Tributyltins Research Articles

Molecular mechanisms of tributyltin-induced alterations in cholesterol homeostasis and steroidogenesis in hamster testis: In vivo and in vitro studies.

Tributyltins (TBT) are ubiquitous and persistent environmental contaminants that disturb normal endocrine function including gonadal function in humans and marine organisms. TBT was administered through oral route to male Syrian hamsters at daily doses of 50, 100, and 150 ppm/kg for 65 days. Changes in testis morphology, immunohistochemistry of iNOS, 3β-HSD, and 17β-HSD, cholesterol transport receptor, nuclear receptors, and transcription factors were analyzed. TBT treatment affected each of these parameters to significant levels in a dose-dependent manner compared to vehicle treated control. Real-time PCR and protein analyses revealed that expression levels of ApoE and LDL-R mRNA were up-regulated in the testis of TBT-treated animals while the expression levels of SR-B1, LXR, PPARs α, β, and γ, SCAP, SREBP 1 and 2, 3β-HSD, 17β-HSD, CYP17A1, and P450SCC were down-regulated. Leydig cells were isolated and separated adopting percoll gradient centrifugation under aseptic condition. The viability of Leydig cell was affected by TBT treatment in a dose- and time-dependent manner. Further, the mechanism of action of TBT was ascertained by siRNA transfection of ApoE, which was upregulated, and SREBP, which was down-regulated. These observations led us to infer that exposure to TBT hinders intracellular cholesterol transport resulting in abnormal sex steroid biosynthesis and alteration of steroidogenic enzyme activities. Finally, we could recognize ApoE and SREBP as the major factors regulating genes that control cholesterol biosynthesis and steroidogenesis that ultimately inhibit the synthesis of testosterone. Therefore, ApoE is one of the important molecular targets that can be intercepted in context of male infertility/male contraception.

Searching for "environmentally-benign" antifouling biocides.

As the result of the ecological impacts from the use of tributyltins (TBT) in shipping, environmental legislation for the registration of chemicals for use in the environment has grown to a monumental challenge requiring product dossiers to include information on the environmental fate and behavior of any chemicals. Specifically, persistence, bioaccumulation and toxicity, collectively known as PBT, are properties of concern in the assessment of chemicals. However, existing measurements of PBT properties are a cumbersome and expensive process, and thus not applied in the early stages of the product discovery and development. Inexpensive methods for preliminary PBT screening would minimize risks arising with the subsequent registration of products. In this article, we evaluated the PBT properties of compounds reported to possess anti-fouling properties using QSAR (quantitative structure-activity relationship) prediction programs such as BIOWIN™ (a biodegradation probability program), KOWWIN™ (log octanol-water partition coefficient calculation program) and ECOSAR™ (Ecological Structure Activity Relationship Programme). The analyses identified some small (Mr < 400) synthetic and natural products as potential candidates for environmentally benign biocides. We aim to demonstrate that while these methods of estimation have limitations, when applied with discretion, they are powerful tools useful in the early stages of research for compound selection for further development as anti-foulants.

Baseline of organotin pollution in fishes, clams, shrimps, squids and crabs collected from the west coast of India

Organotins, especially tributyltins (TBT) are highly toxic to many marine organisms. These compounds are introduced in marine waters by ship trafficking, ship scrapping activities, as antifouling compounds and sewage disposal. Marine fishes, crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from Mumbai, Goa and Karwar on the west coast of India. At these locations average organotin concentration found in fishes, clams, shrimps, squids and crabs was 108, 852, 179, 70 and 89ngSng−1dw, respectively. In all the samples butyltins dominated over phenyltins. The levels of organotins suggest that all the organisms were contaminated with organotins and their consumption may pose health problems to humans.

