Health risk assessment of the intake of butyltin and phenyltin compounds from fish and seafood in Taiwanese population

Occurrence, bioaccumulation, and ecological and health risks of Cd, Sn, Hg, and Pb compounds in shrimp and fish from aquaculture ponds

Aquaculture organisms may accumulate metals to induce health risks. Compared with the focus on total contents, chemical-specific risk assessment makes reasonable but is rare. Herein, we elucidated occurrence of twelve metal compounds in shrimp and fish (edible muscle, one of major metal-containing and generally targeted organs), water, sediment, and feedstuff from two aquaculture ponds in Zhejiang Province (one of the major aquatic production and consumption areas). We detected Cd(II) (0.6 -71.4 μg kg-1 in 100 % prawn but 63 % fish), methylmercury (MeHg, 0.5 -7.1 μg kg-1 in 100 % fish but 61 % shrimp), Pb(II) (0.4 -1.0 μg kg-1 in 57 % fish and 39 % prawn), and trimethyltin and triethyltin (0.4 -0.7 μg kg-1), which were much lower than the maximum limits in China. Pb(II), Cd(II), and Hg(II) up to 0.38 mg kg-1 were main contaminants in sediment while Cd(II) and Pb(II) up to 0.44 mg kg-1 were major contaminants in feedstuff compared with Cd(II), Sn(II), Hg(II), and Pb(II) majored in water at ng L-1 levels. Ecological risks were low in water but high for tributyltin in sediment. Additionally, light bioaccumulation of Cd(II) from sediment for prawn and methylmercury from feedstuff/sediment for crucian and bighead carp was induced. We also found light health risk of triethyl- and trimethyl lead, and Cd(II) (to children) associated with fish/shrimp consumption (edible muscle). This study proved high necessity of chemical-specific assessment, and shall trigger increasing interest to more metallic compounds in a wide range of uncultured and cultured plants and animals.

A critical review on the organo-metal(loid)s pollution in the environment: Distribution, remediation and risk assessment

Toxic metal(loid)s, e.g., mercury, arsenic, lead, and cadmium are known for several environmental disturbances creating toxicity to humans if accumulated in high quantities. Although not discussed critically, the organo-forms of these inorganic metal(loid)s are considered a greater risk to humans than their elemental forms possibly due to physico-chemical modulation triggering redox alterations or by the involvement of biological metabolism. This extensive review describes the chemical and physical causes of organometals and organometal(loid)s distribution in the environment with ecotoxicity assessment and potential remediation strategies. Organo forms of various metal(loid)s, such as mercury (Hg), arsenic (As), lead (Pb), tin (Sn), antimony (Sb), selenium (Se), and cadmium (Cd) have been discussed in the context of their ecotoxicity. In addition, we elaborated on the transformation, speciation and transformation pathways of these toxic metal(loid)s in soil-water-plant-microbial systems. The present review has pointed out the status of toxic organometal(loid)s, which is required to make the scientific community aware of this pressing condition of organometal(loid)s distribution in the environment. The gradual disposal and piling of organometal(loid)s in the environment demand a thorough revision of the past-present status with possible remediation strategies prescribed as reflected in this review.

Micro(nano)plastics in marine medaka: Entry pathways and cardiotoxicity with triphenyltin

The simultaneous presence of micro(nano)plastics (MNPs) and pollutants represents a prevalent environmental challenge that necessitates understanding their combined impact on toxicity. This study examined the distribution of 5 μm (PS-MP5) and 50 nm (PS-NP50) polystyrene plastic particles during the early developmental stages of marine medaka (Oryzias melastigma) and assessed their combined toxicity with triphenyltin (TPT). Results showed that 2 mg/L PS-MP5 and PS-NP50 could adhere to the embryo surface. PS-NP50 can passively enter the larvae and accumulate predominantly in the intestine and head, while PS-MP5 cannot. Nonetheless, both types can be actively ingested by the larvae and distributed in the intestine. 2 mg/L PS-MNPs enhance the acute toxicity of TPT. Interestingly, high concentrations of PS-NP50 (20 mg/L) diminish the acute toxicity of TPT due to their sedimentation properties and interactions with TPT. 200 μg/L PS-MNPs and 200 ng/L TPT affect complement and coagulation cascade pathways and cardiac development of medaka larvae. PS-MNPs exacerbate TPT-induced cardiotoxicity, with PS-NP50 exhibiting stronger effects than PS-MP5, which may be related to the higher adsorption capacity of NPs to TPT and their ability to enter the embryos before hatching. This study elucidates the distribution of MNPs during the early developmental stages of marine medaka and their effects on TPT toxicity, offering a theoretical foundation for the ecological risk assessment of MNPs.

