Ecotoxicological effect of zinc pyrithione in the freshwater fish Gambusia holbrooki

Environmental occurrence, biological effects, and health implications of zinc pyrithione: A review

Due to the detrimental effects on aquatic organisms and ecosystem, tributyltin as a antifouling agent have been banned worldwide since 1990s. As a replacement for tributyltin, zinc pyrithione (ZnPT) has emerged as a new environmentally friendly antifouling agent. However, the widespread use of ZnPT unavoidably leads to the occurrence and accumulation in aquatic environments, especially in waters with limited sunlight. Despite empirical evidence demonstrating the ecotoxicity and health risks of ZnPT to different organisms, there has been no attempt to compile and interpret this data. The present review revealed that over the past 50 years, numerous studies have documented the toxicity of ZnPT in various organisms, both in vitro and in vivo. However, long-term effects and underlying mechanisms of ZnPT on biota, particularly at environmentally realistic exposure levels, remain largely unexplored. In-depth studies are thus necessary to generate detailed ecotoxicological information of ZnPT for environmental risk assessment and management.

Male Reproductive Toxicity of Antifouling Chemicals: Insights into Oxidative Stress-Induced Infertility and Molecular Mechanisms of Zinc Pyrithione (ZPT)

Zinc pyrithione (ZPT), a widely utilized industrial chemical, is recognized for its versatile properties, including antimicrobial, antibacterial, antifungal, and antifouling activities. Despite its widespread use, recent research has shed light on its toxicity, particularly towards the male reproductive system. While investigations into ZPT's impact on male reproduction have been conducted, most of the attention has been directed towards marine organisms. Notably, ZPT has been identified as a catalyst for oxidative stress, contributing to various indicators of male infertility, such as a reduced sperm count, impaired sperm motility, diminished testosterone levels, apoptosis, and degenerative changes in the testicular tissue. Furthermore, discussions surrounding ZPT's effects on DNA and cellular structures have emerged. Despite the abundance of information regarding reproductive toxicity, the molecular mechanisms underlying ZPT's detrimental effects on the male reproductive system remain poorly understood. This review focuses specifically on ZPT, delving into its reported toxicity on male reproduction, while also addressing the broader context by discussing other antifouling chemicals, and emphasizing the need for further exploration into its molecular mechanisms.

Toxic effects and potential mechanisms of zinc pyrithione (ZPT) exposure on sperm and testicular injury in zebrafish

Zinc pyrithione (ZPT) is widely recognized for its beneficial properties as an antifouling, antibacterial, and antifungal agent. Despite its positive industrial contributions, ZPT has been proven to exhibit toxicity towards various ecosystems, particularly affecting marine life. However, there is still a dearth of comprehensive research on ZPT toxicity and its toxicological mechanism in reproductive systems of aquatic organisms. In our study, we conducted a thorough analysis and unveiled a multitude of abnormalities in zebrafish sperm and testicular tissue caused by ZPT exposure, including a dose-dependent diminishing of testosterone levels, various sperm deformities, decreased sperm concentration and motility, and ROS-induced testicular tissue DNA damage. In addition, our study suggested that ZPT-induced testicular damage is associated with heightened oxidative stress, apoptosis, and possible hyperpolarization of the mitochondrial membrane. Through RNA-seq analysis, a total of 409 DEGs associated with ZPT-induced testicular injury were identified, and the hub gene was determined using a protein-protein interaction network (PPI). The genes and pathways uncovered in this study point to potential mechanisms of ZPT exposure on sperm and testicular injury in zebrafish.

