Effects of the parasiticide ivermectin on the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata

Ecotoxicological effects of the emerging contaminant ivermectin on Rhinella arenarum: A comparative study of active ingredient and commercial formulation

Ivermectin (IVM) is a broad-spectrum veterinary antiparasitic used worldwide in cattle breeding. The aim of this study was to evaluate the lethal effects of the active ingredient and a commercial formulation of IVM (1 % active ingredient) in the embryonic stage (S. 4-6) and larval stage (S. 25) of the South American amphibian Rhinella arenarum through chronic standardized bioassays. Also, behavior analysis and oxidative stress and cholinergic effects biomarkers were analyzed at 1, 10 and 100 μg IVM/L concentrations. For the embryonic stage, the active ingredient (96 h- LC50: 15900 μg/L) was more toxic than the commercial formulation (96 h-LC50: 51230 μg/L) during the acute period, while at chronic exposure the commercial formulation was more toxic (504 h-LC50: 10.25 μg/L), compared to the active ingredient (504 h-LC50: 312.80 μg/L). For the larval stage, in acute exposure, the active ingredient (96 h-LC50: 800 μg/L) was more toxic than the commercial formulation (96 h-LC50: 1550 μg/L). In the chronic exposure, the commercial formulation (504 h-LC50: 77.33 μg/L) was more toxic than the active ingredient (504 h-LC50: 195.25 μg/L). Overall, larvae exhibited greater sensitivity to both the active ingredient and the commercial formulation. However, during chronic exposure, embryos were more sensitive to the commercial formulation than larvae. The commercial formulation primarily induced oxidative stress, and both forms of the compound affected behavior and cholinergic effect biomarkers, even at low environmentally relevant concentrations (1 μg/L). These results highlight the potential impact of IVM on aquatic ecosystems.

Considerations and data update for the inference of environmental quality standards for two avermectins widely used in salmon aquaculture

We have updated and reviewed toxicity data for Emamectin benzoate (EMB) and Ivermectin (IVER), two in-feed drugs used to treat sea lice in farmed Atlantic salmon, and inferred new Environmental Quality Standards (EQS) using a deterministic approach or Species Sensitivity Distributions (SSDs) based on available data. We used a SSD model averaging approach and inferred a water acute EQS value of 24.9 ng/L (SSD) for EMB, while previously established chronic water EQS of 0.17 ng/L and sediment benthic EQS of 131 ng/kg dry weight remained unchanged. For IVER, both a water acute EQS of 8.04 ng/L and a chronic water EQS of 3.98 ng/L were inferred using SSDs as well as a benthic EQS of 290 ng/kg dry weight using a deterministic approach. In light of the lack of solubility and tendency of both avermectins to sorb to material benthic EQSs remain the most relevant value to consider for regulators.

Catchment-scale rapid transfer of livestock pharmaceuticals under Mediterranean climate

Various pharmaceuticals are essential for livestock farming, but some are highly toxic to aquatic life if they reach surface water bodies. Mediterranean Climate is characterized by dry summers followed by intense autumn storms. We studied the effect of these climatic conditions on the risk of pharmaceutical residues transfer to streams at the catchment-scale. Pharmaceutical products routinely used in the study area, as well as their application frequency and season, were identified through interviews with farmers. As a proof a concept, three veterinary pharmaceuticals (Fenbendazole (FBZ), Mebendazole (MBZ) and Ivermectin (IVM)) were chosen as model chemicals based on their relatively high usage, their specificity to represent different types of livestock (swine, sheep and cattle), and their ability to be analyzed using the same analytical method. Stream water was analyzed during low flow periods and at high frequency (up to 2 h-1) during flood events. The selected veterinary pharmaceuticals were not detected during low flow, but FBZ and MBZ reached high concentrations for short periods during floods. Due to the event-driven nature of their transfer, a significant load of veterinary pharmaceuticals can reach the river and cause temporary but significant degradation of water quality (e.g. for FBZ, the water concentration reached up to 355 times the predicted no effect concentration (PNEC)). This indicates that special care should be taken to avoid keeping freshly treated livestock on pastures that may become hydrologically connected under wet conditions. In addition, it suggests that low-frequency monitoring is not sufficient to detect those high concentration levels that exist during very short periods.

Wastewater surveillance of pharmaceuticals during the COVID-19 pandemic in Mexico City and the Mezquital Valley: A comprehensive environmental risk assessment

This study tracked five pharmaceutically active compounds (PhACs) in Mexico City's sewage, namely, famotidine, indomethacin, dexamethasone, azithromycin, and ivermectin, which were used to treat COVID-19. The monitoring campaign was carried out over 30 months (May 2020 to November 2022), covering the five COVID-19 waves in Mexico. In the Central Emitter, the main sewage outflow, famotidine displayed levels of 132.57 ± 28.16 ng L-1 (range from < LOQ to 189.1 ng L-1), followed by indomethacin (average 672.46 ± 116.4 ng L-1, range from 516.7 to 945.2 ng L-1), dexamethasone (average 610.4 ± 225.7 ng L-1, range from 233.4 to 1044.5 ng L-1), azithromycin (average 4436.2 ± 903.6 ng L-1, range from 2873.7 to 5819.6 ng L-1), and ivermectin (average 3413.3 ± 1244.6 ng L-1, range from 1219.8 to 4622.4 ng L-1). The concentrations of dexamethasone, azithromycin and ivermectin were higher in sewage from a temporary COVID-19 care unit, by a factor of 3.48, 3.52 and 2.55, respectively, compared with those found in municipal wastewater. In the effluent of the Atotonilco Wastewater Treatment Plant (AWWTP), which treats near 60 % of the Mexico City's sewage, famotidine was absent, while concentrations of indomethacin, dexamethasone, azithromycin and ivermectin were 78.2 %, 76.7 %, 74.4 %, and 88.1 % lower than those in the influent, respectively. The occurrence of PhACs in treated and untreated wastewater resulted in medium to high environmental risk since Mexico City's wastewater is reused for irrigation in the Mezquital Valley. There, PhACs were found in irrigation canals at lower levels than those observed in Mexico City throughout the monitoring. On the other hand, famotidine, indomethacin, and dexamethasone were not found in surface water resulting from the infiltration of wastewater through soil in Mezquital Valley, while azithromycin and ivermectin sporadically appeared in surface water samples collected through 2021. Using an optimized risk assessment based on a semi-probabilistic approach, the PhACs were prioritized as ivermectin > azithromycin > dexamethasone > famotidine > indomethacin.

A review on the fate and effects of contaminants in biosolids applied on land: Hazards and government regulatory policies

The increase in world population growth and its resultant increase in industrial production to meet its need, have continued to raise the volume of wastewater received by treatment plant facilities. This has expectedly, led to an upsurge in the volume of sewage sludge and biosolids generated from wastewater treatment systems. Biosolids are best managed by application on land because of their agronomic benefits. However, this usage has been discovered to negatively affect humans and impact the environment due to the accumulation of minute concentrations of contaminants still present in the biosolid after treatment, hence the need for government regulations. This review article examined the fate and effects of pollutants, especially persistent organic pollutants (PoPs) of concern and emerging contaminants found in biosolids used for land applications, and also discussed government regulations on biosolid reuse from the perspectives of the two major regulations governing biosolid land application-the EU's Sludge Directive and USEPA's Part 503 Rule, in an attempt to draw attention to their outdated contents since enactment, as they do not currently meet the challenges of biosolid land application and thus, require a comprehensive update. Any update efforts should focus on USEPA's Part 503 Rule, which is less stringent on the allowable concentration of biosolid pollutants. Furthermore, an update should include specific regulations on new and emerging contaminants and persistent organic pollutants (PoPs) such as microplastics, pharmaceutical and personal care products (P&PCPs), surfactants, endocrine-disrupting chemicals, flame retardants, pathogens, and organic pollutants; further reduction of heavy metal standard limits, and consideration of soil phosphate-metal interactions to regulate biosolid agronomic loading rate. Future biosolid research should focus on the concentration of TCS, TCC, and emerging pharmaceuticals, as well as Microplastic transport in biosolid-amended soils, soil-plant transfer mechanism, and metabolism of PFAs in the soils; all of which will inform government policies on biosolid application on land.