Organotins in fish, shrimp, and cephalopods from the Pearl River Estuary, China: Dietary exposure risk to Indo-Pacific humpback dolphin and human

Food has regularly been proven to be a key source of exposure to environmental pollutants, drawing attention to the dietary exposure risks of contaminants to mammals with significant daily food intake. Here, the levels of six organotin compounds (OTs) in 18 fish (n = 310), three cephalopods (n = 50), and one shrimp (n = 34) from the Lingdingyang (LDY) and west four region (WFR) of the Pearl River Estuary (PRE) and their dietary exposure risks to Indo-Pacific humpback dolphins and humans were first investigated. Total OT levels ranged from 3.84 to 901. 48 ng/g wet weight (ww) in 22 prey species from the LDY, and from 14.37 to 1364.64 ng/g ww in 19 species from the WFR. The LDY marine species generally accumulated higher butyltin levels but lower phentyltin levels than those in the WFR. All species have a phenyltin degradation index <1 and over 60 % of the sampled species have a butyltin degradation index <1, suggesting the PRE marine species might be exposed to the fresh discharge of OTs. A total of nine marine species exceeded the threshold levels of OT intake for adverse health effects on human juveniles by consumption, all 22 marine species posed high dietary risks to the PRE humpback dolphins. Moreover, probabilistic risk assessment using Monte Carlo simulation revealed that the probabilities of RQ values associated with WFR OT exposure higher than 1 were 18.87 % for human adults, 40.55 % for human juveniles, 100 % for both humpback dolphin adults and humpback dolphin juveniles. Our results highlighted the potentially high dietary exposure risks of OTs to marine mammals and residents in the PRE.

Occurrence of organotin compounds in food: increasing challenge of phenyltin compounds

Concentrations and distribution for 16 organotin compounds were studied in all kinds of foods, including seafood, agricultural products, and wine. Meanwhile, the degradation of the TBT or TPhT was also evaluated. Concentrations of total organotins in seafood, agricultural products, and wine were 1047.2, 469.4, and 13.5 μg Sn/kg. Meanwhile, the most frequently detected organotin in three kinds of samples were TPhT, MPhT, and MPhT, respectively. The results demonstrated that phenyltin may probably become an emerging organotin pollutant. Regarding seafood, organotin concentrations of fish and mollusks were much higher than those of crustaceans. At the same time, a significant positive correlation was observed between the concentrations of TBT and MBT (p < 0.05), and between DBT and MBT(p < 0.0001). Moreover, TPhT was significantly and positively associated with DPhT (p < 0.0001), suggesting that TPhT was the precursor of DPhT. Apart from the likely illegal use of OTs as biocides in antifouling paints for ships, anthropogenic activity like agricultural activity or industrial activity also caused organotin contamination. Further research and more effective measures should be formulated to protect the food safety. Meanwhile, monitoring of the organotin contamination should not only in Qinhuangdao, but also expand to the cities along Bohai Bay.

