Question

What is an endocrine disrupter? Give six examples. Pick two of the examples and describe the birth defects associated with the them, what is the molecular mechanism? What steps should pregnant women take to avoid the effects?

Answer 1

• Endocrine disruptors are substances which either mimic the function of hormone(acts as agonist) or interfere with the function of hormone. Endocrine disruptors can either be natural or man made compounds.
• Endocrine disruptors affect the function of the endocrine system mainly by either shutting off or shutting on the hormonal secretions, therefore altering the communication network throughout the body which is maintained by the endocrine system.
• Endocrine disruptors mainly function in ways i.e. by mimicking the action of hormones occuring naturally in the body, blocking the hormone binding site on receptor, and by altering the metabolism of hormone which result in altered hormonal activity.
• Some common examples of endocrine disruptors include DDT, Bisphenol A, Di(2 ethylhexyl) pthalate, genistein, daidzine and polychlorinated biphenyls, vinclozolin, coumesterol.
• Endocrine disruptors causing birth defects include pthalates and BPA. Pthalates can be found in food packaging materials, personal care products, and various building materials.
• Pthalates bind to epidermal growth factor receptors (EGFR) and modulate PPAR(peroxisome proliferator-activated receptor) which increases cellular stress, thus produces reactive oxygen species in placenta which harm the fetus and PI3/Akt pathway which are responsible for cell survival and differentiation.
• Pthalates are capable of crossing placenta therefore directly affect the foetus which result in premature birth lower birth rate and cardiovascular disease in newborn.
• Bisphenol A is used in production of plastics and epoxy resins. Exposure to BPA decreases levels of HCG ( human chorionic gonadotropin) in the first trimester which result in apoptosis of trophoblast cells, and inhibition of angiogenesis in uterus, BPA activates ERK signalling cascade, downregulating the expression of CYP 19 and CYP11A, which decrease aromatase activity of placenta therefore decreasing levels of estradiol and progesterone. BPA is also reported to inhibit wnt2/β catenin pathway which results in improper cell differentiation causing birth defects in the newborn.
• To avoid the effects of endocrine disruptors pregnant women should avoid smoking and polluted areas(polycyclic aromatic hydrocarbons present in smoke and pollution by products are endocrine disruptors which negatively affect the foetus), avoid used of packaged foods( due to presence of BPA), and should avoid Pthalate based personal care products.