DCOIT unbalances the antioxidant defense system in juvenile and adults of the marine bivalve Amarilladesma mactroides (Mollusca: Bivalvia)

DCOIT is a co-biocide that is part of the formulation of the commercial antifouling Sea-Nine 211® and although it is "safe to use", negative effects have been reported on the antioxidant defense system of non-target organisms. Therefore, the objective of this research was to verify and compare the response of antioxidant enzymes of juveniles and adults of Amarilladesma mactroides exposed to DCOIT. The animals were exposed to solvent control (DMSO 0.01%) and DCOIT (measured concentration 0.01 mg/L and 0.13 mg/L) for 96 h, then gills, digestive gland and mantle were collected for analysis of the enzymatic activity of glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). The results revealed that adults, in relation to juveniles, have low basal activity of GST and SOD enzymes in the gills and digestive gland and high basal activity of SOD and CAT in the mantle. DCOIT did not alter GST activity in the gills of any life stage, while both concentrations decreased SOD and CAT in adults. In the digestive gland, it was observed that DCOIT (0.13 mg/L) decreased the GST activity in adults and CAT in juveniles, and both concentrations of the co-biocide decreased the SOD and CAT in adults. In the mantle, DCOIT (0.13 mg/L) increased CAT in juveniles. We conclude that juveniles have greater basal activity of antioxidant enzymes than adults and, in addition, DCOIT negatively affected the adults of A. mactroides, mainly decreasing the activity of GST, SOD and CAT in the gills and digestive gland of these organisms.

Ecological risk assessment of booster biocides in sediments of the Brazilian coastal areas

Although booster biocides (Irgarol, diuron, chlorothalonil, dichlofluanid, and DCOIT) have been detected in sediments along the Brazilian coastal areas, the risk associated to their occurrence and levels is still unknown. Thus, the ecological risk of booster biocides to sediment-dwelling organisms from the Brazilian coast was assessed using a risk characterization approach through the Risk Quotient (Measured environmental concentration (MEC)/Predicted no effect concentrations (PNECs)). Sedimentary PNECs for Irgarol, diuron, chlorothalonil and DCOIT were derived based on published ecotoxicological data from both freshwater and marine studies, while a NORMAN methodology was used to derived it for dichlofluanid. Results showed that DCOIT, diuron, Irgarol, chlorothalonil, and dichlofluanid can pose high risk on 47%, 35%, 15%, 1% and 1%, respectively, of the 113 Brazilian sites appraised. Considering the trend of expansion of navigation/maritime activities, DCOIT may worsen its impact over the coastal areas of Brazil, especially ports, but also ship/boatyards, marinas, and maritime traffic zones. The present study is an important contribution to support advance on policy formulation concerning booster biocides worldwide, particularly considering the lack of regulation on the use of antifouling biocides in Brazil.

Copper ecological risk assessment using DGT technique and PNEC: A case study in the Brazilian coast

Estuarine systems are vulnerable to metals stress, such as copper (Cu). Thus, the development of applicable tools to improve routine monitoring programs is increasingly necessary. In the present work a comprehensive Ecological Risk Assessment (ERA) was implemented by coupling the Measured Environmental Concentration (MEC), based on labile Cu (DGT) and the total dissolved Cu concentration. Additionally, toxicity data related to site-specific Predicted No Effect Concentration (PNEC) were used. As case study, estuarine areas were selected on Brazilian coast, previously reported as Cu release in shipyard areas. The results indicated an increase in concentrations of dissolved and labile Cu during the application of antifouling paints. In locations where more vessels in maintenance were found, the concentration of Cu-DGT exceeded the PNEC value (0.16 μg.L^-1) and represented an important part of the total dissolved fraction (>93 %). The MEC/PNEC quotients, showed that shipyard areas represent a high ecological risk. Thus, it is highlighted the need for site-specific environmental assessments to manage complex ecosystems and set in environmental legislation. Consequently, the novel coupling of DGT technique and the derivation of a site-specific PNEC represent an easily applicable tool as an alternative to classical ERAs.

