Accumulation of butyltin compounds in cetaceans from Korean coastal waters

Toxicity of tributyltin chloride on haarder (Liza haematocheila) after its acute exposure: Bioaccumulation, antioxidant defense, histological, and transcriptional analyses

Liza haematocheila is exposed to various chemical contaminants from anthropogenic sources, including tributyltin chloride (TBTC). Yet the toxicity mechanism of TBTC on haarder remains unclear. The haarder was exposed to different doses (0, 10%, 20%, and 50% of LC₅₀-96 h) of TBTC. In this study, the results revealed its high bioaccumulation in the livers and significant alteration for development. The activities of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase decreased after 96-h exposure to TBTC, this accompanied by an increased malondialdehyde level. TBTC exposure caused the intense production of reactive oxygen species, a reduction in total blood cell count in serum, and apoptosis-related alterations in livers, indicating that enhanced oxidative stress occurred in the process of TBTC exposure. Histological results revealed angiorrhexis and infiltration of inflammatory cells, vacuolar degeneration of hepatocytes in the livers, and swelling, fusion, and disintegration of gill organs. Interestingly, the obtained transcriptional profiles indicated that high doses of TBTC caused energy disorder, apoptosis, and adipogenesis restriction mediated by cytokines and adipokines in Jak-STAT and adipocytokine signaling pathways. In summary, acute exposure to high doses of TBTC could impair the antioxidant system and pathways related to energy, apoptosis and adipogenesis, eventually posing a serious challenge to the fitness of haarder individuals and its fish populations as marine resources.

Mexican paradise under threat: The impact of antifouling biocides along the Yucatán Peninsula

Levels of booster biocides (Irgarol, diuron, chlorothalonil, dichlofluanid and DCOIT), organotins (TBT, DBT, MBT, TPhT, DPhT and MPhT) and antifouling paint particles (APPs) were assessed in sediments of sites under the influence of maritime activities along the coastal zone of the Yucatán Peninsula, Mexico. Imposex incidence and organotin levels were also evaluated in seven caenogastropod species. The incidence of imposex was detected in five species from sites nearby fishing harbors and marinas, including the first reports to Gemophos tinctus and Melongena bispinosa. Butyltins levels were higher than phenyltins in gastropod tissues, sediments, and APPs. Regarding booster biocides, chlorothalonil was the most frequently detected compound and DCOIT was the most abundant biocide in sediments. DCOIT levels were registered in APPs from fishing harbors and marina areas. In addition, the highest levels of TBT, Irgarol, diuron and DCOIT exceeded the threshold limits set by international sediment quality guidelines, indicating that toxic effects could be expected in some of the studied areas, thus being a potential threat to marine life. Based on such outputs, Mexico urgently needs to adopt restrictive actions aiming at conserving the rich biological heritage of the Yucatán Peninsula.

Effect of Dibutyltin Dilaurate on Triglyceride Metabolism through the Inhibition of the mTOR Pathway in Human HL7702 Liver Cells

Dibutyltin dilaurate (DBTD) has multiple applications in daily life. However, DBTD is easily deposited in the liver and affects liver functions. This study was designed to explore the effects of DBTD on triglyceride metabolism in human normal hepatocyte HL7702 cells. Our results showed that the intracellular fat contents were dose-dependently decreased by DBTD. The expression of lipolysis genes and proteins were elevated while the lipogenesis genes and proteins were diminished by DBTD. The phosphorylation levels of ribosomal S6 kinase 1 were reduced by both rapamycin and DBTD, indicating that the mTOR pathway was suppressed possibly. The decreased sterol regulatory element-binding protein 1C (SREBP1C) transcription levels, as well as the increased peroxisome proliferator-activated receptor alpha (PPARα) transcription levels, caused by rapamycin and DBTD corresponded to the inactive mTOR pathway. In conclusion, it was possible that DBTD reduced the intracellular triglyceride through depressing the mTOR pathway and affecting its downstream transcription factors.

Microbes a Tool for the Remediation of Organotin Pollution Determined by Static Headspace Gas Chromatography-Mass Spectrometry

Tributyltin (TBT) is one of the most toxic anthropogenic compounds introduced into the marine environment. Despite its global ban in 2008, TBT is still a problem of great concern due to its high affinity for particulate matter, providing a direct and potentially persistent route of entry into benthic sediments. Bioremediation strategies may constitute an alternative approach to conventional physicochemical methods, benefiting from the microorganism’s potential to metabolize anthropogenic compounds. In this work, a simple, precise and accurate static headspace gas chromatography method was developed to investigate the ability of TBT degrading microbes in sedimentary microcosms over a period of 120 days. The proposed method was validated for linearity, repeatability, accuracy, specificity, limit of detection and limit of quantification. The method was subsequently successfully applied for the detection and quantification of TBT and degradation compounds in sediment samples on day 0, 30, 60, 90 and 120 of the experiment employing the principles of green chemistry. On day 120 the concentration of TBT remaining in the microcosms ranged between 91.91 ng/g wet wt for the least effective microbial inoculant to 52.73 ng/g wet wt for the most effective microbial inoculant from a starting concentration of 100 ng/g wet wt.

