Copper Pyrithione Research Articles

Toxicity of Metal Pyrithione Photodegradation Products to Marine Organisms with Indirect Evidence for Their Presence in Seawater

We evaluated the acute toxicities of the metal pyrithiones (MePTs)--copper pyrithione (CuPT) and zinc pyrithione (ZnPT)--to four species of marine algae and a marine crustacean (Tigriopus japonicus). We also performed acute toxicity tests using six of the main MePT photodegradation products: pyridine-N-oxide (PO); 2-mercaptopyridine (HPS); pyridine-2-sulfonic-acid (PSA); 2-mercaptopyridine-N-oxide (HPT); 2,2'-dithio-bis-pyridine ([PS](2)); and 2,2'-dithio-bis-pyridine-N-oxide ([PT](2))-and three marine organisms representing three trophic levels: an alga (Skeletonema costatum), a crustacean (T. japonicus), and a fish (Pagrus major). The acute toxicity values (72-h EC(50)) of CuPT, ZnPT, HPT, (PT)(2), (PS)(2), HPS, PO, and PSA for S. costatum, which was the most sensitive of the test organisms to the chemicals tested, were 1.5, 1.6, 1.1, 3.4, 65, 730, >100,000, and >100,000 microg l(-1), respectively. CuPT was detected in the growth media used for S. costatum tests and in seawater containing HPT or (PT)(2); the concentration of CuPT in seawater containing HPT was highly dependent on the Cu(2+) concentration. These results indicate that in the presence of sufficient Cu(2+), the toxicities of HPT and (PT)(2) should be assessed as CuPT because in Japan MePTs are most frequently used as antifouling booster biocides in conjunction with cuprous oxide.

Biofouling growth in cold estuarine waters and evaluation of some chitosan and copper anti-fouling paints.

Ecological concerns about antifouling paints containing non-green tin and copper compounds have highlighted the need for environmentally friendly alternatives. We report here a field test conducted in estuarine waters over two months designed to evaluate the efficiency of a number of active natural and man-made chemical ingredients added into a silicon-polyurethane marine paint. Early steps of biofouling in cold seawater of the St. Lawrence Estuary (Canada) were observed. Analyses, including dry biomass, flow cytometry and spectrofluorimetry, demonstrated a short-term antibacterial action of chitosan-based paints although no significant anti-algal action was observed. Cuprous oxide paints were efficient against bacteria and algae invasion in the first two weeks, especially those with added organic biocides such as isothiazolone and copper pyrithione. However, the overall dry biomass and chlorophyll a content were similar for all chitosan-and copper-based paints after 63 days. Microscopic observations revealed variation in the highly diverse benthic diatom population including species Navicula, Melosira, Cocconeis, Nitshzcia, Fragilaria and Amphora. Results suggest no real long-term efficiency for tested antifouling paints and highlight a particular need for green antifouling ingredients that are active under northern estuarine conditions.

Inhibition of acetylcholinesterase by metabolites of copper pyrithione (CuPT) and its possible involvement in vertebral deformity of a CuPT-exposed marine teleostean fish

In a previous study, we demonstrated that exposure to an antifouling biocide, copper pyrithione (CuPT), early during life induced vertebral deformity in the larvae of a marine fish, the mummichog ( Fundulus heteroclitus). Skeletal deformities may be caused by inhibition by of acetylcholiensterase (AChE) activity, and to elucidate the mechanism underlying the CuPT-associated vertebral deformity, we first examined whether CuPT, zinc pyrithione (ZnPT), and their degradation products could inhibit AChE activity in the fish. Two of the degradation products, 2,2′-dipyridyldisulfide [(PS) 2] and 2,2′-dithiobispyridine-N-oxide [(PT) 2], but neither CuPT nor ZnPT, exhibited prominent AChE-inhibiting activity. Secondly, thin-layer chromatography revealed that mummichog hepatic microsomes metabolized CuPT to produce (PS) 2 in a microsome-dependent manner. The AChE inhibition induced in CuPT-exposed fish is likely due to (PS) 2 that was produced through metabolism of acquired CuPT. (PS) 2 may cause therefore skeletal deformity in CuPT-exposed fish by means of its neuromuscular blocking properties, through a mechanism similar to that proposed for animals exposed to organophosphorous pesticides.

