Use Of TBT-based Antifouling Paints Research Articles

An absurd scenario in 2021: Banned TBT-based antifouling products still available on the market

Despite the efforts of the International Marine Organization (IMO), through the International Convention on the Control of Harmful Antifouling Systems on Ships to ban the use of TBT-based antifouling paints (September 2008), and the Rotterdam Convention (RC) to forbid the trade of tributyltin (TBT), the situation does not seem to have significantly changed since 2014 when TBT-based paints were shown to be still being manufactured in the United States and offered for sale in stores throughout the Caribbean and Central America. In fact, this study shows that seven years later the same situation not only persists, but may have an even more global distribution than previously thought.

Spatial distribution of butyltins and imposex in eastern Brazilian Amazon

Spatial distribution of Butyltins (BTs) in surface sediments and gastropod tissues were quantified, with samples taken from an estuarine system of the Eastern Amazon, Brazil. The imposex incidence was also assessed using Thaisella coronata (Gastropoda, Mollusca). The sediment sampling was carried out at 19 sites and T. coronata in 6 of those. The highest BTs levels were detected in sediments of a Marine Extractive Reserve (27.1 ng Sn g−1) and in an urban area (19.8 ng Sn g−1). In T. coronata tissues, BTs levels ranged from <5 to 142 ng Sn g−1. Imposex incidence ranged from 0% to 100% and VDSII (penile papillae) was registered in gastropods from 5 out of 6 sampled sites. The results suggest that BTs concentrations are related to sampled area use, but also to the local hydrodynamics, highlighting the importance of an effective control in the use of TBT-based antifouling paints in the Eastern Amazon.

TBT is still a matter of concern in Peru

Tributyltin (TBT) environmental concentrations as well as imposex levels have been declining in several coastal areas worldwide. However, recent studies have shown that TBT contamination is still an important issue along some Latin American coastal areas. Thus, the incidence of imposex and butyltin compounds (BTs) in sediments and gastropod tissues was spatially and temporally (2009 and 2012) appraised in Lima (Peru) along potential TBT sources (harbors and marinas). Despite the general pattern of reduction close to Callao harbor, a clear increment in the levels of imposex (RPLI = 0.0 to 8.4 and 0.0 to 28.4/VDSI = 0.0 to 3.3 and 0.0 to 3.5) and TBT in tissues (25 to 112 and 62 to 146 ng Sn g−1) of Thaisella chocolata were seen from 2009 to 2012 in two sampling sites, respectively, located nearby a newly established marina. Thus, despite the international restrictions on the use of TBT-based antifouling paints are apparently reducing the inputs at international harbors, the present study clearly shows that marinas are still acting as important sources of TBT to the study area due possibly to the lack of legal restrictions on production, trading and/or use of TBT. The present findings reinforce what has been seen along many other Latin American coastal areas.

Assessment of organotins and imposex in two estuaries of the northeastern Brazilian coast

Butyltin compounds (BTs) were used worldwide, especially because of their properties as biocides. Due to its high toxicity, the use of tributyltin (TBT) in antifouling paints has been prohibited in most countries. The occurrence and impact of BTs were assessed in surface sediments and in Stramonita rustica populations of two tropical estuaries that host major ports in northeastern Brazil. ΣBT concentrations ranged from <LOQ to 542ngSng−1 dry weight in sediments while imposex was not observed in S. rustica. This is in contrast to previous studies that reported high incidence of imposex at the same sites. Butyltin degradation index indicates recent input of TBT at levels that might trigger imposex in gastropod species more sensitive than S. rustica. These results emphasize the need of more rigorous controls by local authorities since Brazil has restricted the use of TBT-based antifouling paints.

Imposex and butyltin contamination still evident in Chile after TBT global ban

Imposex in gastropods (Acanthina monodon, Oliva peruviana and Xanthochorus cassidiformis), butyltin levels in surface sediments (Coquimbo and Concepcion) and tissues (Valparaiso and Concepcion) were assessed in three areas under the influence of maritime activities along the central Chilean coast. The highest TBT concentrations were observed in São Vicente Bay (Concepcion), reaching 122.3ngSng−1 in surface sediments and 59.7ngSng−1 in gastropods tissue, while in Valparaiso ranged from 7.4 to 15.8ngSng−1 in biota. The lowest TBT concentrations were detected in sediments from Coquimbo (<2ngSng−1), which can be attributed to a much lower ship/boat traffic (probably using TBT free products) in association to local oceanographic conditions. Despite DBT and MBT were the predominant analytes, recent inputs of TBT were evident in some areas. In fact, fishing boats may be a relevant source since they were the predominant maritime activity in the most contaminated sites. In addition, the absence of significant differences within BTs levels between both genders of A. monodon suggests that tissues from distinct sexes can be indistinctly used for future contamination studies. Imposex incidence was detected in 11 out of 15 sampled sites, indicating that environmental levels of TBT have been sufficient to induce deleterious effects on the exposed organisms. Thus, the impacts caused by TBT in Chilean coastal areas were detectable and consistent with other studies performed in South America. This present environmental contamination is probably due to the lack of regulations forbidding the use of TBT-based antifouling paints in Chile.