A review on the ecotoxicity of macrocyclic lactones and benzimidazoles on aquatic organisms

Despite its wide production and several applications, veterinary antiparasitics from macrocyclic lactones and benzimidazole classes have not received much scientific attention concerning their environmental risks. Thus, we aimed to provide insights into the state of the environmental research on macrocyclic lactone and benzimidazole parasiticides, emphasizing their toxicity to non-target aquatic organisms. We searched for relevant information on these pharmaceutical classes on PubMed and Web of Science. Our search yielded a total of 45 research articles. Most articles corresponded to toxicity testing (n = 29), followed by environmental fate (n = 14) and other issues (n = 2) of selected parasiticides. Macrocyclic lactones were the most studied chemical group (65% of studies). Studies were conducted mainly with invertebrate taxa (70%), with crustaceans being the most predominant group (n = 27; 51%). Daphnia magna was the most used species (n = 8; 15%). Besides, it also proved to be the most sensitive organism, yielding the lowest toxicity measure (EC₅₀ 0.25 μg/L for decreased mobility after 48 h-abamectin exposure) reported. Moreover, most studies were performed in laboratory settings, tracking a limited number of endpoints (acute mortality, immobility, and community disturbance). We posit that macrocyclic lactones and benzimidazoles warrant coordinated action to understand their environmental risks.

Biodegradation of anthelmintics in soils: does prior exposure of soils to anthelmintics accelerate their dissipation?

Anthelmintics (AHs) control animal infections with gastrointestinal nematodes. They reach soil through animal faeces deposited on soils or through manuring. Although soil constitutes a major AH sink, we know little about the mechanisms controlling their soil dissipation. We employed studies with fumigated and non-fumigated soils collected from 12 sheep farms with a variable record of albendazole (ABZ), ivermectin (IVM) and eprinomectin (EPM) use. From each farm, we collected soils from inside small ruminant barn facilities (series A, high exposure) and the associated grazing pastures (series B, low exposure). We asked the following questions: (a) What is the role of soil microorganisms in AH dissipation? (b) Does repeated exposure of soils to AHs lead to their accelerated biodegradation? (c) Which soil physicochemical properties control AH dissipation? Soil fumigation significantly retarded ABZ (DT₅₀ 1.9 and 4.33 days), IVM (34.5 and 108.7 days) and EPM dissipation (30 and 121 days) suggesting a key role of soil microorganisms in AH dissipation. No significant acceleration in AH dissipation was evident in soils from units with a record of the administration of AHs or in soil series A vs series B, suggesting that the level of prior exposure was not adequate to induce their enhanced biodegradation. Significant positive and negative correlations of soil total organic carbon (TOC) and ABZ and IVM dissipation, respectively, were observed. Soil adsorption of AHs increased in the order IVM > ABZ > EPM. TOC controlled soil adsorption of IVM and EPM, but not of ABZ, in support of the contrasting effect of TOC on IVM and ABZ dissipation.

Avermectin Toxicity to Benthic Invertebrates is Modified by Sediment Organic Carbon and Chemical Residence Time

Chemicals used in sea lice management strategies in salmonid aquaculture include the avermectin class of compounds that can accumulate and persist in the sediments underneath salmon farms and directly impact nontarget benthic fauna. The effects of sediment organic carbon content and chemical residence time (CRT) on the lethal and sublethal toxicity of emamectin benzoate (EB; formulation: Slice®) and ivermectin (purified) and a combination of both were examined in two benthic invertebrates, the amphipod Eohaustorius estuarius and the polychaete Neanthes virens. In both species, increased sediment organic carbon content significantly reduced lethal toxicity, a modulation that was more pronounced for ivermectin and combination exposures. At a CRT of 4 months, lethal toxicity was reduced in E. estuarius but was unaffected in N. virens. Sublethal toxicity in N. virens (burrowing behavior) was modulated by sediment organic carbon and CRT in a similar manner to the trend in lethal toxicity. Inconsistencies in behavior (phototaxis) in E. estuarius made conclusions regarding toxicity modification by sediment organic carbon or CRT inconclusive. Our results indicate that environmental factors including sediment organic carbon content and the time compounds reside in sediments are important modifiers of chemotherapeutant toxicity in nontarget benthic species and should be considered when regulatory decisions regarding their use are made. Environ Toxicol Chem 2022;41:1918-1936. © 2022 SETAC.

Environmental Impact of Pharmaceutical Pollutants: Synergistic Toxicity of Ivermectin and Cypermethrin

Veterinary antiparasitic pharmaceuticals as well as pesticides have been detected in surface waters, and they may cause several toxic effects in this environmental compartment. In the present study, we evaluated the toxicity after exposure of different concentration of ivermectin (IVM; 50, 100, and 200 μg L⁻¹) and cypermethrin (CYP; 5, 10, and 25 μg L⁻¹) and the combination of these two compounds at non-toxic concentration (IVM 100 + CYP 5 μg L⁻¹) in zebrafish embryos. Combination of IVM at 100 μg L⁻¹ with CYP at 5 μg L⁻¹ exposure induced hatching delay and malformations at 96 hpf in zebrafish larvae as well as significant induction of cell death in zebrafish larvae. At the same time, the two single concentrations of IVM and CYP did not show a toxic effect on zebrafish development. In conclusion, our study suggests that IVM and CYP show a synergistic effect at common, ineffective concentrations, promoting malformation and cell death in fish development.

Immunotoxicity induced by Ivermectin is associated with NF-κB signaling pathway on macrophages

Ivermectin (IVM) has been widely used as a highly effective and broad-spectrum biopesticide in animal husbandry and agriculture. Considering the frequent environmental and occupational exposure, the various toxic effects caused by IVM should be paid more attention. The immune system is a common target of toxins due to its complexity and sensitivity. The toxicity effect of the immune system may lead to increased susceptibility to infections, with potentially fatal consequences. The immunotoxicity of IVM has received little attention, which poses a challenge to the systematic assessment of safety risks. The purpose of this study was to assess the immunotoxicity of the IVM using in vitro cellular assays. We proved that IVM could inhibit the cell viability, induce DNA damage and enhance apoptosis. In addition to the induction of cytotoxicity, IVM has also been shown to reduce the phagocytic capacity and significantly increase the mRNA expression levels of proinflammatory cytokines IL-6, IL-1 β and TNF-α. Intracellular biochemical assay indicated that activation of the NF-κB signaling pathway, overproduction of reactive oxygen species (ROS), release of cytochrome C, DNA double strand damage. These results indicate that IVM can induce immunotoxicity through induction of immune dysfunction and cytotoxicity. In conclusion, this study supports that IVM can be immunotoxic to macrophages in different ways, and draw attention to the potential immunotoxicity of IVM.

Photo-mediated and advanced oxidative processes applied for the treatment of effluents with drugs used for the treatment of early COVID-19: Review

The COVID-19 pandemic is proving to be one of the most challenging health and social crises ever faced by humanity. Several drugs have been proposed as potential antiviral agents for the treatment of COVID-19 since the beginning of the health crisis. Among them are chloroquine (CQ), hydroxychloroquine (HCQ), ivermectin (IVM), and the combination of QC or HCQ and azithromycin (AZI). The use of these and several other drugs has grown sharply, even if there is proof of ineffectiveness in the early treatment or mild cases of COVID-19. Thus, there is great concern about the potential environmental impacts of the effluents released with the presence of these drugs. Therefore, this work aimed to carry out a literature review on wastewater treatment processes, focusing on removing these substances through advanced oxidation process. As the conventional effluent treatment processes do not have high efficiency for removal, it was concentrated in the literature that had as scope advanced and photo-mediated techniques to remove CQ, HCQ, IVM, and AZI. It is expected, with this work, to highlight the importance of conducting research that contributes to the control of pollution and contamination.

