Tributyltin (TBT) is a widely used organotin compound around the world and was frequently detected in surface waters, which would pose risk to aquatic organisms. However, the mechanisms of TBT-induced toxicity is not full clear. The present study investigated the effects of the tributyltin (TBT) on the blood parameters, immune responses and thyroid hormone system in zebrafish. Fish were exposed to sublethal concentrations of TBT (10 ng/L, 100 ng/L and 300 ng/L) for 6 weeks. The effects of long-term exposure to TBT on blood parameters (NH3, ammonia; GLU, glucose; TP, total proteins; CK, creatine kinase; ALT, alanine aminotransferase; AST, aspartate aminotransferase), immune responses (Lys, lysozyme; IgM, immunoglobulin M) and some indexes related thyroid hormone system (T3, 3,5,3′-triiodothyronine; T4, thyroxine) were measured in zebrafish, as well as the expression of genes related to immune responses and thyroid hormone system. Based on the results, the physiological-biochemical responses was significantly enhanced with an increase in TBT concentration, reflected by the abnormal blood indices, dysregulation of endocrine system and immunotoxicity in zebrafish under TBT stress. The present study greatly extends our understanding of adverse effects of TBT on aquatic organisms.

Tributyltin (TBT), an organotin compound once widely used in agriculture and industry, has been reported to induce obesity and endocrine disruption. Gut microbiota has a strong connection with the host’s physiology. Nevertheless, the influences of TBT exposure on gut microbiota and whether TBT-influenced gut microbiota is related to TBT-induced toxicity remain unclear. To fill these gaps, ICR (CD-1) mice were respectively exposed to TBT at NOEL (L-TBT) and tenfold NOEL (H-TBT) daily by gavage for 8 weeks in the current study. The results showed that TBT exposure significantly increased body weight as well as epididymal fat, and led to adipocyte hypertrophy, dyslipidemia and impaired glucose and insulin homeostasis in mice. Additionally, TBT exposure significantly decreased the levels of T4, T3 and testosterone in serum. Also of note, TBT exposure changed gut microbiota composition mainly by decreasing Bacteroidetes and increasing Firmicutes proportions. To confirm the role of gut microbiota in TBT-induced overweight and hormonal disorders, fecal microbiota transplantation was performed and the mice receiving gut microbiota from H-TBT mice had similar phenotypes with their donor mice including significant body weight and epididymal fat gain, glucose and insulin dysbiosis and hormonal disorders. These results suggested that gut microbiome altered by TBT exposure was involved in the TBT-induced increased body weight, impaired glucose and insulin homeostasis and endocrine disruption in mice, providing significant evidence and a novel perspective for better understanding the mechanism by which TBT induces toxicity.

Tributyltin (TBT) is an organotin environmental pollutant widely used as an agricultural and wood biocide and in antifouling paints. Countries began restricting TBT use in the 2000s, but their use continues in some agroindustrial processes. We studied the acute effect of TBT on cardiac function by analyzing myocardial contractility and Ca²⁺ handling. Cardiac contractility was evaluated in isolated papillary muscle and whole heart upon TBT exposure. Isolated ventricular myocytes were used to measure calcium (Ca²⁺) transients, sarcoplasmic reticulum (SR) Ca²⁺ content and SR Ca²⁺ leak (as Ca²⁺ sparks). Reactive oxygen species (ROS), as superoxide anion (O2•⁻) was detected at intracellular and mitochondrial myocardium. TBT depressed cardiac contractility and relaxation in papillary muscle and intact whole heart. TBT increased cytosolic, mitochondrial ROS production and decreased mitochondrial membrane potential. In isolated cardiomyocytes TBT decreased both Ca²⁺ transients and SR Ca²⁺ content and increased diastolic SR Ca²⁺ leak. Decay of twitch and caffeine-induced Ca²⁺ transients were slowed by the presence of TBT. Dantrolene prevented and Tiron limited the reduction in SR Ca²⁺ content and transients. The environmental contaminant TBT causes cardiotoxicity within minutes, and may be considered hazardous to the mammalian heart. TBT acutely induced a negative inotropic effect in isolated papillary muscle and whole heart, increased arrhythmogenic SR Ca²⁺ leak leading to reduced SR Ca²⁺ content and reduced Ca²⁺ transients. TBT-induced myocardial ROS production, may destabilize the SR Ca²⁺ release channel RyR2 and reduce SR Ca²⁺ pump activity as key factors in the TBT-induced negative inotropic and lusitropic effects.

