Exposure to perfluorooctane sulfonic acid (PFOS) adversely affects the life-cycle of the damselfly Enallagma cyathigerum

Per- and polyfluoroalkyl substance (PFAS) mixtures induce gut microbiota dysbiosis and metabolic disruption in silkworm (Bombyx mori L.)

Mixed legacy and emerging per- and polyfluoroalkyl substances (PFASs) are commonly found in soil and dust; however, the potential toxicity of PFAS mixtures (mPFASs) in insects is unknown. Using 16S rRNA gene sequencing and transcriptome sequencing (RNA-Seq), we evaluated the adverse effects of mPFASs on silkworms, a typical lepidopteran insect. After exposure to mPFASs, the silkworm midgut was enriched with high levels of PFASs, which induced histopathological changes. The composition of the midgut microbiota was significantly affected by mPFAS exposure, and functional predictions revealed significant disruption of some metabolic pathways. RNA-seq analysis revealed that mPFASs significantly changed the transcription profiles. Functional enrichment analysis of the differentially expressed genes also revealed that biological processes related to metabolic pathways and the digestive system were significantly affected, similar to the results of the gut microbiota analysis, suggesting that mPFAS exposure had an adverse effect on the metabolic function of silkworms and may further affect their normal growth. Finally, the significant correlation between abundance changes in the gut microbiota and metabolism/digestion-related genes further highlighted the role of the gut microbiota in mPFAS-related processes affecting the metabolic functions of silkworms. To our knowledge, this study is the first to evaluate the toxic effects of mPFASs in insects and provide basic data for further PFAS toxicity investigations in insects and comprehensive ecological risk assessments of mPFASs.

The Influence of Selected Insecticides on the Oxidative Response of Atta sexdens (Myrmicinae, Attini) Workers

Reactive oxygen species (ROS) are generated as products of normal cellular metabolic activities; however, the use of pesticides to control leafcutter ants leads to unbalanced ROS production. We evaluated the effects of two insecticides (fipronil, sulfluramid) and metallic insecticide complex (magnesium complex [Mg(hesp)2(phen)] (1)) on the superoxide dismutase (SOD), glutathione (GSH) and the overall antioxidant capacity using two different methodologies: total radical-trapping potential (TRAP) and oxygen radical absorbance capacity (ORAC). Media workers of Atta sexdens (C. Linnaeus) were exposed to the insecticides for 24 h, 48 h, 72 h and 96 h before their fat bodies were dissected for analysis. The results showed that although the sulfluramid may cause the production of ROS, its slow action in the organism does not lead to oxidative stress. There is a rise in oxidative stress in workers of leafcutter ants treated with fipronil because SOD significantly increased when compared to the control group. On the other hand, Mg1-complex suppressed both GSH and SOD, indicating that the immune system may be affected by Mg1-complex, which has a delayed activity ideal for its use in chemical pest control. Both TRAP and ORAC evaluated total antioxidant capacities; however, ORAC proved to be a more sensitive method. In conclusion, the Mg1-complex is a new compound that should be further investigated as a potential replacement for fipronil and sulfluramid in pest control.

Meta-Analysis Comparing Nominal and Measured Concentrations of Perfluorooctanoic Acid and Perfluorooctane Sulfonate in Aquatic Toxicity Studies Across Various Experimental Conditions

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are among the most frequently detected chemicals among the per- and polyfluoroalkyl substances in aquatic environments. Because of their high detection frequency, persistence, and potential toxicity, interest in both PFOA and PFOS has increased in recent years. However, a substantial number of PFOA and PFOS toxicity tests only report nominal, or unmeasured, treatment concentrations, which may complicate the determination of protective values. In addition, previous literature has indicated that differences between nominal and measured concentrations of both PFOA and PFOS could be linked to experimental conditions (e.g., feeding regimes for test organisms, test vessel material [glass or plastic], use of solvent, and the presence of substrate). Therefore, this critical review examined whether nominal and measured concentrations were in close agreement with each other among the current PFOA and PFOS aquatic toxicity literature and if experimental conditions were associated with any observed differences. Nominal and measured concentrations in the current PFOA and PFOS aquatic toxicity literature generally displayed a high degree of linear correlation and relatively low median percent differences. Correlations between measured and nominal concentrations were >0.98 for PFOA and >0.95 for PFOS in freshwater tests across experimental conditions. For saltwater tests, correlations of >0.84 were observed for PFOA and PFOS (separate and combined) across experimental conditions. While measured PFOA and PFOS toxicity tests are generally preferred, the present meta-analysis demonstrated that experimental conditions had little influence on observed discrepancies between nominal and measured concentrations, with the exception of PFOS saltwater tests and PFOA and PFOS freshwater studies that contained substrate. Unmeasured tests with these conditions should be considered carefully based on project needs, with the caveat that the data sets for these two experimental conditions were limited. Environ Toxicol Chem 2023;42:2289-2301. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Synergistic survival-related effects of larval exposure to an aquatic pollutant and food stress get stronger during and especially after metamorphosis and shape fitness of terrestrial adults