Benthic Pollution Assessment Based on Macrobenthic Community Structure in Gamak Bay, Southern Coast of Korea

Benthic pollution assessment based on macrobenthic community structure with environmental variables was carried out at twelve stations during two periods on a presumed pollution gradient in Gamak Bay. Univariate and multivariate methods were applied to investigate structural changes in the benthic communities. A clear gradient of pollution effects on the macrobenthic community was observed from the interior to the exterior of the bay. The community on the northwestern basin was severely disturbed due to a low level of hydrodynamics and a large amount of pollutant input from nearby cities. Exterior regions on the southern basin appeared to have the best benthic environmental characteristics among all stations according to most methods of analysis. Central ridge regions and two stations around the islets in the mouth of the bay exhibited intermediate levels of perturbation when compared to the more disturbed interior and undisturbed exterior regions. Pollution effects on the communities were attenuated at the southern area of the central ridge during spring compared to those of summer, where aquacultural farming was densely distributed. The environmental variables primarily correlated to the macrobenthic community structure were total organic carbon (C), organochlorine pesticides (OCPs), and tributyltins (TBTs), contents found on the surface sediment, as anthropogenic variables indicating organic materials.

Review: Biodegradation of tributyltins (organotins) by marine bacteria

AbstractMany marine bacterial strains have an inherent capability to degrade toxic organotin compounds, especially tributyltins (TBTs), that enter into the environment in the form of insecticides, fungicides and antifouling paints as a result of anthropogenic and industrial activities. Significant degradation of these compounds in the ambient environment may take several years, and it is necessary to consider methods or strategies that can accelerate the degradation process. There have been few demonstrations of biological degradation of these organotin biocides exclusively in laboratory‐scale experiments. Compared with the few bench‐scale degradation processes, there are no reports of field‐scale processes for TBT bioremediation, in spite of its serious environmental threat to non‐target organisms in the aquatic environment. Implementation of field‐scale biodegradation of TBT requires inputs from biology, hydrology, geology, chemistry and civil engineering. A framework is emerging that can be adapted to develop new processes for bioremediation of toxic environmental wastes. In the case of TBT bioremediation, this framework incorporates screening and identification of natural bacterial strains, determination of optimal conditions for growth of isolates and TBT degradation, establishment of new metabolic pathways involved in TBT degradation, identification, localization and cloning of genes involved in degradation and in TBT resistance, development of suitable microbial strains using genetic manipulation techniques for practical applications and optimization of practical engineering processes for bioremediation of organotin‐contaminated sites. The present review mainly addresses the aspect of TBT biodegradation with special reference to environmental sources of TBT, chemical structure and biological activity, resistant and degrading bacterial strains, possible mechanisms of resistance and degradation and the genetic and biochemical basis of TBT degradation and resistance. It also evaluates the feasibility and potential of natural and genetically modified TBT‐degrading bacterial strains in field‐scale experiments to bioremediate TBT‐contaminated marine sites, and makes recommendations for more intensive and focused research in the area of TBT bioremediation mediated by marine bacterial strains. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Impact of Tributyltin on Marine Invertebrates

Organotins, and more specifically tributyltins (TBT), are introduced into the marine environment by paints designed to protect ship hulls against biological fouling. Lab tests have shown that bivalve reproduction is affected by TBT concentrations exceeding 20 ng⋅l−1. A dose-effect correlation scale describes the effects on embryogenesis and on larval growth: total larval mortality occurs after 12 days of exposure at a concentration of 200 ng⋅l−1, and inhibition of fertilization at 100 μg⋅l−1. At concentrations close to 1 ng⋅l−1, significant changes are observed in the sexuality of marine gastropods, reflected in an imposition of male characters in females, a phenomenon known as imposex. Imposex evolution in Nucella lapillus females includes: formation of a vas deferens, a channel between prostate and penis existing in males (phase 1), appearance and growth of a penis (phases 2 to 4), sterilization of the subject with blocking of the oviduct and accumulation of eggs within the gland (phases 5 to 6). In the final stages, females become sterile, thereby jeopardizing population renewal. These disturbances occur following exposure at TBT concentrations of 7 to 12 ng⋅l−1 approximately. Physiological and biochemical phenomena leading to imposex are still not well understood. However, there are evidences that TBT exposure tends to increase the testosterone contents in female mollusks, while progesterone and 17 E oestradiol levels remain constant. Since testosterone alone causes penis growth in the females, it is thought that imposex could be attributed to its accumulation originating from inhibition of cytochrome P450-dependent aromatase. The conversion of testosterone into 17 E oestradiol would then be inhibited by TBT. In spite of regulations banning the use of TBT as biocide in antifouling paints, current TBT contamination in coastal areas frequently reaches concentrations likely to cause imposex.