数値モデルによる東京湾の船底防汚塗料(銅ピリチオン)に対する生態リスクの軽減方法の検討

We performed an ecological risk assessment on antifouling paints that contain copper pyrithione (CuPT) which are applied to vessels visiting Tokyo Bay. The Margin of Exposure (MOE = NOEC/EEC) method was used in the risk assessment, with the NOEC set to 0.25μg/L (Skeletonema costatum Growth inhibitor). The EEC was estimated by using a chemical fate model developed at AIST. The Uncertainty Factor (UF) was set to be 100 for this ecological risk assessment. The calculation period was for year 2008, when antifouling paints containing TBT will be substituted for alternative paints, such as those containing CuPT.In this study, the ecological risk was found to be significant because the MOE values were below the UF in the commercial ports of Yokohama, Tokyo and Chiba, but not throughout the entire study area.In Tokyo Bay, the ecological risk posed by CuPT in antifouling paints is at its greatest in the Yokohama port area. In a bid to reduce this risk, we estimated potential reduction in CuPT concentration in high MOE area, such as Yokohama port. This, by the effects of dispersion using water flow and by enhancing photodegradation.

Ecological Risk Assessment of Copper Pyrithione (CuPT) in Tokyo Bay

Ecological Risk Assessment of Copper Pyrithione (CuPT) in Tokyo Bay

Toxicity of Diuron and copper pyrithione on the brine shrimp, Artemia franciscana: The effects of temperature and salinity

Diuron and copper pyrithione (CuPT) are two substances that have been used worldwide as alternatives to tributyltin (TBT) in antifouling paints for the protection of ship hulls. In this study their toxicity against the brine shrimp Artemia franciscana is examined under several combinations of salinity and temperature using the LC20, LC50 and LC80 values found for the 25°C and 35‰ standard conditions. A significant interaction between temperature and salinity effects was observed for both chemicals. Decreasing temperature almost eliminated Diuron's toxicity, while a toxicity reduction was also observed for CuPT. Decreasing salinity decreased Diuron's toxicity, while for CuPT the effect of salinity was more complex. These two natural environmental parameters had a profound influence on the ecotoxicity of the two tested chemicals, and this highlights the importance of considering the implications of such factors when conducting ecological risk assessment.

Early life‐stage toxicity test for copper pyrithione and induction of skeletal anomaly in a teleost, the mummichog (Fundulus heteroclitus)

We used a teleost fish, the mummichog (Fundulus heteroclitus), to conduct early life-stage toxicity testing for copper pyrithione (CuPT). Fertilized mummichog eggs were exposed to CuPT at various concentrations for 50 d under continuous flow-through conditions. Hatchability, survival, growth, and morphologic abnormalities were measured. Hatchability did not differ significantly between any experimental group and control groups. Survival and growth were significantly reduced at 50 d in the groups exposed to 2 or 4 microg/L CuPT. During the test, morphologic abnormalities, such as vertebral deformity and formation of inflammatory masses in the lateral muscles, occurred in fish exposed to CuPT. Light and electron microscopic studies indicated that muscle dysfunction played a role in the vertebral deformity and revealed that the inflammatory mass was composed mainly of macrophages and necrotic myocytes. We consider that macrophages infiltrated and phagocytized necrotic cells, thus forming the inflammatory mass. In addition, acetylcholinesterase activity was markedly decreased in the 2- and 4-microg/L exposure groups, suggesting the skeletal deformity was due to mechanisms similar to those proposed for organophosphorous pesticide exposure.

