Spatiotemporal distribution and risk assessment of organotins in the surface water of the Three Gorges Reservoir Region, China.

The water quality security of the Three Gorges Reservoir during different operating periods has been a subject of recent concern. This study is the first to report the spatiotemporal variability of organotins (OTs) in surface water under dynamic water level conditions in the Three Gorges Reservoir Region (TGRR). TGRR surface water was collected during three monitoring campaigns to analyze butyltins (BTs) and phenyltins (PTs) using a gas chromatography-mass spectrometry system. Our results showed that TGRR surface water was polluted by BTs and PTs, with mono-OTs being the dominant species. A wide range of BTs and PTs concentrations was observed across the study area, but tributyltin (TBT) displayed extensive spatial distribution, and the highest concentrations consistently occurred in the downstream region of the TGRR study area, with a maximum of 393.35 ng Sn/L in Zigui (S27). The total OTs contamination level decreased over time. The diphenyltin concentration exhibited significant seasonal variation, while other OTs showed seasonal changes only during two monitoring campaigns, with the exception of dibutyltin. An ecological risk assessment indicated that both TBT and triphenyltin posed risks to aquatic organisms in TGRR surface water. We urgently recommend continuous monitoring and further measures to prevent and control OTs pollution in the TGRR.

Construction and assessment of reaction models between F1F0-synthase and organotin compounds: molecular docking and quantum calculations.

Organotin compounds are the active components of some fungicides, which are potential inhibitors of the F1F0-ATP synthase. The studies about the reaction mechanism might indicate a pathway to understand how these compounds work in biological systems, however, has not been clarified so far. In this line, molecular modeling studies and density functional theory calculations were performed in order to understand the molecular behavior of those compounds when they interact with the active site of the enzyme. Our findings indicate that a strong interaction with His132 can favor a chemical reaction with organotin compounds due to π-π stacking interactions with aromatic rings of organotin compounds. Furthermore, dependence on molecule size is related to possibility of reaction with the amino acid residue His132. Thus, it can also be noticed, for organotin compounds, that substituents with four carbons work by blocking the subunit a, in view of the high energy transition found characterized by steric hindrance.

Bioaccumulation surveillance in Milford Haven Waterway.

Biomonitoring of contaminants (metals, organotins, polyaromatic hydrocarbons (PAHs), PCBs) was undertaken in Milford Haven Waterway (MHW) and a reference site in the Tywi Estuary (St Ishmael/Ferryside) during 2007-2008. Bioindicator species encompassed various uptake routes-Fucus vesiculosus (dissolved contaminants); Littorina littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and Hediste (=Nereis) diversicolor (sediments). Differences in feeding and habitat preference have subtle implications for bioaccumulation trends though, with few exceptions, contaminant burdens in MHW were higher than the Tywi reference site, reflecting inputs. Elevated metal concentrations were observed at some MHW sites, whilst As and Se (molluscs and seaweed) were consistently at the higher end of the UK range. However, for most metals, distributions in MH biota were not exceptional. Several metal-species combinations indicated increases in bioavailability upstream, which may reflect the influence of geogenic/land-based sources-perhaps enhanced by lower salinity. TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi were close to zero. Phenyltins were not accumulated appreciably in M. edulis, whereas some H. diversicolor populations appear subjected to localized (historical) sources. PAHs in H. diversicolor were distributed evenly across most of MHW, although acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and chrysene were highest at one site near the mouth; naphthalenes in H. diversicolor were enriched in the mid-upper Haven (a pattern seen in M. edulis for most PAHs). Whilst PAH (and PCB) concentrations in MH mussels were mostly above reference and OSPAR backgrounds, they are unlikely to exceed ecotoxicological thresholds. Bivalve Condition indices (CI) were highest at the Tywi reference site and at the seaward end of MH, decreasing upstream-giving rise to several significant (negative) relationships between CI and body burdens. Despite the possible influence of salinity gradient as a complicating factor, multivariate analysis indicated that a combination of contaminants could influence the pattern in condition (and the biomarkers metallothionein and TOSC). Integrating bioaccumulation data with biological and biochemical endpoints is seen as a useful way to discriminate environmental quality of moderately contaminated areas such as MHW and to prioritise cause and effect investigations.

