Distribution and fate of tributyltin in the united states marine environment

Environmentally relevant dose of the endocrine disruptor tributyltin disturbs redox balance in female thyroid gland

Tributyltin (TBT) is an endocrine disruptor used as a biocide in nautical paints. Even though many TBT effects in marine species are known, data in mammals are scarce, especially regarding the thyroid gland. The present study aimed to evaluate the effect of a subchronic exposure to TBT on thyroid oxidative stress of female Wistar rats. Rats received vehicle (control group), 200 or 1000 ng TBT/kg body weight/day for 40 days. After euthanasia, one part of the thyroids were collected in order to assess iodide uptake; activity and/or mRNA expression of thyroperoxidase (TPO) and dual oxidases (DUOXs); activity and/or mRNA expression of catalase, glutathione peroxidase, superoxide dismutase and NADPH oxidase 4 (CAT, GPx, SOD and NOX4); 4-hydroxynonenal (4-HNE) expression and total thiol groups levels; and mRNA expression of estrogen receptors alpha and beta (ERα and ERβ). The remaining part of the thyroid was processed for morphological analysis of estrogen receptor alpha (ERα) and for collagen deposition. Iodide uptake was not changed with treatments. TPO activity and expression were increased in the TBT1000 group (259.81% and 95.17%). The activity, but not mRNA, of CAT (17.36% TBT200; 27.10% TBT1000) and GPx (29.24% TBT200; 28.97% TBT1000) were decreased by TBT. SOD and NADPH oxidase activity, as well as thiol group and 4-HNE levels remained unchanged. Interstitial collagen deposition increased in the TBT200 group (39.54%). The mRNA expression of ERα increased in TBT-treated rats (44.87% TBT200; 36.43% TBT1000), while protein expression was increased but not reaching significance (TBT1000, p = 0.056) by TBT. Therefore, our results show that TBT increases TPO expression and reduces antioxidant enzyme activities in the thyroid gland leading to oxidative stress. Some of these effects could be mediated by the ERα pathway.

Monoalkyl Tin Nano-Cluster Films Reveal a Low Environmental Impact under Simulated Natural Conditions

Recently, monoalkyl oxo-hydroxo tin clusters have emerged as a new class of metal-oxide resist to support the semiconductor industry's transition to extreme ultraviolet (EUV) lithography. Under EUV exposure, these tin-based clusters exhibit higher performance and wider process windows than conventional polymer materials. A promising new monoalkyl precursor, [(BuSn)₁₂ O₁₄ (OH)₆ ][OH]₂ (BuSn), is still in its infancy in terms of film formation. However, understanding potential environmental effects could significantly affect future development as a commercial product. We synthesized and explored the toxicity of nano-BuSn in the alga Chlamydomonas reinhardtii and the crustacean Daphnia magna at exposure concentrations ranging from 0 to 250 mg/L. Nano-BuSn had no effect on C. reinhardtii growth rate irrespective of concentration, whereas high nanoparticle concentrations (≥100 mg/L) increased D. magna immobilization and mortality significantly. To simulate an end-of-life disposal and leachate contamination, BuSn-coated film wafers were incubated in water at various pH values and temperatures for 14 and 90 d to investigate leaching rates and subsequent toxicity of the leachates. Although small quantities of tin (1.1-3.4% of deposited mass) leached from the wafers, it was insufficient to elicit a toxic response regardless of pH, incubation time, or temperature. The low toxicity of the tin-based thin films suggests that they can be an environmentally friendly addition to the material sets useful for semiconductor manufacturing. Environ Toxicol Chem 2019;38:2651-2658. © 2019 SETAC.

Frontiers in endocrine disruption: Impacts of organotin on the hypothalamus-pituitary-thyroid axis

Endocrine disruptors (EDs), chemical substances widely used in industry and ubiquitously distributed in the environment, are able to interfere with the synthesis, release, transport, metabolism, receptor binding, action, or elimination of endogenous hormones. EDs affect homeostasis mainly by acting on nuclear and nonnuclear steroid receptors but also on serotonin, dopamine, norepinephrine and orphan receptors in addition to thyroid hormone receptors. Tributyltin (TBT), an ED widely used as a pesticide and biocide in antifouling paints, has well-documented actions that include inhibiting aromatase and affecting the nuclear receptors PPARγ and RXR. TBT exposure in humans and experimental models has been shown to mainly affect reproductive function and adipocyte differentiation. Since thyroid hormones play a fundamental role in regulating the basal metabolic rate and energy homeostasis, it is crucial to clarify the effects of TBT on the hypothalamus-pituitary-thyroid axis. Therefore, we review herein the main effects of TBT on important metabolic pathways, with emphasis on disruption of the thyroid axis that could contribute to the development of endocrine and metabolic disorders, such as insulin resistance and obesity.

