Imposex occurrence in marine whelks at a military facility in the high Arctic

Organotins in fish, shrimp, and cephalopods from the Pearl River Estuary, China: Dietary exposure risk to Indo-Pacific humpback dolphin and human

Food has regularly been proven to be a key source of exposure to environmental pollutants, drawing attention to the dietary exposure risks of contaminants to mammals with significant daily food intake. Here, the levels of six organotin compounds (OTs) in 18 fish (n = 310), three cephalopods (n = 50), and one shrimp (n = 34) from the Lingdingyang (LDY) and west four region (WFR) of the Pearl River Estuary (PRE) and their dietary exposure risks to Indo-Pacific humpback dolphins and humans were first investigated. Total OT levels ranged from 3.84 to 901. 48 ng/g wet weight (ww) in 22 prey species from the LDY, and from 14.37 to 1364.64 ng/g ww in 19 species from the WFR. The LDY marine species generally accumulated higher butyltin levels but lower phentyltin levels than those in the WFR. All species have a phenyltin degradation index <1 and over 60 % of the sampled species have a butyltin degradation index <1, suggesting the PRE marine species might be exposed to the fresh discharge of OTs. A total of nine marine species exceeded the threshold levels of OT intake for adverse health effects on human juveniles by consumption, all 22 marine species posed high dietary risks to the PRE humpback dolphins. Moreover, probabilistic risk assessment using Monte Carlo simulation revealed that the probabilities of RQ values associated with WFR OT exposure higher than 1 were 18.87 % for human adults, 40.55 % for human juveniles, 100 % for both humpback dolphin adults and humpback dolphin juveniles. Our results highlighted the potentially high dietary exposure risks of OTs to marine mammals and residents in the PRE.

Review on endocrine disrupting toxicity of triphenyltin from the perspective of species evolution: Aquatic, amphibious and mammalian

Triphenyltin (TPT) is widely used as a plastic stabilizer, insecticide and the most common fungicide in antifouling coatings. This paper reviewed the main literature evidences on the morphological and physiological changes of animal endocrine system induced by TPT, with emphasis on the research progress of TPT metabolism, neurological and reproductive regulation in animal endocrine system. Similar to tributyltin (TBT), the main effects of TPT on the potential health risks of 25 species of animals, from aquatic animals to mammals, are not only related to exposure dose and time, but also to age, sex and exposed tissue/cells. Moreover, current studies have shown that TPT can directly damage the endocrine glands, interfere with the regulation of neurohormones on endocrine function, and change hormone synthesis and/or the bioavailability (i.e., in the retinoid X receptor and peroxisome proliferator-activated receptor gamma RXR-PPARγ) in target cells. Importantly, TPT can cause biochemical and morphological changes of gonads and abnormal production of steroids, both of which are related to reproductive dysfunction, for example, the imposex of aquatic animals and the irregular estrous cycle of female mammals or spermatogenic disorders of male animals. Therefore, TPT should indeed be regarded as a major endocrine disruptor, which is essential for understanding the main toxic effects on different tissues and their pathogenic effects on endocrine, metabolism, neurological and reproductive dysfunction.

Pollutants from shipping - new environmental challenges in the subarctic and the Arctic Ocean

Maritime activities in the subarctic and Arctic Ocean are predicted to substantially increase in the future due to climate change and declining sea ice cover. Inevitably, the consequences will be seen in impacts on marine ecosystems in this region at many different levels, such as increased pollution load due to antifouling biocides, polycyclic aromatic hydrocarbons, metals and pharmaceuticals. Here we discuss the current situation and evaluate the effect of increased shipping on the environmental status of subarctic and Arctic waters, in relation to elevated loads of both legacy and emerging pollutants in the region. It is of high importance to evaluate the current levels of selected pollutants, which will most likely rise in near future. Furthermore, it is important to improve our understanding of the effects of these pollutants on marine organisms at high latitudes, as the pollutants may behave differently in cold environments compared to organisms at lower latitudes, due to dissimilar physiological responses and adaptations of the cold-water organisms. Integrative studies are needed to better understand the impact of pollutants on the marine fauna while monitoring programmes and research should be continued, with an increased capacity for emerging pollutants of concern.