A critical review on environmental presence of pharmaceutical drugs tested for the covid-19 treatment

On March 11, 2020, the World Health Organization (WHO) declared COVID-19 a pandemic. The outbreak caused a worldwide impact, becoming a health threat to the general population and its professionals. To date, there are no specific antiviral treatments or vaccines for the COVID-19 infection, however, some drugs are being clinically tested. The use of these drugs on large scale raises great concern about their imminent environmental risk, since the elimination of these compounds by feces and urine associated with the inefficiency of sewage treatment plants in their removal can result in their persistence in the environment, putting in risk the health of humans and of other species. Thus, the goal of this work was to conduct a review of other studies that evaluated the presence of the drugs chloroquine, hydroxychloroquine, azithromycin, ivermectin, dexamethasone, remdesivir, favipiravir and some HIV antivirals in the environment. The research indicated the presence of these drugs in the environment in different regions, with concentration data that could serve as a basis for further comparative studies following the pandemic.

Evaluation of silver nanowires (AgNWs) toxicity on reproductive success of Daphnia magna over two generations and their teratogenic effect on embryonic development

This study assessed the reproductive toxicity of silver nanowires (AgNWs) in Daphnia magna over two consecutive generations. An acute immobilization test was conducted according to the ΟECD 202 guidelines. To perform reproductive toxicity tests in both F0 and F1 generations, the animals were exposed to different concentrations of AgNWs (0, 0.4, 2, 10, and 50 µg L^-1) and pyriproxyfen (0.4 µg L^-1), as a positive control, based on the ΟECD 211 principles. Overall, AgNWs were acutely toxic to D. magna with EC₅₀ value of 0.063 mg L^-1. Compared to the control groups, AgNWs disrupted reproductive performances of D. magna through increasing the egg development time and time to production of first brood as well as decreasing the total offspring production and molting frequency in both F0 and F1 generations. After exposure to AgNWs, the number of male neonates and non-reproductive females increased in the F0 generation, whereas just male neonates raised in the F1 generation. Moreover, AgNWs caused several congenital anomalies including underdeveloped antennae, 2nd antennae, malpighian tube, rostrum, sensory bristles, tail spine, and malformed eyes. Together, AgNWs could disrupt reproductive health of D. magna, and these types of bioperturbations could dramatically change the good health state of aquatic ecosystems.

An analysis of the spatio-temporal occurrence of anthelmintic veterinary drug residues in groundwater

Anthelmintics are antiparasitic drugs used to control helminthic parasites such as nematodes and trematodes in animals, particularly those exposed through pasture-based production systems. Even though anthelmintics have been shown to be excreted into the environment in relatively high amounts as unmetabolized drug or transformation products (TPs), there is still only limited information available on their environmental occurrence, particularly in groundwater, which has resulted in them being considered as potential emerging contaminants of concern. A comprehensive study was carried out to investigate the occurrence of 40 anthelmintic residues (including 13 TPs) in groundwaters (and associated surface waters) throughout the Republic of Ireland. The study focused on investigating the occurrence of these contaminants in karst and fractured bedrock aquifers, with a total of 106 sites (88 groundwaters and 18 surface waters) samples during spring 2017. Seventeen anthelmintic compounds consisting of eight parent drugs and nine TPs were detected at 22% of sites at concentrations up to 41 ng L^-1. Albendazole and its TPs were most frequently detected residues, found at 8% of groundwater sites and 28% of surface water sites. Multivariate statistical analysis identified several source and pathway factors as being significantly related to the occurrence of anthelmintics in groundwater, however there was an evident localised effect which requires further investigation. An investigation of the temporal variations in occurrence over a 13 month period indicated a higher frequency and concentration of anthelmintics during February/March and again later during August/September 2018, which coincided with periods of increased usage and intensive meteorological events. This work presents the first detections of these contaminants in Irish groundwater and it contributes to broadening our understanding of anthelmintics in the environment. It also provides insight to seasonal trends in occurrence, which is critical for assessing potential future effects and implications of climate change.

Daphnia magna model in the toxicity assessment of pharmaceuticals: A review

Daphnia magna is one of the most commonly used model organism to assess toxicity of wide range of pharmaceuticals such as antibiotics, anticancer drugs, antidepressants, anti-inflammatory drugs, beta-blockers and lipid-regulating agents. Currently, daphnia toxicity tests based on immobilisation and lethality standardised by OECD, acute immobilisation test and reproduction test, are mainly used in toxicological studies. Detailed analysis of Daphnia biology allows distinguishing the swimming behaviour and physiological endpoints such as swimming speed, distance travelled, hopping frequency, heart rate, ingestion rate, feeding rate, oxygen consumption, thoracic limb activity which could be also useful in assessment of toxic effects. The advantage of behavioural and physiological parameters is the possibility to observe sublethal effects induced by lower concentrations of pharmaceuticals which would not be possible to notice by using OECD tests. Additionally, toxic effects of tested drugs could be assessed using enzymatic and non-enzymatic biomarkers of daphnia toxicity. This review presents scientific data considering characteristics of D. magna, analysis of immobilisation, lethality, reproductive, behavioural, physiological and biochemical parameters used in the toxicity assessment of pharmaceuticals. The aim of this paper is also to emphasize usefulness, advantages and disadvantages of these invertebrate model organisms to assess toxicity of different therapeutic classes of pharmaceuticals. Also, various examples of application of D. magna in studies on pharmaceutical toxicity are presented.

Toxic Effects of Fine Plant Powder Impregnated With Avermectins on Mosquito Larvae and Nontarget Aquatic Invertebrates

The toxic effects of an avermectin-impregnated fine plant powder (AIFP) against larval Aedes aegypti L. (Diptera: Culicidae), Culex modestus Ficalbi (Diptera: Culicidae), and Anopheles messeae Falleroni (Diptera: Culicidae), as well as selected nontarget aquatic invertebrates, were studied under laboratory conditions. The possibility of trophic transfer of avermectins (AVMs) through the food chain and their toxic effects on predaceous species fed AIFP-treated mosquito larvae was also evaluated. Among mosquitoes, Anopheles messeae were the most sensitive to AIFP, while Cx. modestus exhibited the least sensitivity to this formulation. Among nontarget aquatic invertebrates, the greatest toxicity of AIFP was observed for benthic species (larval Chironomus sp. Meigen (Diptera: Chironomidae), whereas predators (dragonflies, water beetles, and water bugs) exhibited the lowest AIFP sensitivity. AIFP sensitivity of the clam shrimp Lynceus brachyurus O. F. Muller (Diplostraca: Lynceidae), the phantom midge Chaoborus crystallinus De Geer (Diptera: Chaoboridae), and the mayfly Caenis robusta Eaton (Ephemeroptera: Caenidae) was intermediate and similar to the sensitivity of the mosquito Cx. modestus. However, these nontarget species were more resistant than An. messeae and Ae. aegypti. Solid-phase extraction of mosquito larvae treated with AIFP and subsequent high-performance liquid chromatography (HPLC) analysis of the extracts revealed an AVM concentration of up to 2.1 ± 0.3 μg/g. Feeding the creeping water bug Ilyocoris cimicoides L. (Hemiptera: Naucoridae) on the AIFP-treated mosquito larvae resulted in 51% mortality of the predaceous species. But no toxicity was observed for Aeshna mixta Latreille (Odonata: Aeshnidae) dragonfly larvae fed those mosquito larvae. The results of this work showed that this AVM formulation can be effective against mosquito larvae.