An in vitro comparative assessment with a series of new triphenyltin(IV) 2-/4-[(E)-2-(aryl)-1-diazenyl]benzoates endowed with anticancer activities: structural modifications, analysis of efficacy and cytotoxicity involving human tumor cell lines.

Four new triphenyltin(IV) complexes of composition Ph(3)SnLH (where LH=2-/4-[(E)-2-(aryl)-1-diazenyl]benzoate) (1-4) were synthesized and characterized by spectroscopic (((1))H, ((13))C and ((119))Sn NMR, IR, ((119))Sn Mössbauer) techniques in combination with elemental analysis. The ((119))Sn NMR spectroscopic data indicate a tetrahedral coordination geometry in non-coordinating solvents. The crystal structures of three complexes, Ph(3)SnL((1))H (1), Ph(3)SnL((3))H (3), Ph(3)SnL((4))H (4), were determined. All display an essentially tetrahedral geometry with angles ranging from 93.50(8) to 124.5(2)°; ((119))Sn Mössbauer spectral data support this assignment. The cytotoxicity studies were performed with complexes 1-4, along with a previously reported complex (5) in vitro across a panel of human tumor cell lines viz., A498, EVSA-T, H226, IGROV, M19 MEL, MCF-7 and WIDR. The screening results were compared with the results from other related triphenyltin(IV) complexes (6-7) and tributyltin(IV) complexes (8-11) having 2-/4-[(E)-2-(aryl)-1-diazenyl]benzoates framework. In general, the complexes exhibit stronger cytotoxic activity. The results obtained for 1-3 are also comparable to those of its o-analogs i.e. 4-7, except 5, but the advantage is the former set of complexes demonstrated two folds more cytotoxic activity for the cell line MCF-7 with ID(50) values in the range 41-53 ng/ml. Undoubtedly, the cytotoxic results of complexes 1-3 are far superior to CDDP, 5-FU and ETO, and related tributyltin(IV) complexes 8-11. The quantitative structure-activity relationship (QSAR) studies for the cytotoxicity of triphenyltin(IV) complexes 1-7 and tributyltin(IV) complexes 8-11 is also discussed against a panel of human tumor cell lines.

Design, synthesis, characterization and DNA-binding studies of a triphenyltin(IV) complex of N-glycoside (GATPT), a sugar based apoptosis inducer: in vitro and in vivo assessment of induction of apoptosis by GATPT.

The novel organotin complex 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-D-glucose triphenyltin(iv) (GATPT) was synthesized by the reaction of N-glycoside ligand and triphenyltin(iv) chloride. GATPT was characterized by elemental analyses, polarimetry, IR, CD, UV and multinuclear ((1)H, (13)C, (119)Sn) 1D and 2D NMR. The interaction of GATPT with calf thymus DNA was studied by using viscometry, absorption, emission and circular dichoric spectral methods. The DNA binding results suggested the intercalative mode of binding for GATPT with DNA along with simultaneous electrostatic interaction between the Sn(iv) center and the phosphate backbone of the DNA helix. GATPT was tested for its cytotoxic properties against SY5Y, PC-12 and N2A neuronal tumor cell lines. GATPT induced significant apoptosis in the PC-12 cell line characterized by DNA fragmentation and chromosome condensation. Treatment of PC-12 cells with GATPT resulted in a dramatic up-regulation of Bax and Bak and down-regulation of the anti-apoptotic factor Bcl-2. Apoptotic induction by GATPT was shown to be mediated in a p53-dependent manner and loss of p53 impaired the release of cytochrome c from mitochondria to cytosol. Caspase-3 was found to be indispensable for the GATPT triggered apoptosis signaling pathway. Furthermore, in vivo studies using a nude mice model revealed that GATPT exhibits significant antiproliferative activity against tumor development with minimal cytotoxicity. These findings warrant further clinical investigations of GATPT as a therapeutic agent for cancer chemotherapy.

Review of 'emerging' organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids.

