruption of female reproductive tract development by the EDC DES is well documented. A characteristic T-shaped uterus, abnormal oviductal anatomy and function, and abnormal cervical anatomy are characteristic of thisin utero exposure, observed in adulthood, as well as in female fetuses and neonates exposed in utero to DES. Some of these effects are believed to occur through ER? and abnormal regulation of Hox genes. Clinically, an increased risk of ectopic pregnancy, preterm delivery, miscarriage, and infertility all point to the devastating effect an endocrine disruptor may have on female fertility and reproductive health. It is certainly plausible that other EDCs with similar actions as DES could result in some cases of unexplained infertility, ectopic pregnancies, miscarriages, and premature deliveries. Although another major health consequence of DES exposurein utero was development of rare vaginal cancer in DES daughters, this may be an extreme response to the dosage of DES or specific to pathways activated by DES itself. Other EDCs may not result in these effects, although they may contribute to the fertility and pregnancy compromises cited above. Of utmost importance clinically is the awareness of DES exposure (and perhaps other EDC exposures) and appropriate physical exam, possible colposcopy of the vagina/cervix, cervical and vaginal cytology annually, and careful monitoring for fertility potential and during pregnancy for ectopic gestation and preterm delivery.

Endometriosis is an estrogen-dependent gynecological disorder associated with pelvic pain and infertility. There are suggestive animal data of adult exposure to EDCs and development of or exacerbation of existing disease, and there is evidence that in utero exposure in humans to DES results in an increased relative risk = 1.9 (95% confidence interval, 1.2–2.8).

Environmental estrogens effects on the prostate: DES exposure is an important model of endocrine disruption and provides proof-of-principle for exogenous estrogenic agents altering the function and pathology of various end-organs. Maternal usage of DES during pregnancy resulted in more extensive prostatic squamous metaplasia in human male offspring than observed with maternal estradiol alone. Although this prostatic metaplasia eventually resolved during postnatal life, ectasia and persistent distortion of ductal architecture remained. These findings have led to the postulation that men exposed in utero to DES may be at increased risk for prostatic disease later in life, although the limited population studies conducted to date have not identified an association. Nonetheless, several studies with DES in mouse and rat models have demonstrated significant abnormalities in the adult prostate, including increased susceptibility to adult-onset carcinogenesis after early DES exposures. It is important to note that developmental exposure to DES, as with other environmental estrogens, has been shown to exhibit a biphasic dose- response curve with regard to several end-organ responses, and this has been shown to be true for prostatic responses as well. Low-dose fetal exposure to DES or BPA (see full study) resulted in larger prostate size in adulthood compared with controls, an effect associated with increased levels of prostatic ARs. This contrasts with smaller prostate sizes, dysplasia, and aging- associated increases in carcinogenesis found after perinatal high-dose DES exposures as noted above. This differential prostatic response to low vs. high doses of DES and other EDCs must be kept in mind when evaluating human exposures to EDCs because the lack of a response at high doses may not translate into a lack of negative effects at low, environmentally relevant doses of EDCs.

Linking basic research to clinical practice: it should be clear from this Scientific Statement that there is considerable work to be done. A reconciliation of the basic experimental data with observations in humans needs to be achieved through translation in both directions, from bench to bedside and from bedside (and populations) to bench. An example of how human observation and basic research have successfully converged was provided by DES exposure in humans, which revealed that the human syndrome is faithfully replicated in rodent models. Furthermore, we now know that DES exposure in key developmental life stages can have a spectrum of effects spanning female reproduction, male reproduction, obesity, and breast cancer. It is interesting that in the case of breast cancer, an increased incidence is being reported now that the DES human cohort is reaching the age of breast cancer prevalence. The mouse model predicted this outcome 25 yr before the human data became available. In the case of reproductive cancers, the human and mouse data have since been confirmed in rats, hamsters, and monkeys. This is a compelling story from the perspective of both animal models and human exposures on the developmental basis of adult endocrine disease.

Prevention and the “precautionary principle”: although more experiments are being performed to find the hows and whys, what should be done to protect humans? The key to minimizing morbidity is preventing the disorders in the first place. However, recommendations for prevention are difficult to make because exposure to one chemical at a given time rarely reflects the current exposure history or ongoing risks of humans during development or at other life stages, and we usually do not know what exposures an individual has had in utero or in other life stages.

