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Tributyltin and polycyclic aromatic hydrocarbon levels in Mobile Bay, Alabama: a review.

A review of the levels of polycyclic aromatic hydrocarbons (PAH) and tributyltin (TBT) in sediments from Mobile Bay, Alabama, shows that overall levels of PAH decrease from the upper bay (RI) to the lower bay (RIV). Analysis of PAH ratios indicate that pyrogenic sources such as fossil fuel combustion are dominant. There are so few data on TBT in sediments that spatial trends cannot be identified. Levels of PAHs in oyster tissues decrease from the upper bay (RI) to the lower bay (RIII). Although there is no significant temporal trend for PAH levels in bivalves for the US; in the bay, levels in Region II (RII) have decreased significantly and are currently below the national median. There is no trend in Region III (RIII), where levels remain below RII and the national median. RI and RIV had too few data for trend analysis. Mean levels of TBT in oyster tissues decrease from the upper bay (RI) to the lower bay (RIII). Temporal trend analysis indicates a significant decreasing trend for TBT in the US but no significant trend was detected for RII and RIII in Mobile Bay. TBT levels in RII are consistently higher than levels in the US and RIII, which are similar. Data from RI are too limited for analysis and there are no data for RIV.

Alabama↗

Changes in dietary bioaccumulation of tributyltin chloride (TBTCl) in red sea bream (Pagrus major) with the concentration in feed.

The effect of the concentration of tributyltin (TBT) in feed on the dietary bioaccumulation of tributyltin chloride (TBTCl) was studied in an 8-week uptake experiment and a 4-week elimination experiment using red sea bream (Pagrus major). The biomagnification factor (BMF) and the assimilation efficiency (AE) decreased from 0.30 to 0.15 and from 13% to 5.9%, respectively, as the TBT concentration in feed increased from 1.3 to 20 microg/g. The elimination rate constant (k(2)) was independent of the TBT concentration in the fish. Laboratory measurements of the BMF and AE of TBTCl underestimate actual field values if highly contaminated feed is used. Judging from the BMF and AE, the risk of the bioaccumulation of TBTCl through the food chain might be smaller than that of polychlorinated biphenyls.

Animals↗

Butyltins concentration levels and imposex occurrence in snails from the Sicilian coasts (Italy).

Two sampling campaigns have been carried out along the Sicilian coasts within the frame of a European project (Hic-TBT) financed by the LIFE programme. Snails and sediments have been sampled at 5 stations, characterised by very low (Ustica natural sea reserve), low (Ustica harbour), intermediate (Castellamare and Termini Imerese) and high shipping densities (Palermo). Biological and chemical analyses were carried out in order to evaluate the incidence of imposex occurring in snails, and the concentration levels of organotins in sediment and snail samples. Despite the low organotin concentration levels in sediment and snail samples, the results show that imposex is widespread around Sicily. In four locations almost all female snails were affected by imposex at advanced development stages, even in areas with a fairly low shipping density. Only in the natural sea reserve of Ustica Island imposex was relatively less severe. Finally a logarithmic correlation between TBT and imposex stages was observed.

Animals↗

The use of Nucella lapillus (L.) transplanted in cages to monitor tributyltin (TBT) pollution.

Specimens of the gastropod Nucella lapillus were transplanted from their natural habitat to sites affected by tributyltin (TBT) pollution to diverse degrees; individuals were held in cages that also included mussels as food. Subsamples were taken from the cages and the natural site at different time intervals (1, 2 and 5 months) to compare growth, imposex (a set of sexual anomalies caused by TBT) and butyltin concentrations accumulated in female tissues. Individuals in cages experienced negligible mortality and considerable growth. In addition, while the Relative Penis Size Index (RPSI, an index of imposex) remained consistent in the natural site through the experiment, it increased markedly at the implant sites; the same applies to the butyltin residues. These results are discussed to conclude that cage transplanting of N. lapillus is a suitable technique that can quickly (i.e. 1 month) detect differences in the level of TBT contamination among sites; however, extrapolation of experimental results to the field seems to require a longer exposure time (at least 5 months). Finally, the use of such an approach is deemed helpful to interpret the relationship between N. lapillus population dynamics and TBT pollution.

Animals↗

Cost-benefit analysis of the use of TBT: the case for a treatment approach.

