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Front. Endocrinol. | doi: 10.3389/fendo.2019.00799

Editorial on Frontiers Research Topic: Organotins as a Complete Physiologic and Endocrine Disruptor: Role of Disease Development

  • 1Department of Morphology, Health Sciences Center, Federal University of Espirito Santo, Brazil

The tin metal and its alloys have a historic important role of humanity. Studies reported existence of organotin since 1853, however they did not become important for industrial use until the 1940-1960s. Organotins are synthetic chemical tetravalent derivatives of tin (IV) with a general formula of R(4-n) SnXn, where R represents organic substituents and X can be a halide, anion, or an organic group linked covalently through a heteroatom (O, N, S, Cl, etc.) (1). Mono-, di-, tri-, and tetra-organotin have many industrial and agricultural applications, including as PVC catalysts and broad-spectrum biocides (agricultural fungicides, wood preservatives, as well as in antifouling paints for marine vessels) (2). As consequence, the main inputs of triorganotin tributyltin (TBT) into the environment are contaminated water and sediments originating from harbors due improper disposal of antifouling products. TBT has a degradation half-life of days to months in water and up to several years in sediment (3). TBT is very accumulative in different organisms along of food chain; however, its bioaccumulation does not follow environmental equilibrium partitioning (4). Aquatic organisms can be exposed by the water column, sediments and ingestion of contaminated food. Terrestrial organisms may also be exposed via organotin and TBT-contaminated sediments and by ingestion of contaminated food or water (5). Therefore, for the general population, the main route of exposure to most organotin is ingestion, through the consumption of contaminated water, beverages, and food, particularly marine foods (6).Previous studies reported that TBT use as the active component in the marine antifouling ship paints has increased because of its particularly potent algicide/molluscicide actions (7, 8).Historically, organotin exposure (mainly as TBT) was able to leads imposex development, the abnormal induction of male sex characteristics in female gastropod mollusks, representing one the clearest examples of environmental endocrine disruption (2). In addition, other study has shown that TBT exposure can also induce masculinization in fish species (8). Widespread environmental contamination of marine ecosystems with TBT began in the 1960s, leading to several adverse effects in numerous organisms. Therefore, for this motive, its use in antifouling ship paints was prohibited by the International Marine Organization (IMO) in 2008 (9). However, beyond its continued utilization in agriculture, industrial and other processes, it is possible that TBT is still employed in some parts of the world, particularly in countries that are not included in the Antifouling Systems (AFS) convention and/or with poor environmental monitoring/supervision (10). Unfortunately, previous investigation has confirmed that recreational vessels sampled from countries around the Baltic Sea still contain high TBT levels in their paints and may be a source to the environment (11). Other important recent study has shown a higher contamination of organotin in commercial and wild oysters from China (12).From previous studies, we learned that organotin are a diverse organometallic group of widely distributed environmental pollutants and today more than 800 organotin are known.Organotins have pleiotropic toxicological effects on both invertebrate and vertebrate endocrine systems. Organotins, as well as a TBT story is distant from reaching an end; in fact, the discovery of its new potential endocrine disrupting chemicals actions placed it again at the forefront of scientific research. In the USA, more than 80,000 chemicals are registered with the Environmental Protection Agency (EPA), some of which are known or potential endocrine disrupting chemicals (EDCs). About 1000 synthesized chemicals are considered to be EDCs, defined as "exogenous chemical Various in vitro and in vivo studies with crustaceans, gastropods, amphibians, fish, rodents and humans demonstrated that TBT is able to interfere with many physiologic processes, thereby inducing complex toxic effects (13,14,15). A wide range of detrimental responses are observed in mollusks, fish and amphibians exposed to low levels of TBT (0.1-100ng/L), such as imposex, apoptosis, irregular metamorphosis and other important abnormalities (16,17,18).Additionally, organotin may accumulate in birds and sea mammals leading to reproductive and metabolic dysfunctions (19,20). In rodent models, toxicological studies have shown reproductive, metabolic, cardiovascular, renal, neural, immunologic and other abnormalities using different TBT doses (100ng -100mg/Kg) (15, 21). Therefore, data in different animal models demonstrate the deleterious effects of TBT exposure on multiple organ-systems.TBT is a obesogenic chemical (EDC-subclass) that to induce obesity and other metabolic complications by increasing the number of fat cells (and fat storage into existing fat cells), changing the number of calories burned at rest, altering energy balance to favor storage of calories, and altering the mechanisms through which the body regulates appetite and satiety (21,22,23). Therefore, obesogen chemical display the potential to disrupt multiple metabolic signaling pathways in the developing organism that might result in permanent changes in adult physiology (21,22,23). Many of the TBT-initiated obesogenic effects are mediated through metabolic PPAR-γ signaling, which acts as a key regulator of adipocyte differentiation and as a transcriptional regulator and/or effector of target genes, such as C/EBP (CCAAT/enhancer binding proteins), AFABP (adipocyte-specific fatty acid-binding protein), and FATP (fatty acid transport protein) (21,22,23).This research topic brings together 9 review papers on the different and complex toxicologic role of organotin on environment, wild species, such as crustaceans, gastropods, amphibians, fish, as well as rodents and humans' experimental models. Understanding the interplay between organotin, as well as TBT exposure from different sources and physiologic abnormalities are highly relevant for wild life and human health. Clearly, research in this field is advancing at a rapid pace. The articles in this Research Topic highlight novel findings and unanswered questions for future investigation.

Keywords: Organotins, Endocr disrupting chemicals, Physiology, dysfunction, Disease

Received: 07 Oct 2019; Accepted: 01 Nov 2019.

Copyright: © 2019 Graceli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Jones B. Graceli, Department of Morphology, Health Sciences Center, Federal University of Espirito Santo, Vitoria, 29.040-090, Brazil, jbgraceli@gmail.com