In the absence of direct information regarding cause and effect, the precautionary principle is critical to enhancing reproductive and endocrine health. As endocrinologists, we suggest that The Endocrine Society actively engages in lobbying for regulation seeking to decrease human exposure to the many endocrine-disrupting agents. Scientific societies should also partner to pool their intellectual resources and to increase the ranks of experts with knowledge about EDCs who can communicate to other researchers, clinicians, community advocates, and politicians.

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Fertility and Ovarian Function in High-Dose DES-Treated Tall Women

image of tall-girls
Back in the day, school photographers put the tall guys at the back in the middle, the shorter guys on the end. If you were really short, they put you on the end of the middle’ row with the plain Janes — note the gender symmetry. Middle of the front row was always reserved for the prettiest girls. My future wife and I – 1969.

Abstract

Fertility and Ovarian Function in High-Dose Estrogen-Treated Tall Women, National Institutes of Health, NCBI PubMed PMID 21289262, 2011 Feb 2.
Full text: The Endocrine Society, dx.doi.org/10.1210/jc.2010-2244, February 02, 2011.

BACKGROUND/OBJECTIVE
High-dose estrogen treatment to reduce final height of tall girls has been shown to interfere with fertility. Ovarian function has not been studied. We therefore evaluated fertility and ovarian function in tall women who did or did not receive such treatment in adolescence.

METHODS
This was a retrospective cohort study of 413 tall women aged 23-48 yr, of whom 239 women had been treated. A separate group of 126 fertile, normoovulatory volunteers aged 22-47 yr served as controls.

RESULTS
Fertility was assessed in 285 tall women (157 treated, 128 untreated) who had attempted to conceive. After adjustment for age, treated women were at increased risk of experiencing subfertility [odds ratio (OR) 2.29, 95% confidence interval (CI) 1.38-3.81] and receiving infertility treatments (OR 3.44, 95% CI 1.76-6.73). Moreover, fecundity was notably affected because treated women had significantly reduced odds of achieving at least one live birth (OR 0.26, 95% CI 0.13-0.52). Remarkably, duration of treatment was correlated with time to pregnancy (r = 0.23, P = 0.008). Ovarian function was assessed in 174 tall women (119 treated, 55 untreated). Thirty-nine women (23%) exhibited a hypergonadotropic profile. After adjusting for age category, treated women had significantly higher odds of being diagnosed with imminent ovarian failure (OR 2.83, 95% CI 1.04-7.68). Serum FSH levels in these women were significantly increased, whereas antral follicle counts and serum anti-Müllerian hormone levels were decreased.

CONCLUSION
High-dose estrogen-treated tall women are at risk of subfertility in later life. Their fecundity is significantly reduced. Treated women exhibit signs of accelerated ovarian aging with concomitant follicle pool depletion, which may be the basis of the observed subfertility.

Discussion

We evaluated fertility and ovarian function in tall women who did or did not receive high-dose estrogen treatment in adolescence. Our results indicate that treated women experience more difficulties getting pregnant compared with untreated women and more often receive infertility treatments. We show for the first time that abnormal serum levels of hormones related to the hypothalamus-pituitary-gonadal axis, especially FSH, may be involved in the observed subfertility.

First we studied fertility of treated women, which was significantly reduced compared with untreated women. Fifty-six percent of treated women conceived their first pregnancy within 12 months of unprotected intercourse. As a consequence, 43% of treated women visited a doctor because of fertility problems and 28% required some form of infertility treatment. More importantly, we observed a significantly reduced chance of achieving a live birth. At the time of study almost one third of the treated women were suffering from involuntary childlessness for a median of 40 months. This is unexpected in light of earlier findings indicating only a slight reduction in the probability of eventually having a live birth. This may be explained by the fact that we studied fertility only in women who had attempted to conceive, which we believe better represents the women at risk of involuntary childlessness. Our time to pregnancy data are self-reported and may be confounded by recall bias. However, we believe that our conclusions are not affected by such bias because we also assessed fertility based on data such as having received infertility treatments, which is not prone to recall bias and showed similar results.