Organotin contamination in commercial and wild oysters from China: Increasing occurrence of triphenyltin

Organotin contamination in marine environment has been a public concern for many years due to its adverse impacts on biota and human health. This study investigated levels, distribution and health risks of six organotin compounds: tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT) and monophenyltin (MPhT) in commercial and wild oysters in China. The total organotin in commercial oysters ranged from 251 to 1949 ng Sn g^-1 dw (dry weight) >. Two endocrine disruptors TBT and TPhT were detected in these samples with the highest level of 68.1 ± 20.1 ng Sn g^-1 dw and 747 ± 7.3 ng Sn g^-1 dw, respectively. For wild oysters, the concentrations of total organotins varied from 33.3 to 2671 ng Sn g^-1 dw. Butyltins were dominated by TBT with the mean level of 26.1 ± 30.0 ng Sn·g^-1 dw and showed no significant spatial variation between the southern and northern coastal zones (p > 0.05). However, compared with the north, phenyltin levels especially TPhT were much higher in the south coastline (246-1484 ng Sn·g^-1 dw) due to the wider use of TPhT-based biocides in local mariculture and agriculture. Health risk assessment indicated that a daily exposure of TPhT-contaminated oysters (including commercial and wild ones) may pose adverse threats to human particularly children as the risk quotients (RQ) were higher than 1. Organotin contamination (e.g., TPhT) still occurs in the South China's coastal zones after the TBT ban, which deserves future research and effective measures to protect the marine ecosystem and human health.

Size, season and origin of gastropods matter in imposex assessments

Through controlled exposure to tributyltin (TBT), the effects of season, size, and population origin were evaluated on imposex incidence in Stramonita brasiliensis. Four experiments were carried out with organisms collected from three different sites on the Brazilian coast (Torres - Rio Grande do Sul, Farol de Santa Marta - Santa Catarina, and Aracruz - Espírito Santo). S. brasiliensis were anesthetized, sexed, measured, classified by size in small (< 30 mm), medium (≥ 30 to ≤ 40 mm), or big (> 40 mm) and injected in the foot muscle with 0.5 μg g^-1 of TBT. Organisms were maintained during one month in aquariums with clear marine water under controlled laboratory conditions. One month after injection, the imposex assessments showed that the population from the southeast (tropical) region was more sensitive to TBT than the population from the south of Brazil (the temperate region). A greater sensitivity in the small and medium categories was observed. Females were also more susceptible to TBT when exposed during their reproductive period. Thus, the present study highlighted the need to ensure that intrinsic biological factors related to organisms are considered in such biomonitoring studies to avoid misinterpretation of results.

From TBT to booster biocides: Levels and impacts of antifouling along coastal areas of Panama

Antifouling biocides in surface sediments and gastropod tissues were assessed for the first time along coastal areas of Panama under the influence of maritime activities, including one of the world's busiest shipping zones: the Panama Canal. Imposex incidence was also evaluated in five muricid species distributed along six coastal areas of Panama. This TBT-related biological alteration was detected in three species, including the first report in Purpura panama. Levels of organotins (TBT, DBT, and MBT) in gastropod tissues and surficial sediments ranged from <5 to 104 ng Sn g^-1 and <1-149 ng Sn g^-1, respectively. In addition, fresh TBT inputs were observed in areas considered as moderate to highly contaminated mainly by inputs from fishing and leisure boats. Regarding booster biocides, TCMTB and dichlofluanid were not detected in any sample, while irgarol 1051, diuron and DCOIT levels ranged from <0.08 to 2.8 ng g^-1, <0.75-14.1 ng g^-1, and <0.38-81.6 ng g^-1, respectively. The highest level of TBT (149 ng Sn g^-1) and irgarol 1051 (2.8 ng g^-1), as well as relevant level of DCOIT (5.7 ng g^-1), were detected in a marina used by recreational boats. Additionally, relatively high diuron values (14.1 ng g^-1) were also detected in the Panama Canal associate to a commercial port. DCOIT concentrations were associated with the presence of antifouling paint particles in sediments obtained nearby shipyard or boat maintenance sites. The highest levels of TBT, irgarol 1051, and diuron exceeded international sediment quality guidelines indicating that toxic effects could be expected in coastal areas of Panama. Thus, the simultaneous impacts produced by new and old generations of antifouling paints highlight a serious environmental issue in Panamanian coastal areas.

Intersexuality in aquatic invertebrates: Prevalence and causes

This review is the first assembling information on intersexuality in aquatic invertebrates, from freshwater to estuarine and marine environments. Intersex is a condition whereby an individual of a gonochorist (separate sexes) species has oocytes or distinct stages of spermatogonia, at varying degrees of development, within the normal gonad of the opposite gender (i.e. spermatocytes in the ovary or oocytes in the testis), often involving alterations in the gonadal structure, reproductive tract or external genitalia. By the end of 2016 we found approximately 340 records of aquatic invertebrate species evidencing signs of intersexuality (or imposex), all comprised within the Phyla Mollusca and Arthropoda. Gastropod molluscs are by far the group with more examples documented (256 species), followed by crustaceans, i.e., decapods, copepods and amphipods. To our knowledge no further cases of intersexuality were known concerning other invertebrate taxa. Despite some reports suggesting that a baseline level of intersexuality may occur naturally in some populations, the causes are multifaceted and mostly linked with environmental contamination by estrogenic and organotin endocrine disrupting chemicals (EDCs), parasitism, and genetic/environmental sex determination abnormalities. A more comprehensive discussion about the origin of intersexuality, prevalence and causes, knowledge gaps and future research directions in the light of new omics scientific advances (genomics, proteomics and transcriptomics) is also provided. The lack of studies linking molecular responses of invertebrate intersex individuals to multiple stressors represents a true challenge to be further investigated in the future.