The current climate of hostility towards the use of tributyltin (TBT) as an active ingredient in ship anti-fouling paint appears to be based on a very biased assessment of its environmental impact. While many national and international regulatory agencies are moving towards further restriction, and a complete ban is under active discussion, a number of factors appear to have been ignored. The economic impact of a ban on TBT when no adequate substitute exists could be substantial. Environmentally, consequences would include a substantial increase in the consumption of fossil fuel, with corresponding increases in carbon dioxide and sulphur dioxide emissions; the construction of more vessels; the transfer of ship-building, ship-repairing and ship-breaking activities from well-regulated to unregulated or under-regulated areas in the developing world; and a shift from sea transport to less environmentally acceptable forms of transport. Experience in Europe and other parts of the developed world shows that existing restrictions, where they are properly enforced, are probably adequate to alleviate the environmental damage associated with TBT. Some existing legislation acts to inhibit the search for effective substitutes. The environmental benefits of TBT have been ignored. Little thought has been given to a technical, rather than a legislative solution to controlling TBT inputs to the environment. A method is described for treating TBT-contaminated wastewaters, which has been successfully tested in prototype at full scale. Legislative measures against TBT will do nothing to address the problem of the existing backlog of contaminated material, nor even to permit the IMO proposal for the removal of TBT from all ships by 2008 to be successfully concluded in an environmentally safe manner, since no provision has been made for the disposal of the existing TBT; most probably it will be dumped in environmentally sensitive, unregulated areas in the developing world.

Cost-Benefit Analysis↗

The use of imposex to assess tributyltin contamination in coastal waters and open seas.

Imposex in muricid gastropods has been used to monitor tributyltin (TBT) contamination worldwide. Pollution was severe during the 1980s but regulations prohibiting the use of TBT-based antifoulants on vessels < 25 m in length have been highly effective in reducing TBT levels in coastal waters. Large vessels are still sources of TBT and major ports, especially those with dry docking and repair facilities, continue to be hot-spots of contamination. Measures of imposex suggest that severe pollution is normally localised to within a few kilometres of them. Mild imposex, possibly as a result of TBT pollution (although other causes have not been ruled out), has been described in whelks Buccinum undatum from offshore waters of the southern and central North Sea. However, the species is still abundant there and the occurrence of imposex does not seem to have affected its breeding performance. Imposex was mild or absent in populations of dogwhelks from open oceanic sites around the north Atlantic Ocean, suggesting that the oceans are free of contamination at biologically significant levels.

Animals↗

Environmental impact of TBT: the French experience.

The deleterious effects of TBT released by antifouling paints were first documented in Arcachon Bay (France) at the end of the 1970s. As a result of the high level of water contamination, the production of Pacific oysters was severely affected by a complete lack of reproduction and the appearance of calcification anomalies which were responsible for a strong decline in the marketable value of the remaining stock. Regulations that had been successively adopted from January 1982 had positive effects on the recovery of the oyster grounds by reducing ambient water concentrations. Most antifouling paints act by releasing toxicants into the water which avoid the fixation of the organisms responsible for fouling. The use of these paints results in significant inputs of biocides in the waters. The harmful effects on non-target organisms were first evidenced in the bay of Arcachon (France) where the most acute disturbances were recorded following tributyltin (TBT) contamination.

Animals↗

The second order effects on commercial shipping of restrictions on the use of TBT.

Increased hull roughness reduces vessel speed and increases fuel consumption. These are first order effects of restricting or prohibiting the use of antifouling paints. Reduced transport capacity and increased capital costs are frequently recognised as second order effects of such reductions in fleet efficiency. This paper focuses on other second order effects of prohibiting or restricting the use of TBT-based antifoulings. The potential cost increases will affect high-speed vessels most severely. These vessels are the segment of the shipping industry that is most relevant to the political drive in Europe towards shifting the balance of transport of goods towards sea rather than road transport for environmental reasons. Any decision to restrict or prohibit these paints would tend also to induce a shift from local to global environmental problems, which would be more difficult to manage.

Commerce↗

Neuro-endocrine biomarkers of pollution-induced stress in marine invertebrates.

