Monobutyltin Research Articles

Determination of butyltin compounds in fish and mussel samples at trace levels by vortex assisted dispersive liquid-liquid microextraction-gas chromatography mass spectrometry

An accurate and precise analytical method for the determination of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) compounds has been proposed in this study. Dispersive liquid-liquid microextraction (DLLME) was used to isolate and preconcentrate the analytes from the sample matrix. Some parameters such as type of extraction solvent, type of dispersive solvent, volume of buffer solution, mixing period and derivatization period were optimized with a univariate approach. The optimum amounts of extraction solvent, dispersive solvent and derivatizing agent were determined by a Box-Behnken Design (BBD) experiment. To assess the significance of experimental parameters and their interactions, experimented results of all analyte were evaluated with analysis of variance (ANOVA). The optimum DLLME-GC–MS method was validated by analytical figures of merit and the limits of detection for MBT, DBT and TBT were calculated as 0.4, 0.6 and 0.5 μg/kg, respectively. The optimum method was applied to four aquatic samples including two different fish and mussel samples. The selected organotin compounds were not detected in four samples. Percent recovery results for fish and mussel samples were found to be 84.2–89.5% and 94.9–112.6%, respectively.

Accumulation of organotin compounds on mangroves in coastal ecosystems

AbstractTo elucidate the details of both the current status of contamination and the accumulation of organotin compounds (OTs) in mangroves in coastal ecosystems, we determined the concentrations of butyltin compounds (BTs) and phenyltin compounds (PTs) in sediment and mangrove leaves collected from mangrove forests in Merambong and Tinggi Island, Malaysia. Butyltins were detected in all sediment samples collected from both regions, whereas PTs were not detected. The levels of tributyltin (TBT) compounds in the sediment samples were lower than those from previous studies conducted in Malaysia and at other sites in South-east Asia. In both Merambong and Tinggi Island, the average proportions of dibutyltin (DBT) and monobutyltin (MBT), which are degradation products of TBT, were ~70%. This result suggests that the input of TBT has decreased in Malaysia. The proportions of DBT and MBT in the sediment from Merambong were higher than those from Tinggi Island. The concentrations of TBT in mangrove leaves from Tinggi Island were significantly higher than those from Merambong. MBT was the most dominant type among the BTs in mangrove leaves from both Merambong and Tinggi Island. The ratios of the BTs burden in mangrove leaves to the BTs concentration in sediment from Merambong and Tinggi Island averaged 3.1 and 6.2, respectively. Among the values of BTs, the MBT values were found to be the highest in both regions.

Preliminary studies about the role of physicochemical parameters on the organotin compound dynamic in a South American estuary (Bahía Blanca, Argentina)

This work provides a preliminary study of the destination, mobility, and availability of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in contaminated sediments and water column within Puerto Rosales Port, located in the middle zone of the Bahía Blanca Estuary (Argentina). Therefore, this study presents the first comprehensive results of the role of several physicochemical parameters (temperature, pH, Eh, salinity, turbidity, organic matter, chlorophyll, and macronutrients) in behavior of organotin compounds (OTCs) in a marine-coastal ecosystem. The samples were collected seasonally in May, August, and November during 2014. Levels of OTCs were determined in sediments and water column samples by means of gas chromatography-mass spectrometry analysis. Degradation index analyses suggested not recent inputs of TBT at the area of study. However, results submitted a continuous input of TBT into the column water; further, its distribution and degradation pattern were shown to be influenced by salinity, turbidity, particulate organic matter, chlorophyll, and nitrates. These last two parameters, chlorophyll and nitrates, also were very important for sediment samples. Chlorophyll together with high temperatures recorded in the surface sediments triggers biodegradation process of TBT and DBT resulting in high MBT levels while nitrates seemed to promote debutylation process. Furthermore, pH appeared to influence drastically the adsorption/desorption activity of TBT and DBT in sediment. Finally, the Eh obtained suggested a degradation of TBT thanks to the presence of Fe (III) in this compartment. In addition, in fact, the results outlined a possible MBT additional input that contributes to the pollution observed in the study area. Graphical abstract Organotin compounds behavior according to several physicochemical parameters.