Butyltin contamination in Northern Chilean coast: Is there a potential risk for consumers?

Imposex is the superimposition of non-functional male sex organs in gastropod females. This syndrome is a hormonal imbalance induced by tributyltin (TBT) which have been used in antifouling paints formulation. The present study aimed to perform an integrated environmental assessment of imposex and butyltin (BT) contamination using surface sediments and tissues of Thaisella chocolata (an edible gastropod) from northern Chile. The results showed imposex incidence in 11 out of 12 sites. In the most contaminated sites, which are areas under the influence of maritime activities, and also used for fishing and aquaculture, RPLI were over 60 and VDSI over 4 (high incidence of sterile females). Exceptionally high contamination levels and evidences of fresh inputs of tributyltin (TBT) were detected along the studied area. TBT levels above 300 and 90ngSng^-1, respectively, were recorded in sediments and edible gastropod tissues of 6 sites. Thus, a daily ingestion of 90 to 173g of T. chocolata foot (4 to 8 organisms) from the most contaminated sites will certainly lead to the consumption of BT exceeding the tolerable daily intake recommended by European Food Safety Authority. It is reasonable to consider that human risk is even higher if daily consumption of additional seafood is considered. Moreover, some contaminated sites were located within the marine reserve "Isla Grande Atacama", indicating that even marine protected areas are under the influence of TBT contamination. These findings suggest that current levels of TBT in the studied area are sufficient to induce harmful effects on the environment and constitutes a potential threat to seafood consumers. Thus, national regulatory actions toward environmental protection and food safety of local populations are still mandatory, even after 8years of the TBT global ban by IMO.

Spatiotemporal distributions of butyltin compounds in various intertidal organisms along the Samcheok and Tongyeong coasts of Korea

Thirteen years ago, the Korean Government introduced a regulation prohibiting the use of tributyltin (TBT), which was a component of antifouling paints. A subsequent decline in the concentration of butyltins (BTs) was recorded in seawater and the sediment, however, the current concentration of BTs in biota has not been well documented. The spatiotemporal distribution and concentration of BTs was recorded in biota from 2013 to 2015 along the coasts of Samcheok and Tongyeong using GS/MSD analysis. Crustaceans contained the greatest concentrations of BTs, followed by gastropods, fishes, and bivalves. We found that the concentration of BTs was greater at Tongyeong compared to Samcheok, because of the geographical characteristics of the area. We also confirmed that the regulation has been effective by showing that the TBT concentration decreased over the 3-year study period. The TBT levels of gastropods and bivalves fell within the limits of the guidelines and/or the effective concentration of the toxicological endpoint reported previously. The concentration of BTs also varied among species, being dependent on the weight of the soft tissue. Furthermore, the greater quantities of BTs degradation products compared to TBT confirmed the absence of recent inputs of pollutants during the study periods. However, compared with other Asian countries, biota BTs were greater in Korea, with noticeably greater concentrations along the south coast. Thus, further investigation of the distribution of BTs along the Korean coasts is required in the future. In conclusion, our results provide useful information about the recent trends of BTs in Korea.

The obesogen tributyltin

The obesogen hypothesis postulates the role of environmental chemical pollutants that disrupt homeostatic controls and adaptive mechanisms to promote adipose-dependent weight gain leading to obesity and metabolic syndrome complications. One of the most direct molecular mechanisms for coupling environmental chemical exposures to perturbed physiology invokes pollutants mimicking endogenous endocrine hormones or bioactive dietary signaling metabolites that serve as nuclear receptor ligands. The organotin pollutant tributyltin can exert toxicity through multiple mechanisms but most recently has been shown to bind, activate, and mediate RXR-PPARγ transcriptional regulation central to lipid metabolism and adipocyte biology. Data in support of long-term obesogenic effects on whole body adipose tissue are also reported. Organotins represent an important model test system for evaluating the impact and epidemiological significance of chemical insults as contributing factors for obesity and human metabolic health.

Butyltin compounds in liver of harbour porpoises (Phocoena phocoena) from the UK prior to and following the ban on the use of tributyltin in antifouling paints (1992-2005 & 2009)

Liver butyltin concentrations (monobutyl, dibutyl and tributyltin (TBT)) in harbour porpoises (n=410) have been determined during 1992-2005, and again in 2009 following a ban on the use of tributyltin-based antifouling paints on ships. The aim was to assess the effectiveness of the regulation, which was implemented during 2003-2008. Since the ban was put in place summed butyltin concentrations have declined. Also, the percentage of animals in which TBT was detected has fallen sharply, indicating the cessation of fresh inputs. In 1992, 1993 and 1995, TBT was detected in 100% of samples analysed. In 2003-2005, once the implementation of the ban had begun, this fell to 61-72%, and in 2009, following the completion of the ban, had reduced to 4.3% (i.e. in only 1 of 23 samples analysed). Thus we conclude that the ban has proved effective in reducing TBT inputs to the seas from vessels.