The environmental risks of pharmaceuticals beyond traditional toxic effects: Chemical differences that can repel or entrap aquatic organisms

The aim of the present study was to assess the risks of four different pharmaceutical active compounds (PhACs; diazepam, metformin, omeprazole and simvastatin). Acute and chronic toxicities were studied using the bacterium Aliivibrio fischeri and the microalgae Pseudokirchneriella subcapitata; while the repellency and attractiveness were assessed by avoidance tests with juvenile Cypirinus carpio using a multi-compartmented exposure system. Omeprazole was found to be an acutely toxic drug (EC₅₀: 0.015 mg/L), while the other PhACs, except simvastatin, showed some chronic toxicity. Regarding avoidance, simvastatin and omeprazole induced an escape response for 50% of the fish population at 0.032 and 0.144 mg/L, respectively; contrarily, diazepam was attractive, even at lethal concentrations, representing a dangerous trap for organisms. The toxicity of the PhACs seemed not to be directly related to their repellency; and the mode of action seems to determine the repellency or attractiveness of the chemicals. Contamination by PhACs is of concern due to the environmental disturbance they might cause, either due to their acute and chronic toxicity (at the individual level), repellency (at the ecosystem level: loss of local biodiversity) or attraction to potentially lethal levels.

Highly sensitive multi-residue analysis of veterinary drugs including coccidiostats and anthelmintics in pond water using UHPLC-MS/MS: application to freshwater ponds in Flanders, Belgium

Veterinary drugs, such as coccidiostats and anthelmintics are routinely administered in extensive animal husbandry, finding their way into the aquatic environment through urine and/or feces of treated animals kept outdoors or by the application of contaminated liquid manure on agricultural fields and subsequent mechanisms of surface run-off, leaching and drift. Several of these compounds are known to exert acute and chronic toxicity effects on aquatic organisms, and can lead to changes in biodiversity and ecosystem functioning. The overall objective of this research was to develop, validate and apply a highly sensitive, multi-residue SPE-UHPLC-MS/MS method for the determination of 12 coccidiostats, registered as a feed supplement or veterinary medicine in Europe and three regularly used anthelmintics, in pond water, often functioning as amphibian habitat. Sample extraction was optimized using a fractional factorial resolution design. Pond water filtration efficiency (i.e. 80-118%, ≤25% RSD) and matrix effects (i.e. 72-119%, ≤39% RSD) were evaluated using water from respectively 3 and 20 different ponds in Flanders. By incorporating internal standards, overall results improved and adequate precision values (i.e.≤15%) were obtained according to the EMA guidelines. Acceptable within-run and between-run apparent recoveries, satisfactory precision as well as good linearity were demonstrated according to the CD 2002/657/EC, SANTE/12682/2019 and VICH 49 guidelines, except for robenidine for which the between-day precision was between 21.0 and 34.5%. Sample storage stability studies indicated that storage at 4 °C and analysis performed within 96 hours after sampling was sufficient to avoid loss by degradation for all compounds, excluding robenidine. Values for the limit of detection (LOD) and quantification (LOQ) were in nanograms per liter, which was essential for the environmental application of this novel method. The method was successfully applied on grab water samples from the water surface of 18 different ponds across Flanders, Belgium, detecting amprolium and levamisole at concentrations below the LOQ of 2.5 ng L^-1 and at 250.0 ng L^-1 or below the LOQ of 250.0 ng L^-1, respectively. In conclusion, our newly developed method may provide insights about the contamination status of amphibian breeding ponds.

Environmental fate of the anti-parasitic ivermectin in an aquatic micro-ecological system after a single oral administration

Background

Ivermectin (IVM) has been widely used in the aquaculture industry since its efficacy against parasites. However, the degradation of IVM was very slow in aquatic environments and the environmental fate of IVM in a complete aquatic system was still not clear. Therefore, comparable studies in a complete aquatic system were merited and helped to elucidate the environmental fate and effects of IVM.

Methods

An aquatic micro-ecological system containing an aquatic environment (water and sediment) and aquatic organisms (invertebrates, aquatic plants and fish) was built to simulate the natural rearing conditions. A single dose of 0.3 mg kg^-1 body weight of IVM was given to the fish by oral gavage. Water, sediment, the roots and leaves of the aquatic plants, the soft tissue of the invertebrates and the visceral mass and muscle of fish samples were collected at 0.5 hours, 1 day, 7 days, 15 days, 30 days, 45 days, 60 days and 70 days after the treatment. IVM concentration in each sample was determined using ELISA method.

Results

IVM was quickly and widely distributed into the whole aquatic system in one day, and then was highly accumulated in organisms resulting in long-term residues. IVM was exchanged multiple times between the different media, which caused continuous fluctuations in the concentration of IVM in the water and sediment. It was worth noting that there was a second peak value of IVM in the fish and invertebrates after 30 days. The environmental fate of the IVM in the aquatic micro-ecological system showed that the drug was transferred from the fish to aquatic plants in the first seven days, and then gathered in the water and sediment, finally accumulating in the invertebrates. Our results indicated that an effective aquatic micro-ecological system was successfully established, and it could be applied to the study the environmental fate of IVM, which will aid the scientific use of this anti-parasitic agent during aquaculture.

Sorption and leaching behavior of bithionol and levamisole in soils

The batch experiments were conducted to understand sorption process of bithionol (BIT) in yellow soil (YS) and red soil (RS), while column leaching experiments were performed to evaluate the leaching behavior of BIT and levamisole (LEV) in the tested soils. The adsorption and desorption data fitted well with the Freundlich isotherms (R² ≥ 0.94). The distribution coefficient of BIT in the YS and RS were 104 and 98.3 L/kg, respectively. Hysteresis was observed for bithionol desorption in the YS and RS, with hysteresis coefficient of 0.917 and 0.928, respectively. Dissolved organic matter (DOM) addition and acid condition enhanced the adsorption of BIT in the soil. Both BIT and LEV showed poor leaching potential in the tested soils. More than 80% of BIT and LEV remained in the surface soil layer and the amount of the two target compounds in the leachates accounted for less than 1% of overall recovery. DOM showed little influence on the concentration of BIT and LEV in the leachates collected at different time. The results could fill the gap on the behavior of BIT and LEV in soil under laboratory conditions.

Swimming activity in zebrafish larvae exposed to veterinary antiparasitic pharmaceuticals

Veterinary antiparasitic pharmaceuticals have been detected in surface waters and several of these pharmaceuticals act on the nervous system on the target organisms implying that neurological effects also might be of concern in non-target animals such as fish. We tested if exposure to antiparasitic pharmaceuticals affect swimming activity in 6 days old zebrafish larvae. The results revealed that most pharmaceuticals did not cause any effects in swimming activity. However, larvae exposed to 0.58 mg/L doramectin displayed reduced swimming activity even though they were classified as normal, having no morphological abnormalities.

Trans-generational effects of ivermectin exposure in dung beetles

Ivermectin is a powerful antiparasitic drug commonly used in cattle. Ivermectin residues are excreted in dung, threatening non-target coprophagous fauna such as dung beetles. This can have severe ecological and economic consequences for dung degradation and soil fertility. Even though the negative effects of direct ivermectin exposure on dung-degrading organisms are well known, effects could extend across generations. Here, we tested the effects of paternal or maternal exposure to ivermectin on offspring in the dung beetle Euoniticellus intermedius. This species is a classic study subject in ecotoxicology and sexual selection because males have a cephalic horn that is under intense selection via male-male competition. After confirming a negative effect of ivermectin on the number of emerged beetles, we found trans-generational effects of ivermectin exposure on the horn size of male offspring. Surprisingly however, this trans-generational effect only occurred when only the father was exposed. We detected no trans-generational effects of ivermectin exposure on offspring number, sex ratio or body size. Our results confirm that ivermectin not only has a strong effect on exposed individuals but also in their progeny. Our study opens new questions about the mechanisms responsible for parental effects and their long-term fitness consequences in contaminated habitats.