We also studied the effects of treatment within treated women only. We found that although age at initiation of treatment was not associated with outcome, duration of treatment was significantly correlated with time to pregnancy. Women with a TTP of more than 12 months had on average been treated for 3 months longer. Although the effect of oral contraceptives on subsequent fertility has not been extensively studied, one study has reported an effect of estrogen dose on conception delay. Recent studies did not find such an association, possibly because low-dosage estrogen pills were used. Because of no variation in dosage in our population, we were unable to study the effect of estrogen dose more specifically.

Next, we analyzed ovarian function to study possible causes of the reduced fertility. Ovarian function was categorized based on serum gonadotropin levels. We observed an increased frequency of women with a hypergonadotropic profile. Our principal finding is that treated women are at increased risk of being diagnosed with IOF compared with untreated women. To account for normal changes in ovarian function in the late reproductive stages, treated and untreated women were divided into two age categories for the analysis of ovarian function. Taking these age categories into account, the odds of IOF diagnosis in treated women was almost 3-fold higher than in untreated women. Although ovarian function was primarily categorized based on serum FSH levels, the diagnosis of IOF was also supported by other parameters. We observed significantly decreased antral follicle counts and serum AMH levels in women with IOF as compared with normogonadotropic tall women. Serum AMH is currently the best marker for primordial follicle pool size because in the ovary it is expressed in granulose cells of follicles that have undergone recruitment but have not yet been selected for dominance. In addition, AMH plays an important role in regulating folliculogenesis because it is involved in determining the individual FSH threshold of early antral follicles. In addition, we believe some other possible pathologies, such as PCOS, can now be excluded as a potential cause of the observed infertility because of prevalence levels similar to the estimated population frequency.

Finally, we compared our results to a cohort of healthy fertile controls. Parameters of ovarian function were comparable between normogonadotropic tall women and these controls. Comparison with hypergonadotropic women confirmed that parameters of ovarian function in these women are indicative of accelerated follicle pool depletion.

The results of our study do not only validate earlier epidemiological findings from an Australian study but may also provide physicians with clinically useful information aiding in the diagnosis and treatment of estrogen-treated tall women with fertility problems. To our best knowledge, this is the first report establishing ovarian dysfunction in these women. It seems that follicle dynamics have changed in that respect that a considerable number of these women seem to suffer from accelerated follicle loss being reflected by increased serum FSH levels along with decreased AMH levels as well as low antral follicle counts. Hence, it seems that tall women who have been treated with estrogens in the past are prone to lose their reproductive capacity earlier in life, and they should be counseled accordingly.

In conclusion, we evaluated fertility and ovarian function in later life of tall women who did or did not receive high-dose estrogen treatment in adolescence. We found that estrogen-treated women experienced more difficulties conceiving and more often received medical treatment for infertility compared with untreated women. Treated women had a decreased chance of achieving at least one live birth. We observed a possible dose-response relationship because duration of treatment was correlated with time to pregnancy. Finally, we showed that treated women were at increased risk of being diagnosed with IOF. They exhibit signs of accelerated ovarian aging with concomitant follicle pool depletion, which may be the basis of the observed subfertility. However, the mechanism behind this accelerated follicle loss by high-dose estrogen treatment remains unknown and requires future research.

Click to download the full study.

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Reproductive performance of women with müllerian anomalies

uterinecongenitalanomalies
Classification of the anomalies of Müllerian duct developed by American Fertility Society (1988) and reproduced by Troiano and McCarthy.

Abstract

Reproductive performance of women with müllerian anomalies, Current opinion in obstetrics & gynecology, NCBI PubMed PMID: 17495638, 2007 Jun.

PURPOSE OF REVIEW
This review discusses current diagnostic techniques for müllerian anomalies, reproductive outcome data, and management options in reproductive-age women.

RECENT FINDINGS
Multiple retrospective studies have investigated reproductive outcomes with müllerian anomalies, but few current prospective studies exist. Uterine anomalies are associated with normal and adverse reproductive outcomes such as recurrent pregnancy loss and preterm delivery, but not infertility. Furthermore, unicornuate, didelphic, bicornuate, septate, arcuate, and diethylstilbestrol-exposed uteri have their own reproductive implications and associated abnormalities. Common presentations of müllerian anomalies and current diagnostic techniques are reviewed. Surgical intervention for müllerian anomalies is indicated in women with pelvic pain, endometriosis, obstructive anomalies, recurrent pregnancy loss, and preterm delivery. Although surgery for most uterine anomalies is a major intervention, the uterine septum is preferentially managed with a hysteroscopic procedure. Several recent studies and review articles discuss management of the septate uterus in asymptomatic women, infertile women, and women with a history of poor reproductive outcomes. Current assessment of reproductive outcomes with uterine anomalies and management techniques is warranted.