Synergistic toxic effects of zinc pyrithione and copper to three marine species: Implications on setting appropriate water quality criteria

Zinc pyrithione (ZnPT) is widely applied in conjunction with copper (Cu) in antifouling paints as a substitute for tributyltin. The combined effects of ZnPT and Cu on marine organisms, however, have not been fully investigated. This study examined the toxicities of ZnPT alone and in combination with Cu to the diatom Thalassiosira pseudonana, polychaete larvae Hydroides elegans and amphipod Elasmopus rapax. Importantly, ZnPT and Cu resulted in a strong synergistic effect with isobologram interaction parameter λ > 1 for all test species. The combined toxicity of ZnPT and Cu was successfully modelled using the non-parametric response surface and its contour. Such synergistic effects may be partly due to the formation of copper pyrithione. It is, therefore, inadequate to assess the ecological risk of ZnPT to marine organisms solely based on the toxicity data generated from the biocide alone. To better protect precious marine resources, it is advocated to develop appropriate water quality criteria for ZnPT with the consideration of its compelling synergistic effects with Cu at environmentally realistic concentrations.

Combined effects of an antifouling biocide and nutrient status on a shallow-water microbenthic community

The complex systems of shallow-water sediments are today subjected to varying nutri- ent inputs combined with other anthropogenic stressors, such as toxicants. The effects of differences in nutrient status of the sediment combined with short-term, low-level exposure to the anti-fouling biocide copper pyrithione (CPT) were studied in a 38 d experiment using intact sediment in a flow- through mesocosm system. Abundance and diversity of microphytobenthos, bacteria and meiofauna were assessed together with sediment-water oxygen and nutrient fluxes (day and night) and denitri- fication. More effects were found for the sediment with higher nutrient status, but these combined effects could not be predicted by adding the separate effects of nutrients and CPT observed for the sediment with low nutrient status. Biomass and diversity of microphytobenthos increased later on in the experiment due to CPT exposure, as did bacterial activity and abundance. CPT exposure also increased the proportion of nematodes in the meiofauna. Generally, prokaryotic functions appeared more affected by CPT exposure than eukaryotic. Differences in the response of functional variables suggest that eukaryotic photoautotrophs possess a higher functional redundancy than heterotrophs. Among nutrient fluxes the nitrogen cycling was affected through changed rates of ammonium flux and denitrification. The integrated analyses show a clearer effect of CPT on the community structure under low-nutrient status, while CPT affected the community function more in the high-nutrient system. All treatments show convergence of function, in both light and dark, towards the end of the experiment, whereas the structure remained separated due to the nutrient regime.

Direct and indirect effects of an antifouling biocide on benthic microalgae and meiofauna

When multitrophic, natural communities are exposed to a contaminant, indirect, food-web mediated effects may become as important as direct toxic effects. In this study the antifouling agent copper pyrithione (CPT) was used as a model toxicant to study toxic effects on microphytobenthos (MPB) and meiofauna, as well as on the interaction between them. The hypothesis was that exposure to CPT will decrease meiofaunal grazing pressure and that this effect would result in increased primary production and biomass of MPB. Two laboratory experiments (16 and 29days long) were performed, using natural sediment that was exposed to both acute and repeated exposure of CPT (final dose 5 nmol CPT per g dry weight sediment). Variables measured included light utilization efficiency of MPB (PAM fluorometry), primary production ( 14C-uptake), chl a content of the sediment, algal composition, meiofauna biomass and meiofaunal grazing pressure on MPB ( 14C-incubations). Although CPT, added as a single dose or repeatedly, affected both MPB and meiofauna, no strong mechanistic evidence for a top-down control was found. The clearest direct CPT effects were seen for MPB function (light utilization efficiency and primary production), while algal biomass and composition were only marginally affected. MPB recovered rapidly from the toxicant exposure, a finding that verified the conclusion from previous experiments that the MPB community is highly resilient. The magnitude of the direct response of the microalgae depended on whether the total dose of CPT was added as one initial dose or divided between several additions; effects were larger after one initial dose. Although meiofauna biomass decreased at CPT exposure in both experiments, this decline was not reflected in decreased grazing pressure on MPB. Meiofauna grazed between 1 and 12% of the algal biomass per day. The lack of a clear top-down effect from CPT on MPB could have several both biological and methodological reasons, such as low sensitivity of the meiofaunal species to CPT, and a combination of simultaneously operating bottom-up and top-down effects from CPT.