Spatiotemporal distribution of organotin compounds in the coastal water of the Bahía Blanca estuary (Argentina).

Several areas within the Bahía Blanca estuary (BBE), with different maritime traffic intensity, were studied in order to confirm the presence and assess the distribution of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in the water column. The organotin compounds (OTCs) were determined in the water samples-taken in summer, autumn, winter, and spring of 2014-by gas chromatography coupled to mass spectrometry after liquid-liquid extraction with hexane. The incidence of TBT throughout the whole sampling period indicated a continuous presence of this compound to the study area. However, in accordance with the butyltin degradation index (BDI), TBT was not recently introduced in the BBE. Furthermore, the average TBT levels exceeded the international guideline established by the Oslo-Paris commission (0.62 ng Sn L-1). As a result, certain biological effects could be expected to occur in sensitive species such as mussels. While DBT were below the detection limit in the 75% of the samples analyzed, MBT was detected in all the samples and no significant differences were found among the concentrations measured in the different seasons (Kruskal-Wallis test, p > 0.05). In addition, no correlations were found among the OTCs levels and the evaluated physiochemical parameters (Spearman coefficient, p > 0.05).

A Validated Routine Method for Butyltin Determination in Seafood by Gas Chromatography Inductively Coupled Plasma Isotope Dilution Mass Spectrometry.

Organotin compounds are anthropogenic metal species with multiple uses as pesticides, preservatives, antifouling agents, biocides, and catalysts. Butyltins are the main organotin compounds found in biota, and the highest levels are found in marine foodstuffs. In this paper, we present the figures of merit for an in-house validated method for routine analysis of butyltins in seafood using GC inductively coupled plasma isotope dilution MS. The working range of the method spanned several orders of magnitude from 3.3-1013, 2.4-785, and 0.3-900 ng Sn/g dry weight for monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT), respectively. The trueness of the method was evaluated by analyzing Certified Reference Materials (CRMs) ERM CRM 477 (Mussel Tissue) and NIES CRM 15 (Scallop). Recoveries, with RSD % in parentheses, were 78 (±14), 80 (±6), and 88% (±8%) for MBT, DBT, and TBT in ERM CRM 477 and 96% (±5%) for TBT in NIES CRM 15. Good agreements were found between experimental uncertainties and uncertainties predicted for single-laboratory validated methods calculated from the maximum standard measurement uncertainty function. The method has proven to be robust, and the wide range of seafood validated ensures that the method is applicable for measuring butyltins in marine tissue.

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.

Occurrence of tumors among gastropods Plicopurpura pansa (Gastropoda: Neogastropoda) in the Port of Manzanillo, Mexico.

In order to evaluate the health of Plicopurpura pansa, a species considered vulnerable, a population of this gastropod living in proximity to the port of greatest cargo movement in Mexico was monitored seasonally during 1year. Morphometric characteristics and sexual proportion were recorded. A macroscopic analysis was carried out to detect malformations and imposex; a histological analysis was performed to evaluate disseminated and gonadal neoplasias; the presence/absence in soft tissues of butyltin species (BTs) as possible contamination agents was also estimated. A total of 508 P. pansa specimens were collected. The largest specimens were obtained in winter. The coefficients of determination inside the port were low (R2 = 0.453). In general, there was a greater proportion of females than males throughout the year. Distinctive foot malformations (tumors) were recorded, but without signs of imposex. The histological examination confirmed the presence of disseminated neoplasias in the foot and gonads of P. pansa in the Port of Manzanillo. The comparative analysis of the morphological and histological features of the studied gastropod population allowed us to recognize impact patterns in relation to proximity to the port. There were high concentrations of monobutyltin (MBT) and greater abundance of tumors in heavier specimens; this was associated with port proximity zones. P. pansa could therefore serve as a sensitive bioindicator of environmental health in marine systems.

