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)

Contamination and toxic effects of persistent endocrine disrupters in marine mammals and birds

In recent years, several species of marine mammals and birds have been affected by uncommon diseases and unusual mortalities. While several possible causative factors have been attributed for these events, a prominent suspect is exposure to man-made toxic contaminants. Particularly, some of these man-made chemicals can disrupt normal endocrine physiology in animals. At CMES, our studies focus on exposure and toxic effects of endocrine disrupting chemicals, particularly organochlorines, in higher trophic level wildlife. Endocrine disrupting chemicals, such as organochlorine insecticides, polychlorinated biphenyls, organotins etc. are found in tissues of a wide variety of wildlife. Extremely high concentrations have been found in animals afflicted with diseases and/or victims of mass mortalities. Elevated contamination by organochlorines has been found in open sea animals such as cetaceans and albatrosses, which seemed to be attributable to their low capacity to metabolize toxic persistent contaminants. Significant correlations between biochemical parameters (serum hormone concentrations and cytochrome P450 enzyme activities) and residues of endocrine disrupting chemicals were found in some species of marine animals, which indicates that these chemicals may impose toxic effects in animals even at the current levels of exposure. In general, water birds and marine mammals accumulated the dioxin-like compounds with much higher concentrations than humans, implying higher risk from exposure in wildlife. The future issues of endocrine disrupting chemicals in humans and wildlife will have to be focused in developing countries.

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 health effects of selected organotin compounds: a review

The toxicity of selected tin compounds is reviewed. Over the years, a variety of uses has been found for organic and inorganic tin compounds, as fungicides, as stablizers in plastics, moluscicides, and miticides; they have also been suggested as insect chemosterilants and for other industrial uses. Many of these products are unpalatable when mixed into diets and have been suggested as rodent repellents. Inhaling tin as dust or fumes may cause a benign pneumoconiosis in exposed workers. The organotin compounds can be divided into alkyltin and aryltin compounds. The trimethyl and triethyltin compounds are well absorbed from the gastrointestinal tract and are the most toxic in this group. Triethyltin particularly produces status spongiosus of the white matter of the central nervous system. Most of the other alkyl and aryl tin compounds are poorly absorbed from the gastrointestinal tract, and are less toxic when given orally than when given parentally. Only one compound, tricyclohexyltin hydroxide, is now registered by the Environmental Protection Agency as a miticide. This product produces skin irritation in rabbits. Studies should be conducted to determine whether it causes contact dermatitis in humans.

Microbial interactions with tributyltin compounds: detoxification, accumulation, and environmental fate

While inorganic forms of tin are of relatively low toxicity towards microorganisms, the more lipid-soluble organotins can be highly toxic. Generally, trisubstituted (R3SnX) organotins are more toxic than di- (R2SnX2) and monosubstituted (RSnX3) compounds; the anion (X) apparently having little influence on toxicity. However, many microorganisms exhibit resistance to organotins, a phenomenon of relevance to the environmental cycling of organotins and also to novel biological methods of treatment. Organotin degradation can involve the sequential removal of organic moieties to yield less toxic derivatives, e.g. debutylation of tributyltin compounds to di- and monobutylins. Such degradation is known to take place in bacteria, algae and fungi, and this provides one route for detoxification. In addition, microorganisms are capable of accumulating tributyltin compounds, and this is another mechanism of removal from solution. The high lipid solubility of organotins ensures cell penetration and association with intracellular sites, while cell wall components also play an important role. Of the fungal wall components, melanin pigments are capable of TBT binding, and the addition of melanin to growing cultures can remove toxicity; melanised strains are also more sensitive than albino strains of the same species. To date, little attention has been paid to the biotechnological exploitation of these interactions for the degradation of tributyltin or its removal from solution. This paper describes some interactions of microorganisms (bacteria, cyanobacteria, microalgae, and fungi) with tributyltin compounds, with particular reference to toxicity, bioaccumulation and detoxification. Such processes should receive due consideration in any environmental management programme.