Organotin compounds in seafood by ultrasonic assisted extraction and gas chromatography-triple quadrupole tandem mass spectrometry

Although restricting environmental quality values for organotin compounds (OTs) are set by Directive 2013/39/EU of the European Parliament, marine environment remains being affected due to maritime circulation at global scale. Fish and seafood accumulate OTs, making fish and seafood consumption the main source of OTs in humans. Because of the fish and seafood matrices complexity and the required low limits of detection, a robust and fast procedure for the quantification of OTs in fish and seafood, using ultrasound-assisted extraction and gas chromatography-tandem mass spectrometry, was validated and applied. Detection (2.7 µg Sn kg-1) and quantification (8.0 µg Sn kg-1) limits, repeatability and intermediate precision (<10%), accuracy by analysing ERM®-CE477 Mussel Tissue and analytical recoveries (65-122%) were assessed. Multivariate analysis shown that the matrix effect for some OTs displayed good negative correlation with the fat and protein content. Health risk assessment of OTs intake revealed no serious risk for human consumption.

Origin, dietary exposure, and toxicity of endocrine-disrupting food chemical contaminants: A comprehensive review

Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.

Organotin contamination in seafood from the Yucatán Peninsula, Mexico: Is there a potential risk for the health of consumers?

Since seafood is considered an important source of organotin compounds (OTCs), the present study assessed the potential risk to human health of ingesting butyltins (BTs) and phenyltins (PhTs) along with this type of food. Seafood samples were collected at five fishing sites in the Yucatán Peninsula (Mexico) during February and March 2018. In general, organotins were detected in all samples, suggesting a widespread occurrence of these compounds in the investigated region. The average concentration of total organotins in the muscle of demersal fish (Lutjanus synagris, Lutjanus campechanus, Calamus pennatula, Haemulon plumierii, Rhomboplites aurorubens), pelagic fish (Euthynnus alletteratus, and Opisthonema oglinum), gastropods (Melongena bispinosa and Strombus pugilis), oyster (Crassostrea virginica) and shrimp (Penaeus duorarum) was 146.7 ± 76.2, 93.1 ± 92.6, 61.0 ± 53.0, 76.7 ± 2.6, and 28.8 ± 2.7 ng Sn g-1 dry weight, respectively. Overall, MPhT among PhTs was the dominant compound in fish, while TBT among BTs was the dominant compound in shellfish. Regarding the toxic OTCs, TBT followed by DBT were the predominant compounds in all seafood species, while TPhT was below the quantification limit in most samples. The estimated daily intake values were lower than the tolerable daily intake (TDI) for the sum of organotins established by the European Food Safety Authority (EFSA). Furthermore, the hazard quotients (HQ) and hazard indices (HI) values were all lower than 1, suggesting that daily exposure to these levels of organotins is unlikely to cause any harm to the human health of seafood consumers at the Yucatán Peninsula. Thus, consumers may not be at risk through the inclusion of these investigated seafood species in their normal diet. However, due to the increasing coastal urbanization, maritime activities, and the likely illegal use of tin-based paints in Mexico, additional monitoring is needed to assess organotin levels in other regions along the Mexican coastal zone and using other seafood species.

Organotins in a food web from the Three Gorges Reservoir, China: Trophic enrichment and potential health risk

Triphenyltin (TPhT) and tributyltin (TBT) remain widely present in various aquatic environments despite restrictions on their use in many countries for many years. The biomagnification of these compounds in the aquatic food web remains controversial. This study reports the bioaccumulation of TPhT and TBT in aquatic animals in the Three Gorges Reservoir (TGR), a deep-water river channel-type reservoir and the largest reservoir in China. We measured TPhT, TBT and their metabolites in 2 invertebrates, 27 fish and the aquatic environment. The logarithmic bioaccumulation factors of TPhT and TBT were 4.37 and 3.77, respectively, indicating that TPhT and TBT were enriched in organisms of the TGR. Both TPhT and TBT concentrations were significantly and positively correlated with trophic level, with trophic magnification factors of 3.71 and 3.63, respectively, indicating that TPhT and TBT exhibited similar trophic enrichment in the freshwater food web of the TGR. The results of health risk assessment showed that although all hazard index (HI) values were <1, more attention should be paid to the health risk to children associated with consumption of aquatic products (HI = 0.67). This study provides powerful evidence of trophic enrichment of TPhT and TBT in a freshwater food web in a deep-water river channel-type reservoir and provides valuable data regarding organotins in aquatic animals in the TGR.

