|Endocrine disruptors: new threatenings for reproduction|
Endocrine disruption compounds (EDCs) represent one of the most controversial environmental issues of our époque. So far, many substances, both natural and artificial, have been recognized to interfere with endocrine signaling pathways. In intact laboratory animals, this interaction has been documented to generate adverse health outcomes by impairing normal functions. With regard to humans, evidence is limited and inconsistent to clearly establish a causal inference, however, accumulating data incriminate endocrine disrupting chemicals to reproductive (1). Also Exposure to specific environmental toxins, including polychlorinated biphenyls, dioxins, phthalates, polybrominated diphenyl ethers (PBDEs), and other halogenated organochlorines, has been shown to interfere with the production, transportation, and metabolism of thyroid hormones by a variety of mechanisms (2). Recently, as a result of animal models and preliminary human studies, a new area of interest has arisen concerning the implication of endocrine disruptors in the etiology of obesity and diabetes, the two major, life-threatening, epidemics of modern world (1).
Declining conception rates and the high incidence of female reproductive disruptions warrant evaluation of the impact of EDCs on female reproductive health. Publications related to the contribution of EDCs to disorders of the ovary (aneuploidy, polycystic ovary syndrome, and altered cyclicity), uterus (endometriosis, uterine fibroids, fetal growth restriction, and pregnancy loss), breast (breast cancer, reduced duration of lactation), and pubertal timing were identified and reviewed. EDCs contribute to numerous human female reproductive disorders and emphasize the sensitivity of early life-stage exposures. Many research gaps are identified that limit full understanding of the contribution of EDCs to female reproductive problems. Moreover, there is an urgent need to reduce the incidence of these reproductive disorders, which can be addressed by correlative studies on early life exposure and adult reproductive dysfunction together with tools to assess the specific exposures and methods to block their effects (3).
Earlier age at menarche is associated with higher PCB levels while risk of delay is associated with higher lead levels. Evidence that the timing of exposure produces different effects isobserved and may be relevant to a considerable proportion of the US population (4).
(1) Diamanti-Kandarakis, E., Palioura, E., Kandarakis, S.A., Koutsilieris, M., 2010. The Impact of Endocrine Disruptors on Endocrine Targets. Horm. Metab. Res. 23 Apr. [Epub ahead of print]
(2) Patrick, L., 2009. Thyroid disruption: mechanism and clinical implications in human health. Altern. Med. Rev. 14(4), 326-46.
(3) Crain, D.A., Janssen, S.J., Edwards, T.M., Heindel, J., Ho, S.M., Hunt, P., Iguchi, T., Juul, A., McLachlan, J.A., Schwartz, J., Skakkebaek, N., Soto, A.M., Swan, S., Walker, C., Woodruff, T.K., Woodruff, T.J., Giudice, L.C., Guillette, L.J.Jr., 2008. Female reproductive disorders: the roles of endocrine-disrupting compounds and developmental timing. Fertil. Steril. 90(4), 911-40.
(4) Schell, L.M., Gallo, M.V., 2010. Relationships of putative endocrine disruptors to human sexual maturation and thyroid activity in youth. Physiol. Behav. 99(2), 246-53.