Organotin exposure stimulates steroidogenesis in H295R Cell via cAMP pathway

Organotin compounds (OTs) are used in a range of industrial products, such as antifouling paints, agricultural pesticides and stabilizers. Owing to potential endocrine-disrupting effects, human exposure to such compounds is a concern. Nevertheless, little is known about the adverse effect of OTs on adrenocortical function in organisms. In this study, the human adrenocortical carcinoma cell (H295R) model was used to investigate effects of OTs on steroidogenesis and potential causes for such endocrine disruption was examined. H295R cells were exposed to several commonly used OTs, including triphenyltin (TPT), tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT), and the production level of steroid hormones were quantified. TPT and TBT decreased the production levels of 17β-estradiol, aldosterone, and cortisol, but increased that of testosterone. Furthermore, the expression levels of ten major steroidogenic genes (HMGR, StAR, CYP11A1, 3βHSD2, CYP17, CYP19A1, CYP21, CYP11B1, CYP11B2, and 17βHSD) were examined and both up-regulation of CYP11B2 and down-regulation of StAR, 3βHSD2, CYP19A1, CYP21 and CYP11B1 by TPT and TBT were observed. Intracellular levels of ATP and cyclic adenosine monophosphate (cAMP) and the activity of adenylate cyclase (AC) decreased in the H295R cells treated with TPT and TBT. No obvious changes in H295R were found with the treatment of DBT and MBT. These results suggest that OTs may stimulate steroidogenesis in vitro via inhibition of cAMP signaling pathway.

Occurrence and health risk assessment of organotins in waterworks and the source water of the Three Gorges Reservoir Region, China.

The occurrence and health risks of organotins (OTs) in the waterworks and source water in the Three Gorges Reservoir Region (TGRR), China were assessed in this study. Water samples were collected at four waterworks (A, B, C, and D) in March and July 2012 to analyze butyltins (BTs) and phenyltins (PTs) using a gas chromatography-mass spectrometry (GC-MS) system. Our results showed that both the waterworks and their nearby water sources were polluted by OTs, with PTs being the most dominant species. Monobutyltin (MBT), monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) were detected in most of the analyzed water samples. The highest concentrations of OTs in influents, effluents, and source water in March were 52.81, 17.93, and 55.32ngSnL-1, respectively. Furthermore, significant seasonal changes in OTs pollution were observed in all samples, showing pollution worse in spring compared with summer. The removal of OTs by the conventional treatment processes was not stable among the waterworks. The removal efficiency of OTs in July reached 100% at plant B, while that at plant C was only 38.8%. The source water and influents shared similar composition profiles, concentrations, and seasonal change of OTs, which indicated that OTs in the waterworks were derived from the source water. A health risk assessment indicated that the presence of OTs in the waterworks would not pose a significant health risk to the population, yet their presence should not be ignored.

Selective non-chromatographic determination of tributyltin in sediments using EDTA and diphenylcarbazone as masking agent

