Evaluation of environmental levels and biological impact of TBT in Malta (central Mediterranean)

Chemical monitoring for butyltins in bulk seawater, surface microlayer and superficial sediments determined that the two main local sources of marine contamination by tributyltin (TBT) compounds in Malta are ship-repairing dockyards and marinas. In bulk seawater, TBT values ranged from below the detection limit of 5 ng Sn l(-1) to 300 ng Sn l(-1); in sediments derived from the most polluted areas, TBT concentrations as high as 1500 ng Sn g(-1) were measured. At TBT levels found in local harbours, several sublethal biological responses are possible and were observed, including a significant reduction in MFO enzyme system activities of fish; digestive cell atrophy in the oyster Ostrea edulis; and induction of imposex in the snail Hexaplex trunculus. The latter two responses are evident at TBT concentrations below the environmental quality standard (20 ng TBT l(-1)). The ecological implications of these results are discussed and it is concluded that exposure of marine organisms to TBT in local harbours may be expected to lead to a reduction in the long-term survival of a number of such organisms. For these reasons, both the use of TBT-based antifouling paints for pleasure boats as well as drydock practices need to be controlled by appropriate regulations and their enforcement.     

The impact of the banning of tributyltin-based antifouling paints on the Sydney rock oyster, Saccostrea commercialis.

Two years after the banning in New South Wales (Australia) of tributyltin (TBT)-based antifouling paints for vessels under 25 metres in length, the impact on the Sydney rock oyster, Saccostrea commercialis, has been assessed. Reduced growth and shell deformities present before banning were found to be absent and healthy oysters contained TBT at concentrations close to the detection limit of 0.2 micrograms Sn kg-1. High tissue concentrations of both copper and zinc, prior to banning were also significantly reduced. This behaviour was predicted by field experiments which showed that TBT had a synergistic effect on the uptake of copper. The distribution of both TBT and copper in the various organs of the oyster were examined in an attempt to explain this synergism.     

Butyltins in sediments and deposit-feeding bivalves Scrobicularia plana from Arcachon Bay,France

A survey was conducted in Arcachon Bay during the summer of 1993 to determine the concentrations of tributyltin (TBT) and two degradation products in sediments and deposit-feeding bivalves Scrobicularia plana; the recruitment of juvenile clams to one site was also investigated. The three butyltins were detected in all sediment samples; however, the concentrations of TBT (from 7 to 30 ng Sn g⁻¹) were far lower than the literature values shown to have adverse effects on populations of sediment-dwelling bivalves. TBT levels in adult S. plana were similarly reduced (from 28 to 165 ng Sn g⁻¹), and they were consistently lower than the values predicted by the modelled bioavailability of TBT in sediments. On the other hand, recruitment to that particular site was negligible when compared to that recorded in the 1970s; the same applies to the adult density in this and other sites. This decline of the local S. plana populations is discussed in relation to present and past TBT pollution.     

Organochlorines in Greenland marine fish, mussels and sediments

Shorthorn sculpin (Myoxocephalus scorpius), polar cod (Boreogadus saida), blue mussels (Mytilus edulis) and sediments were sampled in Greenland 1994-1995 at three locations at the west coast and one at the east coast. Fish liver, mussel soft tissue and sediments were analysed for PCBs (10 congeners), DDTs (pp,'), HCHs (alpha, beta, gamma), HCB and trans-nonachlor. The overall geometric mean concentrations found for PCBs were 17 micrograms kg-1 wet wt. in shorthorn sculpin liver, 33 micrograms kg-1 wet wt. in polar cod liver, and 0.86 microgram kg-1 wet wt. in blue mussels. For the three species, the geometric mean concentrations for DDTs were 11, 36, and 0.39 micrograms kg-1 wet wt., respectively; for HCHs: 8.7, 32 and 0.56 micrograms kg-1 wet wt., respectively; for HCB: 4.2, 11 and 0.06 micrograms kg-1 wet wt., respectively; and for trans-nonachlor: 6.3, 19 and 0.16 microgram kg-1 wet wt., respectively. All organochlorines in the sediment samples were below the detection limit of 0.1 microgram kg-1 dry weight. For sculpins and mussels, most organochlorine compounds were found to increase with increasing lipid content. The weight of mussels did not influence organochlorine concentrations, whereas organochlorine content in general increased with fish length of sculpins. The concentrations were found to be comparable to levels in other Arctic regions, but orders of magnitude lower than levels found in the southern part of the North Sea. Organochlorine concentrations in sculpins showed a decreasing trend following the ocean current flowing from north to south at the east coast and from south towards north at the west coast of Greenland. The proportion of higher chlorinated PCBs (Cl atoms > or = 6) in sculpin liver followed the decreasing trend of PCB concentrations.     