How do biocidals affect the non-target marine organisms: the short-term effects of antifouling agent sodium pyrithione on Mediterranean mussels (Mytilus galloprovincialis, Lamark 1819)

The metallic pyrithiones are used as antifouling paints for marine vehicles against fouling organisms. However, they are dissolved in marine water and have negative impacts on marine non-target organisms. This study evaluated the adverse effects of sodium pyrithione (NaPT) on Mytilus galloprovincialis using total hemocyte counts (THCs), oxidative stress and antioxidant parameters, and histopathological observations. Mussels were exposed to 0.1 and 1 μg/L NaPT for 96 h. The THC values of the NaPT-exposed mussels significantly decreased (p < 0.05). Lipid peroxidation and advanced oxidative protein products of digestive gland and gill tissues were decreased but only the digestive gland tissues of 0.1 μg/L NaPT values were significantly decreased compared to control groups (p < 0.05). Histological alterations were observed in the gill and the digestive gland tissues revealing malformations and hyperplasia of gill lamella; degenerations and loss of tubules of digestive gland after exposure to NaPT for 96 h. As a result, biocidal sodium pyrithione has adverse effects on the mussels even in short-term exposures and low concentrations.

Zinc pyrithione (ZPT) -induced embryonic toxicogenomic responses reveal involvement of oxidative damage, apoptosis, endoplasmic reticulum (ER) stress and autophagy

Zinc pyrithione (ZPT) is a frequently used organometallic biocide, carrying potentially adverse consequences to multiple species in the environment. Previously we have demonstrated its embryonic, organ developmental and liver metabolic toxicity of zebrafish. However, details of ZPT toxicity during embryogenesis are still limited. The present study was designed to evaluate the effects and possible mechanisms of ZPT-induced embryonic toxicogenomic responses by morphological investigations, transcriptome and gene quantitative analysis, as well as biochemical assays. The results revealed that treatment with ZPT caused embryogenesis toxicity, specifically in irregular cell division and rearrangement, delayed differentiations of eyes and notochords, the epiboly and germ ring formation and somite segmentation defects. In addition, ZPT exposure altered gene expression during early embryonic development, especially related with morphological abnormities and metabolic dysfunctions including reduction of oxidoreductase activity. Activities of antioxidants and caspases examinations showed inductions of oxidative stress and apoptosis by ZPT and quantitative analysis of marker genes further indicated that ZPT also triggered endoplasmic reticulum (ER) stress and autophagy. Thus, we deduce here that ZPT-induced embryonic toxicogenomic responses reveal involvement of oxidative damage, apoptosis, endoplasmic reticulum (ER) stress and autophagy.

Standard and biochemical toxicological effects of zinc pyrithione in Daphnia magna and Daphnia longispina

Chemical toxicity in the environment may be the consequence of exposure of living organisms to multiple substances, with distinct putative effects. Among this mulytiplicity of chemicals that occur in the wild, pharmaceutical drugs and antifoulers are prone to exert toxic effects on non-target organisms. To characterize the toxicity elicited by a compound of this specific class, the present study used standard and biochemical-based tools to quantify the toxic response of the antifouler and antidandruff zinc pyrithione in Daphnia magna and Daphnia longispina. The analised parameters were immobility, reproduction, behavioral alteration (swimming patterns), anti-oxidant defense (catalase activity), metabolism (GSTs activities), and neurotoxicity (ChE activity) after exposure to sublethal concentrations of this drug. Exposure to zinc pyrithione has been shown to have neurotoxic and oxidative effects, with changes in swimming behavior. There were no changes in reproductive traits of exposed individuals, from both species. The obtained data demonstrate that ecologically relevant levels of zinc pyrithione can deleteriously alter critical parameters in two distinct freshwater microcrustacean species, although with distinct toxicity patterns and outcomes.

Gender-differentiated metabolic abnormalities of adult zebrafish with zinc pyrithione (ZPT) -induced hepatotoxicity