Combined nutrient–toxicant effects on a shallow-water marine sediment system: sensitivity and resilience of ecosystem functions

Effects of nutrient status and short-term, low-level exposure to the antifouling biocide copper pyrithione (CPT) on intact shallow-water sediment were studied in an outdoor experiment, focusing on basic ecosystem functions driven by microorganisms. These functions were trophic sta- tus (autotrophy/heterotrophy), direction of dissolved inorganic nitrogen (DIN) flux, and the ratio of algal N assimilation:denitrification, and were based on measurements of daily sediment-water oxy- gen and nitrogen fluxes and denitrification. Bacterial production and biomass of microphytobenthos, meiofauna, and bacteria were also measured. The recovery of the functions was studied for 38 d. CPT exposure did not change basic ecosystem functions; the sediment remained autotrophic and a net sink of DIN, where microalgal N incorporation far exceeded denitrification. However, CPT affected individual N-cycling variables (ammonium flux, denitrification), as well as community respiration and bacterial production, with the direction of the response depending on sediment nutrient status. Significant CPT effects were more frequent in the nutrient-enriched sediment. Direct toxic effects were followed by indirect food-web-mediated (top-down) effects, leading to different timing and direction of effects with different sediment nutrient status. Permutational multivariate analysis of variance showed that initial CPT effects on system functions in both nutrient regimes were followed by an oscillating recovery process, where effects remained longer in the nutrient-enriched sediment. While single CPT exposure events may not affect general metabolic functions (oxygen flux) — at least not in net autotrophic sediments — repeated CPT exposure of sediment microbiota may impact nitro- gen cycling in shallow, eutrophied waters.

Toxic Effects of Pyrithione Antifouling Biocides on Some Marine Organisms

We evaluated the acute toxicity values (96-h LC50) of the antifoulants copper pyrithione (CuPT) and zinc pyrithione (ZnPT) on a teleost, red sea bream, and a crustacean, toy shrimp. The 96-h LC50s were ranging from 2.5 μg/L to 120 μg/L. The joint toxicity tests of the pyrithiones with Cu using toy shrimp revealed that, in the ZnPT and Cu mixture, conversion of ZnPT to the more toxic CuPT occurred. The early life-stage toxicity test was also conducted for CUPT using a teleost, mummichog, and the result showed that the no observed effect concentration and the lowest observed effect concentration were 0.06 μg/L and 0.22 μg/L, respectively. Additionally, morphological abnormality such as vertebral deformity and tumor formation in lateral muscle were found to be induced by the long-term exposure to CuPT.

Concentrations of Antifouling Biocides in Sediment and Mussel Samples Collected from Otsuchi Bay, Japan

Organotin compounds (OTs) and representative booster biocides were measured in sediment and mussels from Otsuchi Bay, Japan. The mean amounts of tributyltin (TBT) and triphenyltin (TPT) compounds in sediment were 13 microg kg(-1) dry and 3 microg kg(-1) dry, respectively. Representative booster biocides (Sea-Nine 211, Diuron, Dichlofluanid, Irgarol 1501, M1, which is a degradation compound of Irgarol 1051, and Copper pyrithione) were also detected in sediment from Otsuchi Bay. OT concentrations were higher than those of the measured booster biocides. Otsuchi Bay was divided into four parts by cluster analysis based on OT concentrations in sediment sampled from the bay. These areas included the vicinity of a shipyard, a small fishing port, the closed inner area of the bay, and the mouth of the bay. Higher concentrations of TBT and TPT and a higher ratio of TBT to total BTs were observed in the vicinity of the shipyard. A higher concentration of TPT in comparison with TBT was detected in a small fishing port. Furthermore, OT concentrations in the mouth of the bay were higher than those in the closed-off section. OT concentrations in mussels decreased with distance from the shipyard. Otsuchi Bay was then divided into three parts by cluster analysis based on the concentrations of representative booster biocides found in the bay's sediment. These areas included the vicinity of a shipyard, a small fishing port, and other sites. Concentrations of Diuron and Irgarol 1051 in the vicinity of a shipyard and a small fishing port were dramatically high in comparison with the other sites. Copper pyrithione and Dichlofluanid in addition to Diuron and Irgarol 1051 were also detected in the area of a small fishing port. The concentrations of antifouling biocides were highest in the water in front of the shipyard and showed a marked decrease with distance from the shipyard.