Organotin contamination in sediments from the Western Mediterranean enclosures following 10 years of TBT regulation

Organotin (OT) compounds, namely butyl and phenyl, were measured in 38 recent sediments collected in harbours of the Western Mediterranean Sea (Northern: 4 and Southern: 9) and domestic and industrial sewage disposal sites (Northern: 9 and Southern: 1). Butyltins were the predominant tin species identified as being tributyltin (TBT) widespread in the whole area which suggests recent inputs of OTs. The highest levels of TBT were detected in commercial harbours associated with inputs from large vessels (average value: 5.0 microg TBT g(-1). Moreover, relatively high TBT values were also detected in fishing and recreational boating areas (average level ca. 1.0 microg TBTg(-1)). Phenyltin derivatives occurred at lower levels than butyltins being the monophenyltin the predominant compound (average values 45-945 ng g(-1)). The large predominance of the phenyltin degradation products (i.e. mono and diphenyltin) over the parent compound (i.e. triphenyltin) suggests that there are almost no recent inputs of these compounds. Furthermore, a comparative study of the OT occurrence in the sewage sludge disposal sites offshore Barcelona and Almeria (domestic) and into the Tarragona harbour (industrial) shows that domestic primary sewage sludge effluents can contribute to coastal OT pollution (244ng TBT g(-1)). Nevertheless, sewage sludge is a secondary source of OT contamination in the coastal environment in comparison to commercial harbours. In a comparative study with previous data collected in the late 1980s, the present study reveals that OT regulations established in the Mediterranean region in 1991 on the use of TBT-based antifouling paints have been effective in marinas, but reveals a significant TBT contamination in commercial and fishing harbours.     

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.     

(Tri)butyltin biotic degradation rates and pathways in different compartments of a freshwater model ecosystem

Experiments were conducted in controlled temperate freshwater ecosystems (microcosms) to determine the persistence and biogeochemical dynamic of tributyltin (TBT) and its degradation products. TBT and its derivatives were monitored simultaneously for 23 days (552 h) in sediment-water systems, with or without macroorganisms (macrophytes: Elodea canadensis and gastropods: Lymnaea stagnalis). Biphasic TBT removal from the water column was significantly enhanced by the presence of biota. The persistence of TBT in biota was assessed by a kinetic approach of the different bioaccumulation pathways and associated metabolisms adopted by the snails and the macrophytes in response to the TBT contamination. Furthermore, sediment acted for the final sink for butyltins in both types of microcosms, with more than 70% of TBT and its metabolites recovered in this compartment after two weeks of exposure. Degradation pathways in sediments of both biotic and abiotic microcosms appeared to represent a key process in TBT cycle and were characterized by half-lives in the range of one month. Specific transformation and transfer pathways of TBT as reactional mechanisms are discussed and modelled assessing in detail the role of each compartment with regards to the fate of TBT in the model aquatic ecosystems.     