ABSTRACTTwo analytical procedures based on the generation of volatile tributyltin derivatives, their separation by headspace solid-phase microextraction (HS SPME) and subsequent determination using plasma optical emission spectrometry (OES) have been developed for the selective determination of trace tributyltin (TBT) in the presence of other butyltins and inorganic tin in sediments without the use of chromatography. A microwave-assisted leaching of tin compounds from the sediment using 25%v/v acetic acid is applied for sample pretreatment. The first method takes advantage of TBT chloride releasing from the lecheate after adding 3 M hydrochloric acid, and subsequent separation of the analyte by HS SPME using Carboxen-poly(dimethylsiloxane) (CAR/PDMS). The second method involves the use of masking agents, namely ethylenediaminetetraacetic acid (EDTA) and diphenylcarbazone (DFC), which form stable chelates with monobutyltin (MBT) and dibutyltin (DBT), respectively, followed by the ethylation of tributyltin at pH 5 using sodium tetraethylborate (NaBEt4) solution. The final concentration of NaBEt4 is 0.05%w/v. The parameters affecting the TBT derivatisation and separation by HS SPME have been optimised including the selection of SPME fibre coating (PDMS, CAR/PDMS), the amount of masking agents and NaBEt4 added, sorption time (2–40 min) and sorption temperature (25–60°C). Higher sensitivity and robustness are attained with the method involving ethylation derivatisation, leading to the limit of detection (LOD) of 3 ng L−1. The selective release of TBT is observed from aqueous solutions, where the concentrations of MBT and DBT were in 2–50-fold excess to TBT. The SPME-TD-MIP-OES methods have been validated against several certified reference materials (CRMs), including SOPH-1 marine sediment, PACS-2 marine sediment and BCR 646 freshwater sediment.

A Validated Routine Method for Butyltin Determination in Seafood by Gas Chromatography Inductively Coupled Plasma Isotope Dilution Mass Spectrometry.

Organotin compounds are anthropogenic metal species with multiple uses as pesticides, preservatives, antifouling agents, biocides, and catalysts. Butyltins are the main organotin compounds found in biota, and the highest levels are found in marine foodstuffs. In this paper, we present the figures of merit for an in-house validated method for routine analysis of butyltins in seafood using GC inductively coupled plasma isotope dilution MS. The working range of the method spanned several orders of magnitude from 3.3-1013, 2.4-785, and 0.3-900 ng Sn/g dry weight for monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT), respectively. The trueness of the method was evaluated by analyzing Certified Reference Materials (CRMs) ERM CRM 477 (Mussel Tissue) and NIES CRM 15 (Scallop). Recoveries, with RSD % in parentheses, were 78 (±14), 80 (±6), and 88% (±8%) for MBT, DBT, and TBT in ERM CRM 477 and 96% (±5%) for TBT in NIES CRM 15. Good agreements were found between experimental uncertainties and uncertainties predicted for single-laboratory validated methods calculated from the maximum standard measurement uncertainty function. The method has proven to be robust, and the wide range of seafood validated ensures that the method is applicable for measuring butyltins in marine tissue.

Occurrence of organotins in the aquatic environment during an operating cycle of the Three Gorges Reservoir, China.

Organotins (OTs) pollution in the aquatic environment of the Three Gorges Reservoir (TGR) was assessed during the reservoir's operating cycle. Butyltins (BTs) and phenyltins (PhTs) in the water phase and suspended particulate matter (SPM) at different water levels were analysed. It was found that the distribution of OTs in the surface and bottom water phases were similar, with the dominant OTs being BTs at the low water level and PhTs at the high water level. The detection rates and concentrations of OTs in the water phase at the high water level were both higher than those at the low water level, with most OTs being monobutyltin (MBT) at the low water level and monophenyltin (MPhT) at the high water level. The concentrations of OTs in SPM at the low water level were higher than those at the high water level, and BTs, especially dibutyltin (DBT) and tributyltin (TBT), were the predominant OTs whether surface or bottom layer at each water level. The BTs and SPM concentrations had a significant positive relationship in all samples, indicating that the SPM concentration would determine the distribution of BTs in the aquatic environment of the TGR region (TGRR). The difference in the distribution of OTs at the different water levels indicated that the hydrological and hydraulic behaviour of the TGR influences OTs transport in the aquatic environment of the TGRR.