Imposex is a disorder caused by organotins, mainly tributyltin, which results in the appearance of male sexual characteristics in females of gastropod mollusks. The main objective of this work was to make a critical analysis of the relationship between imposex and butyltin body burdens in Nucella lapillus and Nassarius reticulatus. Specifically, this study evaluates possible additive effects among butyltins, proposes scales of effects based on robust statistical criteria as alternatives to existing ones and defines the body burdens of TBT in N. lapillus and N. reticulatus corresponding to the assessment classes (ACs) of the Vas Deferens Sequence Index (VDSI) established by OSPAR. Data of organotin body burdens and biological effects was retrieved from the ICES Dataset and from scientific literature. All responses, except the percentage of females displaying Imposex (IMPF) in Nucella lapillus, showed a sigmoidal profile regarding to the body burden of mono- (MBT), di- (DBT) and tributyltin and sum of butyltins (SumBTs). TBT and the SumBTs were better indicators of the VDSI or Relative Penis Size Index/Relative Penis Length Index (RPSI/RPLI) responses than MBT or DBT in most cases. From a statistical point of view, RPSI/RPLI and VDSI were better indicators of contamination by TBT than IMPF, although both RPSI and RPLI showed lower sensitivity than VDSI. The model used for describing the joint effect of butyltins provided a statistically significant fitting to the data assuming a null effect for both MBT and DBT for N. lapillus, and a lower toxic contribution of MBT and DBT with respect to TBT for N. reticulatus. RPSI or RPLI values, equivalent to the ACs for VDSI, were proposed as alternative criteria when measuring moderate to high levels of imposex. TBT concentrations in N. reticulatus and N. lapillus tissues, corresponding to the ACs were calculated and provided valuable information for cross-species comparisons.

Tributyltin is a biocide used in nautical paints, aiming to reduce fouling of barnacles in ships. Despite the fact that many effects of TBT on marine species are known, studies in mammals have been limited, especially those evaluating its effect on the function of the hypothalamus-pituitary-thyroid (HPT) axis. The aim of this study was to investigate the effects of subchronic exposure to TBT on the HPT axis in female rats. Female Wistar rats received vehicle, TBT 200 ng kg−1 BW d−1 or 1000 ng kg−1 BW d−1 orally by gavage for 40 d. Hypothalamus, pituitary, thyroid, liver and blood samples were collected. TBT200 and TBT1000 thyroids showed vacuolated follicular cells, with follicular hypertrophy and hyperplasia. An increase in epithelial height and a decrease in the thyroid follicle and colloid area were observed in TBT1000 rats. Moreover, an increase in the epithelium/colloid area ratio was observed in both TBT groups. Lower TRH mRNA expression was observed in the hypothalami of TBT200 and TBT1000 rats. An increase in Dio1 mRNA levels was observed in the hypothalamus and thyroid in TBT1000 rats only. TSH serum levels were increased in TBT200 rats. In TBT1000 rats, there was a decrease in total T4 serum levels compared to control rats, whereas T3 serum levels did not show significant alterations. We conclude that TBT exposure can promote critical abnormalities in the HPT axis, including changes in TRH mRNA expression and serum TSH and T4 levels, in addition to affecting thyroid morphology. These findings demonstrate that TBT disrupts the HPT axis. Additionally, the changes found in thyroid hormones suggest that TBT may interfere with the peripheral metabolism of these hormones, an idea corroborated by the observed changes in Dio1 mRNA levels. Therefore, TBT exposition might interfere not only with the thyroid axis but also with thyroid hormone metabolism.