Occurrence of Butyltin Compounds in Human Blood

Residues of butyltin compounds, including mono- (MBT), di- (DBT) and tributyltins (TBT), were measured in human blood collected from central Michigan, U.S.A. MBT, DBT, and TBT were detected in 53, 81, and 70% of the 32 blood samples examined. Concentrations of butyltins were in the order of MBT > DBT ≥ TBT, with total butyltin concentrations ranging from less than the limit of detection to 101 ng/mL. Exposure of humans to butyltin compounds used as stabilizers or as biocides in household articles has been regarded as a source in addition to the ingestion of contaminated foodstuffs. There was no significant difference in concentrations of butyltin compounds between sexes. Concentrations of butyltin compounds did not exhibit pronounced age-dependency, which is different from those observed for persistent pollutants such as polychlorinated biphenyls (PCBs). In general, concentrations of butyltins measured in blood were less than that affected human natural killer lymphocytes (a primary immune defense against...

Organotins in Zebra Mussels ( Dreissena polymorpha) from the Saint Lawrence River

Toxic antifouling compounds such as organotins have been released in the aquatic ecosystems throughout the world and can be bioaccumulating in biota. The purpose of this study was to assess the use of zebra mussels ( Dreissena polymorpha) as a biomonitor for investigating the geographical variations of organotin bioavailability along the St. Lawrence River. The presence of organotins (tributyltins (TBT) and triphenyltins (TPT)) and their degradation products were measured in the soft tissues of zebra mussels collected from 11 sites along the St. Lawrence River (between Cornwall and Ile d’Orleans) in June 1996. TBT and TPT were generally low (< 0.001 to 0.030 μg/g wet weight) and were similar to those reported in Kingston Harbour, Ontario in Canada and Nieuwkoop and Brielse meer in the Netherlands. The highest concentration of TBT (1.44 μg/g wet weight) was found in mussels from Bassin Louise, a marina in Quebec City. This suggests that zebra mussels are effive biomonitors of organotin compounds and that residual levels in the sediment, or illegal use of antifouling paints still remain problematic in localized sectors of the river. A more detailed study on the availability of TBT in marinas and harbors along the freshwater part of the St. Lawrence River is recommended.

Organotin compounds in marine water and sediments from the port of Ensenada, Baja California, Mexico

During September and October 1995, samples of surface sediments and water were collected to develop an analytical set-up to determine the concentrations of the organic compounds known as tributyltins (TBTs), including tributyl-, dibutyl- and monobutyltin. The method was then used to measure the levels of these contaminants in the port of Ensenada, Baja California. The method is based on hydride generation with atomic absorption detection. The concentrations determined were found to be relatively high (33 to 1021 ng g–1 of Sn in sediments and 66 to 469 ng L–1 in water samples), when compared to those obtained in similar works at San Diego Bay in California, USA. Comparisons are also made with other geographical locations. These results suggest that the port of Ensenada is an area that is receiving substantial amounts of these chemicals and might already be affecting the health of local biota. Two sources of these chemicals were identified: the activities associated with painting and cleaning of both commercial and sport boats, and the presence, at the time of the sampling, of an old platform near the entrance to the port facilities. The presence of the three compounds suggests that there is a permanent entry of these pollutants; furthermore, the presence of decreasing concentrations, starting with the more butylated compounds, suggests a recent introduction. Thc higher concentrations found in the sediment samples indicates the existence of an eflicient method of removal from the water column to the sediments of these compounds. The removal mechanism is associated with the presente of organic matter in the port area. In the sediments, the distribution of TBTs was partially dictated by the organic content, as a significant correlation (α = 0.05) between TBT concentration and organic content was found.