Tributyltin--critical pollutant in whole water samples--development of traceable measurement methods for monitoring under the European Water Framework Directive (WFD) 2000/60/EC

Tributyltin is listed as one of the priority substances in the European Water Framework Directive (WFD). Despite its decreasing input in the environment, it is still present and has to be monitored. In the European Metrology Research Programme project ENV08, a sensitive and reliable analytical method according to the WFD was developed to quantify this environmental pollutant at a very low limit of quantification. With the development of such a primary reference method for tributyltin, the project helped to improve the quality and comparability of monitoring data. An overview of project aims and potential analytical tools is given.

Investigation on the interaction between endocrine disruptor triphenyltin with human serum albumin

The interaction between triphenyltin (TPT) and human serum albumin (HSA) in physiological buffer (pH=7.4) was investigated by the fluorescence quenching technique. The results of fluorescence titration revealed that TPT could strongly quench the intrinsic fluorescence of HSA through a static quenching procedure. The apparent binding constants K and number of binding sites n of TPT with HSA were 2.51×10(3) and 0.96 at 298 K which were obtained by the fluorescence quenching method. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) were positive, which indicated that the interaction of TPT with HSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance r between donor (HSA) and acceptor (TPT) was calculated to be 3.13 nm based on Forster's non-radiative energy transfer theory. The results of synchronous fluorescence, three-dimensional fluorescence and circular dichroism (CD) spectra showed that the triphenyltin induced conformational changes of HSA.

Studies on the interaction between triphenyltin and bovine serum albumin by fluorescence and CD spectroscopy

The interaction between triphenyltin (TPT) and bovine serum albumin (BSA) in physiological buffer (pH=7.4) was investigated by the fluorescence quenching technique. The results of fluorescence titration revealed that TPT could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The apparent binding constants K and number of binding sites n of TPT with BSA were (7.04±0.0057)×10(2) and (0.77±0.016) which were obtained by the fluorescence quenching method. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) were positive, which indicated that the interaction of TPT with BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance r between donor (BSA) and acceptor (TPT) was calculated to be 3.05nm based on Forster's non-radiative energy transfer theory. The results of synchronous fluorescence, three-dimensional fluorescence and Circular Dichroism (CD) spectra showed that the triphenyltin induced conformational changes of BSA.

Exposure to tributyltin and triphenyltin induces DNA damage and alters nucleotide excision repair gene transcription in Sebastiscus marmoratus liver

Tributyltin (TBT) and triphenyltin (TPT) coexist in the aquatic environment. However, the effects of TBT, TPT and a mixture of the two on DNA damage in marine fish livers and the mechanism involved remain to be elucidated. In the present study, we assessed their ability to cause hepatic DNA damage in Sebastiscus marmoratus liver and we investigated the related mechanism. The results showed that TBT, TPT and the mixture significantly decreased liver DNA integrity in a dose-dependent manner. Using Pearson correlation coefficient analysis, we identified that the hepatic total tin concentration was significantly correlated with hepatic DNA integrity after exposure to TBT alone and combined exposure to TBT and TPT. In order to clarify the mechanism which influences DNA repair, the mRNA levels of nucleotide excision repair (NER) genes were determined using real-time PCR analysis. The results showed that NER gene expression levels were disturbed. The expression of XPB, ERCC1, and DNA Pol ɛ was significantly decreased after treatment with TBT, TPT and the mixture, while the expression of PCNA, HR23B, XPG, and DNA lig III was significantly increased in treated-groups compared to the control. Based on this, we proposed that TBT, TPT and a mixture of the two induced DNA damage in marine fish livers by altering the transcription levels of the NER genes.