Pulsed distribution of organotins in the turbidity maximum zone of the Yangtze Estuary throughout a tidal cycle

This study investigated the concentration fluctuation of organotin compounds in the Turbidity Maximum Zone (TMZ) of the Yangtze Estuary within a tidal cycle. Organotin concentrations varied greatly during the tidal cycle with dissolved organotins ranged from 39 to 682 ng Sn·L^-1 and 40-1588 ng Sn·L^-1, and particulate organotins ranged from 59 to 467 ng Sn·g^-1 dw and 21-429 ng Sn·g^-1 dw in TMZ water close to Hengsha Island and Jiuduansha Island, respectively. Meanwhile, the maximum levels of organotins appeared at each period of tidal transition, suggesting the tidal-driven pulsed exposure of organotins was prevalent in the estuaries. Besides, the organic carbon-normalized partition coefficients (K_oc) of tri-organotins between suspended particulate matter (SPM) and aqueous phase were correlated with the phase distribution of natural organic matter (NOM). The dissolved tri-organotins were also associated with the properties of dissolved organic carbon (DOC) including aromaticity, hydrophobicity, and chromophoricity. Hence, pulsed exposure on organotins in the TMZ are highly dictated by the dynamic environmental conditions (i.e., SPM and NOM) with the tidal currents, which could further provide information to assess organotin ecological risks accurately in estuaries.

Triphenyltin exposure causes changes in health-associated gut microbiome and metabolites in marine medaka

Triphenyltin (TPT), an organic compound with a wide range of applications, is often detected in water bodies and aquatic animals. However, the mechanism underlying the biological metabolic health problems caused by long-term exposure to environment concentrations of TPT remains unclear. The morphology and gene expression in the gut and liver were investigated; and 16SrRNA gene amplification sequencing and non-targeted LC-MS/MS metabonomics were investigated after marine medaka (Oryzias melastigma) was treated with 1, 10, and 100 ng/L TPT for 21 days. During prolonged exposure to TPT, the adaptation mechanism maximized the energy of absorption, increased the length of intestinal microvilli, reduced the number of rough endoplasmic reticulum in the liver, and caused loss of weight. TPT exposure significantly changed the intestinal microbiome of marine medaka, thereby resulting in a significant decrease in microbial diversity. Following exposure to 100 ng/L TPT, the metabolic profiles were significantly changed and the altered metabolites were mainly concentrated in the lipid metabolic pathway. Finally, based on comprehensive network analysis, the association between the significantly changed bacteria and metabolites contributed further to the prediction of the impact of TPT on the host. This study provides a novel insight into the underlying mechanisms of host metabolic diseases caused by TPT and emphasizes the importance of monitoring pollutants in the environment.

The effects of TPT and dietary quercetin on growth, hepatic oxidative damage and apoptosis in zebrafish

The objective of this study was to determine the effects of triphenyltin (TPT) and dietary quercetin on the growth, oxidative stress and apoptosis in zebrafish. A total of 240 fish were divided into 4 groups with three replicates as follows: fish were fed with the basal diet as the control group (D1), only 10 ng/L TPT (D2), 10 ng/L TPT + 100 mg/kg quercetin (D3), and only 100 mg/Kg quercetin as the D4 group. At the end of the study period (56 d), the results showed that the growth performance of the fish that were fed 100 mg/kg quercetin was significantly higher than that of fish that were exposed to 10 ng/L TPT. Quercetin ameliorated oxidative stress, which decreased malondialdehyde (MDA) and nitric oxide (NO) levels and improved antioxidant enzyme activities. The mRNA expressions of the key apoptotic gene and pro-inflammatory cytokines were significantly induced by TPT exposure. However, dietary quercetin prevented a marked increase in the Bax, caspase3 and caspase9 transcript abundances that were induced by TPT. In addition, the quercetin treatments decreased inflammation by regulating the NF-kB signalling pathway. In conclusion, our findings suggested that TPT induced oxidative stress and apoptosis in zebrafish and that the pretreatment with quercetin showed an ameliorative role. Dietary 100 mg/ kg quercetin helps to prevent oxidative damage, apoptosis and inflammation in TPT treated zebrafish.