Proposal for a Monitoring Concept for Veterinary Medicinal Products with PBT Properties, Using Parasiticides as a Case Study

The aim of this work is to prepare a proposal for the post-authorization monitoring (PAM) of veterinary medicinal products (VMP), in particular parasiticides. Such a monitoring might especially be useful for parasiticides identified as Persistence Bioaccumulation Toxicity (PBT) substances, i.e., chemicals that are toxic (T), persist in the environment (P) and bioaccumulate (B) in food chains and, thus, pose a hazard to ecosystems. Based on a literature search, issues to be considered when performing such a PAM are discussed (e.g., residue analysis, compartments to be included, selection of organisms and the duration of monitoring studies). The outcome of this discussion is that—and despite that there are huge challenges in detail (e.g., in terms of analytical chemistry or taxonomy)—the technical performance of such a PAM is not the main problem, since most of the chemical and biological methods to be used are well-known (partly even standardized) or could be adapted. However, it is very difficult to define in detail where and when a monitoring should be performed. The main problem is to link exposure to effects of a certain parasiticide in a way that any impact can directly be related to the use of this parasiticide. Therefore, a “Targeted Environmental Monitoring” (TEM) is proposed, which is essentially a combination between a field study and a PAM.

Influence of Select Antibiotics on Vibrio fischeri and Desmodesmus subspicatus at μg L-1 Concentrations

The presence of pharmaceuticals in the aquatic environment is a contemporary reality and it is necessary to understand more about the effects of this presence on organisms. The purpose of this work was to assess the ecotoxicity of antibiotics metronidazole, nitrofurantoin, trimethoprim, and sulphamethoxazole (single and mixture) in Vibrio fischeri and Desmodesmus subspicatus at μg L^-1 concentrations. The evaluation of the toxic effect of the antibiotics on V. fischeri and D. subspicatus was based on fluorescence and bioluminescence tests, respectively, using nominal concentrations. When tested individually, the four antibiotics gave rise to a toxic effect on the evaluated organisms. Sulphamethoxazole caused a higher toxic effect on V. fischeri and D. subspicatus from 7.81 to 500 μg L^-1. Trimethoprim and sulphamethoxazole showed hormesis for the concentrations, which ranged from 7.81 to 62.5 μg L^-1. The mixture of antibiotics induced a toxic effect on the V. fischeri and D. subspicatus organisms (from 0.03 to 1 μg L^-1 concentrations) than when the antibiotics were evaluated individually. These results were significant since water quality problems are widespread all over the word, and emerging pollutants such as antibiotics have been detected in the aquatic environment in very low concentrations.

Ivermectin alters reproductive success, body condition and sexual trait expression in dung beetles

Ivermectin is a very common parasiticide used in livestock. It is excreted in the dung and has negative effects on survival and reproduction of dung-degrading organisms, including dung beetles. Here we exposed the dung beetle Euoniticellus intermedius to different concentrations of ivermectin in the food and evaluated reproductive success and the expression of traits associated with survival and reproduction under laboratory conditions. It is the first time the effects of ivermectin were evaluated on offspring physiological condition and the expression of a secondary sexual trait. We also registered the number of emerged beetles, sex ratio and body size of emerged adult beetles. Besides reducing the number of emerged beetles and body size, as found in the same and other insects, ivermectin at high doses reduced muscle mass while at intermediate doses it increased lipid mass. Ivermectin changed offspring sex ratio and at high doses increased the size of male horn, which is an important trait defining the male mating success. Our results highlight the importance of regulating parasiticide usage in livestock in order to maintain ecosystem services provided by dung beetles and confirm that contaminants impose new environmental conditions that not only impact on wild animal survival, but also on evolutionary processes such as sexual selection.

Prospective Environmental Risk Assessment for Sediment-Bound Organic Chemicals: A Proposal for Tiered Effect Assessment

A broadly accepted framework for prospective environmental risk assessment (ERA) of sediment-bound organic chemicals is currently lacking. Such a framework requires clear protection goals, evidence-based concepts that link exposure to effects and a transparent tiered-effect assessment. In this paper, we provide a tiered prospective sediment ERA procedure for organic chemicals in sediment, with a focus on the applicable European regulations and the underlying data requirements. Using the ecosystem services concept, we derived specific protection goals for ecosystem service providing units: microorganisms, benthic algae, sediment-rooted macrophytes, benthic invertebrates and benthic vertebrates. Triggers for sediment toxicity testing are discussed.We recommend a tiered approach (Tier 0 through Tier 3). Tier-0 is a cost-effective screening based on chronic water-exposure toxicity data for pelagic species and equilibrium partitioning. Tier-1 is based on spiked sediment laboratory toxicity tests with standard benthic test species and standardised test methods. If comparable chronic toxicity data for both standard and additional benthic test species are available, the Species Sensitivity Distribution (SSD) approach is a more viable Tier-2 option than the geometric mean approach. This paper includes criteria for accepting results of sediment-spiked single species toxicity tests in prospective ERA, and for the application of the SSD approach. We propose micro/mesocosm experiments with spiked sediment, to study colonisation success by benthic organisms, as a Tier-3 option. Ecological effect models can be used to supplement the experimental tiers. A strategy for unifying information from various tiers by experimental work and exposure-and effect modelling is provided.

Multilevel assessment of ivermectin effects using different zebrafish life stages

Several studies have shown high toxicity of the veterinary pharmaceutical ivermectin (a semisynthetic avermectin) for aquatic invertebrates however, few data is found for fish species. The present study evaluated the toxicity of ivermectin, to embryos, juveniles, and adults of zebrafish at different levels of biological organization including developmental, behavioural and biochemical. Toxicity tests were performed based on OECD protocols and mortality and behavioural changes were assed for all stages. Biochemical responses were assessed in adults and embryos and included cholinesterases (ChEs), catalase (CAT) (only in embryos), glutathione-S-Transferase (GST), lactate dehydrogenase (LDH) and vitellogenin (VTG) like proteins (only in embryos). Genotoxicity was evaluated in adults. Results showed a higher sensitivity of juvenile and adults of zebrafish (96h-LC10 values of 14.0 and 55.4μg/L, respectively). For embryos a 96h-LC10 of 147.1μg/L was calculated, moreover developmental anomalies and hatching inhibition were observed only at high concentrations (>400μg/L), whereas biochemical and behavioural responses occurred at lower concentrations (<60μg/L). Behavioural responses (lethargy) occurred in all life stages. Biochemical responses were observed including the inhibition of GST in adults and changes in ChE, CAT, LDH activities and VTG levels in embryos. Ivermectin did not show to be genotoxic for adult fish. The species sensitivity distribution analysis, based on fish and invertebrate species, indicated a Hazardous Concentration for 5% of the population (HC5) value of 0.057μg/L; suggesting high sensitivity of both groups to ivermectin and a high risk of this compound to aquatic ecosystems.