Long-term temporal trends (1992-2008) of imposex status associated with organotin contamination in the dogwhelk Nucella lapillus along the Icelandic coast

Using the dogwhelk Nucella lapillus as a biomonitor, we evaluated the organotin contamination along the Icelandic coast over nearly two decades. In 2008, adult dogwhelks collected from 30 locations were examined for imposex status. In 2009, tissue concentrations of six organotin species in dogwhelks from 16 of the 30 locations were analysed using gas chromatography-mass spectrometry. Tributyltin was the most predominant residue ranging from 2.07 to 70.38 μg kg(-1) dw, while triphenyltin was also detected at concentrations up to 22.79 μg kg(-1) dw. Higher total organotin concentrations and imposex indices were observed at locations near large harbours (Reykjavík and Hafnarfjörður). By comparing the current imposex results with those of previous surveys (1992-2003), we found that recovery was slow near the large harbours, but more apparent near the smaller harbours. We also observed a notable increase in imposex at several northwest sites implying incessant input of organotins.

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

Prosobranch snails have been afflicted globally by a condition whereby females develop male sex characteristics, most notably a penis. This condition, known as imposex, has been causally associated with the ubiquitous environmental contaminant tributyltin (TBT). Deduction of the mechanism by which TBT causes imposex has been hampered by the lack of understanding of the normal endocrine regulation of reproductive tract recrudescence in these organisms. We have reviewed the relevant literature on the environmental and endocrine factors that regulate reproductive tract recrudescence, sexual differentiation, and reproduction in gastropods. We provide a cohesive model for the environmental-endocrine regulation of reproduction in these organisms, and use this information to deduce a most likely mechanism by which TBT causes imposex. Photoperiod appears to be the predominant environmental cue that regulates reproductive tract recrudescence. Secondary cues include temperature and nutrition which control the timing of breeding and egg laying. Several hormone products of the central and peripheral nervous systems have been identified that contribute to recrudescence, reproductive behaviors, oocyte maturation and egg laying. Retinoic acid signaling via the retinoid X-receptor (RXR) has shown promise to be a major regulator of reproductive tract recrudescence. Furthermore, TBT has been shown to be a high affinity ligand for the RXR and the RXR ligand 9-cis retinoic acid causes imposex. We propose that TBT causes imposex through the inappropriate activation of this signaling pathway. However, uncertainties remain in our understanding of the environmental-endocrine regulation of reproduction in gastropods. Definitive elucidation of the mechanism of action of TBT awaits resolution of these uncertainties.

DNA hypomethylation induced by tributyltin, triphenyltin, and a mixture of these in Sebastiscus marmoratus liver

Tributyltin (TBT) and triphenyltin (TPT) coexist in freshwater and marine environments. However, the effects of TBT, TPT, and a mixture of the two on DNA methylation in marine fish livers and the mechanism involved remain to be elucidated. Previous study have proved that abnormal methylation patterns are induced by the balance of transmethylation reaction including the tissue level of S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) or the activity of DNA (cytosine-5) methyltransferase 1 (DNMT1). Therefore, in the present study, we assessed their ability to cause hepatic DNA hypomethylation in Sebastiscus marmoratus liver and the related mechanism. The results showed that TBT, TPT, and a mixture of the two significantly induced DNA hypomethylation in the fish livers in a dose-dependent manner. Using Pearson correlation coefficient analysis, we identified strong linear correlations between S-adenosylhomocysteine, S-adenosylmethionine, or the SAM to SAH ratio and the hepatic genome-wide 5-methylcytosine content of the DNA, but no correlation between the latter and the DNMT1 expression level. It is therefore proposed that the organotins hypomethylation induced in the marine fish livers was due to altering the balance of the substrate and the product in transmethylation reactions.

Environmental levels, toxicity and human exposure to tributyltin (TBT)-contaminated marine environment. a review. b_antizar@hotmail.com

Tributyltin (TBT) is a toxic chemical used for various industrial purposes such as slime control in paper mills, disinfection of circulating industrial cooling waters, antifouling agents, and the preservation of wood. Due to its widespread use as an antifouling agent in boat paints, TBT is a common contaminant of marine and freshwater ecosystems exceeding acute and chronic toxicity levels. TBT is the most significant pesticide in marine and freshwaters in Europe and consequently its environmental level, fate, toxicity and human exposure are of current concern. Thus, the European Union has decided to specifically include TBT compounds in its list of priority compounds in water in order to control its fate in natural systems, due to their toxic, persistent, bioaccumulative and endocrine disruptive characteristics. Additionally, the International Maritime Organization has called for a global treaty that bans the application of TBT-based paints starting 1 of January 2003, and total prohibition by 1 of January 2008. This paper reviews the state of the science regarding TBT, with special attention paid to the environmental levels, toxicity, and human exposure. TBT compounds have been detected in a number of environmental samples. In humans, organotin compounds have been detected in blood and in the liver. As for other persistent organic pollutants, dietary intake is most probably the main route of exposure to TBT compounds for the general population. However, data concerning TBT levels in foodstuffs are scarce. It is concluded that investigations on experimental toxicity, dietary intake, potential human health effects and development of new sustainable technologies to remove TBT compounds are clearly necessary.