Nitric oxide (NO) is a molecular mediator of the non-specific immune response of vertebrates but production has also been recorded in response to bacterial infection in invertebrates. Together with biogenic amines and cytokines, production of NO in invertebrate phagocytic haemocytes is thought to represent a putative stress response. In this study the hypothesis that NO might be a sensitive biomarker of stress in invertebrates has been tested. The spectrophotometric Griess assay for nitrite and nitrate has been modified so that the final breakdown products of NO are suitable for measurement in invertebrate haemolymph. The assay was linear in the range 1-100 microM with a sensitivity of 4 microM. The baseline NOx measurement in unstressed mussels was 0.74 mM NOx/mg protein. Mytilus edulis were kept at 15 micro C in filtered seawater for at least 2 days prior to exposure to TBTO (0.001-0.1 mg/l) for 24 h. Preliminary results suggest that TBTO perturbs the NO response and that the outlined assay protocol is a sensitive means of detecting those changes. It is proposed that NO measurements potentially offer a highly sensitive, non-invasive means of monitoring stress responses associated with environmental change.

Adaptation, Physiological↗

Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan.

The consumption of contaminated seafood has been reported as an important route of human exposure to metals in Taiwan. We consider the concentrations of TBT, Cu, Zn, Cd, As, and the consumption of oysters of Taiwanese to be the important information related to public health in Taiwan. Therefore, the aim of this study was to evaluate the public health risks associated with TBT, Cu, Zn, Cd and As from shellfish for the general population and fishermen of Taiwan. In general, TBT concentrations in various oysters ranging from 0.32 to 1.51 microg/g dry wt. varied with sampling locations. The highest TBT, Cu, and Zn geometric mean (GM) concentrations in oysters of 1.51, 1180 and 1567 microg/g dry wt. were obtained from the Hsiangshan coastal area. The values of oyster consumption for fishermen were 94.1 and 250 g/day for typically and maximally exposed individuals, respectively. In particular, the highest intake (250 g/day) from fishermen was almost two times greater than that of the general population (139 g/day). The THQ (target hazard quotient) values of Hsiangshan's fishermen are 3.87 and 20.50 for TBT and Cu for maximally exposed individuals are higher than other oyster culture areas. It is interesting that those consuming oysters from Hsiangshan, Lukang, Taishi caused abnormally high THQs of TBT and other metals (100% over 1.0), and TBT was attributed to only 3-21% of the total THQs in different fishermen of Taiwan. Our results suggest that current environmental levels of TBT and other metals are associated with a significant potential threat to human health for fishermen resident in coastal areas of Taiwan.

Adult↗

Inhibition of coral fertilisation and larval metamorphosis by tributyltin and copper.

Fertilisation and larval metamorphosis of reef-building corals are important life history events leading to recruitment of juvenile corals to reef populations. Little is known of the sensitivity of these early life phases to pollution, or their relative susceptibility to certain toxicants compared with established coral colonies. Inhibition of fertilisation and larval metamorphosis of the coral Acropora millepora (Ehrenberg, 1834) was assessed in response to solutions of the antifoulants tributyltin (TBT) and copper (Cu) using laboratory-based bioassays. Nominal concentrations that inhibited 50% fertilisation and metamorphosis (IC50) were calculated from 4 h fertilisation and 24 h metamorphosis assays and were based on introduced dose. Cu was most potent towards fertilisation with an IC50 of 17.4 micrograms/l. TBT however, proved more toxic to larval metamorphosis having an IC50 of 2.0 micrograms/l. Inert surfaces coated with either Cu- or TBT-based antifouling paint also inhibited fertilisation and metamorphosis. The degree of inhibition was correlated with surface area of the paint coating. These results indicate fertilisation and metamorphosis of coral can be sensitive to active components of antifouling paints.

Animals↗

Immune function, hepatic CYP1A, and reproductive biomarker responses in the gulf killifish, Fundulus grandis, during dietary exposures to endocrine disrupters.

The gulf killifish, Fundulus grandis, was used to determine the influence of biological rhythms on three biomarker responses. We first developed monoclonal antibodies against the model's immunoglobulins and vitellogenin in order to measure antibody responses and vitellogenesis, respectively. We then treated adults with 10, 1, 1, and 10 ppm of Aroclor 1254, tribuyltin, 3-methylcholanthrene, and nonyl-phenol, respectively, in mixtures over a 16-week period. The study followed Vibrio anguillarum-specific antibody responses, hepatic CYP1A, and plasma vitellogenin levels in the morning and again in the evening at 2-week intervals. The contaminated diet suppressed secondary antibody responses, but only in the morning. The contaminated diet also altered CYP1A, but not vitellogenesis. In addition, fish in the control group exhibited daily and seasonal differences in specific antibody levels and CYP1A induction. Moreover, circulating vitellogenin levels in control males sampled in the morning increased throughout the exposure, but remained below those of females. This study underscores the need to consider normal physiological rhythms when employing biomarkers in toxicology.