Despite their ban on small vessels in 1989 in the EU, organotin compounds (OTCs) are still being released into the environment due to their presence in historic paint layers on leisure boats. 23 paint samples scraped from recreational boats from three countries around the Baltic Sea were analyzed for total tin (Sn) and OTCs. Two antifouling paint products were also subjected to the same analyses. A new method for the detection of Sn in paint flake samples was developed and found to yield more accurate results compared to four different acid digestion methods. A new method was also developed for the extraction of OTCs from ground paint flakes. This endeavor revealed that existing methods for organotin analysis of sediment may not have full recoveries of OTCs if paint flakes are present in the sample. The hull paint samples had Sn concentrations ranging from 25 to 18,000 mg/kg paint and results showed that tributyltin (TBT) was detected in all samples with concentrations as high as 4.7 g (as Sn)/kg paint. TBT was however not always the major OTC. Triphenyltin (TPhT) was abundant in many samples, especially in those originating from Finland. Several other compounds such as monobutyltin (MBT), dibutyltin (DBT), tetrabutyltin (TeBT), monophenyltin (MPhT) and diphenyltin (DPhT) were also detected. These could be the result of degradation occurring on the hull or of impurities in the paint products as they were also identified in the two analyzed paint products. A linear correlation (r2 = 0.934) was found between the total tin content and the sum of all detected OTCs. The detection of tin can therefore be used to indicate the presence of OTCs on leisure boats.

Probabilistic environmental quality criteria for Naphthalene (Nap), Phenanthrene (Phe), Fluoranthene (Flu), Pyrene (Pyr), Triclosan (TCS), Tributyltin (TBT), Chlorpyrifos (CPY), Diuron (DUR), γ-Hexaclorocyclohexane (γ-HCH), Bisphenol A (BPA) and 4-Nonylphenol (4-NP) were derived from acute toxicity data using saltwater species representative of marine ecosystems, including algae, mollusks, crustaceans, echinoderms and chordates. Preferably, data concerns sublethal endpoints and early life stages from bioassays conducted in our laboratory, but the data set was completed with a broad literature survey. The Water Quality Criteria (WQC) obtained for TBT (7.1·10⁻³ μg L⁻¹) and CPY (6.6· 10⁻³ μg L⁻¹) were orders of magnitude lower than those obtained for PAHs (ranging from 3.75 to 45.2 μg L⁻¹), BPA (27.7 μg L⁻¹), TCS (8.66 μg L⁻¹) and 4-NP (1.52 μg L⁻¹). Critical values for DUR and HCH were 0.1 and 0.057 μg L⁻¹ respectively. Within this context, non-selective toxicants could be quantitatively defined as those showing a maximum variability in toxicity thresholds (TT) of 3 orders of magnitude across the whole range of marine diversity, and a cumulative distribution of the TT fitting to a single log-logistic curve, while for selective toxicants variability was consistently found to span 5 orders of magnitude and the TT distribution showed a bimodal pattern. For the latter, protective WQC must be derived taking into account the SSD of the sensitive taxa only.