Analysis and dissipation of the antiparasitic agent ivermectin in cattle dung under different field conditions

Cattle treated with the veterinary parasiticide ivermectin fecally excrete residues. The authors report the exposition and dissipation characteristics of these residues in dung of ivermectin-treated cattle and in soil beneath this dung on pastures in Canada, France, Switzerland, and The Netherlands. Residues were quantified for dung collected from cattle after 3 d, 7 d, 14 d, and 28 d posttreatment and subsequently exposed in the field for up to 13 mo. The authors optimized a high-performance liquid chromatography-fluorescence detection method to detect ivermectin residues in dung and soil matrices. They showed that a solid phase extraction and purification step generally can be eliminated to reduce the time and cost of these analyses. They also found that the addition of water to relatively dry samples improves the extraction efficiency of residues. They then analyzed the field samples to document differences in ivermectin dissipation in cattle dung among sites, with 50% dissipation times of up to 32 d and 90% dissipation times >396 d. They further showed that the dissipation characteristics of residues are comparable between dung of ivermectin-treated cattle and dung to which ivermectin has been added directly. Lastly, they report the first use of a desorption electrospray ionization-high-resolution-mass spectrometric method to detect residues of metabolites in a dung matrix. Environ Toxicol Chem 2016;35:1924-1933. © 2016 SETAC.

Abamectin in soils: Analytical methods, kinetics, sorption and dissipation

Abamectin is a broad-spectrum antiparasitic agent that has been widely employed in veterinary medicine and has also been used as a pesticide in agriculture. Veterinary drugs may reach the soil and may be transported to surface and ground waters, posing risks to terrestrial and aquatic organisms. Sorption, transformation and transport processes are primarily responsible for the fate of these substances in the environment. In this study, the sorption and the aerobic dissipation of abamectin in Brazilian soils (sand, clay and sandy-clay) were evaluated. For sorption studies, batch equilibrium experiments were performed. Sorption and desorption isotherms were fitted to the Freundlich model. Abamectin showed a high affinity to soil particles, with Freundlich sorption and desorption coefficients ranging from 44 to 138 μg(1-1/n) (cm(3))(1/n) g(-1) and from 89 to 236 μg(1-1/n) (cm(3))(1/n) g(-1), respectively. Dissipation of abamectin was evaluated in sterile and non-sterile soils in an aerobic and dark environment under controlled temperature and humidity. The time required for a 50% reduction of the amount of abamectin present in non-sterile soils was up to 4 days, and the time period for 90% dissipation was up to 12 days. In sterilized soils, there was no reduction in the concentration of abamectin over 37 days of exposure, suggesting that aerobic microbial degradation must have been the primary mechanism responsible for the dissipation of abamectin in soils.

Effects of ivermectin on Danio rerio: a multiple endpoint approach: behaviour, weight and subcellular markers

Ivermectin (IVM) is a broad acting antihelmintic used in various veterinary pharmaceuticals. It has been shown that IVM enters the aquatic compartment and adversely affects organisms including fish. This study is based on the hypothesis that long term exposure to IVM affects fish and thus, the main objective was to assess the chronic effects of 0.25 and 25 µg IVM/L to zebrafish using multiple endpoints representative of several levels of biological organization: weight, behaviour (swimming and feeding) and subcellular markers including biomarkers for oestrogenicity (vitellogenin-VTG), oxidative stress (catalase-CAT and glutathione-S-transferase-GST) and neurotransmission (cholinesterase-ChE). Concentrations as low as 0.25 µg IVM/L disrupted the swimming behaviour, causing fish to spend more time at the bottom of aquaria. Such reduction of the swimming performance affected the feeding ability which is likely responsible for the weight loss. The effects on weight were gender differentiated, being more pronounced in males (0.25 µg IVM/L) than in females (25 µg IVM/L). Fish exposed to 25 µg/L exhibited darker coloration and mild curvature of the spine. No effects on VTG and AChE were observed, but a reduction on CAT and GST levels was observed in fish exposed to 25 µg IVM/L, although these alterations probably only reflect the general condition of the fish which was significantly compromised at this concentration. Despite that predicted environmental concentrations of IVM are below 0.25 µg/L, the behavioural effects may be translated into important ecological impacts, e.g. at predator-prey interactions where fish competitive advantage can be decreased. Future work should address the link between behaviour disruption and population fitness. The current study was based on a one experiment and multiple endpoint (anchored) approach, allowing the results to be integrated and linked towards a mechanistic understanding.

Effect of ivermectin on the larvae of Anopheles gambiae and Culex quinquefasciatus

Background

Ivermectin is used extensively globally for treatment of helminthic and ectoparasitic infections in animals and humans. The effect of excreted ivermectin on non-target organisms in aquatic and terrestrial environments has been increasingly reported. Due to its low water solubility and adsorption to sediments, the ivermectin exposure-risk to aquatic organisms dwelling in different strata of water bodies varies. This study assessed the survival of larvae of Anopheles gambiae Giles and Culex quinquefasciatus Say, when exposed to low concentrations of ivermectin under laboratory conditions.

Methods

A total of 1800 laboratory reared mosquito larvae of each species were used in the bioassays. Twelve replicates were performed, each testing 6 concentrations of ivermectin (0.0, 0.001, 0.01, 0.1, 1.0 and 10.0 parts per million (ppm)) against third instar larvae of An. gambiae and Cx. quinquefasciatus. Larval mortality was recorded at 24 and 48 h post addition of ivermectin.

Results

Survival declined markedly with increase in ivermectin concentration in both species. While mean survival of An. gambiae at 24 h of exposure was 99.6 %, 99.2 % and 61.6 % in 0.001, 0.01 and 0.1 ppm of ivermectin, respectively, the mean survival of Cx. quinquefasciatus at the same dosage and time was 89.2 %, 47.2 % and 0.0 %. A similar pattern, but with higher mortality, was observed after 48 h of exposure. Comparison between the species revealed that Cx. quinquefasciatus larvae were significantly more affected by ivermectin than those of An. gambiae, both at 24 and 48 h.

Conclusions

Low concentrations of ivermectin in the aquatic environment reduced the survival of larvae of An. gambiae and Cx. quinquefasciatus, with the effect being more marked in the latter species. It is suggested that this difference may be due to the different water strata occupied by the two species, with ivermectin adsorbed in food that sediment being more readily available to the bottom feeding Cx. quinquefasciatus than the surface feeding An. gambiae larvae.

Fate of ivermectin in the terrestrial and aquatic environment: mobility, degradation, and toxicity towards Daphnia similis

Ivermectin (IVM) is a broad-spectrum antiparasitic drug that is regularly employed in veterinary medicine. In this work, the sorption and desorption of IVM in two Brazilian soils (N1-sand and S2-clay) as well as its leaching capacity, dissipation under aerobic conditions, and degradation in aqueous solution by photocatalysis with TiO2 in suspension were evaluated. The kinetic sorption curves of IVM were adjusted to a pseudo-second-order model. The sorption and desorption data were well fitted with the Freundlich isotherms in the log form (r > 0.96). The Freundlich sorption coefficient (K F (ads) ) and the Freundlich desorption coefficient (K F (des) ) were 77.7 and 120 μg(1-1/n) (cm(3))(1/n) g(-1) and 74.5 and 138 μg(1-1/n) (cm(3))(1/n) g(-1), for soils N1 and S2, respectively. A greater leaching capacity of IVM was observed for the sandy soil N1 than for the clay soil S2. Under aerobic conditions, the dissipation (DT50) at 19.3 °C was 15.5 days (soil N1) and 11.5 days (soil S2). Photocatalysis with UVC and TiO2 in suspension resulted in the degradation of 98 % of IVM (500 μg L(-1)) in water in 600 s. The toxicity (Daphnia similis) of the solutions submitted to the photocatalytic process was completely eliminated after 10 min.

Acute Toxicity and Environmental Risks of Five Veterinary Pharmaceuticals for Aquatic Macroinvertebrates

Due to the high use of antibiotics and antiparasitics for the treatment of livestock, there is concern about the potential impacts of the release of these compounds into freshwater ecosystems. In this context, the present study quantified the acute toxicity of two antibiotics (sulfadiazine and sulfadimidine), and three antiparasitic agents (flubendazole, fenbendazole, ivermectin) for nine freshwater invertebrate species. These experiments revealed a low degree of toxicity for the sulfonamide antibiotics, with limited implications in the survival of all test species at the highest test concentrations (50 and 100 mg/L). In contrast, all three antiparasitic agents indicated on the basis of their acute toxicity risks for the aquatic environment. Moreover, chronic toxicity data from the literature for antiparasitics, including effects on reproduction in daphnids, support the concern about the integrity of aquatic ecosystems posed by releases of these compounds. Thus, these pharmaceuticals warrant further careful consideration by environmental risk managers.