Maternal exposure to tributyltin during early gestation increases adverse pregnancy outcomes by impairing placental development

Tributyltin (TBT) is a persistent organotin pollutant widely used as agricultural and wood biocides, exhibiting well-documented toxicity to reproductive functions in aquatic organisms. However, the effect of TBT on early pregnancy and placental development has been rarely studied in mice. Pregnant mice were fed with 0, 0.2, and 2 mg/kg/day TBT from gravid day 1 to day 8 or 13. TBT exposure led to an increase in the number of resorbed embryo and a reduction in the weight of fetus at gestational days 13. Further study showed that TBT significantly decreased placental weight and area, lowered laminin immunoreactivity and the expressions of placental development-related molecules including Fra1, Eomes, Hand1, and Ascl2. Moreover, TBT treatment markedly inhibited the placental proliferation and induced up-regulation of p53 and cleaved caspase-3 proteins, and down-regulation of Bcl-2 protein. In addition, TBT administration increased levels of malondialdehyde and H₂ O₂ and decreased activities of catalase and superoxide dismutase. Collectively, these results suggested TBT-induced adverse pregnancy outcomes during early pregnancy might be involved in developmental disorders of the placenta via dysregulation of key molecules, proliferation, apoptosis, and oxidative stress.

Review on endocrine disrupting toxicity of triphenyltin from the perspective of species evolution: Aquatic, amphibious and mammalian

Triphenyltin (TPT) is widely used as a plastic stabilizer, insecticide and the most common fungicide in antifouling coatings. This paper reviewed the main literature evidences on the morphological and physiological changes of animal endocrine system induced by TPT, with emphasis on the research progress of TPT metabolism, neurological and reproductive regulation in animal endocrine system. Similar to tributyltin (TBT), the main effects of TPT on the potential health risks of 25 species of animals, from aquatic animals to mammals, are not only related to exposure dose and time, but also to age, sex and exposed tissue/cells. Moreover, current studies have shown that TPT can directly damage the endocrine glands, interfere with the regulation of neurohormones on endocrine function, and change hormone synthesis and/or the bioavailability (i.e., in the retinoid X receptor and peroxisome proliferator-activated receptor gamma RXR-PPARγ) in target cells. Importantly, TPT can cause biochemical and morphological changes of gonads and abnormal production of steroids, both of which are related to reproductive dysfunction, for example, the imposex of aquatic animals and the irregular estrous cycle of female mammals or spermatogenic disorders of male animals. Therefore, TPT should indeed be regarded as a major endocrine disruptor, which is essential for understanding the main toxic effects on different tissues and their pathogenic effects on endocrine, metabolism, neurological and reproductive dysfunction.

Occurrence of organotin compounds in seafood from Hong Kong market

The degree of organotin compounds (OTCs), including dibutyltin, tributyltin, triphenyltin and dioctyltin, contamination in seafood purchased in 2017 and 2018 from Hong Kong market was studied. Edible portions of 341 seafood samples, including fish, crustaceans and molluscs, were used for analysis by gas chromatograph coupled to an inductively coupled plasma mass spectrometry (GC-ICP/MS). The method detection limits and quantification limits of OTCs were below or equal to 0.25 and 1.0 μg Sn kg^-1 respectively. Triphenyltin accounted for the majority amongst other OTCs and was detected in 53% of samples. In general, mean total OTCs levels of fish (24 μg Sn kg^-1) were higher than crustaceans (14 μg Sn kg^-1) and molluscs (15 μg Sn kg^-1). The highest detected levels of triphenyltin, tributyltin, dibutyltin and dioctyltin were found to be 480, 24, 4.5 and 0.89 μg Sn kg^-1 in a mangrove snapper, noodle fish, coral clam and giant grouper respectively.