Fifteen years of imposex and tributyltin pollution monitoring along the Portuguese coast

IMO’s Anti-Fouling Systems convention banned the use of organotin-based antifouling systems in 2008 as the ultimate effort to stop tributyltin (TBT) inputs into the marine environment. One of the hazardous effects of TBT is imposex (the superimposition of male sexual characters onto gastropod females), a phenomenon that may cause female sterility and the gastropod populations decline. Despite previous European Union legislation had already been shown effective in reducing the imposex levels along the Portuguese coast, this study intends to confirm these decreasing trends after 2008 and describe the global evolution in the last 15 years. Imposex levels were assessed in two bioindicators – the dog-whelk Nucella lapillus and the netted-whelk Nassarius reticulatus (Gastropoda, Prosobranchia) – in 2011 and 2014, and the results were compared with previous years. Both species showed progressive decreasing trends in imposex levels over the last 15 years; median values of the vas deferens sequence index (VDSI) fell from 3.96 to 0.78 in N. lapillus and from 3.39 to 0.29 in N. reticulatus. The temporal/spatial evolution of imposex suggests an apparent shift of TBT hotspots, being now restricted to fishing ports and marinas in detriment of large commercial harbours where TBT levels fell rapidly. Butyltins were measured in the whole tissues of N. lapillus females collected in 2014: monobutyltin (MBT) varied from < DL (detection limit: 1 ng Sn/g) to 13 ng Sn/g dw, dibutyltin (DBT) from 2.2 to 27 ng Sn/g dw and TBT from 1.5 to 55 ng Sn/g dw. Although TBT body burden has declined over time, the butyltin degradation index ([MBT]+[DBT])/[TBT] exhibited values < 1 in c. a. 90% of the sites assessed, suggesting that recent TBT inputs are still widespread in the Portuguese coast eventually due to illegal use of TBT antifouling systems and TBT desorption from sediments.

Simultaneous Cell Disruption Extraction and Purification Followed by Two-phase Derivatization Procedure for the Determination of Organotin Compounds in Wet Biological Samples by GC–MS

Freeze-dried biological samples used for the determination of organotin compounds (OTCs) involve complicated or tedious pretreatment (e.g., freeze-drying) that may result in loss of analyst or contamination. In the present study, a rapid and accurate method for determination of five kinds of OTCs—monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPhT) and triphenyltin (TPhT) in fresh biota samples—was developed and further compared with freeze-dried tissues. It involved a sample preparation method of simultaneous extraction and purification of OTCs in fresh biological samples, which was developed with ultrasonic cell disruption and primary secondary amine (PSA) adsorption, and followed by two-phase (organic solvent and cell membrane phases) derivatization before the analysis by gas chromatography–mass spectrometry. The extraction efficiency from biota matrices was relatively better with the acetate/acetic acid and tropolone into methanol as extraction agents and primary secondary amine as grease-removing agents. The retention of cell membrane-like materials as well as 25% of ethyl acetate as co-extraction reagents used after centrifugation improved the targeted OTCs’ recoveries. The proposed method, under the optimal condition, has shown satisfactory performance in wet biological samples. The limits of detection obtained were less than 10 ng Sn g−1 ww (wet weight) for all analytes. Spiked recoveries were within the range 89–118% and the relative standard deviations were less than 7% (n = 5) when quantified by matrix-matched calibration curves. Finally, the applicability of this new method was further verified by comparing the results from wet and freeze-dried oyster tissues collected from two coastal cities in China.

Speciation of organometallic compounds of Hg, Sn, and Pb in the market garden soil in Ngaoundéré (Cameroon)

The objective of this work is to study the contamination of market garden soils by organomercury compounds (OMC), organotin compounds (OTC), and organolead compounds (OLC) using combustion debris (CD) as fertilizers. Therefore, two parcels of land used for gardening are rented on two sites. Soils were plowed and amended with CD. Samples of non-amended and amended soils were treated and then organometallic compounds of Hg, Sn, and Pb were analyzed by GC–ICP–MS. The results obtained revealed the presence of methyl-mercury (MeHg) in the soil at concentrations varying from non-detected in non-amended soil to 171.6 µg/kg in amended soil. Among the OLC identified, tetra-ethyl-lead (TEtPb) is the most represented in the soil with concentrations ranging from 18.45 to 44,612 µg/kg. OTC has also been identified with a predominance of mono-butyl-tin (MBT) followed by tri-methyl-tin (TMT) and di-methyl-tin (DMT). Soil treatments to CD have a significant influence on soil contamination to OMC, OTC, and OLC. This means that a significant amount of organometallic compounds found in amended soils would come from either direct or indirect CD.