Chemicals and biological products used in south-east Asian shrimp farming, and their potential impact on the environment--a review

A wide variety of chemicals and biological products are used to treat the water and sediment of ponds in semi-intensive and intensive south-east Asian shrimp farming. These products are also often used in shrimp hatcheries and to disinfect equipment for shrimp pond management. In spite of the size and importance of the shrimp farming industry in several south-east Asian countries, documentation of the quality and quantity of chemicals and biological products used during farming is scarce. This paper is a compilation of the literature available on substances used in shrimp farming, and the possible environmental effects of these products are analysed to the extent allowed by the limited information. The role of shrimp farm managers, the chemical industry, governments, inter-governmental organisations and scientists in the development of a sustainable practice is discussed. It is concluded that shrimp farmers should reduce the use of chemicals and biological products because of the risks to the environment, human health and to production, and also, because many chemicals and biological products used in pond management have not been scientifically shown to have a positive effect on production. Clearly, the use of some chemicals, i.e. certain antibiotics, poses a risk of danger towards human health. Some chemicals used in shrimp farming, such as organotin compounds, copper compounds, and other compounds with a high affinity to sediments leave persistent, toxic residues, and are likely to have a negative impact on the environment. However, to assess the reality of these risks, substantial new information about the quantity of chemicals used in marine south-east Asian shrimp farming is needed.

Neurotoxic effects of occupational exposure to organotins

The authors gave 22 chemical workers neurological, psychiatric, and neuropsychological examinations and placed them in one of two groups according to their degree of exposure to trimethyltin chloride spillage during January 1978. Other chemicals to which they had been exposed were dimethyltin dichloride and methyl chloride. Specific and nonspecific symptoms of intoxication of the CNS showed a significantly greater frequency in the highly exposed group, including cycles of depression and destructive rage, each lasting a few hours. These observations should alert diagnosticians to this type of occupational exposure.

Triphenyltin as a potential human endocrine disruptor

Organotin compounds have been implicated as reproductive toxicants and endocrine disruptors primarily through studies in aquatic organisms, with little information available in mammals. Among the organotins, aryltins have been less studied than alkyltins. Extensive data is available on mammalian developmental and reproductive toxicity of one aryltin compound, triphenyltin (TPT), from toxicity studies conducted in connection with the registration of triphenyltin hydroxide (TPTH) as a pesticide and supporting publications from the open literature. Indications of adverse functional and morphological effects on the reproductive tract of rats were reported in a dose range of 1.4-20 mg/kg/d. Gonadal histopathology (both ovaries and testes) and infertility were affected at the higher doses, while reproductive-tract cancer, smaller litter sizes, and reproductive organ weights were affected at the lower end of the dose range. In vitro studies indicate that TPT can directly activate androgen receptor-mediated transcription and inhibit enzymes that are involved in steroid hormone metabolism. These data suggest that the aryltin TPT can be active as a reproductive toxicant in mammals and may be a human endocrine disruptor.

Disruption of glucocorticoid action by environmental chemicals: potential mechanisms and relevance

Glucocorticoids play an essential role in the regulation of key physiological processes, including immunomodulation, brain function, energy metabolism, electrolyte balance and blood pressure. Exposure to naturally occurring compounds or industrial chemicals that impair glucocorticoid action may contribute to the increasing incidence of cognitive deficits, immune disorders and metabolic diseases. Potentially, "glucocorticoid disruptors" can interfere with various steps of hormone action, e.g. hormone synthesis, binding to plasma proteins, delivery to target cells, pre-receptor regulation of the ratio of active versus inactive hormones, glucocorticoid receptor (GR) function, or export and degradation of glucocorticoids. Several recent studies indicate that such chemicals exist and that some of them can cause multiple toxic effects by interfering with different steps of hormone action. For example, increasing evidence suggests that organotins disturb glucocorticoid action by altering the function of factors that regulate the expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) pre-receptor enzymes, by direct inhibition of 11beta-HSD2-dependent inactivation of glucocorticoids, and by blocking GR activation. These observations emphasize on the complexity of the toxic effects caused by such compounds and on the need of suitable test systems to assess their effects on each relevant step.