A broad spectrum of organic chemicals is essential to modern society. Once discharged from industrial, domestic and urban sources into the urban wastewater collection system they may transfer to the residual solids during wastewater treatment and assessment of their significance and implications for beneficial recycling of the treated sewage sludge biosolids is required. Research on organic contaminants (OCs) in biosolids has been undertaken for over thirty years and the increasing body of evidence demonstrates that the majority of compounds studied do not place human health at risk when biosolids are recycled to farmland. However, there are 143,000 chemicals registered in the European Union for industrial use and all could be potentially found in biosolids. Therefore, a literature review of 'emerging' OCs in biosolids has been conducted for a selection of chemicals of potential concern for land application based upon human toxicity, evidence of adverse effects on the environment and endocrine disruption. To identify monitoring and research priorities the selected chemicals were ranked using an assessment matrix approach. Compounds were evaluated based upon environmental persistence, human toxicity, evidence of bioaccumulation in humans and the environment, evidence of ecotoxicity and the number and quality of studies focussed on the contaminant internationally. The identified chemicals of concern were ranked in decreasing order of priority: perfluorinated chemicals (PFOS, PFOA); polychlorinated alkanes (PCAs), polychlorinated naphthalenes (PCNs); organotins (OTs), polybrominated diphenyl ethers (PBDEs), triclosan (TCS), triclocarban (TCC); benzothiazoles; antibiotics and pharmaceuticals; synthetic musks; bisphenol A, quaternary ammonium compounds (QACs), steroids; phthalate acid esters (PAEs) and polydimethylsiloxanes (PDMSs). A number of issues were identified and recommendations for the prioritisation of further research and monitoring of 'emerging' OCs for the agricultural use of biosolids are provided. In particular, a number of 'emerging' OCs (PFOS, PFOA and PCAs) were identified for priority attention that are environmentally persistent and potentially toxic with unique chemical properties, or are present in large concentrations in sludge, that make it theoretically possible for them to enter human and ecological food-chains from biosolids-amended soil.

Butyltin occurrence and risk assessment in the sediments of the Iberian Peninsula.

The occurrence of butyltin (BT) compounds in more than 50 recent sediment samples of the Iberian Peninsula, collected in the harbours of the western Mediterranean Sea (Spain) and the North Atlantic Ocean (Portugal), including domestic and industrial sewage disposal sites, has been assessed. The highest levels of tributyltin (TBT) (7673 microg kg(-1)dry wt.) were detected in commercial harbours associated with inputs from large vessels. However, relatively high TBT values (about 2150 microg kg(-1)dry wt.) were also detected in fishing and recreational boating areas. Spanish marinas and harbours are more polluted in terms of TBT (5-7673 microg kg(-1)dry wt.) compared to those in Portugal (4-12 microg kg(-1)dry wt.). Generally, the Mediterranean sediments show a BT distribution characterized by the predominance of TBT over the degradation products dibutyl (DBT) and monobutyltin (MBT), indicating the presence of recent inputs, in contrast to the Portuguese coastal distribution. Calculation of butyltin degradation indexes (BDI) confirmed a different trend, depending on the area. Furthermore, a comparative study of the occurrence of BT in different sewage sludge disposal sites shows that domestic primary sewage sludge effluents can contribute to coastal BT pollution, but to a lesser extent when compared with harbours. Historical trends (1995-2003) for Barcelona harbour reveal that BT regulations on the use of TBT-based antifouling paints have not been fully effective. Finally, a comparison against the existing sediment quality guidelines (SQGs) indicated that acute toxic effects could only be expected for TBT in some Mediterranean harbours; conversely, in every North Atlantic Ocean station, a lesser environmental threat for the harbour benthic community is expected.

Assessment of adsorption behavior of dibutyltin (DBT) to clay-rich sediments in comparison to the highly toxic tributyltin (TBT).

The sorption behavior of dibutyltin (DBT) to four types of natural clay-rich sediments as a function of pH and salinity was studied. The strongest affinity of DBT was found to the montmorillonite-rich sediment, which is characterized by the highest specific surface area and cation exchange capacity of the four used sediments. Kd values range between 12 and 40 (l/kg) on simulated marine conditions (pH 8, salinity 32%). A maximum of DBT adsorption was found at a salinity of 0% and pH 6. Desorption occurred over the entire studied pH range (4-8) when contaminated sediments interact with butyltin-free water. The maximum of desorption coincided with the minimum of adsorption, and vice versa. The results of DBT adsorption are compared with tributyltin (TBT), and the mechanism of the adsorption process is discussed.