Shell disturbances and butyltins burden in commercial bivalves collected from the Bizerta lagoon (northern Tunisia)

Shell disturbances and soft tissues butyltin burden were investigated in commercial bivalves Lithophaga lithophaga, Mytilus galloprovincialis, Solen marginatus and Crassostrea gigas from the Bizerta lagoon. Shell disturbances were found in all bivalves, being scarce in S. marginatus. In the internal valve of L. lithophaga, burrowing annelids and sipunculids living inside galleries were observed, while in the external valve, brown-blackish or white stains were found. In M. galloprovincialis, a yellowish mass located at the shell anterior side was found fixed firmly to the pearly layer by a hard brownish structure covering some annelid elliptic eggs. In the internal shell layer of some specimens collected in April, embryos belonging to tubiculous annelids at various developmental stages were observed. In C. gigas, shell thickening was revealed in some specimens corresponding to white doughy deposits at the internal valve and between shell layers. In S. marginatus, only one specimen showing a cavity at the posterior site was found. Total butyltin concentrations in the studied bivalves varied between 30 and 245 ng/g dry weight with tributyltin (TBT) being the predominant compound. The highest concentration was recorded in L. lithophaga collected from the Bizerta Bay and the lowest concentration in S. marginatus from Maghraoua. This study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet.

Organotins in North Sea brown shrimp (Crangon crangon L.) after implementation of the TBT ban

The organotin (OT) compounds tributyltin (TBT) and triphenyltin (TPhT) are potent biocides that have been used ubiquitously in antifouling paints and pesticides since the mid-1970s. These biocides are extremely toxic to marine life, particularly marine gastropod populations. The European Union therefore took measures to reduce the use of TBT-based antifouling paints on ships and ultimately banned these paints in 2003. Despite sufficient data on OT concentrations in marine gastropods, data are scarce for other species such as the North Sea brown shrimp (Crangon crangon), a dominant crustacean species in North Sea inshore benthic communities. The present study provides the first spatial overview of OT concentrations in North Sea brown shrimp. We have compared these data with historical concentrations in shrimp as well as with sediment concentrations. We have also addressed the effect on the shrimp stock and any human health risks associated with the OT concentrations found. TBT and TPhT in shrimp tail muscle ranged from 4 to 124 and from 1 to 24μgkg−1 DW, respectively. High levels are accumulated in estuarine areas and are clearly related with sediment concentrations (biota-sediment accumulation factor ∼10). Levels have decreased approximately 10-fold since the ban took effect, coinciding with a recovery of the shrimp stock after 30years of gradual regression. Furthermore, the OT levels found in brown shrimp no longer present a human health risk.

Imposex and butyltin concentrations in Bolinus brandaris (Gastropoda: Muricidae) from the northern Tunisian coast

The imposex incidence and butyltin concentration i.e. tributyltin with its di- and mono-substituted metabolites were investigated in the muricid Bolinus brandaris sampled from two sites on the northern Tunisian coast (the Lagoon of Bizerta and the small Gulf of Tunis). Both populations had imposex, with stages of imposex development varying between VDS 1 and VDS 4.3. All imposex indices (imposex frequency (I %), female penis length, female vas deferens length, vas deferens sequence index, relative penis length index, and vas deferens length index) were significantly higher in snails from the Bizerta lagoon. Butyltins were detected in the whole tissues of both sexes from the two sites. TBT levels were higher in gastropods collected from the lagoon of Bizerta (12.65 ±1.48 ng Sn g( - 1) dw in female and 15.21 ±1.13 ng Sn g( - 1) dw in male) than in individuals from the Gulf of Tunis (10.71 ±1.26 ng Sn g( - 1) dw in female and 11.65 ±1.63 ng Sn g( - 1) dw in male), corroborating the data of imposex analysis. These results confirmed that B. brandaris could be used as a bioindicator species of butyltin pollution in the studied areas. In addition, this study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet.