Organotin compounds in Brachidontes rodriguezii mussels from the Bahía Blanca Estuary, Argentina

Levels of tributyltin and its breakdown compounds, including the first record of monobutyltin (MBT) in history for Latin America, were determined in native mussels (Brachidontes rodriguezii) by means of CG-MS, after extraction/derivatization assisted by ultrasound. The samples were collected in 2013 in Bahía Blanca Estuary (Argentina) at 6 sites, which reflect different levels of maritime activities.Total butyltins (TBts = TBT+ DBT+ MBT) levels ranged from 19.64 to 180.57ng Sn g−1 dry weight. According to the Oslo-Paris commission, the results indicated that 73.9% of mussels could be under biological effects risks associated with TBT pollution. In accordance with the calculated bioaccumulation factors, approximately 56% of samples appeared to have accumulated TBT through the sediments.All sampling sites were shown to be impacted by organotin compounds (OTCs) showing variable levels through seasons, which could be related with the variation of the water temperature.Degradation index analyses suggested aged inputs of TBT possibly under a general degradation process at the area of study. In addition, the occurrence of DBT and MBT could not be uniquely attributed to the degradation pathway of the TBT; in fact, results outlined the possible contribution of some punctual and diffuse sources at the area such as proximity to plastic industries, industrial effluents, sewage outlets and domestic wastewaters.

Biomonitoring of metals by aquatic mosses in a mining region

The aim of this work is to estimate background concentrations of organometallic compounds, such as tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT), monophenyltin (MPhT), methylmercury (MeHg), inorganic mercury (iHg) and diethyllead (Et2Pb) in the aquatic environment at the French national scale.Both water and sediment samples were collected all over the country, resulting in 152 water samples and 123 sediment samples collected at 181 sampling points. Three types of surface water bodies were investigated: rivers (140 sites), lakes (19 sites) and coastal water (42 sites), spread along the 11 French river basins. The choice of sites was made on the basis of previous investigation results and the following target criteria: reference, urban sites, agricultural and industrial areas. The analytical method was properly validated for both matrices prior to analysis, resulting in low limits of quantification (LOQ), good precision and linearity in agreement with the Water Framework Directive demands. The results were first evaluated as a function of their river basins, type of surrounding pressure and water bodies. Later, background concentrations at the French national scale were established for both water and sediment matrices, as well as their threshold, i.e., the concentration that distinguishes background from anomalies or contaminations. Background concentrations in water are ranging between <0.04–0.14 ng Hg. L−1 for MeHg, <0.14–2.10 ng Hg. L−1 for iHg, <1.0–8.43 ng Pb. L−1 for Et2Pb and 0.49–151 ng Sn. L−1, <0.08–3.04 ng Sn. L−1 and <0.08–0.25 ng Sn. L−1 for MBT, DBT and TBT, respectively. For sediments, background concentrations were set as <0.09–1.11 ng Hg. g−1 for MeHg, <0.06–24.3 ng Pb. g−1 for Et2Pb and <1.4–13.4 ng Sn. g−1, <0.82–8.54 ng Sn. g−1, <0.25–1.16 ng Sn. g−1 and <0.08–0.61 ng Sn. g−1 for MBT, DBT, TBT and DPhT, respectively. TBT occurs in higher concentrations than the available environmental protection values in 24 and 38 sampling sites for both water and sediment samples, respectively. Other phenyltins (MPhT and TPhT) did not occur above their LOQ and therefore no background was possible to establish. Throughout this work, which is the first assessment of background concentrations for organometallic compounds at the French national level ever being published, it was possible to conclude that over the last 10–20 years organotin concentrations in French river basins have decreased while MeHg concentration remained stable.

