Endocrine disruptors and thyroid function - a relationship? A systematic review about thyroid effects of endocrine disruptors

摘要

Endocrine disruptors (ED) are several widespread compounds, either natural or artificial, that can alterthe physiological homeostasis of the natural blood born substances and which actually represent a controversialenvironmental topic for public health. This study is a systematic review about the relationship between EDs andthyroid dysfunctions in order to clarify the dispute or actualize the problem.PubMed and the Cochrane Library were searched systematically for English, Italian and Spanishpublications on the EDs human health effect on thyroid function. All in vivo study designs were included. Tworeviewers conducted the research independently, in February 2012, using the specific keywords/mesh terms.At the end of the review process 98 primary studies and 61 reviews were selected of 1581 primarystudies and 239 reviews initially found. 78 of them were already described in the five most recent reviews (2008-2010) on this topic; the reviews had been summarized and updated with the 20 studies not included in them.Our study underlines a relationship between ED exposure and FT3, FT4 and TSH alteration, especiallyfor polychlorinated biphenyl, polybromophenyl ether, perchlorate, dioxins/dioxin and bisphenol A. However nostudy shows a significant relationship with any pathological and clinical expression of thyroid disease, mainlydue to several confounding variables in the observational studies, both environmental and genetic. Major riskconditions are represented by pregnancy status and breast feeding due to the importance of the thyroid hormonesin fetal neurodevelopment.Despite most studies declaring they needed further research about this topic to settle the relationshipbetween ED and thyroid disease, most authors were worried about the potential health effects on severalendocrine targets and in frail conditions. They recommended a precautionary and integrated approach based onprimary prevention activities, through screening and health education campaigns, and the reduction orelimination of these substances as suggested by internationalconferences. This opens the possibility forinnovative collaboration between medical research, hygiene prevention and international legislation in the hopeto set up a new dimension in the approach to many diseases.