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.

Chemicals trophic for the thymus: risk for immunodeficiency and autoimmunity

The thymus is considered as the privileged site of T-lymphocyte generation. The organ is extremely vulnerable to the toxic action of chemicals. The classical example is the "acute stress-induced involution" mediated by glucocorticoid steroid hormones from the adrenal cortex. Nowadays a number of substances have been identified that act in a differential way on the thymus. Examples presented are some organotin compounds acting on immature lymphoblasts in the outer cortex, glucocorticosteroids acting on small thymocytes in the cortex, 2,3,7,8-tetrachlorodibenzo-p-dioxin acting on epithelial cells in the cortex, and cyclosporin acting on dendritic cells and epithelium in the medulla. The mechanisms of toxicity include receptor binding (Ah, aryl hydrocarbon receptor; dioxin); the Ca(2+)-dependent activation of an endogenous endonuclease resulting in DNA fragmentation ("programmed cell death" or apoptosis; dioxin and glucocorticosteroids); and interference with cell proliferation (some organotin compounds). The consequences of toxicity can be a decrease in thymic output of newly-generated T-lymphocytes (i.e. generation of a new T-cell repertoire), or induction of autoimmune symptoms by the creation of unwanted repertoire. This latter phenomenon may be applicable to cyclosporin that under specified conditions can induce so-called syngeneic graft-vs-host disease. This survey presents a brief description of the function of the thymus and the various thymic cell populations involved. Thereafter the susceptibility to toxic insults and the mechanisms of toxicity are reviewed. Finally, the consequences of toxic action for the host defence system, and hence the health status, are considered.

Imposex and organotin compounds in ports of the Mediterranean and the Atlantic: Is the story over?

Organotin compounds are toxic substances released into the marine environment from antifouling paints. Sixty-two years following their first application and 9years after the complete ban on their use as biocides in 2003 (EC No. 782/2003), their negative impact on mollusks was still evident, as illustrated by imposex (i.e. the masculinization of female gastropods). This phenomenon is widely used to investigate tributyltin (TBT) pollution, with Hexaplex trunculus and Nassarius nitidus being considered as sensitive bioindicators. H. trunculus specimens and sediment samples collected from the ports of Cagliari (Sardinia), El Kantaoui (Tunisia) and Olhão (Portugal), along with N. nitidus individuals from the port of Faro (Portugal), were used for the assessment of imposex intensity and organotin pollution in these areas. High imposex frequency and organotin concentrations (TBT, triphenyltin (TPhT) and their degradation products) were observed, especially in Sardinia, implying that these chemicals remain a significant pollution issue in the specific Mediterranean ports. Moreover, the highly significant relationship established between penis length of imposex-affected females H. trunculus and TBT/TPhT concentrations offers a rapid and nonsacrificial proxy model for assessing the impact of organotins in coastal environments. Finally, the complementary use of more than one TBT bioindicator is advised in order to obtain more accurate results in detailed monitoring studies of TBT pollution.