Estrogen-mediated protection of the organotin-degrading strain Metarhizium robertsii against oxidative stress promoted by monobutyltin

Dibutyltin (DBT) is a global pollutant characterized by pro-oxidative properties. The fungal strain Metarhizium robertsii can eliminate high levels of DBT efficiently. In this study, induction of oxidative stress as well as its alleviation through the application of natural estrogens during the elimination of DBT by M. robertsii were evaluated. During the first 24 h of incubation, the initial concentration of DBT (20 mg l−1) was reduced to 3.1 mg l−1, with simultaneous formation of a major byproduct – monobutyltin (MBT). In the presence of estrone (E1) or 17β-estradiol (E2), the amounts of dibutyltin residues in the fungal cultures were found to be approximately 2-fold higher compared to cultures without estrogens, which was associated with the simultaneous utilization of the compounds by cytochrome P450 enzymes. On the other hand, MBT levels were approximately 2.5 times lower in the fungal cultures with the addition of one of the estrogens. MBT (not DBT) promotes the generation of O2–, H2O2, and NO at levels 65.89 ± 18.08, 4.04 ± 3.62, and 27.92 ± 1.95, respectively. Superoxide dismutase and catalase activities did not show any response of the M. robertsii strain against the overproduction of superoxide anion and hydrogen peroxide. Application of E1 as well as E2 ensured non-enzymatic defense against nitrosative and oxidative stress through scavenging of nitrogen and oxygen reactive species, and limited their levels from 1.5-fold to 21-fold, depending on the used estrogen.

Efficient dibutyltin (DBT) elimination by the microscopic fungus Metarhizium robertsii under conditions of intensive aeration and ascorbic acid supplementation

Dibutyltin (DBT) is an environmental pollutant characterized by immunotoxic, neurotoxic, and pro-oxidant properties. In this study, an attempt was made to enhance DBT elimination by the Metarhizium robertsii strain. We observed enhanced fungal growth in the bioreactor (pO2 ≥ 20%) compared to flask cultures (μmax increased from 0.061 to 0.086 h−1). Moreover, under aerated conditions, M. robertsii mycelium with “hairy” morphology biodegraded DBT (20 mg l−1) 10-fold faster in the bioreactor than in the flask cultures. Monobutyltin (MBT) and a hydroxylated derivative of MBT (OHBuSnH2) were detected as by-products of dibutyltin debutylation. Simultaneous usage of glucose and butyltins indicates the comatabolic nature of monobutyltin and dibutyltin removal. In order to protect fungal cells from oxidative stress caused by DBT presence, vitamin C (20 mg l−1) was applied. Supplementation with ascorbic acid (AA) resulted in a 3-fold acceleration of MBT removal during the first 7 h of incubation. Using the HPLC-MS/MS technique, a quantitative analysis of malondialdehyde (MDA), a marker of oxidative stress, was performed. In the AA presence, a decrease in the MDA amount (about 45%) was observed compared to the case with fungal cells exposed to DBT alone.

The importance of environmental factors and matrices in the adsorption, desorption, and toxicity of butyltins: a review.

Butyltins (BTs) are considered as a group of the most important organometallic compounds in industry and agriculture. Due to their widespread use, large amounts of BTs including tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) have entered into the environment, and subsequently causing detrimental effects on humans and aquatic organisms. This work provides a critical review of recent studies on the adsorption, desorption, bioaccumulation, and toxicity of BTs that can notably influence the distribution of BTs in the environment. Influence of environmental factors (e.g., pH and salinity) and adsorbents in the matrices (e.g., minerals, organic carbons, and quartz) on the adsorption, desorption, and toxicity of BTs is particularly addressed.