Utilization of nSiO2, fly ash, and nSiO 2/fly ash composite for the remediation of triphenyltin (TPT) from contaminated seawater

The removal of triphenyltin chloride from contaminated simulated seawater with adsorption method was discussed. The adsorbents used are fly ash, nSiO2, and nSiO2/fly ash composite. The results showed that the adsorption of the adsorbents increases with increase in the adsorbent dose, contact time, pH, stirring speed, initial TPT concentration, and decreased with increase in temperature. The adsorption fitted well with the Freundlich isotherm, showing that the adsorbent and TPT combined with function groups and the adsorption kinetics followed the pseudo-second-order kinetic model. The thermodynamic parameters were also evaluated. Optimal conditions for the adsorption of TPT from simulated seawater were applied to TPT removal from natural seawater. A higher removal efficiency of TPT (>99%) was obtained for the nSiO2/fly ash composite but not for fly ash and nSiO2.

TBT contamination of remote marine environments: ship groundings and ice-breakers as sources of organotins in the Great Barrier Reef and Antarctica

Remote marine environments such as many parts of the Great Barrier Reef (GBR) and the Antarctic are often assumed to be among the most pristine natural habitats. While distance protects them from many sources of pollution, recent studies have revealed extremely high concentrations of organotins in areas associated with shipping activities. Sediments at sites of ship groundings on the GBR have been found to contain up to 340,000 microg Sn kg(-1). Very high concentrations (up to 2290 microg Sn kg(-1)) have been detected in nearshore Antarctic sediments adjacent to channels cut through sea ice by ice-breaking vessels. In both cases, the bulk of the contamination is associated with flakes of antifouling paint abraded from vessel hulls, resulting in patchy but locally intense contamination of sediments. These particulates are likely to continue releasing organotins, rendering grounding sites and ice-breaking routes point-sources of contamination of surrounding environments. While the areas exposed to biologically-harmful concentrations of leached chemicals are likely to be limited in extent (1000-10,000 m(2)), deposition of antifouling paints constitutes a persistent ecological risk in otherwise pristine marine environments of high conservation value. The risk of contamination of GBR and Antarctic sediments by organotins needs to be considered against an important alternative risk: that less effective antifouling of ships hulls may increase the frequency of successful invasions by non-indigenous species. Additional options to minimise ecological risk include accident prevention and reducing organotin contamination from grounding sites through removal or treatment of contaminated sediments, as has been done at some sites in the GBR.

Organotin pollution in deep-sea fish from the northwestern Mediterranean

Aquatic pollution resulting from extensive usage of organotin compounds has been of great concern due to their deleterious effects in nontarget organisms. However, organotin contamination in deep-sea ecosystems has been rarely studied. The presentwork attempted to determine butyltin and phenyltin compounds in deep-sea fish collected between 1000 and 1800 m depth in the NW Mediterranean. The concentration of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), aswell astriphenyltin (TPT),and mono- anddiphenyltin (MPT, DPT) was determined in different tissues (liver, gills, digestive tube, and muscle) of several fish species. Total butyltin residues were up to 175 ng/g wet wt, and they were comparable to levels found in coastal fish collected along the Catalan coast. In contrast, deep-sea fish contained much higher levels of phenyltins (up to 1700 ng/g wet wt), and particularly TPT (up to 1430 ng/g wet wt), than previously reported concentrations in shallow-water organisms. The obtained results confirm the long-range transport of organotin compounds to the deep-sea environment, and the subsequent exposure of fish inhabiting nonpoint source areas. The use of TPT in agriculture or as an antifouling agent, its transport to the deep-sea environment associated to particulate matter, and its nonbiodegradable nature in the food chain may account for the high residue levels detected in deep-sea organisms.

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)

Analytical procedures for the determination of organotin compounds in sediment and biota: a critical review

Analytical procedures reported over the last 10 years for the determination of organotin compounds in sediment and biota have been critically reviewed in terms of sample handling, sensitivity, analytical cost, environmental acceptance, accuracy and precision. Critical steps in the analytical procedures are identified. Finally, research needs in extraction and determination are suggested.