To improve the ecological risk assessment of aquatic pollutants it is needed to study their effects not only in the aquatic larval stage, but also in the terrestrial adult stage of the many animals with a complex life cycle. This remains understudied, especially with regard to interactive effects between aquatic pollutants and natural abiotic stressors. We studied effects of exposure to the pesticide DNP (2,4-Dinitrophenol) and how these were modulated by limited food availability in the aquatic larvae, and the possible delayed effects in the terrestrial adults of the damselfly Lestes viridis. Our results revealed that DNP and low food each had large negative effects on the life history, behaviour and to a lesser extent on the physiology of not only the larvae, but also the adults. Food limitation magnified the negative effects of DNP as seen by a strong decline in larval survival, metamorphosis success and adult lifespan. Notably, the synergism between the aquatic pollutant and food limitation for survival-related traits was stronger in the non-exposed adults than in the exposed larvae, likely because metamorphosis is stressful itself. Our results highlight that identifying effects of aquatic pollutants and synergisms with natural abiotic stressors, not only in the aquatic larval but also in the terrestrial adult stage, is crucial to fully assess the ecological impact of aquatic pollutants and to reveal the impact on the receiving terrestrial ecosystem through a changed aquatic-terrestrial subsidy.

Broad toxicological effects of per-/poly- fluoroalkyl substances (PFAS) on the unicellular eukaryote, Tetrahymena pyriformis

Per-/Poly- fluoroalkyl substances represent emerging persistent organic pollutants. Their toxic effects can be broad, yet little attention has been given to organisms at the microscale. To address this knowledge shortfall, the unicellular eukaryote Tetrahymena pyriformis was exposed to increasing concentrations (0-5000 μM) of PFOA/PFOS and monitored for cellular motility, division and function (i.e., phagocytosis), reactive oxygen species generation and total protein levels. Both PFOA/PFOS exposure had negative impacts on T. pyriformis, including reduced motility, delayed cell division and oxidative imbalance, with each chemical having distinct toxicological profiles. T. pyriformis represents a promising candidate for assessing the biological effects these emerging anthropogenically-derived contaminants in a freshwater setting.

Persistent, bioaccumulative, and toxic chemicals in insects: Current state of research and where to from here?

The ongoing decline in the biomass, abundance, and species number of insects is an established fact. Persistent, bioaccumulative, and toxic chemicals (PBTs) - persistent organic pollutants (POPs) and, in the case of our study, mercury (Hg) - play an important role, but their effect on insect populations is insufficiently investigated. Here, the current state of research on PBTs related to insects is examined with a systematic literature study using Web of Science™. We investigate time trends of research intensity compared with other organisms, insect orders and chemicals analyzed, chemicals' effects on insects, and geographical aspects. We show that research intensity increased in the early 1990s, but studies on PBTs in insects are still underrepresented compared with other organisms. The taxonomic focus lies strongly on dipterans. The predominance of studies on DDT suggests its relevance in the context of disease-vector management. Phenotypic and acute effects on insects were more often investigated than genotypic and chronic effects. Laboratory-bred insects and wild-bred insects were examined equally often, pollutant exposure and analysis were conducted predominantly in the laboratory. Mostly habitats with a medium or high human impact were studied, and natural and near-natural habitats are understudied. The sources of the substances are often unknown. Most studies were carried out in economically rich continents, including North America, Europe, and Australia. The numbers of publications dealing with Asia, South America, and Africa are comparatively low, although the control of vector-borne diseases with POPs is still intensively practiced there. We identify gaps in the research - among others, refined analytical methods for biomarkers and for the examination of chronic effects, combinations of field and laboratory experiments to analyze the same problem, and a global approach for the monitoring of PBTs will be needed for accelerating the dearly needed progress in the research of PBTs in insects.