Triphenyltin disrupts intracellular Zn2+ homeostasis in rat thymic lymphocytes

Triphenyltin (TPT), previously used as an agricultural fungicide and industrial antifoulant, is now considered an environmental pollutant. The effect of TPT on human health is concerning due to its presence as a contaminant in seafood. In this study, the changes in intracellular Zn²⁺ concentration ([Zn²⁺]i) and cellular content of nonprotein thiols ([NPT]i) induced by triphenyltin chloride (TPTCH), were measured in rat thymic lymphocytes. This was studied by flow-cytometry using the fluorescent probes FluoZin-3-AM and 5-chloromethylfluorescein diacetate (5-CMF-DA). Incubation with TPTCH, at 0.1 μM or more (up to 3 μM), increased [Zn²⁺]i in a concentration-dependent manner. The TPTCH-induced elevation in [Zn²⁺]i was due to the increase in membrane Zn²⁺ permeability and intracellular Zn²⁺ release. Incubation with TPTCH at 0.3 μM significantly increased [NPT]i levels, whereas the addition of an intracellular Zn²⁺ chelator had no effect on the same. TPT at higher concentrations (1 or 3 μM) reduced [NPT]i. TPT may disturb intracellular Zn²⁺ signaling in lymphocytes that disturbs cellular functions.

Populations Collapses in Marine Invertebrates Due to Endocrine Disruption: A Cause for Concern?

In the beginning of the twenty first century, the International Program on Chemical Safety published a document entitled Global Assessment of the State-Of-The-Science of Endocrine Disruptors. The work indicated only weak evidence of endocrine-related effects in human populations, and in wild animal populations. This document was revised in 2012 (State of the Science of Endocrine Disrupting Chemicals-2012) (1). The new document and the extensive scientific evidence it provided showed clearly that ED effects could be a risk to human and wildlife health. These works, however, were focused in human health and related animal models, mainly vertebrates and particularly mammals. It can be argued that invertebrates and many other taxa are important parts of all ecosystems, and, in many instances, have been shown to be also vulnerable to endocrine disruption. Thus, this work is aimed to show some observations on important marine invertebrate taxa, from an ecological point of view. The most important example of endocrine disruption in marine wild populations is the imposex response of marine gastropods, known for more than 40 years, and worldwide used to evaluate marine antifouling pollution. Among the mollusks, other important natural resources are bivalve species, used as human food sources and cephalopods, free-living, highly specialized mollusks, and also human food sources. Effects derived from endocrine disruptors in these species indicate that consumption could bring these compounds to human populations in an almost direct way, sometimes without any form of cooking or preparation. While discussing these questions, this work is also aimed to stimulate research on endocrine disruption among the invertebrate taxa that inhabited our oceans, and on which these effects are poorly known today.

Organotin contamination in commercial and wild oysters from China: Increasing occurrence of triphenyltin

Organotin contamination in marine environment has been a public concern for many years due to its adverse impacts on biota and human health. This study investigated levels, distribution and health risks of six organotin compounds: tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT) and monophenyltin (MPhT) in commercial and wild oysters in China. The total organotin in commercial oysters ranged from 251 to 1949 ng Sn g^-1 dw (dry weight) >. Two endocrine disruptors TBT and TPhT were detected in these samples with the highest level of 68.1 ± 20.1 ng Sn g^-1 dw and 747 ± 7.3 ng Sn g^-1 dw, respectively. For wild oysters, the concentrations of total organotins varied from 33.3 to 2671 ng Sn g^-1 dw. Butyltins were dominated by TBT with the mean level of 26.1 ± 30.0 ng Sn·g^-1 dw and showed no significant spatial variation between the southern and northern coastal zones (p > 0.05). However, compared with the north, phenyltin levels especially TPhT were much higher in the south coastline (246-1484 ng Sn·g^-1 dw) due to the wider use of TPhT-based biocides in local mariculture and agriculture. Health risk assessment indicated that a daily exposure of TPhT-contaminated oysters (including commercial and wild ones) may pose adverse threats to human particularly children as the risk quotients (RQ) were higher than 1. Organotin contamination (e.g., TPhT) still occurs in the South China's coastal zones after the TBT ban, which deserves future research and effective measures to protect the marine ecosystem and human health.

