What we know and what’s accepted
Over the past 40 years, there has been an increase in the number of studies and meta-analyses investigating the potential effect of endocrine disrupting chemicals (EDCs) on fertility. Today, it is known that there are numerous environmental and occupational factors that can affect one’s fertility and fecundity capacity during the peri/post conception period. It is accepted that most EDCs interfere with, or mimic steroid hormone action; predominantly affecting estrogen, androgen, and thyroid hormone signaling pathways. A disruption in the normal homeostatic control of these steroid hormones can have a great impact on specific molecular processes altering single or multiple biological functions.
How endocrine disrupting chemicals (EDCs) interact with reproductive systems
Some EDCs can interact with the male and female reproductive systems, leading to endocrine disruption in the testis and ovaries. Although EDCs have various mechanisms of action, they exert their effects mainly via binding transcription factor receptors. During peak reproductive age, EDCs may alter the expression and activity of enzymes required for the synthesis and catabolism of testicular and ovarian sex steroids. Moreover, these chemicals can affect the expression of hormone receptors and their ability to bind endogenous ligands. For example, in males, the literature has reported a negative correlation between disrupted spermatogenesis and lifestyle factors, such as, alcohol consumption, cigarette smoking, drug use, and obesity caused by a high-energy diet. In females, the negative impact of EDCs on infertility diseases has been predominantly studied in animals. Many disorders have been described, such as low ovarian weight, impaired folliculogenesis, high aneuploidy rates, and the acceleration of follicular atresia. Indeed, women exposed to some endocrine-disrupting pesticides (such as atrazine, lindane) have an elevated risk of long menstrual cycles, anovulation, premature ovarian insufficiency, and the presence of endometriosis pathophysiologies.
Impact on placentation, embryonic defects, fetal development, recurrent miscarriage and female infertility
In our experience, in an IVF clinic in the Picardie region of France, we have observed that exposure to various pesticides, with an endocrine-disrupting action, are associated with poor oocyte quality (maturation and competency), embryonic defects, and poor IVF outcomes. Additionally, some pesticide compounds are linked to specific causes of female infertility, such as premature ovarian insufficiency, polycystic ovarian syndrome, and endometriosis. It was reported that EDCs can reduce embryo implantation rates, increase the chance of miscarriage, and increase the incidence of placental and post-natal abnormalities. EDCs can affect endometrium receptivity, leading to implantation failure, by modifying keys elements of the immune response relevant to pregnancy and immune tolerance. This can have a detrimental effect on placentation, fetal development, and can be a contributing risk factor in recurrent miscarriage, preeclampsia, and preterm birth.
Endocrine disrupting chemicals, DNA and disease risk
During pregnancy, exposure to EDCs during critical periods of fetal development can alter DNA methylation patterns, leading to inappropriate developmental gene expression and elevated disease risk. Moreover, EDCs can influence gene expression without modifying DNA sequences. It is commonly accepted that the transgenerational inheritance of parentally acquired traits is conveyed by epigenetic alterations also known as “epimutations”.
Conclusion
The negative impact of exposure to various endocrine-disrupting chemicals is becoming a worldwide public health issue. Indeed, the community should be informed about the fertility decline, low ongoing pregnancy rates, and elevated risk of miscarriage associated with exposure to high doses of pesticides for example. However, it is important to keep in mind that humans are exposed to EDCs mixtures composed of hundreds of chemicals every day and not a single chemical in isolation.
References
Moncef Benkhalifa (1,2,3), Debbie Montjean (2), Hafida Corsi-Cauet (3), Henri Copin (1,3), Véronique Bach (3), Pierre Miron (2), Rosalie Cabry (1,3)
- Reproductive Medicine and Reproductive Genetics, University Hospital & School of Medicine. Picardie University Jules Verne. Amiens, France
- Centres d’aide médicale à la procréation Fertilys, Laval and Brossard, Laval, Québec, Canada
- PERITOX Laboratory. Picardie University Jules Verne. Amiens, France
Publish on: May 7 2023 in Procréation | Fécondation in vitro