Imposex and organotin prevalence in a European post-legislative scenario: Temporal trends from 2003 to 2008

Imposex levels and organotin tissue concentrations were assessed in Nassarius reticulatus females collected between June and August 2008 at 23 sites along the Portuguese coast. Females with imposex were present at all sampling sites with highest levels inside main harbors. Imposex parameters across sampling stations varied between 6.3% and 100% for %I, 0.2–4.4 for VDSI, 0.1–7.8 mm for FPL, 0.3–88.9% for RPLI and 0.0–1.1 for AOS. TBT levels varied between 3.5 and 380 ng Sn g −1 dw, representing an average proportion of 50.4% of total butyltins (∑BTs = MBT + DBT + TBT). Sterile females were detected at two locations. Highly significant correlations between imposex and TBT levels were found. The efficacy of the EU legislation banning the use of TBT-based antifouling paints since 2003 (EC Regulation 782/2003) was evaluated by comparing the levels of imposex observed in 2008 with those reported for 2003. OTs tissue concentrations were also determined in preserved samples collected in 2003. There was a decrease in imposex and TBT tissue contamination between 2003 and 2008 indicating that a decline in TBT pollution has occurred in the Portuguese coast since the implementation of the legislation. Considering that the EC Regulation 782/2003 is an anticipation of the IMO AFS Convention, a global scale decrease in TBT pollution can be expected in the near future. Despite the rapid amelioration in the Portuguese coast, TBT pollution is still a problem as the Ecological Quality Objective (EcoQO) proposed by OSPAR Commission was not achieved in 91% of the surveyed sites.

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

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

Macrofaunal recovery following TBT ban

In the United Kingdom, the use of TBT-based anti-fouling paints on small vessels was banned in 1987, and a biological study of the Crouch Estuary, a yachting centre on the south-eastern coast of the UK, was conducted in order to determine the ecological improvements resulting from this legislation. We present the changes in the macro-infaunal communities along the estuary in relation to declining TBT concentrations between 1987 and 2005. Although the major changes in response to the ban were observed within the first 3 years (primarily an increase in the number of crustacean taxa and a shift in community structure), with changes still apparent between three and 5 years, the temporal duration of this study allowed the rapidity of the response to be truly determined.

Exploring the use of caged Nucella lapillus to monitor changes to TBT hotspot areas: A trial in the River Tyne estuary (UK)

Caged dogwhelks (Nucella lapillus) and mussels (Mytilus edulis) were placed in situ at sites along the River Tyne (UK) in order to investigate the potential for monitoring any change in tributyltin (TBT) mediated effects. After 6 months the development of imposex was investigated in the dogwhelks and concentrations of TBT were determined in the whole tissues of both species. Sites within the estuary showed a high degree of imposex, whilst those at sites North and South of the estuary mouth exhibited significantly lower induction. Concentrations of TBT measured in the dogwhelk and mussel tissues showed the same pattern. The success of the caging technique, occurrence of imposex at other UK sites and the need for further monitoring at TBT impacted locations in the light of current international controls on the use of TBT-based antifouling paints on sea-going vessels are discussed.

Imposex in Nucella lapillus, a bioindicator for TBT contamination: re-survey along the Portuguese coast to monitor the effectiveness of EU regulation

Imposex, a bioindicator of TBT contamination, was re-examined in 2000, five years after the first survey, in populations of the dogwhelk Nucella lapillus sampled along the Portuguese coast, in order to monitor the effectiveness of the 1993 Portuguese legislation based on EU regulation to restrict the use of TBT-based antifouling paints on ships not longer than 25 m. The results obtained during this study indicate that TBT contamination has increased along the Portuguese coast over the five-year period, indicating an inefficacy of the partial ban. The degree of imposex had increased more near small harbours than near ports supporting commercial vessels.

Survey for the occurrence of antifouling paint booster biocides in the aquatic environment of Greece.

Since the restriction imposed by European Union regulations on the use of TBT-based antifouling paints on boats below 25 m in length, new terms have been introduced in the 'small boat' market. Replacement products are generally based on copper metal oxides and organic biocides. Several studies have demonstrated the presence of these biocides in European ports and marinas of Spain, France, Germany and the United Kingdom. An extended survey of the antifouling biocides chlorothalonil, dichlofluanid, irgarol 1051 and sea-nine 211 was carried out in Greek ports and marinas of high boating activities from October 1999 to September 2000. The sampling sites were: Piraeus, Elefsina, Thessaloniki, Patras, Chalkida, Igoumenitsa, and Preveza (Aktio). The extraction of these compounds from the seawater samples was performed off-line with C18 solid phase extraction (SPE) disks while the determination was carried out with gas chromatography coupled to electron capture (ECD), thermionic (FTD) and mass spectroscopy (MS) detectors. The concentration levels of biocides were higher during the period from April to October. This seasonal impact depends on the application time of antifouling paints and mimic trends in the seasonal distribution of biocides in other European sites.