SUMMARY
Müllerian anomalies, especially uterine anomalies, are associated with both normal and adverse reproductive outcomes, and management in infertile women remains controversial.

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DES Grand Daughters Menstrual and Reproductive Characteristics

image of menstrual-cup
This 2006 data provide evidence of menstrual irregularity, delayed menstrual regularization, and increased infertility in DES Grand Daughters. Although this data provide limited evidence of an increased frequency of adverse pregnancy outcomes in third-generation women, most have not married or attempted to start families, and further follow-up will assess their reproductive experience.. Menstrual cup.

Abstract

Menstrual and reproductive characteristics of women whose mothers were exposed in utero to diethylstilbestrol (DES), International journal of epidemiology, NCBI PubMed PMID: 16723367, 2006 Aug.

Full text: Oxford Journals, Medicine & Health, International Journal of Epidemiology, Volume 35, Issue 4Pp. 862-868, doi: 10.1093/ije/dyl106, August 2006.

Background
In women, prenatal exposure to diethylstilbestrol (DES) is associated with adult reproductive dysfunction. The mouse model, which replicates many DES outcomes, suggests DES causes epigenetic alterations, which are transmissable to daughters of prenatally exposed animals. We report menstrual and reproductive characteristics in a unique cohort comprising daughters of women exposed prenatally to DES.

Methods
Menstrual and reproductive outcomes and baseline characteristics were assessed by mailed questionnaire in 793 women whose mothers had documented information regarding in utero DES exposure.

Results
Mean age at menarche was 12.6 years in both groups,

  • but daughters of the exposed women attained menstrual regularization later (mean age of 16.2 years vs. 15.8 years; P = 0.05),
  • and were more likely to report irregular menstrual periods, odds ratio (OR) = 1.54 [95% confidence interval (95% CI 1.02–2.32)].

A possible association between mothers’ DES exposure and daughters’ infertility was compatible with chance, age, and cohort adjusted OR = 2.19 (95% CI 0.95–5.07). We found limited evidence that daughters of the exposed had more adverse reproductive outcomes, but daughters of exposed women had fewer live births (1.6) than the unexposed (1.9) (P = 0.005).

Conclusions
The high risk of reproductive dysfunction seen in women exposed to DES in utero was not observed in their daughters, but most women in our cohort have not yet attempted to start their families, and further follow-up is needed to assess their reproductive health. Our findings of menstrual irregularity and possible infertility in third-generation women are preliminary but compatible with speculation regarding transgenerational transmission of DES-related epigenetic alterations in humans.

Excerpts and Discussion

The mean birth weight of offspring appeared lower in daughters of the exposed than in the unexposed (3374.2 g vs. 3540.5 g) (P = 0.08).

Our data indicate that DES Grand Daughters attain menstrual regularity at a slightly later age than daughters of the unexposed and are more likely to experience menstrual irregularity.

Our study suggests that infertility may also be more frequent in the DES Grand Daughters, and that DES exposure may exacerbate age-related infertility, a possibility compatible with findings in men who were exposed to DES in utero. The proportion of third-generation women affected by infertility (5%) in this study was far lower than that observed in the (second) generation of women exposed in utero to DES (30%).

In the prenatally exposed women, infertility is primarily due to anatomic anomalies of the uterus or fallopian tubes; other diagnoses, including hormonal/ovulatory problems, play a less striking role. Anatomic and tissue anomalies were not observed in a study of 28 third-generation women, but the number of participants was too small to rule out a low prevalence, and some irregularities (e.g. uterine, tubal) might not be evident on physical examination.

Further follow-up is needed to confirm the possible infertility in the third-generation women, and to evaluate specific diagnoses, which may provide insight into DES-related mechanisms.

It is well-known that women exposed to DES in utero have increased pregnancy complications and adverse birth outcomes, including ectopic pregnancy, pregnancy loss, and preterm delivery. Our data are not conclusive regarding adverse pregnancy outcomes in third-generation women, although daughters of the exposed had somewhat fewer live born children and babies of slightly lower average birth weight. Further follow-up will be essential to assess reproductive outcomes as more of the third-generation women enter their reproductive years.