Oxidative effects of the pharmaceutical drug paracetamol on the edible clam Ruditapes philippinarum under different salinities

Paracetamol, a drug with analgesic and antipyretic properties, is one of the most used substances in human therapeutics, being also frequently detected in aquatic environments. Recent studies report its toxicity towards aquatic species, but the overall amount of data concerning its effects is still scarce. Global changes, likely alterations in abiotic conditions, including salinity, can modulate the interactions of contaminants with biota, conditioning the toxicological responses elicited also by pharmaceuticals. The present article describes the oxidative toxic effects posed by paracetamol on the clam species Ruditapes philippinarum under different salinity conditions. The results demonstrated the establishment of an oxidative-based effect, with significant alteration of several parameters, such as superoxide dismutase (SOD) and the ratio of reduced/oxidized glutathione (GSH/GSSG). Water salinity influenced the response of clams exposed to different paracetamol concentrations, showing the importance of studying physiological traits under realistic test conditions, which are likely to vary in great extent as a result of climate change.

Environmental effects of anticholinesterasic therapeutic drugs on a crustacean species, Daphnia magna

The presence of pharmaceutical drugs in the environment is an important field of toxicology, since such residues can cause deleterious effects on exposed biota. This study assessed the ecotoxicological acute and chronic effects of two anticholinesterasic drugs, neostigmine and pyridostigmine in Daphnia magna. Our study calculated 48 h-EC50 values for the immobilization assay of 167.7 μg L(-1) for neostigmine and 91.3 μg L(-1) for pyridostigmine. In terms of feeding behavior, we calculated a 5 h-EC50 for filtration rates of 7.1 and 0.2 μg L(-1) for neostigmine and pyridostigmine, respectively; for the ingestion rates, the calculated EC50 values were, respectively, 7.5 and 0.2 μg L(-1) for neostigmine and pyridostigmine. In the reproduction assay, the most affected parameter was the somatic growth rate (LOECs of 21.0 and 2.9 μg L(-1) for neostigmine and pyridostigmine, respectively), followed by the fecundity (LOECs of 41.9 and 11.4 μg L(-1) for neostigmine and pyridostigmine, respectively). We also determined a 48 h-IC50 for cholinesterase activity of 1.7 and 4.5 μg L(-1) for neostigmine and pyridostigmine, respectively. These results demonstrated that both compounds are potentially toxic for D. magna at concentrations in the order of the μg L(-1).

Toxicity of 15 veterinary pharmaceuticals in zebrafish (Danio rerio) embryos

Extensive use of veterinary pharmaceuticals may result in contamination of water bodies adjacent to pasture land or areas where animal manure has been applied. In order to evaluate the potential risk to fish embryos 15 veterinary pharmaceuticals were investigated by use of an extended zebrafish embryo toxicity test. Chemical analysis of the exposure medium was performed by solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) for 11 of the compounds and potential metabolism by the embryos was studied for albendazole, febantel, fenbendazole and oxfendazole. Newly fertilized zebrafish eggs were exposed under static conditions in 96-well plates for 6 days to the pharmaceuticals: 5 antibacterials and 10 antiparasitics. Endpoints including mortality, malformations and other sublethal responses were recorded at 24, 48 and 144 h post fertilization (hpf). The pharmaceuticals causing the highest toxicity were antiparasitics whereas the tested antibacterials, danofloxacin, enrofloxacin, tylosine, trimethoprim and oxytetracyclin had a much lower toxic potency in zebrafish embryos. Most toxic were fenbendazole, albendazole and flumethrin with no observed effect concentrations (NOECs) around 0.02 mg/L. The overall NOEC was determined by lethality for the following pharmaceuticals: albendazole, fenbendazole and oxfendazole. Sublethal endpoints, including malformations, side-laying embryos, tremors, reduced movements and altered heart rate increased the sensitivity of the tests and determined the overall NOECs for febantel, doramectin, ivermectin, flumethrin and toltrazuril. Exposure to doramectin and ivermectin caused a decrease in movements at 24 hpf and a decrease in heart rate at 48 hpf. Flumethrin exposure resulted in decreased time to hatching, except at the highest concentrations, and caused an increase in heart rate at 48 hpf. In contrast, toltrazuril caused an increased time to hatching and a decrease in heart rate. Chemical analysis of the exposure medium after the tests revealed great differences between nominal and measured concentrations, emphasizing the need of including analysis of the actual exposure concentrations. The results indicated that metabolism of albendazole into its sulfoxide protected the embryos from toxicity. Albendazole was metabolized efficiently into albendazole sulfoxide at lower exposure concentrations, resulting in reduced toxicity. At higher concentrations, an increasing proportion of albendazole remained unmetabolized and embryo mortality occurred. Metabolism by the embryos of febantel into fenbendazole and oxfendazole and of fenbendazole into oxfendazole was demonstrated. It is suggested that the toxic effect of febantel in zebrafish embryos is due to metabolism into fenbendazole.

Evaluation of the Daphnia magna reproduction test for detecting endocrine disruptors

The Daphnia 21 d reproduction test is considered as a comprehensive and decisive test in the OECD Conceptual Framework for testing and assessment of endocrine disrupting chemicals (EDCs). However, how to interpret results of the Daphnia 21 d reproduction test for identification, risk assessment and testing strategy of EDCs remains an unsolved issue. This study analysed a total number of 135 published studies encompassing 86 known EDCs and non-EDCs with different modes of action. Our results show that the majority of effects on apical endpoints (survival, molting, growth, time to reproductive maturity, brood size, the number of broods, and the total number of offspring) do not seem to be EDC-specific. In contrast, the endpoint sex ratio is likely specific to juvenile hormones and their mimics. Variability is quantified for three most reported endpoints survival, the total number of offspring and sex ratio. Quantification of the endpoint sensitivity shows that the sensitivity of the sex ratio is lower than that of the total number of offspring. The Daphnia 21 d reproduction test gives insufficient information to conclude if a substance is an EDC or not. EDCs that are potent in assays in vitro may not be potent in the Daphnia 21 d reproduction test. We conclude that the Daphnia 21 d reproduction test is important for deriving No Observed Effect Concentrations for risk assessment but may produce false negatives in identification of EDCs when used on its own. A targeted testing strategy for selection of species, tests, and endpoints is suggested for identifying EDCs.

A review on the toxicity and non-target effects of macrocyclic lactones in terrestrial and aquatic environments

The avermectins, milbemycins and spinosyns are collectively referred to as macrocyclic lactones (MLs) which comprise several classes of chemicals derived from cultures of soil micro-organisms. These compounds are extensively and increasingly used in veterinary medicine and agriculture. Due to their potential effects on non-target organisms, large amounts of information on their impact in the environment has been compiled in recent years, mainly caused by legal requirements related to their marketing authorization or registration. The main objective of this paper is to critically review the present knowledge about the acute and chronic ecotoxicological effects of MLs on organisms, mainly invertebrates, in the terrestrial and aquatic environment. Detailed information is presented on the mode-of-action as well as the ecotoxicity of the most important compounds representing the three groups of MLs. This information, based on more than 360 references, is mainly provided in nine tables, presenting the effects of abamectin, ivermectin, eprinomectin, doramectin, emamectin, moxidectin, and spinosad on individual species of terrestrial and aquatic invertebrates as well as plants and algae. Since dung dwelling organisms are particularly important non-targets, as they are exposed via dung from treated animals over their whole life-cycle, the information on the effects of MLs on dung communities is compiled in an additional table. The results of this review clearly demonstrate that regarding environmental impacts many macrocyclic lactones are substances of high concern particularly with larval instars of invertebrates. Recent studies have also shown that susceptibility varies with life cycle stage and impacts can be mitigated by using MLs when these stages are not present. However information on the environmental impact of the MLs is scattered across a wide range of specialised scientific journals with research focusing mainly on ivermectin and to a lesser extent on abamectin doramectin and moxidectin. By comparison, information on compounds such as eprinomectin, emamectin and selamectin is still relatively scarce.