Zinc pyrithione (ZPT) is an extensively used microbicidal agent and its toxicity to multiple organs has been gradually recognized. However, details of the mechanism of ZPT toxicity are lacking and profile studies at metabolic level are still greatly limited. In this work we investigated the effects of ZPT on metabolic pathways of zebrafish liver after twenty-one days of exposure. Our integrated approach was underpinned by gas chromatography coupled with mass spectroscopy (GC-MS) and liver function analysis. Metabolomic profiles were generated from the livers of ZPT-treated zebrafish and 172 significantly altered metabolite peaks were detected. As a result, ZPT caused altered perturbation of metabolic pathways in male and female zebrafish liver. Moreover, ZPT induced the liver injury with the changes of the metabolites 2,4-diaminobutyric acid (2,4-DABA) with significant distinction between male and female zebrafish. ZPT caused gender-differentiated liver metabolic changes associated with the disruption of glycogenolysis and glycolysis metabolism, purine and pyrimidine metabolism, oxidative phosphorylation, arginine biosynthesis, and amino acid metabolism. Conclusively, exposure of ZPT may result in gender-differentiated metabolic abnormalities of adult zebrafish with induced hepatotoxicity.

Waterborne zinc pyrithione modulates immunity, biochemical, and antioxidant parameters in the blood of olive flounder

In this study, potential immunological and hematological effects of different concentrations (0, 1, 10, and 50 μg L^-l) of waterborne zinc pyrithione (ZnPT) were studied in the blood of the olive flounder Paralichthys olivaceus over 30 days. Reduced alternative complement activity (ACH50) and lysozyme activity were measured in fish exposed to 10 and/or 50 μg L^-l of ZnPT for 20 days. Decreased levels of total Ig were also observed in response to 10 and/or 50 μg L^-l ZnPT during the exposure period. Levels of cortisol, a marker of stress, were significantly increased by 10 and 50 μg L^-l ZnPT from day 10, and by 1 μg L^-l exposure on day 30. The levels of red blood cells (RBCs) and white blood cells (WBCs) decreased following exposure to 10 and/or 50 μg L^-l ZnPT, while no significant change was observed in hemoglobin level. Concentrations of total protein and albumin were significantly reduced with 50 μg L^-l ZnPT at day 20. Alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase activities were significantly increased following exposure to 10 and/or 50 μg L^-l ZnPT. Lipid peroxidation was induced by ZnPT, and higher concentrations (10 and 50 μg L^-l) significantly increased intracellular malondialdehyde levels during exposure. Regarding the subsequent antioxidant response, intracellular glutathione levels increased significantly in response to 10 and 50 μg L^-l ZnPT on days 20 and 30. Similarly, catalase and superoxide dismutase activity was significantly increased in response to 10 and 50 μg L^-l ZnPT after day 10. Taken together, changes in the studied parameters suggested the immunotoxicity of ZnPT, with modulations observed in hematological homeostasis and oxidative stress induction in the blood of olive flounder.

Behavioral and biochemical effects of the antifouler and antidandruff zinc pyrithione on the freshwater fish Gambusia holbrooki

The presence of pharmaceutical residues in the aquatic environment is receiving great attention since the levels of these substances have significantly increased in this compartment, potentially leading to adverse ecological effects. Zinc pyrithione (ZnPt) is a widely used organometallic biocide, which is incorporated into antifouling formulas, such as paints, to prevent the establishment of biofilms on surfaces exposed to the aquatic environment. It is also used in cosmetics, such as antidandruff shampoos and soaps. Considering this wide use, and the absence of a significant amount of data on the toxicity of ZnPt especially towards non-target organisms, the objective of this study was to characterize the toxicity of ZnPt, on several ecological relevant endpoints assessed in the fish Gambusia holbrooki. For this purpose, we measured traits related to feeding and aggressive behavior, as well as indicators of oxidative stress (CAT and GSTs), neurotoxicity (AChE), and anaerobic metabolism (LDH), after acute and chronic exposures to ZnPt. In terms of behavioral features, the feeding test showed the occurrence of significant differences between the control animals and those exposed to a concentration of ZnPt of 45 μg/L. In addition, ZnPt caused changes in terms of oxidative stress biomarkers (CAT and GSTs), for both exposure periods. ZnPt was also capable of causing changes in the cholinergic neurotransmission functioning and anaerobic metabolism, but only following the chronic exposure.