Organochlorine and organotin compounds in Caspian seals (Phoca caspica) collected during an unusual mortality event in the Caspian Sea in 2000

Polychlorinated biphenyls (PCBs), organochlorine pesticides and organotin compounds were determined in the blubber and liver of Caspian seals (Phoca caspica) found stranded on the coast of the Caspian Sea during an outbreak of canine distemper virus (CDV) in 2000. Among organochlorines analyzed, DDTs were the most dominant contaminants with concentrations ranging from 6.3 to 470 microg/g on a lipid-weight basis. Caspian seals collected in 2000 during the epizootic had higher concentrations of organochlorines than healthy individuals sampled in 1998. However, the blubber layer was generally thinner in the seals collected in 2000 than those in the previous surveys. Although compositions of organochlorine pesticides in seals suggested that the contamination status in the Caspian Sea is improving, the levels found in Caspian seals in 2000 were comparable to those in other marine mammals that have suffered from epizootics. This implies that the present status of contamination found in Caspian seals poses a risk of immunosuppression. Concentrations of butyltin compounds in livers of seals ranged from 0.49 to 17 ng/g on a wet-weight basis and octyltin compounds were below limit of detection in all the samples analyzed, suggesting less contamination by organotin compounds in the Caspian Sea.

Toxic substances and the nervous system: the role of clinical observation

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Specific detection of organotin compounds with a recombinant luminescent bacteria

Organotin compounds are widely used as biocides in marine and terrestrial environments. Several currently used techniques allow either the measurement of the chemicals or their effects on living organisms. Our current research focuses on the development of a complementary method based on a bacterial bioluminescence-based bioassay for the specific detection of organotin compounds. The performance of the bioassay was assessed. The Escherichia coli bacterial strain used in this study is specific for TBT and DBT (with Cl, Br or I as the halogen group) with the central tin atom important for light production. The assay is conducted after overnight culture of the bacterial strain, followed by 60 min of contact time with the organotin compound for significant light production. The detection limits were found to be 0.08 microM for TBT (26 microgl(-1)) and 0.0001 microM for DBT (0.03 microgl(-1)) with a linear range of one logarithm. The repeatability of the bioassay is 8% and the reproducibility for TBT and DBT was approximately 14%. Lyophilization of the strains did not significantly modify the detection limit as well as the range of detection. Applications of the bioassay to environmental samples are discussed.

Imposex in the rock shell, Thais clavigera, as evidence of organotin contamination in the marine environment of Korea

Imposex was measured in the rock shell, Thais clavigera, from the coast of the Korean peninsula. Frequency of imposex was 0% at two reference sites, but at 47 out of 61 sites, frequency of imposex was recorded as 100%. The degree of imposex was relatively high at the sites near a harbor and a shipyard. Tributyltin (TBT) and triphenyltin (TPT) concentrations in T. clavigera ranged from 5 to 508 ng/g and from 3 to 2460 ng/g, respectively. A significant positive relationship was found between degree of imposex and organotin concentration, whereas a significant negative relationship was obtained between female-to-male sex ratio and the degree of imposex. During a field transplantation of T. clavigera from a pristine area to a port, TBT and TPT were accumulated in T. clavigera, and imposex was induced. T. clavigera shows considerable potential as a bioindicator species of the adverse effects of TBT and TPT contamination.

Tributyltin and triphenyltin induce spermatogenesis in ovary of female abalone, Haliotis gigantea

Two-month flow-through exposure experiments of tributyltin (TBT) and triphenyltin (TPhT) were conducted with abalone, Haliotis gigantea. Nominal concentrations of 100 ng TBT/l and 100 ng TPhT/l caused significant spermatogenesis in ovaries of exposed females. There were also significantly more contracted primary oocytes observed in females exposed to either TBT or TPhT than controls. The incidence of two types of unknown cells was also significant in females exposed to TPhT. No significant histological changes were observed in testis of exposed males. This ovarian spermatogenesis caused by TBT and/or TPhT resembles gastropod imposex. Remarkably high concentrations of TBT and TPhT were observed in the head (including central nervous system ganglia), compared to muscles concentrations. Accumulation of TBT and TPhT in the head may disturb reproductive hormonal regulators through neuropeptides released from ganglia. This, as well as possible aromatase inhibition, may be one of the inducers for spermatogenesis in the abalone ovaries.