An evaluation of free water surface wetlands as tertiary sewage water treatment of micro-pollutants

Increased attention is currently directed towards potential negative effects of pharmaceuticals and other micro-pollutants discharged into the aquatic environment via municipal sewage water. A number of additional treatment technologies, such as ozonation, have therefore been suggested as promising tools for improving the removal efficiency of pharmaceuticals in existing Sewage Treatment Plants (STPs). Constructed wetlands are also capable of removing a variety of micro-pollutants, including some pharmaceuticals, and could hence be a resource efficient complement to more advanced treatment technologies. The purpose of the present study was therefore to increase the knowledge base concerning the potential use of constructed wetlands as a treatment step to reduce emissions of organic micro-pollutants from municipal sewage effluents. Under cold winter conditions, incoming and outgoing waters from four Swedish free water surface wetlands, operated as final treatment steps of sewage effluent from municipal STPs, were sampled and analyzed for levels of a set of 92 pharmaceuticals and 22 inorganic components as well as assessed using subchronic ecotoxicity tests with a macro-alga and a crustacean. Sixty-five pharmaceuticals were detected in the range from 1 ng L(-1) to 7.6 μg L(-1) in incoming and outgoing waters from the four investigated wetlands. Although the sampling design used in the present study lacks the robustness of volume proportional to 24h composite samples, the average estimated removal rates ranged from 42% to 52%, which correlates to previous published values. The effects observed in the ecotoxicity tests with the macro-alga (EC(50)s in the range of 7.5-46%) and the crustacean (LOECs in the range of 11.25-90%) could not be assigned to either pharmaceutical residues or metals, but in general showed that these treatment facilities release water with a relatively low toxic potential, comparable to water that has been treated with advanced tertiary treatments. From the present study it can be concluded that constructed wetlands may provide a complementary sewage treatment option, especially where other treatment is lacking today. To fully remove micro-pollutants from sewage effluent, however, other more advanced treatment technologies are likely needed.

Lethal effects of abamectin on the aquatic organisms Daphnia similis, Chironomus xanthus and Danio rerio

Abamectin is used as an acaricide and insecticide for fruits, vegetables and ornamental plants, as well as a parasiticide for animals. One of the major problems of applying pesticides to crops is the likelihood of contaminating aquatic ecosystems by drift or runoff. Therefore, toxicity tests in the laboratory are important tools to predict the effects of chemical substances in aquatic ecosystems. The aim of this study was to assess the potential hazards of abamectin to the freshwater biota and consequently the possible losses of ecological services in contaminated water bodies. For this purpose, we identified the toxicity of abamectin on daphnids, insects and fish. Abamectin was highly toxic, with an EC(50) 48 h for Daphnia similis of 5.1 ng L(-1), LC(50) 96 h for Chironomus xanthus of 2.67 μg L(-1) and LC(50) 48 h for Danio rerio of 33 μg L(-1).

Semifield assessment of the runoff potential and environmental risk of the parasiticide drug ivermectin under Mediterranean conditions

INTRODUCTION

The antiparasitic ivermectin is of particular concern to regulatory agencies. Ivermectin can reach the environment through the direct emission of dung from livestock on pasture and via manure application on agricultural lands.

METHODS

A semifield study was conducted for assessing the ivermectin dynamic in runoff and drainage waters from dung-treated soils placed on experimental trays. The experiment was conducted under natural Mediterranean conditions. Realistic pasture and arable land applications were assessed using dung of treated animals and compared with a positive control (spraying the ivermective solution without dung).

RESULTS

Similar concentrations were obtained in all three treatments for drainage waters, with values ranging from <5-10 to about 20 ng/l. However, strong treatment-related variation was observed in runoff waters, with the highest concentrations found in the spray treatment (9-188 ng/l), followed by the arable land (<5-88 ng/l) scenario, and concentrations not exceeding 6 ng/l in the pasture scenario. Ivermectin levels in runoff particles were up to 1,660 and 5,890 ng/kg dry weight for the pasture (I1) and arable land (I2) scenarios, respectively. Ivermectin was only detected in the drainage and runoff waters collected in the first rainfall events after treatment.

CONCLUSIONS

The measured concentrations in water (0.006-0.118 ng/ml) and runoff particles (0.052-5.89 ng/mg dry suspended matter) are orders of magnitude higher than those provoking effects on aquatic and benthonic communities under experimental and mesocosm conditions, suggesting a clear risk for aquatic systems in the vicinity of pasture areas of treated animals or arable soil fertilized with its manure.

Morphological changes in Daphnia galeata induced by a crustacean terpenoid hormone and its analog

Terpenoid hormones in insects (i.e., juvenile hormones) have various effects on physiology, morphology, and behavior, producing a wide range of phenotypic variation. Recent studies have shown that sex determination in cladoceran crustaceans is under the strong control of a major terpenoid hormone of crustaceans, methyl farnesoatote (MF). It can be easily conceived that MF is also a major determinant of other traits in cladocerans. In the present study, morphological changes known as antipredatory responses in a cladoceran Daphnia galeata in response to exposure to MF and a juvenile hormone-mimicking pesticide, fenoxycarb, were investigated. Morphological change was studied using neonates less than 24 h old, exposed either to MF at the concentrations from 1.9 to 30 µg/L, or fenoxycarb at the concentrations from 13 to 200 ng/L, for 6 d. Animals developed a longer helmet at 1.9 µg/L of MF and 25 ng/L of fenoxycarb, and showed a concentration-dependent elongation. However, the tail spine was reduced in size in a concentration-dependent manner. Results of the present study not only give new insight into the mechanisms of inducible defenses in cladocerans, but also provide invaluable information to understand ecological and evolutionary consequences of endocrine disruption through the shift in biological interaction between predator and prey.

Effects of the veterinary pharmaceutical ivermectin in indoor aquatic microcosms

The effects of the parasiticide ivermectin were assessed in plankton-dominated indoor microcosms. Ivermectin was applied once at concentrations of 30, 100, 300, 1000, 3000, and 10,000 ng/l. The half-life (dissipation time 50%; DT₅₀) of ivermectin in the water phase ranged from 1.1 to 8.3 days. The lowest NOEC(community) that could be derived on an isolated sampling from the microcosm study by means of multivariate techniques was 100 ng/l. The most sensitive species in the microcosm study were the cladocerans Ceriodaphnia sp. (no observed effect concentration, NOEC = 30 ng/l) and Chydorus sphaericus (NOEC = 100 ng/l). The amphipod Gammarus pulex was less sensitive to ivermectin, showing consistent statistically significant reductions at the 1000-ng/l treatment level. Copepoda taxa decreased directly after application of ivermectin in the highest treatment but had already recovered at day 20 posttreatment. Indirect effects (e.g., increase of rotifers, increased primary production) were observed at the highest treatment level starting only on day 13 of the exposure phase. Cladocera showed the highest sensitivity to ivermectin in both standard laboratory toxicity tests as well as in the microcosm study. This study demonstrates that simple plankton-dominated test systems for assessing the effects of ivermectin can produce results similar to those obtained with large complex outdoor systems.