Accumulation and trophic transfer of organotins in a marine food web from the Danish coastal waters

The presence of organotin compounds, e.g., tributyltin (TBT) and triphenyltin (TPhT) including the di- and monosubstituted breakdown products, was studied in a representative marine food web in order to assess the accumulation potential at different trophic levels in Danish coastal waters. This included samples of two species of seaweed, four species of invertebrates, four species of fish, five species of birds and two species of mammals. All organisms were sampled away from harbour areas and the organotin concentrations found in this study can therefore be considered to reflect a general level in organisms living in Danish coastal waters. All the samples analysed contained organotin compounds. The highest hepatic concentrations of butyltins were found in flounder (60-259 ng g-1 wet weight [ww], as Sn), eider duck (12-202 ng g-1 ww) and harbour porpoise (134-2283 ng g-1 ww). The lowest concentrations were found in seaweed and a plant-feeding bird. TPhT or its degradation products were also found in most of the samples with the highest concentrations in flounder (9.8-74 ng g-1 ww), cod (23-28 ng g-1 ww) and great black-backed gull (19-24 ng g-1 ww). This indicates an input of TPhT in the region, probably from the use as antifouling agent. A high variance in accumulation potential was found between the species, even between species at the same trophic level, which probably reflects the species-specific differences in exposure routes and the capabilities to metabolise and eliminate the organotin compounds. This study gives evidence of the importance of biomagnification of butyltin in harbour porpoises and, to a lesser extent, in fish and birds.     

Analytical aspects of the gas chromatographic determination of tributyltin and metabolites in environmental samples

Tributyltin and its metabolites were determined in environmental samples by gas chromatography using a flame photometric detection method. The analytical method involved the propylation of the organotins and the use of a recovery standard to correct for inefficient recovery. A detection limit of 5 ng Sn l(-1) for seawater, and 5 ng Sn g(-1) for sediments, was obtained when the detector was equipped with an optical filter; however, this concentration limit, which is higher than the environmental quality standard for TBT, could be improved by a factor of 100 on removing the filter. The limitations imposed by the choice of recovery and internal standards were discussed and it was shown that the possible presence of Sn(II) had no effect on the total extractable inorganic tin, as determined by the analytical protocol. The identification of unexpected mixed methylbutyltins in TBT-contaminated sediments was described, and the implications of the existence of such compounds were discussed.     

Fate of organotins in sewage sludge during anaerobic digestion

Adsorption onto sewage sludge is an important process for the elimination of tributyltin (TBT) from wastewater. However as the disposal of sewage sludge to agricultural land is a significant route for recycling biosolids, there exists an issue as to whether the potential long-term build-up of organotins in agricultural soil is acceptable, from a human health and environmental point of view. For the sustainable use of biosolids in agriculture it is essential to control and reduce the quantities of persistent pollutants such as organotins in sewage sludge. In this study, a sampling program was designed to establish the levels of TBT (and other organotins) in sewage sludge and their reduction during anaerobic treatment and processing prior to disposal. Experiments were also undertaken to assess the fate of TBT in laboratory scale anaerobic digesters where the influence of digester operating parameters could be evaluated. Organotin concentrations were determined using capillary gas chromatography with flame photometric detection. The results demonstrated that the majority of TBT remained concentrated in the solid phase (sewage sludge). Concentrations of TBT in sewage sludge were approximately 18 mg kg(-1) (dry weight) and both laboratory experiments and fieldwork demonstrated that degradation of TBT during anaerobic digestion of sludge was minimal.     

Accumulation of butyltin compounds in cobia Rachycentron canadum raised in offshore aquaculture sites

Butyltin residues (monobutyltin, MBT; dibutyltin, DBT; tributyltin, TBT; tetrabutyltin, TeBT) in the sea water and in the cobia (Rachycentron canadum) from aquaculture sites located offshore of Penhu island, Taiwan, were collected and quantified. The average concentrations of MBT, DBT, TBT and TeBT in sea water were n.d.-28+/-3, 4.0+/-0.6-88+/-13, n.d.-43+/-4, and n.d.-7+/-1 ng l(-1), respectively. The total butyltin (sum of MBT, DBT, TBT, TeBT) residues in the skin, dorsal muscle, ventral muscle, dark muscle, and liver of the cobia were in the range of 72+/-12-2270+/-85, 79+/-11-688+/-33, 82+/-14-1715+/-104, 93+/-13-803+/-47, and n.d.-52,745+/-252 ng g(-1) (wet weight), respectively. Although in this study in most cases, the highest concentration of total butyltin residues was found in liver or skin, in some cases, the highest concentration was found in muscle tissue. The crude lipid content in the skin, dorsal muscle, ventral muscle, dark muscle, and liver of these cobia was in the range of 7.9+/-0.1-28+/-1%, 11.7+/-0.8-29+/-1%, 11.5+/-0.3-44+/-3%, 24.2+/-0.4-48.4+/-0.4%, and 55.7+/-0.1-87.7+/-0.4% (wet weight), respectively. The concentrations of crude lipid content, and the concentrations of total butyltin residues in these tissues were not correlated.     