Screening of Marine Algal Extracts for Anti-settlement Activities against Microalgae and Macroalgae

The ban on the use of TBT-based antifouling paints for boats under 25 m in length has lead to a search for new non-toxic antifoulants. One of the most promising alternative technologies to heavy metal based antifouling paint is the development of antifouling coatings whose active ingredients are naturally occurring compounds from marine organisms. This is based on the principle that marine organisms also face the problem of the presence of epibionts on their own surfaces. In this study, the antifouling activity of a series of aqueous, ethanolic and dichloromethane extracts from thirty algae from the North East Atlantic coast was investigated. The extracts were tested in laboratory assays against species representative of two major groups of fouling organisms, viz . macroalgae and microalgae. The activity of several extracts was comparable to that of heavy metals and biocides (such as TBTO and CuSO 4 ) currently used in antifouling paints and their lack of toxicity with respect to the larvae of oysters and sea urchins suggests a potential for novel active ingredients.

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 μg TBT g −1). Moreover, relatively high TBT values were also detected in fishing and recreational boating areas (average level ca. 1.0 μg TBT g −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 Almerı́a (domestic) and into the Tarragona harbour (industrial) shows that domestic primary sewage sludge effluents can contribute to coastal OT pollution (244 ng 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.

Improvements in the Epifauna of the Crouch Estuary (United Kingdom) Following a Decline in TBT Concentrations

In the United Kingdom, the use of TBT-based anti-fouling paints on small vessels was banned in 1987, and a biological study of the Crouch Estuary, a yachting centre on the south-eastern English coastline, was initiated in order to monitor any associated changes. The macrobenthic infauna and epifauna were sampled between 1987 and 1992, and again in 1997. Epifaunal sampling in 1997 showed that an earlier increase in sedentary taxa had been sustained, and also that a large population of the native oyster Ostrea edulis had become established upstream. Multivariate analysis revealed continuance of a trend towards directional change in community composition at inner estuary stations, where TBT concentrations were historically much higher. These observations, along with evidence of established populations of a range of ascidian species in the inner estuary after an initial marked increase in densities, provide circumstantial evidence of an underlying improvement in environmental conditions following the TBT ban in 1987.

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 Value and Validity of Community-based Research: TBT Contamination of the North Sea

Data collected by volunteers in a survey of imposex in the dogwhelk Nucella lapillus from North Sea coasts correlated closely with independent measures made by an experienced scientist. There had been significant recovery from imposex since an earlier survey in 1991, even in populations which had been classified as sterile at that time. The study has attracted media attention, and may therefore have had some impact on the current debate on the need to regulate further (or ban altogether) the use of TBT-based anti-fouling paints.

Unregulated use of TBT-based antifouling paints in Israel (eastern Mediterranean):high contamination and imposex levels in two species of marine gastropods

The use of tributyltin (TBT)-based antifouling paints is unregulated in Israel, and levels of contamination are high along the Mediterranean coastline there. This is indicated by concentrations of butyltins found in the tissue, and by imposex in the whelks Stramonita haemastoma and Hexaplex trunculus. Both the old (since 1974) and new (since late 1995) marinas we studied are hotspots of pollution. Imposex indices were very high at the old marina (RPSI > 100, VDSI 4 to 5); all female H. trunculus and some S. haemastoma were sterile within a distance of ca 1 km from it. The new marina offered a unique opportunity to witness the rapid and intense response of the whelks to TBT pollution in an open coastline. Despite a marked decrease in levels of contamination at distances of 1 to 2 km from both marinas, there were nevertheless detectable levels of butyltins sufficient to cause imposex in reference sites far from high shipping activity. There is evidence that TBT contamination affects abundance and relative growth rates, of male and female, of the 2 whelks around the marinas. Differences in biological response to TBT were observed between the 2 whelk species: S. haemastoma had higher levels of organotins than H. trunculus in most study sites, which may be related to different sensitivity or accumulation rates. In S. haemastoma a male-biased sex ratio was revealed around the old Tel Aviv marina, which may be derived from either female mortality or from a complete sex change in some females. Further development of marinas at coastal resorts is undesirable, certainly in the absence of regulations limiting the use of TBT-based antifoulants, and the establishment of such regulations is highly recommended.