Click to download the full study.

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Reducing the Adult Height of Tall Girls with DES: Effects on Fertility

image of tall-girls
Estrogens have been used to reduce the height of unusually tall girls since the 1950s based upon the concept that, during normal puberty, increased estrogen levels lead to epiphyseal fusion in the long bones. DES treatment in adolescence seems to reduce female fertility in later life by 40%.

Abstract

Oestrogen treatment to reduce the adult height of tall girls: long-term effects on fertility, Lancet (London, England), NCBI PubMed PMID 15500896, 2004 Oct.

BACKGROUND
Treatment with oestrogen to reduce the adult height of tall girls has been available since the 1950s. We undertook a retrospective cohort study to assess the long-term effects of this treatment on fertility.

METHODS
Eligible participants were identified from the records of Australian paediatric endocrinologists who assessed tall girls from 1959 to 1993, and from self-referrals. Individuals included girls who had received oestrogen treatment (diethylstilboestrol or ethinyl oestradiol) (treated group) and those who were assessed but not treated (untreated group). Information about reproductive history was sought by telephone interview.

FINDINGS
1432 eligible individuals were identified, of whom 1243 (87%) could be traced. Of these, 780 (63%) completed interviews: 651 were identified from endocrinologists’ records, 129 were self-referred. Treated (n=371) and untreated (n=409) women were similar in socioeconomic and other characteristics. After adjustment for age, treated women

  • were more likely to have ever tried for 12 months or more to become pregnant without success (relative risk [RR] 1.80, 95% CI 1.40-2.30);
  • more likely to have seen a doctor because they were having difficulty becoming pregnant (RR 1.80, 1.39-2.32);
  • and more likely to have ever taken fertility drugs (RR 2.05, 1.39-3.04).

Time to first pregnancy analysis showed that the treated group was 40% less likely to conceive in any given menstrual cycle of unprotected intercourse (age-adjusted fecundability ratio 0.59, 95% CI 0.46-0.76). These associations persisted when self-referred women were excluded.

INTERPRETATION
High-dose oestrogen treatment in adolescence seems to reduce female fertility in later life. This finding has implications for current treatment practices and for our understanding of reproductive biology.

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Five Scary and Shocking Facts about Diethylstilbestrol

1. As early as 1939, researchers had shown that DES Diethylstilbestrol could cause cancer and changes in the reproductive tracts of mice and rats, but drug companies ignored these results ; they also tested DES on pregnant women without consent.

Image from A Healthy Baby Girl, a 1996 documentary in which filmmaker Judith Helfand chronicles the health consequences of her in utero exposure to diethylstilbestrol
DES did not lead to healthier babies, nor did it prevent miscarriages, according to research that began appearing in 1953

2. In 1953, a study of 2000 women at the University of Chicago showed that DES did not prevent miscarriage; on the contrary, it was associated with increases in premature labor and a higher rate of abortions.

3. Despite this study, the drug continued to be used.  It wasn’t until 1971 that American drug companies were legally obliged to label DES “unsuitable for pregnant women”.  The FDA did not ban the drug but issued a contraindication which means that the drug DES continued to be prescribed to pregnant women even after the link between a rare form of vaginal cancer in young women and prenatal exposure to DES was established.

4. A whole generation of new medical students and doctors don’t know about Diethylstilbestrol, yet a study published in 2011 confirmed lifetime risk of adverse health effect in DES daughters (the youngest are in their mid 30’s early 40’s).  DES is one of those cases where the patients often know more about its effects than the doctors.

5. DES is a multi-generational tragedy.  Research by the Netherlands Cancer Institute in 2002 suggests that hypospadias a misplaced opening of the penis occurred 20 times more frequently among third-generation sons.  In laboratory studies of elderly third-generation DES-exposed mice born to DES daughter mice, an increased risk of uterine cancers, benign ovarian tumors and lymphomas were found.  Third-generation male mice were shown to be at risk for certain reproductive tract tumors.

Are we going to ignore these results like we did in 1939?

Third-generation children, the offspring of DES daughters and DES sons, are just beginning to reach the age when relevant health problems can be studied.  Funding for more research is critically needed to continue to look for evidence of reproductive abnormalities and cancers among third-generation DES women and men to ensure they receive appropriate follow-up care.