Study of the accumulation of tributyltin and triphenyltin compounds and their main metabolites in the sea bass, Dicentrachus labrax, under laboratory conditions

Accumulation of two triorganotins, tributyltin (TBT) and triphenyltin (TPhT), has been studied by exposing the sea bass, Dicentrachus labrax, to different concentrations of both compounds, under controlled laboratory conditions. D. labrax juvenile fish were acclimatized in a laboratory and isolated to four groups. One group was used as control (first group), while the other three were exposed, during 28 days, in tanks with seawater containing simultaneously 2.5 microg/l TBT and 2.5 microg/l (second group), 5 microg/l TBT and 5 microg/l (third group) and 15 microg/l TBT and 15 microg/l (fourth group), respectively. The higher exposure dose caused mortality to all animals after 48 h. In the other two groups, quantitative analysis of TBT and TPhT was carried out, weekly, on the target organs (muscle and liver). Also, the main metabolites of TBT, monobutyltin (MBT) and dibutyltin (DBT), and TPhT, monophenyltin (MPhT) and diphenyltin (DPhT) were monitored. Gas chromatography (GC) coupled to mass spectrometry in tandem (MS/MS) mode was used for their identification. The results of analysis of TBT and TPhT showed that D. labrax accumulated the compounds from the first week, although the levels depended on medium concentration exposure. Liver was found to accumulate higher concentrations of TBT and TPhT than muscle.     

Polycyclic musk fragrances in different environmental compartments in Berlin (Germany)

The aim of this study was to obtain data about the contamination of different environmental compartments (102 surface water samples, 59 sediment samples and 165 eel samples) by polycyclic musks (HHCB, AHTN, ADBI, AHMI, and ATII) within the framework of an exposure monitoring program. Results for HHCB (Galaxolide) gave the following mean values in areas strongly polluted with sewage: surface water 1.59 micrograms l-1; sediment 0.92 mg kg-1 d.w. and eel 1513 micrograms kg-1 f.w. (in the edible portion) (6471 micrograms kg-1 lipid). The following average concentrations were found in waters hardly contaminated with sewage: surface water 0.07 microgram l-1, sediment < 0.02 mg kg-1 and eel 52 micrograms kg-1 f.w. (445 micrograms kg-1 lipid). Mean concentrations of 6.85 micrograms l-1 (maximum: 13.3 micrograms/l) could be measured at sewage treatment plants' outlets. It could be shown that these polycyclics are highly suited to use as indicators of the degree of contamination of waters with organic substances originating from sewage. A mean bioconcentration factor (BCF) on wet weight of 862 (HHCB) and 1069 (AHTN) for the transfer from water to eel under natural conditions could be calculated. The corresponding BCF-values based on the lipid content of eel were 3504 (HHCB) and 5017 (AHTN).     

A review of organotin regulatory strategies, pending actions, related costs and benefits