Cytochrome P450 differences in normal and imposex-affected female whelk Buccinum undatum from the open North Sea

Normal and imposex-affected female Buccinum undatum were sampled from the open North Sea at three locations, one with low, and two with high shipping densities. Cytochrome P450 components and P450 aromatase activity were determined in the microsomal fractions isolated from pooled digestive gland/gonads. Cytochrome P450 aromatase activity was significantly higher (P < 0.05) in normal females collected in the low shipping density area (1,325 +/- 295 fmol/h/mg protein) than levels from imposex animals from a high shipping density area (620 +/- 287 fmol/h/mg protein). A negative correlation was found between aromatase activity and organotin body burden (r = -0.99). Levels of CYP450, cytochrome b5 and NADPH cytochrome c reductase activity did not show differences among groups. This is the first field evidence of depressed aromatase activity in imposex affected females, although additional research under laboratory controlled conditions is required to fully understand the mechanisms underlying the development of imposex in this species.

Organotins and imposex in the rock shell, Thais clavigera, from oyster mariculture areas in Taiwan

The amounts of organotin compounds such as butyltins [sigma BTs: tributyl- (TBT), dibutyl- (DBT), monobutyl- (MBT)] and phenyltins [sigma PhTs: triphenyl- (TPhT), diphenyl- (DPhT) and monophenyl- (MPhT)] in rock shells, Thais clavigera, from the northern (Shiangsan), central (Lukang) and southern (Chiku) Taiwan oyster mariculture areas varied with season and location. High values of sigma BTs (mainly TBT) and low values of sigma PhTs (mainly TPhT) were found during winter (January 1999) at Shiangsan, while high amounts of sigma PhTs (mainly TPhT) and low sigma BTs (mainly TBT) were found during summer (August 1998) at Lukang. The snails were also affected by imposex. Imposex at Shiangsan, Lukang and Chiku increased from 67.1, 59.3 and 36.7% in summer to 100, 100 and 80% in winter, respectively. Relative penis size indices similar trend at Chiku site. No male displayed rock shells were found at Shiangsan and Lukang in winter. Linear correlations between pseudopenis length versus TBT (r = 0.7655, P < 0.001), DBT (r = 0.4253, P < 0.05), MBT (r = 0.5865, P < 0.01) and TPhT (r = -0.6160, P < 0.01) were obtained significant. Among 200 samples, significant positive correlations between length (pseudopenis/shell) ratio of female versus TBT (r = 0.6944, P < 0.005) and sigma BTs (r = 0.6413, r < 0.01) were also observed. The weak correlations between length (pseudopenis/shell) ratio of female versus DBT (r = 0.3085) and MBT (r = 0.4240, P < 0.1) and TPhT (-0.4917, P < 0.05; negative correlation) could indicate that DBT, MBT and TPhT have little or no effect on the development of imposex in rock shells.

Imposex and organotin concentrations in Buccinum undatum and Neptunea antiqua from the North Sea: relationship to shipping density and hydrographical conditions

The presence and the development of imposex were investigated in the common whelk (Buccinum undatum) and the red whelk (Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (< 63 microm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of > or = 100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (> 10 ships day(-1)), intermediate (5--10 ships day(-1)), and low (< 5 ships day(-1)). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction < 63 microm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea.

The role of retinoic acid receptors and their cognate ligands in reproduction in a context of triorganotin based endocrine disrupting chemicals

Retinoic acid (RA), an active form of vitamin A, regulates the embryonic development, male and female reproduction and induces important effects on the cell development, proliferation, and differentiation. These effects are mediated by the retinoid (RAR) and rexinoid nuclear receptors (RXR), which are considered to be a ligand-activated, DNA-binding, trans-acting, and transcription-modulating proteins, involved in a general molecular mechanism responsible for the transcriptional responses in target genes. Organotin compounds are typical environmental contaminants and suspected endocrine disrupting substances. They may affect processes of reproductive system in mammals, predominantly via nuclear receptor signaling pathways. Triorganotins, such as tributyltin chloride (TBTCl) and triphenyltin chloride (TPTCl), are capable to bind to RXR molecules, and thus represent potent agonists of RXR subtypes of nuclear receptors not sharing any structural characteristics with endogenous ligands of nuclear receptors. Th is article summarizes selected effects of biologically active retinoids and rexinoids on both male and female reproduction and also deals with the effects of organotin compounds evoking endocrine disrupting actions in reproduction.