The presence of organic pollutants in the aquatic environment, usually found at trace concentrations (i.e., between ng L−1 and μg L−1 or even lower, known as micropollutants), has been highlighted in recent decades as a worldwide environmental concern due to their difficult elimination by conventional water and wastewater treatment processes. The relevant information on constructed wetlands (CWs) and their application for the removal of a specific group of pollutants, 41 organic priority substances/classes of substances (PSs) and 8 certain other substances with environmental quality standards (EQS) listed in Directive 2013/39/EU as well as 17 contaminants of emerging concern (CECs) of the Watch List of Decision 2015/495/EU, is herein reviewed. Studies were found for 24 PSs and 2 other substances with EQS: octylphenol, nonylphenol, perfluorooctane sulfonic acid, di(2-ethylhexyl)phthalate, trichloromethane, dichloromethane, 1,2-dichloroethane, pentachlorobenzene, benzene, polychlorinated dibenzo-p-dioxins, naphthalene, fluoranthene, trifluralin, alachlor, isoproturon, diuron, tributyltin compounds, simazine, atrazine, chlorpyrifos (chlorpyrifos-ethyl), chlorfenvinphos, hexachlorobenzene, pentachlorophenol, endosulfan, dichlorodiphenyltrichloroethane (or DDT) and dieldrin. A few reports were also published for 8 CECs: imidacloprid, erythromycin, clarithromycin, azithromycin, diclofenac, estrone, 17-beta-estradiol and 17-alpha-ethinylestradiol. No references were found for the other 17 PSs, 6 certain other substances with EQS and 9 CECs listed in EU legislation.

Microplastics are ubiquitous in natural waters and affect the environmental fate of hydrophobic organic micropollutants. This study evaluated the impacts of four microplastics, polypropylene (PP), polyethylene (PE), polystyrene (PS) and polymethyl methacrylate (PMMA), on the photodegradation of organotin compounds (OTCs) under UV₃₆₅ irradiation (2.3 ± 0.1 W m⁻²). The experiments were performed by mixing PP, PE, PS or PMMA microparticles with tri-organotins in artificial seawater. The photodegradation of OTCs in microplastic suspensions was influenced by the absorptivity onto microplastics. The decomposition rate of tributyltin (TBT) in UV-irradiated PP suspensions was greater than trimethyltin (TMT) and triphenyltin (TPhT) (p < 0.01). The adsorption capacities of OTCs (e.g., TBT) on PP particle surfaces were significantly lower than those on PE surfaces (p < 0.05) but similar with those on PMMA due to the different surface areas, shapes, and surface hydrophobicity of microplastics. TBT degraded faster (9.1%) in PS than in PMMA suspension (11.2%) within 240 min, respectively. However, only less than 5.4% was photodegraded in PP suspension due to the light scattering or absorption of the large sized PP particles. This study provided new insight into the impacts of microplastics on photodegradation of micropollutants in natural waters.

The analysis of lipid disruption in invertebrates is limited by our poor knowledge of their lipidomes and of the associated metabolic pathways. For example, the mechanism by which exposure of the crustacean Daphnia magna to tributyltin, juvenoids, or bisphenol A increase the accumulation of storage lipids into lipid droplets is largely unknown/presently unclear. Here we analyze transcriptome changes subsequent to this lipid accumulation effect induced by either the pesticide pyriproxyfen (a juvenoid agonist), the plasticizer bisphenol A, or the antifouling agent tributyltin. Changes in the whole transcriptome were assessed after 8 and 24 h of exposure, the period showing the greatest variation in storage lipid accumulation. The three compounds affected similarly to a total of 1388 genes (965 overexpressed and 423 underexpressed transcripts), but only after 24 h of exposure. In addition, 225 transcripts became up-regulated in samples exposed to tributyltin for both 8 h and 24 h. Using D. melanogaster functional annotation, we determined that upregulated genes were enriched in members of KEGG modules implicated in fatty acid, glycerophospholipid, and glycerolipid metabolic pathways, as well as in genes related to membrane constituents and to chitin and cuticle metabolic pathways. Conversely, down-regulated genes appeared mainly related to visual perception and to oocyte development signaling pathways. Many tributyltin specifically upregulated genes were related to neuro-active ligand receptor interaction signaling pathways. These changes were consistent with the phetotypic effects reported in this and in previous studies that exposure of D. magna to the tested compounds increased lipid accumulation and reduced egg quantity and quality.