Achieving consensus on equitable and effective national and global regulation(s) for the use of organotins as biocides in antifouling boat bottom paints has proven to be very complex and difficult for a variety of reasons as discussed in this paper. There appears to be broad agreement among stakeholders about the effectiveness of tributyltin (TBT) in antifouling paints. A draft Assembly Resolution prepared by the Marine Environmental Protection Committee (MEPC) of the International Maritime Organization (IMO) to propose a global ban on the use of organotins in antifouling paints was approved by the IMO at its 21st regular session (November 1999). In approving the Resolution, the Assembly agreed that a legally binding instrument (global convention--an international treaty) be developed by the Marine Environmental Protection Committee that should ensure by 1 January 2003, a ban on the application of tributyltin (TBT)-based antifouling paints; and 1 January 2008 as the last date for having TBT-based antifouling paint on a vessel. The Assembly also agreed that a diplomatic conference be held in 2001 to consider adoption of the international legal instrument. Monitoring, policing, enforcement, fines and record-keeping are yet to be defined. In addition, the MEPC has also proposed that IMO promotes the use of environmentally-safe anti-fouling technologies to replace TBT. Existing national regulations in the US and Europe have: (1) restricted the use of TBT in antifouling boat bottom paints by vessel size (less than 25 m in length), thus eliminating TBT from the smaller and recreational vessels that exist in shallow coastal waters where the impacted oysters species grow; (2) restricted the release rates of TBT from co-polymer paints; and (3) eliminated the use of free TBT in paints. The present movement toward a global ban suggests that the above regulatory approach has not been sufficient in some countries. Advocates of the ban cite international findings of: (1) higher levels of TBT in surface waters of ports and open waters; (2) imposex still occurring and affecting a larger number of snail species; (3) TBT bioaccumulation in selected fisheries; and (4) the availability of 'comparable' alternatives (to TBT) with less environmental impact. The global ban has been absent of a policy debate on the: (1) lack of 'acceptable and approved' alternatives in many nations; (2) appreciation of market forces in nations without TBT regulations; (3) full consideration of the economic benefits from the use of TBT; (4) 'acceptance' of environmental impacts in marinas, ports and harbors; and (5) realization of the 'real' time period required by ships for antifoulant protection (is 5-7 years necessary or desirable?). Estimates of fuel savings range from $500 million to one billion. In assessing the environmental impact from TBT, there are two sources: the shipyard painting vessels and the painted vessel itself. Today vessels can be painted with regulated or banned antifouling materials by boatyards in a country that does not have TBT regulations and subsequently travel in international and regulated national waters and thus bringing the impact back to the country which was trying to prevent it. Worse, local and national regulations for TBT have proven to be the antithesis of the popular environmental cliché--'Think Globally and Act Locally.' Legislative policies enacted by 'regulated' countries to regulate the use of TBT to protect (their) local marine resources have subsequently had far reaching environmental and economic impacts which have in essence transferred TBT contamination to those countries least able to deal with it. Market forces are selective for cheap labor and cheap environments. 'Unregulated' countries have unknowingly accepted the environmental and human health risks to gain the economic benefits from painting TBT on ships. (ABSTRACT TRUNCATED)     

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.     

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.     

Organochlorines in Greenland lake sediments and landlocked Arctic char (Salvelinus alpinus)

Lake sediments and landlocked Arctic char (Salvelinus alpinus) were sampled in 1994 and 1995 at four different locations in Greenland, three at the west coast and one at the east coast. Sediments, char muscle and char liver were analysed for PCBs (10 congeners), DDTs (pp'), HCHs (alpha, beta, gamma), dieldrin, HCB and chlordanes (5) and char in addition to toxaphene (total and 4 congeners). All organochlorines in the sediment samples were below the detection limit of 0.1 microgram kg-1 dry wt., while the overall geometric means in Arctic char muscle were, in microgram kg-1 wet wt., for PCBs 11 (range 1-140), for DDTs 4.0 (1-35), for HCHs 0.4 (0.06-1.5), for dieldrin 0.7 (< 0.1-4.2), for HCB 0.7 (0.09-3.8), for chlordanes 4.8 (1-57) and for total toxaphene 13 (1-180). The sums of PCBs, DDTs, chlordanes and total toxaphene disclosed higher concentrations in muscle of char from the east coast compared to char from the west coast. Dieldrin and HCB showed the same tendency, but less pronounced, while the sum of HCHs were found in highest concentrations at the west coast. PCB, DDT, chlordane and toxaphene concentrations showed a decreasing trend following the East Greenland Current. Principal component analysis on PCB congeners showed that the proportion of higher chlorinated PCBs (Cl > 5) were higher in Qaqortoq in south Greenland compared to the three other sampling areas in Greenland. However, no correlation was seen either between degree of chlorination and latitude or between degree of chlorination and PCB concentrations.     