Different stress from parasites and mate choice in two female morphs of the blue-tailed damselfly

In Odonates, female colour polymorphism is common and implies the presence of two or more female types with different colours and behaviours. To explain this phenomenon, several hypotheses have been proposed that consider morph frequency, population density, the presence of parasites, and mating behaviour. We studied the blue-tailed damselfly Ischnura elegans, a species with a blue androchrome morph and two gynochrome morphs (the common green infuscans, and the rare orange rufescens-obsoleta). The size of adult males and females, the presence of parasites, and pairing behaviour between males and the three female morphs was assessed in field conditions throughout the reproductive season in NW Italy. Moreover, growth and emergence success of larvae produced by the different morphs was analyzed in standardized conditions. In the field, males showed a preference for the gynochrome infuscans females, despite a similar frequency of androchrome females. In test conditions, male preference for the infuscans females was also observed. Paired males and paired androchrome females were larger than unpaired individuals, while there were no differences in size between paired and unpaired infuscans females. Males and androchrome females were more parasitized than infuscans females. The survival and emergence success of larvae produced by androchrome females was higher than those of offspring produced by the infuscans females. Our results suggest that a higher survival of progeny at the larval stage could counterbalance the higher parasitism and the lower pairing success of andromorph adult females and highlight the importance of considering the whole life-cycle in polymorphism studies.

Key Considerations for Accurate Exposures in Ecotoxicological Assessments of Perfluorinated Carboxylates and Sulfonates

Toxicity reference values for per- and polyfluoroalkyl substances (PFAS) vary even when the same test organism is studied. Although the need to confirm dosing solution concentrations is widely accepted, there are no experimental data to inform best practices when PFAS solutions are prepared. Laboratory data indicate that dissolution time of PFAS solids causes statistically significant deviations between nominal and measured concentrations. Mixing times for select PFAS varied between 2 and 5 h, depending on carbon fluorine chain-length. Environ Toxicol Chem 2021;40:677-688. © 2020 SETAC.

Influence of Perfluorobutanoic Acid (PFBA) on the Developmental Cycle and Damage Potential of the Beet Armyworm Spodoptera exigua (Hübner) (Insecta: Lepidoptera: Noctuidae)

Perfluorobutanoic acid (PFBA), one of the short-chain replacement perfluoroalkyl substances, has been shown to accumulate in plants. The potential of PFBA to modulate the developmental cycle of the beet armyworm, Spodoptera exigua, a polyphagous pest, was investigated. Second-instar larvae were fed with PFBA-spiked artificial diets and leaves from soybean plants grown with PFBA-spiked irrigation water. Spiked PFBA concentrations were 200 μg/kg for the artificial diet, whereas 405 to 15,190 ng/kg accumulated in the soybean leaves. The larvae fed with the PFBA-spiked diet showed a significant increase in weight gain compared with the controls over a 7-day exposure period. A similar weight gain trend was observed with larvae fed with the PFBA-containing soybean leaves, with the dose-response data fitting into a Brain-Cousens hormesis model with a 57% stimulation over controls. The artificial diet treatments showed 66.7% metamorphosed larva to pupa at 9 days after exposure (dpe) compared with 33.3% of the controls. The adult emergence at 16-dpe followed a similar trend with 57.7% and 33.3%, respectively, for the exposed and control groups. The duration of transition from larvae to adults was more symmetrical and 0.5 day faster for the exposed groups over controls. The beet armyworm caused more damage on leaves from the PFBA exposed plants in a nonmonotonic dose-response manner. The results suggest PFBA may have a stimulatory impact on some hormonal signaling pathways at low doses.