Animals↗

Genotoxic, cytotoxic and developmental effects of tributyltin oxide (TBTO): an integrated approach to the evaluation of the relative sensitivities of two marine species.

Adopting an integrated approach the potential genotoxic, cytotoxic and developmental effects of tributyltin oxide (TBTO), a known endocrine-disrupting agent for neogastropods, have been evaluated in two ecologically relevant invertebrates: Mytilus edulis (blue mussel) and Platynereis dumerilli (rag worm). Following determination of the maximum tolerated dose (MTD) in terms of developmental and survival effects, the embryo-larval stages of these organisms were exposed to a range of concentrations of TBTO, and analysed for cytotoxic (proliferation rate index) and genotoxic (sister chromatid exchanges and chromosomal aberrations) effects. The study suggested that: (1) TBTO is both toxic and genotoxic to embryo-larval stages of both species; (2) at comparable concentrations, for developmental and genotoxic effects, P. dumerilii (non-target species) is more sensitive compared to M. edulis (target species); and (3) genotoxic effects are more closely tied with the development and survival of the organisms. The study emphasises the need of the evaluation of genotoxic potential of other endocrine-disrupting agents in different taxonomic groups.

Animals↗

Imposex still evident in eastern Australia 10 years after tributyltin restrictions.

A survey of imposex in Thais orbita (Neogastropoda) along the New South Wales (NSW) coast, Australia, found imposex was still widespread 10 years after a partial ban on tributyltin (TBT) based antifouling paints. Transplant experiments also revealed that imposex was induced in T. orbita over a period of 9 weeks in Sydney Harbour, NSW. A comparison of the imposex data with that collected shortly after the introduction of restrictions on TBT revealed a general decline in imposex frequency occurring at open coast sites, an exception being the site at South West Rocks. Sites located within harbour/bay areas did not display a decline in imposex frequency but a decline in the severity of imposex was apparent. The observed decrease in imposex values in T. orbita may reflect a general decrease of butyltin contamination within the coastal environment. However, the persistence of contamination "hotspots" within harbours and bays remains a concern.

Animals↗

Routes of TBT uptake in the clam Ruditapes decussatus. I. Water and sediments as vectors of TBT uptake.

This study assesses the relative importance of water and sediments as vectors of TBT uptake in the sediment-dwelling suspension feeder, Ruditapes decussatus. Accumulation of TBT was determined in R. decussatus exposed for 60 days to moderately high but environmentally realistic levels of TBT in water (100 ng Snl(-1)) and sediments (0.8 microg Sn g(-1) dw), separately or in combination, using constant-flow systems. The results indicate that this species accumulates TBT predominantly from water. Although some accumulation from sediments does occur, the processing of large amounts of water needed to sustain the filter-feeding habits of this species is a prime determinant of TBT uptake. The route of exposures reflected in tissue distributions of TBT in R. decussatus. However, gills are the most important site for accumulation of TBT from water, irrespective of whether contaminated sediments are present or not.

Animals↗

Routes of TBT uptake in the clam Ruditapes decussatus. II. Food as vector of TBT uptake.

Marine bivalves are exposed to contaminants via the aqueous phase, sediments and food. Nevertheless, the relative importance of these phases as uptake vectors of contaminants in these marine organisms has not been well studied. Phytoplankton concentrate contaminants from seawater and given their position at the base of most marine food webs, these algal cells may play critical roles in the transfer of contaminants to higher trophic levels. This study assesses the relative importance of microalgae as a vector of tributylin (TBT) uptake in the infaunal, suspension-feeding bivalve Ruditapes decussatus. Accumulation of TBT via the algal diet was determined by experimental exposure of R. decussatus to 14C-TBT labelled phytoplankton Isochrisis galbana, for a period up to 60 days. The digestive tract of these clams initially accumulates TBT preferentially from food. After a few weeks of exposure, internal remobilization results in a more widespread partitioning of TBT amongst tissues.

Animals↗