Histopathological evidence of antagonistic effects of tributyltin on benzo[a]pyrene toxicity in the Arctic charr (Salvelinus alpinus)

We previously reported that long-term (54 days), repeated intraperitoneal exposure to low doses of tributyltin (TBT; 0.3 mg/kg) inhibited the metabolic activation of co-administered benzo[a]pyrene (BaP; 3 mg/kg) in the Arctic charr (Salvelinus alpinus); BaP, in turn, stimulated the metabolism and/or excretion of TBT. Here, we report the results of histopathological examinations of liver, kidney and pseudobranch tissue samples originating from these same fish. The results revealed higher lesion incidences at all sampling time points (Days 8, 32 and 56) among BaP-exposed fish compared with fish exposed to either TBT alone or combined with BaP. The severity of lesions like necrosis was also higher in BaP-exposed fish. Moreover, hepatic basophilic foci were observed exclusively in fish exposed to BaP alone. Together, these results provide new evidences that TBT can antagonize BaP toxicity in fish exposed to both pollutants under controlled laboratory conditions. In contrast, BaP does not appear to provide protection against TBT toxicity.     

Sea-nine antifoulant: an environmentally acceptable alternative to organotin antifoulants

This article reviews previously reported data on the performance, environmental fate, and environmental modeling of Sea-Nine 211 antifoulant (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one). Since organotins are an industry standard, the environmental fate and environmental modeling results of tributyltin (TBT) are compared to those of the Sea-Nine antifoulant for reference. Laboratory and field tests results have shown Sea-Nine antifoulant to be highly effective. Five years of commercial use has confirmed this. Sea-Nine antifoulant and TBT were compared in an environmental risk assessment to predict their effects on the environment. Sea-Nine antifoulant was degraded rapidly in the environment by microorganisms. Its half-life in aerobic and anaerobic microcosm studies was less than 1 h. TBT degraded slowly under aerobic and anaerobic conditions with half-lives ranging from 6 to 9 months. The degradation products of Sea-Nine antifoulant were ring-opened compounds with greatly reduced toxicity. TBT degraded to dibutyltin species, which were still toxic and persistent in the environment. Bioaccumulation studies in fish showed essentially no bioaccumulation of the Sea-Nine biocide. The bioaccumulation of TBT was significant, with bioconcentration factors as high as 10000. The Sea-Nine antifoulant showed no chronic or reproductive toxicity to marine species, while TBT showed a wide range of effects on growth, development, and reproduction at levels as low as 2 parts per trillion (ppt). Computer modeling using the Exposure Analysis Modeling System (EXAMS) predicted maximum concentrations of Sea-Nine biocide of up to 10 ppt, far below the maximum acceptable environmental concentration (MAEC) of 630 ppt. The maximum predicted concentrations of TBT were as high as 345 ppt, far above the UK Environmental Standard in seawater of 2 ppt.     

Toxicity and bioaccumulation of tributyltin and triphenyltin on oysters and rock shells collected from Taiwan maricuture area

The present study was undertaken to evaluate the toxicity of tributyltin (TBT) on oysters (Crassostrea gigas) and bioaccumulation of TBT and triphenyltin (TPhT) on oysters and rock shells (Thais clavigera) from mariculture areas of Taiwan. When treated with concentrations of 0.08, 0.40, 2.00, 10.00 and 50.00 microg TBT/L, the 48-, 72-, 96- and 120-h LC50s of oysters were 44.6, 18.4, 17.9 and 14.3 microg TBT/L, respectively. In the bioaccumulation experiments, oysters and rock shells were exposed to various concentrations of organotins, i.e. A: control, B: 0.40 microg TBT/L, C: 0.40 microg TPhT/L, and D: 0.20 microg TBT/L + 0.20 microg TPhT/L. In general, TPhT was faster accumulated than TBT in both oysters and rock shells and oysters had a higher elimination capability than rock shells. Additionally, greater bioaccumulation and elimination rates had been observed in female oysters than males. To rock shells, the bioaccumulation rate of organotins in imposex females was greater than males and females.