Arsenic, lead and cadmium concentrations in caudal crests of the yacare caiman (Caiman yacare) from Brazilian Pantanal

Wetlands are environments of extreme importance due to their high biodiversity and invaluable ecosystem services. Nevertheless, wetlands worldwide are under the increasing threat of the effects of contaminants, which put at risk the biota and the ecosystems. Herein the concentrations of non-essential and toxic elements arsenic (As), lead (Pb) and cadmium (Cd) in caudal crests of the yacare caiman (Caiman yacare) from the Brazilian Pantanal, one of the largest wetlands in the world, were investigated aiming to compare concentrations in individuals from a large pristine area (Southern Pantanal) to animals from an area close to potential sources of anthropogenic emissions (Northern Pantanal). Levels above the limit of detection were found for all the elements in the majority of the analysed samples. The highest mean concentration was detected for As in samples from both sites, followed by Pb and Cd in samples from Southern Pantanal, and Cd and Pb in samples from Northern Pantanal. Significant negative correlations were found between As and Cd concentrations and the size of the individuals from the Southern Pantanal. Surprisingly, concentrations of all three elements were higher in pristine Southern Pantanal, but with significant differences only for Cd. This result suggests that natural sources and processes may be acting for the mobilisation and availability of As, Pb and Cd for Southern Pantanal biota, which reflected in the contamination of C. yacare. Data from the literature showed higher levels of As, Pb and Cd in abiotic compartments in Southern Pantanal and adjacent plateaus in comparison to Northern Pantanal, corroborating the higher concentrations detected in biotic samples from the south. Thus, natural sources seem to play a relevant role in the contamination of biota by As, Pb and Cd in Southern Pantanal, characterising an intriguing pattern that could be tested for other species.

Toxicity of methylparaben to green microalgae species and derivation of a predicted no effect concentration (PNEC) in freshwater ecosystems

Methylparaben (MeP) is one of the most used preservatives in the industry; however, the toxic effects on aquatic ecosystems are still poorly understood. Therefore, this study was conducted (1) to identify and compare the toxic effects of MeP on physiological parameters of different green microalgae species, using suitable mathematical models; and (2) to estimate a PNEC value for MeP in freshwater ecosystems, adopting either the deterministic or the probabilistic approaches. Toxicity tests were carried out with three green microalgae (Pseudopediastrum boryanum, Desmodesmus communis, Raphidocelis subcapitata), in which different endpoints such as growth rate, chlorophyll-a, and cell viability were measured and compared through the effective concentration which caused a response in x% of test organisms (ECx). ECx were obtained by adjusting different non-linear regression models for each microalgae dataset. Chlorophyll-a endpoint resulted in the lowest EC₅₀ values, respectively 125, 81.2, 18.3 mg L^-1 for D. communis, P. boryanum and R. subcapitata, showing R. subicapitata as the most sensitive, and D. communis as the most tolerant species to MeP (P < 0.05). PNEC was estimated from the present study and previous reports resulting in 5.7 and 65 μg L^-1, respectively for the deterministic (PNECd) and the probabilistic (PNECp) approach. The development of chronic assays using test organisms from different ecological groups is encouraged to provide robust PNECp. In this meantime, we recommend the use of the estimated PNECd to support MeP risk assessments and policy formulation.

Potential ecotoxicity of metals leached from antifouling paint particles under different salinities

Antifouling paint particles (APPs) are residues generated during maintenance of vessels. In boat maintenance areas of South America, waste generation and disposal are not completely regulated. Therefore, APPs can enter into the aquatic environment and act as a source of contamination by metals and other biocides. Thus, the aim of the present study was to evaluate the potential ecotoxicity of the metal mixture present in APPs leached under different salinities. Therefore, the copepod Acartia tonsa was exposed to different concentrations of a leachate solution prepared by the addition of APPs (1.25g/L) in artificial saline water (salinities 5, 15 and 30). Thereafter, complexing agents (EDTA and sodium thiosulfate) were added to the experimental media in order to evaluate metal influence in APPs toxicity. APPs leachate solutions were very toxic to A. tonsa, reaching an estimated LC₅₀ of 1% at salinities 5% and 15%, and 2% at salinity 30. The addition of the chelators in leachate solutions showed that metals are the major responsible compounds for the observed toxicity. Moreover, results from the calculated toxic units suggested a slightly synergic effect between Cu and Zn in the paint formulation. A metal speciation modelling showed that Zn was predominant as a free ion at all salinities, therefore, explaining the high leachate toxicity. Furthermore, the release of Zn was observed more at lower salinities, whereas Cu was observed at higher salinities. APPs are frequently released in estuarine systems, under conditions of salinity gradients. Therefore, navigated estuaries might be under the threat of this neglected residue.