Distribution, biomagnification, and elimination of butyltin compound residues in common cormorants (Phalacrocorax carbo) from Lake Biwa, Japan

Concentrations of butyltin compounds (BTs) were determined in various body tissues of common cormorants (Phalacrocorax carbo) collected from the Lake Biwa, Japan. Elevated concentrations of butyltins were detected in the feathers of cormorants. Among other organs and tissues, butyltin levels were also higher in the kidney (290+/-150 ng/g) and liver (270+/-260 ng/g), ranging from 115 to 544 ng/g and 142 to 1007 ng/g (wet wt basis), respectively. The accumulation of BTs in cormorant bodies was in the order of MBT>DBT>TBT and their organ specific burdens were in the order of muscle>/=feathers>skin>liver>rest of the tissues and organs. The higher levels of BTs residues in feather suggested the excretion of about one fourth of their body burden during a complete molting cycle, which has been a natural detoxification mechanism in these birds. Based on the whole body concentrations of BTs in cormorants (42-160 ng/g wet wt) and fish (10-55 ng/g wet wt) biomagnification factors were assessed to be in the range of 1.1-4.1. To our knowledge, this is the first fundamental study to substantially indicate the contamination and kinetics of BTs in wild birds.

Tributyltin distribution in the coastal environment of Peninsular Malaysia

The occurrence of tributyltin (TBT) is reported in the coastal waters of a few selected sites in Peninsular Malaysia. Water, bivalves and sediment samples collected were analysed specifically for TBT using sensitive analytical methods which involved a solvent extraction procedure with appropriate clean-up followed by graphite furnace atomic absorption spectrometric measurements. The levels of TBT in the seawater in unexposed areas were found in the range from <3.4 to 20 ng litre(-1) as compared to coastal areas with high boat and ship activities where TBT levels in seawater were generally above 30 ng litre(-1), with the highest level found at 281.8 ng litre(-1). TBT levels in the tissues of random cockle and soft-shell clam samples from local markets were found in the range from <0.5 to 3.7 ng g(-1) wet weight. The levels of TBT found in green mussel samples both from the market (23.5 ng g(-1) wet weight) and those from a mussel farm (14.2 ng g(-1) wet weight) indicate slight accumulation of TBT. In sediments, TBT levels were found ranging from <0.7 ng g(-1) dry weight in unexposed coastal sites to as high as 216.5 ng g(-1) dry weight for a site within a port area.

Long term behaviour and degradation kinetics of tributyltin in a marina sediment

One-meter sediment cores sampled in a marina have been submitted to extensive characterization and organotin speciation. Geochemical homogeneity has been demonstrated. Butyltin species are present at all depths with a predominance of TBT or MBT in the upper or lower layers, respectively. Seasonal variations of butyltin compounds have been identified and together with a knowledge of local conditions we estimate the sediment layers represent 14 years of deposition. A first order multi-step kinetic model of the sequential degradation of TBT in, successively, DBT, MBT and Sn (IV) is proposed. The half-life of TBT was estimated (on a 14-year period) to be 2.1 years and those of DBT and MBT (on a 5-year period) 1.9 and 1.1 years, respectively.

Degradation of tri-n-butyltin in Ise Bay sediment

The vertical distribution patterns of the transformation products of tri-n-butyltin (TBT) in sediment cores collected from 6 sites in Ise Bay, Japan indicated that TBT was transformed by two pathways: methylation and debutylation. Anaerobic incubation of sediment spiked with TBT showed that the methylation was mainly supported by sulfate reducing activity and debutylation was mainly supported by nitrate reducing activity. These results showed that contribution of the two transformation reactions of TBT varied according to the dominant microbial activities in the sediment. The two types of vertical distribution of butyltins observed in the sediment cores appear to be the result of different dominant microbial activity in the sediment.

Determination of butyltin species in sewage and sludge by gas chromatography-atomic absorption spectrometry

A method for the extraction and determination of butyltin compounds in sewage and sludge is reported. Sewage and sludge samples are acidified and shaken for 2 h. The various butyltin species are extracted quantitatively by tropolone (cycloheptatrienone) in toluene, followed by ethylation to their tetraalkyl-substituted forms, BuSnEt3, Bu2SnEt2, Bu3SnEt and Et4Sn, all of which can be separated and determined by a gas chromatographic-atomic absorption spectrometric technique. The non-pesticidal octyltin species and acid-leachable SnIV species can also be determined by this method. Detection limits expressed as Sn are 40 ng dm-3 and 2 ng g-1 dry mass for sewage and sludge, respectively. Analyses of some samples from Canadian treatment plants are given.