Study of the effects of zinc pyrithione in biochemical parameters of the Polychaeta Hediste diversicolor: evidences of neurotoxicity at ecologically relevant concentrations

Nowadays there are various groups of biocidal chemical agents, which can be used in diverse areas, such as personal hygiene, disinfection, antiparasitic action, and also in antifouling mixtures or paints. The versatility and efficacy of some of these agents favors their use and ultimate release into the aquatic environment, where they may still exert toxic activity. Zinc pyrithione is classified as a metal biocide with bactericidal, algicidal, and fungicidal actions. It has been formulated in antifouling paints, which prevent the formation of biofilms in submerged structures, and has also been used for dermocosmetic purposes, in shampoos for the treatment of dandruff and seborrhea. Some of the uses of zinc pyrithione are responsible for its direct release as flakes that reach the bottom sediments, especially in estuarine areas. Considering this fate, the ecotoxicity assessment of its effects towards sediment organisms, namely Polychaetous species, is extremely important. The present study characterized the acute potential toxicity of zinc pyrithione in terms of parameters of oxidative stress (catalase, glutathione S-transferases (GSTs), and thiobarbituric acid reactive substances (TBARS)), and neurotoxicity (acetylcholinesterase) which were evaluated in individuals of the polychaete Hediste diversicolor. Regarding the results obtained, only the activity of GSTs and AChE was significantly altered in relation to non-exposed animals. This set of results indicates that oxidative stress did not occur.

Apoptosis in HepG2 cells induced by zinc pyrithione via mitochondrial dysfunction pathway: Involvement of zinc accumulation and oxidative stress

Zinc pyrithione (ZPT) is widely used as a substitute booster biocide for tributyltin and is also an additive to antidandruff shampoos and medical cosmetic products. ZPT and pyrithione have been detected in different environmental matrices and biota, suggesting that it may pose health threats to aquatic organisms and even humans. The present study used HepG2 cells, a human hepatoma cell line, to study the hepatotoxicity of ZPT (0.1-5.0 μM). ZPT treatment caused marked viability reduction and induced apoptosis depending on its dose used. ZPT-induced apoptosis involved an increased Bax/Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome c release, and enhanced caspase-9/-3 activity. In addition, a significant elevation in the amount of zinc ions and oxidative stress was evident. The involvement of these in ZPT-induced apoptosis was confirmed by toxicity comparison with analogs of ZPT and the observation that pretreatment with antioxidants afforded protection. Overall, these results suggest that ZPT induces zinc accumulation, oxidative stress, and subsequent apoptosis by causing mitochondrial dysfunction. Importantly, ROS was an initial and prolonged signal in ZPT-induced apoptosis in HepG2 cells.

Microwave-mediated synthesis of zinc oxide nanoparticles: a therapeutic approach against Malassezia species

A successful protocol was developed to aid in the reduction in dandruff-causing fungi, namely Malassezia globasa and Malassezia furfur. Both the species were isolated from volunteers aged between 20 and 22 suffering from dandruff, cultured ex vivo, and tested against the presence of synthesised zinc oxide nanoparticles (ZnNP). Direct microscopy, scanning electron microscopy (SEM), and biochemical assays specific to Malassezia species were conducted to identify dandruff-causing fungal species. Microwave-mediated synthesis of ZnNP was performed and characterised by UV-vis, X-ray diffraction, and SEM. The nanoparticles were tested against both Malassezia species and proved highly effective in inhibiting these fungi, although M. furfur was more susceptible than M. globosa. An optimum amount of 100 ppm was found to be sufficient to work as an antifungal agent. Synergistic effects of ZnNP with commercial shampoos were tested, and the result showed enhanced antifungal effects. To mimic the natural biofilm formed by these species on human skin, the formation of fungal biofilm was allowed on polystyrene coverslips. ZnNP was effective in eradication biofilm. Since zinc is an essential mineral for all living organism and is considered as biocompatible, the synthesised nanomaterials can be used in the formulation of antidandruff shampoos.