Lesions of the Skin in Process Workers Caused by Contact with Butyl Tin Compounds

(RECEIVED FOR PUBLICATIONNOVEMBER29,1957) Theindustrial production ofalkyl tinderivatives hasincreased rapidly inrecent years,butlittle is knownaboutthehazards toman whichmay exist inthehandling ofthese substances. Interest inthe matterhasbeensharpened by thecatastrophic results ofa therapeutic trial ofone ofthegroup, diethyl tindi-iodide, inthetreatment offurunculosis. Thecompound was given orally andcaused thedeathof102persons,cerebral oedemabeing foundatnecropsy(British Medical Journal, 1958). Manyofthosewhosurvived were left withparaplegia or other permanentneurological damage. Asfarasexperimental workon animals isconcerned, interstitial oedemaofthewhitematterof thebrainandcordwas foundbyMagee,Stoner, andBarnes (1957) inratspoisoned bycertain triethyl tincompounds. Stoner, Barnes, andDuff(1955) studied thetoxicity ofa numberofalkyl tinderivatives forseveral species, andadvised caution inthe handling oforgano-tin compounds, particularly of theethyl series, because oftheeffect these substances hadupon thecentral nervoussystem. BarnesandStoner(1958) showedthatrepeated application ofdibutyl tindichloride to theskin oftheratdamagednotonlytheskinbutalsothe biliary tract, proving thatthecompound was being absorbed percutaneously. Present Investigation Thispapergives an accountoftheskinlesions seenamong processandlaboratory workers engaged inthemanufacture ofdibutyl and tributyl tin compounds. Processing ofOrgano-tin Compounds.-Of the alkyl tincompounds madeatPureChemicals Ltd., dibutyl andtributyl tinderivatives, withtetrabutyl tin, constitute thegreater partandare aloneconsidered here.Dibutyl tinsare chiefly usedas stabilizers inplastics andaspolymerizers in silicone manufacture. Tributyl tins havebeenfound effective against certain fungi (vanderKerkand Luijten, 1954) andareusedasfungicides inpaper making, paint manufacture, andinthepreservation

Lesions of the skin in process workers caused by contact with butyl tin compounds.

(RECEIVED FOR PUBLICATIONNOVEMBER29,1957) Theindustrial production ofalkyl tinderivatives hasincreased rapidly inrecent years,butlittle is knownaboutthehazards toman whichmay exist inthehandling ofthese substances. Interest inthe matterhasbeensharpened by thecatastrophic results ofa therapeutic trial ofone ofthegroup, diethyl tindi-iodide, inthetreatment offurunculosis. Thecompound was given orally andcaused thedeathof102persons,cerebral oedemabeing foundatnecropsy(British Medical Journal, 1958). Manyofthosewhosurvived were left withparaplegia or other permanentneurological damage. Asfarasexperimental workon animals isconcerned, interstitial oedemaofthewhitematterof thebrainandcordwas foundbyMagee,Stoner, andBarnes (1957) inratspoisoned bycertain triethyl tincompounds. Stoner, Barnes, andDuff(1955) studied thetoxicity ofa numberofalkyl tinderivatives forseveral species, andadvised caution inthe handling oforgano-tin compounds, particularly of theethyl series, because oftheeffect these substances hadupon thecentral nervoussystem. BarnesandStoner(1958) showedthatrepeated application ofdibutyl tindichloride to theskin oftheratdamagednotonlytheskinbutalsothe biliary tract, proving thatthecompound was being absorbed percutaneously. Present Investigation Thispapergives an accountoftheskinlesions seenamong processandlaboratory workers engaged inthemanufacture ofdibutyl and tributyl tin compounds. Processing ofOrgano-tin Compounds.-Of the alkyl tincompounds madeatPureChemicals Ltd., dibutyl andtributyl tinderivatives, withtetrabutyl tin, constitute thegreater partandare aloneconsidered here.Dibutyl tinsare chiefly usedas stabilizers inplastics andaspolymerizers in silicone manufacture. Tributyl tins havebeenfound effective against certain fungi (vanderKerkand Luijten, 1954) andareusedasfungicides inpaper making, paint manufacture, andinthepreservation