Acute toxicity of pyrithione antifouling biocides and joint toxicity with copper to red sea bream (Pagrus major) and toy shrimp (Heptacarpus futilirostris)

We evaluated the median lethal concentrations (LC50s) of the pyrithione (PT) antifoulants copper pyrithione (CuPT) and zinc pyrithione (ZnPT) to a teleost, red sea bream (Pagrus major), and a crustacean, toy shrimp (Heptacarpusfutilirostris). The 96-h LC50 values of CuPT and ZnPT, on the basis of actual concentrations, were 9.3 and 98.2 R.g/L, respectively, for red sea bream and 2.5 and 120 microg/L, respectively, for toy shrimp. Histological observations revealed that the secondary lamellae of the gill filaments of the experimental fish were heavily damaged after exposure to the PTs, suggesting that fatal hypoxemia was one cause of death. Because CuPT and ZnPT are usually used in combination with Cu, we also estimated the joint toxicities of the PTs with Cu using the LC50 values of the PTs and those of Cu (84.4 and 113 microg/L for red sea bream and toy shrimp, respectively). The results suggested that the joint toxicity of the ZnPT and Cu mixture is more than the additive toxicities of CuPT and Cu, especially in toy shrimp. The enhancement of toxicity in the mixture was inferred to be caused by conversion of ZnPT to the more toxic CuPT in the presence of Cu.

Toxicity reduction of metal pyrithiones by near ultraviolet irradiation

Zinc pyrithione (ZnPT) or copper pyrithione (CuPT) have been effectively used as ship-antifouling agents, as an alternative to organotin compounds. Because of their instability in light and a lack of suitable analytical procedures, there is little data on their residue levels in environmental matrices. It is possible to investigate the fate of such compounds by toxicity alteration with certain treatments. The purpose of this study was to evaluate the degradation of pyrithiones through toxicity reduction by near ultraviolet (UV-A) irradiation. Metal pyrithiones dissolved in acetonitrile were irradiated with a UV-A lamp for 0, 0.5, 1, and 2 h, and were subjected to UV spectral measurement and toxicity evaluation using both sea urchin and freshwater rotifer bioassays. For the bioassays, photolyzed samples were dissolved in dimethyl sulfoxide after evaporation of the acetonitrile. The changes in UV spectra of photolyzed ZnPT or CuPT showed a time-dependent degradation, and the UV spectra at 2 h irradiation suggested substantial decomposition. Toxicities of ZnPT and CuPT were 12 and 5 microg/L as 24 h LC50 to the survival of rotifers and 10(-6) ng/L and 2.3 ng/L as 27 h EC50 to normal pluteus formation, respectively. By evaporation of the acetonitrile, the EC50 of ZnPT was 2.2 ng/L, which was the same as that of CuPT. The EC50s of ZnPT or CuPT for both species increased with longer irradiation times. Photolyzed ZnPT or CuPT demonstrated substantial degradation in the UV spectra, but possessed marked toxicity, which is probably due to toxic degradation products. One reason why photolyzed CuPT was toxic to rotifers was explained by the high toxicity of copper ions formed by UV-A irradiation.

Acute Toxicity Tests to Verify Transchelation of Zinc Pyrithione to Copper Pyrithione under the Presence of Copper Ions

Acute Toxicity Tests to Verify Transchelation of Zinc Pyrithione to Copper Pyrithione under the Presence of Copper Ions

Study of Acute Toxicity of Copper Pyrithione to Bafununi {Hemicentrotus pulcherrimus) During Its Early Developmental Stages

Study of Acute Toxicity of Copper Pyrithione to Bafununi {Hemicentrotus pulcherrimus) During Its Early Developmental Stages