Obesity and asthma: the role of environmental pollutants

Air pollution is a well-known risk for lung diseases, including asthma. Growing evidences suggesting air pollution as a novel risk factor for the development of obesity. Several Epidemiological studies have ascertained an association between various ambient and indoor air pollutants and obesity by medium of endocrine disruptive chemicals that can disrupt the normal development and homeostatic controls over adipogenesis and energy balance and induce obesity. Several obesity-induced mechanisms have been proposed that increases this vulnerability of obese individuals to harmful effects of air pollution rendering them more susceptible to developing air-pollution driven incident asthma or worsening of already existing asthma.

Occupational irritant contact folliculitis associated with triphenyl tin fluoride (TPTF) exposure

Triphenyl tin fluoride (TPTF) is a bioactive organo-tin compound used in concentrations 2-12% as anti-foulants in boat paints. The chemical is moderately toxic to the skin. An occupational irritant contact folliculitis from TPTF in a marine paint plant worker is described. Contact allergy was excluded by patch testing. An attempt to reproduce the follicular reaction in man, rabbit and guinea pig was unsuccessful.

Imposex reduction and residual butyltin contamination in southern Brazilian harbors

The imposex incidence was appraised in South American gastropods, considering the scenario before and after the global ban of tributyltin (TBT). A statistically significant reduction in imposex indexes was observed in Stramonita haemastoma collected in 2006 and 2010 from areas under the influence of four coastal harbors from southern Brazil. This reduction may be because of the effectiveness of the global ban issued by the International Maritime Organization, although the restrictions on TBT-based antifouling paints in Brazil might also have helped. Even so, a residual organotin contamination was still detected in female tissues (levels ranged from 7.6 to 164.9 ng Sn/g for TBT; from <2 to 214.5 ng Sn/g for dibutyltin; from <3.5 to 178.8 ng Sn/g for monobutyltin; and from <1.5 to 53 ng Sn/g for triphenyltin). Thus, although a reduction in imposex and environmental levels of organotins is expected in every ocean worldwide soon after the implementation of national and international restriction regulations, this will depend on the effectiveness of the global TBT ban; the effectiveness of local restrictions on producing, selling, and using TBT-based antifouling paints; and specific characteristics of local sediments, because metabolization rates and sorption/desorption of TBT previously deposited might affect its environmental bioavailability. Therefore, the reduction trend detected in the present study cannot be extrapolated to other Brazilian or South American coastal areas.

Monitoring the organotin contamination in the Taihu Lake of China by bivalve mussel Anodonta woodiana

As a part of the pilot study on "Freshwater Mussel Watch", butyltin (monobutyltin, MBT; dibutyltin, DB; tributyltin, TBT), and phenyltins (monophenyltin, MPT; diphenyltin DPT; triphenyltin TPT) were analyzed in soft tissues of 15 bivalve mussels Anodonta woodiana sampled from five separate sites (Huzhou, Xueyan, Dapu, Sansandao, and Wulihu) around the Taihu Lake of China in 2004. The residue of total butyltins and total phenyltins in the all mussels ranged 142-1693 and 3.0-90 ng Sn g(-1) dry weight, respectively. Except for the mussels from Xueyan, DBT and MBT accounted more than 60% of total butyltins in those from other four sites. In contrast, TPT were usually almost 100% of the mussels studied. The present study provides most recent information about the organotin contamination in the Taihu Lake, and suggests Anodonta woodiana can be used as a suitable bioindicator.