Review: ecotoxicity of organic and organo-metallic antifouling co-biocides and implications for environmental hazard and risk assessments in aquatic ecosystems

Hazard assessments of Irgarol 1051, diuron, 2-(thiocyanomethylthio)benzothiazole (TCMTB), dichloro-octylisothiazolin (DCOIT), chlorothalonil, dichlofluanid, thiram, zinc pyrithione, copper pyrithione, triphenylborane pyridine (TPBP), capsaicin, nonivamide, tralopyril and medetomidine were performed to establish robust environmental quality standards (EQS), based on predicted no effect concentrations (PNECs). Microalgae, zooplankton, fish and amphibians were the most sensitive ecological groups to all the antifoulants evaluated, especially in the early life stages. No differences were identified between freshwater and seawater species. The use of toxicity tests with non-standard species is encouraged because they increase the datasets, allowing EQS to be derived from probabilistic-based PNECs whilst reducing uncertainties. The global ban of tributyltin (TBT) has been heralded as a major environmental success; however, substitute antifoulants may also pose risks to aquatic ecosystems. Environmental risk assessments (ERAs) have driven decision-makings for regulating antifouling products, but in many countries there is still a lack of regulation of antifouling biocides which should be addressed.

Uptake, tissue distribution and depuration of triclosan in the guppy Poecilia vivipara acclimated to freshwater

The agent triclosan has been extensively used in different personal care products as a broad-spectrum antimicrobial and preservative agent. Due to its continuous release into the environment, including discharge via wastewater treatment plants, triclosan has been widely detected in aquatic environments. There is growing interest in improving the knowledge about the environmental fate of triclosan due to its possible bioaccumulation and the toxicity it may pose to organisms, such as fish and other non-target species. To investigate the distribution and bioconcentration of triclosan in fish, Poecilia vivipara was exposed to 0.2mgL(-1). Contents of triclosan in whole fish, brain, gonads, liver, muscle and gills were quantified by LC-MS/MS. When lipid normalised concentration was used, the liver exhibited the highest concentration followed by the gills, gonads, brain and muscle tissues. Bioconcentration was increased with time reaching a steady-state around 7-14days for most all tissues. After 24h depuration, triclosan concentrations declined >80% in all tissues except liver, in which triclosan takes longer to be depurated. These results not only clearly indicate that triclosan accumulated in P. vivipara, with tissue-specific bioconcentration factors (BCF) that ranged from 40.2 to 1025.4, but also show that the elimination of triclosan after transferring the fish to triclosan-free freshwater is rapid in all tissues.

Toxicity tests aiming to protect Brazilian aquatic systems: current status and implications for management

The current status of toxicological tests performed with Brazilian native species was evaluated through a survey of the scientific data available in the literature. The information gathered was processed and an electronic toxicology database (http://www.inct-ta.furg.br/bd_toxicologico.php) was generated. This database provides valuable information for researchers to select sensitive and tolerant aquatic species to a large variety of aquatic pollutants. Furthermore, the toxicology database allows researchers to select species representative of an ecosystem of interest. Analysis of the toxicology database showed that ecotoxicological assays have significantly improved in Brazil over the last decade, in spite of the still relatively low number of tests performed and the restricted number of native species tested. This is because most of the research is developed in a few laboratories concentrated in certain regions of Brazil, especially in Southern and Southeast regions. Considering the extremely rich biodiversity and the large variety of aquatic ecosystems in Brazil, this finding points to the urgent need for the development of ecotoxicological studies with other groups of aquatic animals, such as insects, foraminifera, cnidarians, worms, amphibians, among others. This would help to derive more realistic water quality criteria (WQC) values, which would better protect the different aquatic ecosystems in Brazil. Finally, the toxicology database generated presents solid and science based information, which can encourage and drive the Environmental Regulatory Agencies in Brazil to derive WQC based on native species. In this context, the present paper discusses the historical evolution of ecotoxicological studies in Brazil, and how they have contributed to the improvement of the Brazilian Federal and Regional regulations for environment.