Acute toxic responses of embryo-larval zebrafish to zinc pyrithione (ZPT) reveal embryological and developmental toxicity

Zinc pyrithione (ZPT) is widely used in industrial and human daily life, due to its broad antimicrobial spectrum activity. Persistent accumulation of ZTP in the aquatic environment and bioaccumulation in the living organisms attracts more and more attention. However, only very limited information is available so far for the evaluation of systematic toxicity effects of ZPT on multiple organs development. This study intends to deepen our knowledge about the potential toxicity elicited by ZPT by assessing its acute effects on zebrafish (Danio rerio) through morphological, histological and molecular investigations. It has been verified that ZPT exhibits a broad spectrum of toxicity which causes growth retardation and tissue pathological and physiology alternations in heart, liver, eye, notochord, kidney and other organisms of zebrafish. The acute toxicity values of LC50 (95% CI) 96-h is calculated as 0.073 μM. Furthermore, the organ toxicity was verified due to up-regulation of expression of biomarker genes related to organ function and development. In sum, this study demonstrats systematic acute embryological and developmental toxicity of the ZPT on zebrafish embryos/larvae.

An integrated approach to assess the impacts of zinc pyrithione at different levels of biological organization in marine mussels

The mechanisms of sublethal toxicity of the antifouling biocide, zinc pyrithione (ZnPT), have not been well-studied. This investigation demonstrates that 14-d sublethal exposure to ZnPT (0.2 or 2 μM, alongside inorganic Zn and sea water controls) is genotoxic to mussel haemocytes but suggests that this is not caused by oxidative DNA damage as no significant induction of oxidised purines was detected by Fpg-modified comet assay. More ecologically relevant endpoints, including decreased clearance rate (CR), cessation of attachment and decreased tolerance of stress on stress (SoS), also showed significant response to ZnPT exposure. Our integrated approach was underpinned by molecular analyses (qRT-PCR of stress-related genes, 2D gel electrophoresis of proteins) that indicated ZnPT causes a decrease in phosphoenolpyruvate carboxykinase (PEPCK) expression in mussel digestive glands, and that metallothionein genes are upregulated; PEPCK downregulation suggests that altered energy metabolism may also be related to the effects of ZnPT. Significant relationships were found between % tail DNA (comet assay) and all higher level responses (CR, attachment, SoS) in addition to PEPCK expression. Principal component analyses suggested that expression of selected genes described more variability within groups whereas % tail DNA reflected different ZnPT concentrations.

Efficacy and Ecotoxicity of Novel Anti-Fouling Nanomaterials in Target and Non-Target Marine Species

Biofouling is a global problem that affects virtually all the immersed structures. Currently, several novel environmentally friendly approaches are being tested worldwide to decrease the toxicity of biocides in non-fouling species, such as the encapsulation/immobilization of commercially available biocides, in order to achieve control over the leaching rate. The present study addresses the toxicity of two widely used booster biocides, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), in its free and incorporated forms in order to assess their toxicity and anti-fouling efficacy in target and non-target species. To achieve this goal, the following marine organisms were tested; the green microalgae Tetraselmis chuii (non-target species) and both target species, the diatom Phaeodactylum tricornutum and the mussel Mytilus edulis. Organisms were exposed to both biocides, two unloaded nanostructured materials and nanomaterials loaded with biocides, from 10 μg/L to 100 mg/L total weight, following standard protocols. The most eco-friendly and simultaneously efficient anti-fouling solution against the two photosynthetic species (nanoclays loaded with ZnPT) was then tested on mussels to assess its lethal efficacy (LC₅₀ = 123 μg/L) and compared with free biocide (LC₅₀ = 211 μg/L) and unloaded material (LC₅₀ > 1000 μg/L). A second exposure test with sub-lethal concentrations (lower than 100 μg/L), using mussels, was carried out to assess biochemical changes caused by the tested compounds. Oxidative stress, detoxification and neurotransmission markers were not responsive; however, different antioxidant patterns were found with free ZnPT and loaded nanoclay exposures. Thus, the immobilization of the biocide ZnPT into nanoclays proved to be a promising efficient and eco-friendly anti-fouling strategy.