Intra-axonal Ca2+ mobilization contributes to triphenyltin-induced facilitation in glycinergic transmission of rat spinal neurons

Triphenyltin (TPT) is an organotin compound causing environmental hazard to many wild creatures. Our previous findings show that TPT increases of the frequency of spontaneous glycinergic inhibitory postsynaptic currents (sIPSCs) in rat spinal neurons without changing the amplitude and 1/e decay time. In our study, the effects of 2-aminoethoxydiphenyl borate (2-APB), dantrolene sodium, and thapsigargin on sIPSC frequency were examined to reveal the contribution of intra-axonal Ca²⁺ mobilization by adding TPT. 2-APB considerably attenuated the TPT-induced facilitation of sIPSC frequency while dantrolene almost completely masked the TPT effects, suggesting that the TPT-induced synaptic facilitation results from the activation of both IP₃ and ryanodine receptors on endoplasmic reticulum (ER) membrane, though inositol triphosphate (IP₃) receptor is less sensitive to TPT. Thapsigargin itself significantly increased the sIPSC frequency without affecting the current amplitude and decay time. Successive addition of TPT could not further increase the sIPSC frequency in the presence of thapsigargin, indicating that thapsigargin completely masked the facilitatory action of TPT. Results suggest that TPT activates the IP₃ and ryanodine receptors while TPT inhibits the Ca²⁺-pump of ER membranes, resulting in the elevation of intra-axonal Ca²⁺ levels, leading to the increase of spontaneous glycine release from synaptic vesicles.

Effects of triphenyltin on glycinergic transmission on rat spinal neurons

Glycine is a fast inhibitory transmitter like γ-aminobutyric acid in the mammalian spinal cord and brainstem, and it is involved in motor reflex, nociception, and neuronal development. Triphenyltin (TPT) is an organometallic compound causing environmental hazard to many wild creatures. Our previous findings show that TPT ultimately induces a drain and/or exhaustion of glutamate in excitatory presynaptic nerve terminals, resulted in blockage of neurotransmission as well as methylmercury. Therefore, we have investigated the neurotoxic mechanism how TPT modulates inhibitory glycinergic transmission in the synaptic bouton preparation of rat isolated spinal neurons using a patch clamp technique. TPT at environmentally relevant concentrations (3-300 nM) significantly increased the number of frequency of glycinergic spontaneous and miniature inhibitory postsynaptic currents (sIPSC and mIPSC) without affecting the current amplitude and decay time. The TPT effects were also observed in external Ca²⁺-free solution containing tetrodotoxin (TTX) but removed in Ca²⁺-free solution with both TTX and BAPTA-AM (Ca²⁺ chelator). On the other hand, the amplitude of glycinergic evoked inhibitory postsynaptic currents (eIPSCs) increased with decreasing failure rate (Rf) and paired pulse ratio (PPR) in the presence of 300 nM TPT. At a high concentration (1 µM), TPT completely blocked eIPSCs after a transient facilitation. Overall, these results suggest that TPT directly acts transmitter-releasing machinery in glycinergic nerve terminals. Effects of TPT on the nerve terminals releasing fast transmitters were greater in the order of glycinergic > glutamatergic > GABAergic ones. Thus, TPT is supposed to cause a strong synaptic modulations on glycinergic neurotransmission in wild creatures.