Environmental fate of the antifouling compound zinc pyrithione in seawater

To perform a thorough risk assessment of the new antifouling compound zinc pyrithione (ZnPT2), additional information regarding the fate of the compound is needed. The present study examined the recovery and transchelation of ZnPT2 in controlled laboratory experiments, photodegradation experiments, and a fate study in a large-scale field experiment. Chemical analyses were performed using a newly developed method for simultaneous analyses of ZnPT2 and copper pyrithione (CuPT2). Furthermore, two antifouling paints containing ZnPT2 were examined for the fate of leaching biocide. Naturally occurring ligands and metals in seawater influence the stability of ZnPT2. The presence of free Cu2+, which is present naturally in the seawater or is released from copper-containing paints, results in a partial transchelation of ZnPT2 into CuPT2. A complete transchelation of ZnPT2 into CuPT2 was observed when Cu2+ was present at an equimolar concentration in the absence of interfering ligands. When ZnPT2 was leached from antifouling paints containing both ZnPT2 and Cu2O, CuPT2 was found, with no trace of ZnPT2. Photodegradation was low in natural waters and absent from 1 m or more below the surface. The results show that ZnPT2 has a low persistence in seawater when leached from antifouling paints. However, the more stable and toxic transchelation product CuPT2 is formed, which has the potential to accumulate in the sediments and, therefore, should be included in both chemical analysis and risk assessment of ZPT2.

Degradation of antifouling booster biocides in water

The concentrations of booster compounds were surveyed in the port of Osaka, Japan. The concentrations of Sea-Nine 211, Diuron and Irgarol 1051 in water samples from the port of Osaka were in the ranges <0·30–0·55 ng l−1, 13–350 ng l−1, 1·3–77 ng l−1, respectively. Pyrithiones were not detected in water samples. The levels of Diuron and Irgarol 1051 in the port of Osaka were high in the mooring area for small and medium-hull vessels with poor flushing.Susceptibility of bacterial populations in estuarine water to antifouling biocides was studied. Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione dissolved in dimethyl sulfoxide (DMSO) were added to estuarine water and number of colony forming units (CFU) of bacteria in estuarine water was counted using R2A agar plate. The CFU was not decreased at the concentration less than 1·0 mg/l of Diuron, Irgarol 1051 and Copper pyrithione. However, CFU was decreased at 0·1 mg/l of Sea-Nine 211. Degradation of Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione by bacteria in estuarine water was studied using a die-away method. At an initial concentrations of 0·1 mg/l, observed half-lives of Sea-Nine 211 and Copper pyrithione were 10 and 20 days, respectively. In contrast, Diuron and Irgarol 1051 were degraded scarcely during 60 days of culture.Photodegradation of these booster biocides by sunlight and UV light were studied. Under UV, all biocides were below detection limit after one day of irradiation. Under sunlight, Copper pyrithiones were also below detection limits after one day. Drastic decrease of Sea-Nine 211 concentration was observed after one day. Diuron and Irgarol 1051 scarcely decreased during 17 days of sunlight irradiation.

Seasonal variations in the effect of zinc pyrithione and copper pyrithione on pelagic phytoplankton communities

The relationship between environmental factors, community composition and the sensitivity of pelagic phytoplankton to the antifouling agents zinc pyrithione (ZPT) and copper pyrithione (CPT) was studied using phytoplankton communities collected from March until August 2001 in Roskilde fjord, Denmark. Sensitivity to ZPT and CPT was measured as EC 50 values obtained from dose–response curves of photosynthesis to ZPT and CPT. EC 50 for ZPT and CPT varied between 2 and 60 nM and 4 and 25 nM, respectively. Changes in sensitivity throughout the season were related to changes in phytoplankton community composition and density, and to nutrient levels. It was found that the variation in sensitivity of ZPT and CPT was related to the abundance of the groups Cryptophyceae, Bacillariophycaea and Dinophyceae when they were dominating the community. Furthermore, the sensitivity to ZPT was increased at low concentrations of phosphate per cell (<0.2 nmol/cell). For CPT there was a negative correlation between toxicity and phosphate concentration in the water. Consequently, in aquatic environments where phytoplankton is phosphate limited the effect of ZPT and CPT may be enhanced.