Occurrence and health risk assessment of organotins in waterworks and the source water of the Three Gorges Reservoir Region, China

The occurrence and health risks of organotins (OTs) in the waterworks and source water in the Three Gorges Reservoir Region (TGRR), China were assessed in this study. Water samples were collected at four waterworks (A, B, C, and D) in March and July 2012 to analyze butyltins (BTs) and phenyltins (PTs) using a gas chromatography-mass spectrometry (GC-MS) system. Our results showed that both the waterworks and their nearby water sources were polluted by OTs, with PTs being the most dominant species. Monobutyltin (MBT), monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) were detected in most of the analyzed water samples. The highest concentrations of OTs in influents, effluents, and source water in March were 52.81, 17.93, and 55.32 ng Sn L^-1, respectively. Furthermore, significant seasonal changes in OTs pollution were observed in all samples, showing pollution worse in spring compared with summer. The removal of OTs by the conventional treatment processes was not stable among the waterworks. The removal efficiency of OTs in July reached 100% at plant B, while that at plant C was only 38.8%. The source water and influents shared similar composition profiles, concentrations, and seasonal change of OTs, which indicated that OTs in the waterworks were derived from the source water. A health risk assessment indicated that the presence of OTs in the waterworks would not pose a significant health risk to the population, yet their presence should not be ignored.

Effects of Organotins on Crustaceans: Update and Perspectives

Organotins (OTs) are considered some of the most toxic chemicals introduced into aquatic environments by anthropogenic activities. They are widely used for agricultural and industrial purposes and as antifouling additives on boat hull's paints. Even though the use of OTs was banned in 2008, elevated levels of OTs can still be detected in aquatic environments. OTs' deleterious effects upon wildlife and experimental animals are well documented and include endocrine disruption, immunotoxicity, neurotoxicity, genotoxicity, and metabolic dysfunction. Crustaceans are key members of zooplankton and benthic communities and have vital roles in food chains, so the endocrine-disrupting effects of tributyltin (TBT) on crustaceans can affect other organisms. TBT can disrupt carbohydrate and lipid homeostasis of crustaceans by interacting with retinoid X receptor (RXR) and crustacean hyperglycemic hormone (CHH) signaling. Moreover, it can also interact with other nuclear receptors, disrupting methyl farnesoate and ecdysteroid signaling, thereby altering growth and sexual maturity, respectively. This compound also interferes in cytochrome P450 system disrupting steroid synthesis and reproduction. Crustaceans are also important fisheries worldwide, and its consumption can pose risks to human health. However, some questions remain unanswered. This mini review aims to update information about the effects of OTs on the metabolism, growth, and reproduction of crustaceans; to compare with known effects in mammals; and to point aspects that still needs to be addressed in future studies. Since both macrocrustaceans and microcrustaceans are good models to study the effects of sublethal TBT contamination, novel studies should be developed using multibiomarkers and omics technology.

Organotin Exposure and Vertebrate Reproduction: A Review

Organotin (OTs) compounds are organometallic compounds that are widely used in industry, such as in the manufacture of plastics, pesticides, paints, and others. OTs are released into the environment by anthropogenic actions, leading to contact with aquatic and terrestrial organisms that occur in animal feeding. Although OTs are degraded environmentally, reports have shown the effects of this contamination over the years because it can affect organisms of different trophic levels. OTs act as endocrine-disrupting chemicals (EDCs), which can lead to several abnormalities in organisms. In male animals, OTs decrease the weights of the testis and epididymis and reduce the spermatid count, among other dysfunctions. In female animals, OTs alter the weights of the ovaries and uteri and induce damage to the ovaries. In addition, OTs prevent fetal implantation and reduce mammalian pregnancy rates. OTs cross the placental barrier and accumulate in the placental and fetal tissues. Exposure to OTs in utero leads to the accumulation of lipid droplets in the Sertoli cells and gonocytes of male offspring in addition to inducing early puberty in females. In both genders, this damage is associated with the imbalance of sex hormones and the modulation of the hypothalamic-pituitary-gonadal axis. Here, we report that OTs act as reproductive disruptors in vertebrate studies; among the compounds are tetrabutyltin, tributyltin chloride, tributyltin acetate, triphenyltin chloride, triphenyltin hydroxide, dibutyltin chloride, dibutyltin dichloride, diphenyltin dichloride, monobutyltin, and azocyclotin.