Ecological and health risk assessment of perfluorooctane sulfonate in surface and drinking water resources in China

Perfluorooctane sulfonate (PFOS) is a synthetic substance with a great number of applications. However, it persists in the environment and is potentially toxic to organisms. Although China has been the main manufacturer and consumer for PFOS, the national pollution level and potential risk of this chemical are yet to be determined. This study aimed to provide an overview of PFOS contamination in surface and drinking water across China and to assess the potential ecological and health risks. Available monitoring data for PFOS in surface and drinking water were evaluated. PFOS was found to be ubiquitous in China, but the overall level of contamination was low compared with that in other countries. The southeast coastal area of China, with major PFOS-related companies, was characterized by relatively high PFOS exposure concentrations. The most sensitive effects was screened and applied to assess the ecological risk using the joint probability curve method. The probability of exceeding the growth and development toxicity for 5% of aquatic species was 0.65% in Chinese surface waters, while the highest probability of 0.90% was in Tai Lake in east China. Considering the average daily dose (ADD) for the Chinese population, the health risk posed by PFOS through drinking water ranged from 1.31 × 10^-4 to 13.91. Besides the relatively high health risk existed in east China, most health risks in China were acceptable.

Neonicotinoid insecticides hinder the pupation and metamorphosis into adults in a crabronid wasp

Neonicotinoid insecticides are associated with a decline in the diversity and distribution of bees and wasps (Hymenoptera: Aculeata). The effects of neonicotinoids on the metamorphosis of aculeates have never been addressed in detail; however, recent evidence suggests that neonicotinoids induce wing abnormalities. We hypothesized that the metamorphosis success of bees and wasps differs in response to contact exposure to field-realistic concentrations of neonicotinoid insecticides or in response to combined exposure to neonicotinoid insecticides and benzimidazole fungicides. We treated prepupae of the model crabronid wasp Pemphredon fabricii with field-realistic concentrations of four neonicotinoids, acetamiprid, imidacloprid, thiacloprid and thiamethoxam, and/or with the benzimidazole fungicide thiabendazole. Treatment with acetamiprid or imidacloprid decreased the pupation rates to only 39% and 32%, respectively. Treatment with thiacloprid or thiamethoxam did not affect the pupation rate when applied alone, but the subsequent treatment of thiacloprid- or thiamethoxam-treated prepupae with thiabendazole led to significant decreases in pupation rates. A high concentration of acetamiprid, which severely affected the pupation rates, had moderate effects on metamorphosis into adults, resulting in 53% metamorphosis success (as opposed to 95% metamorphosis success in the water-treated group). However, imidacloprid or thiamethoxam treatment resulted in only 5%-10% metamorphosis success into adults. Overall survival decreased in response to treatment with any of the neonicotinoids or benzimidazoles or their combinations, with extremely low survival (<2%) following combined treatment with imidacloprid and thiabendazole or thiamethoxam and thiabendazole. In conclusion, neonicotinoids alter insect metamorphosis success, which can be further potentiated by their combination with other agrochemicals, such as benzimidazoles.

Effects of Perfluoralkyl Substances on a Multigenerational Scale: A Case Study with Chironomus riparius (Diptera, Chironomidae)

A multigenerational test with Chironomus riparius was performed to assess long-term effects on life-traits of exposure to selected perfluoroalkyl compounds: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorobutane sulfonate (PFBS). These persistent contaminants are widespread in aquatic ecosystems at low concentrations, possibly exerting long-term toxicity. Larvae of C. riparius of a native population were exposed for 10 generations to 10 μg/L nominal concentrations of PFOS, PFOA, and PFBS, comparable with the maximum values found in European rivers. All treatments showed reduced growth at most/several generations. No effects on survival, development, and reproduction were found. A final tolerance-induction test was performed exposing the pre-exposed experimental cohorts to 100 µg/L PFOS and 150 µg/L PFOA for a whole life cycle. Factorial analysis of variance revealed no difference between treatments (i.e., PFOS vs PFOA), indicating no induced tolerance. Instead, organisms pre-exposed to PFBS were the most stressed, followed by those pre-exposed to PFOA and PFOS, with earlier emergence and reduced adult weight. The results may be related to general stress and genetic erosion induced by long-term laboratory culture, but also to long-term toxicant exposure. However, no effects at the population level (population growth rate) were proved, and thus a toxicity risk in real ecosystems at the tested concentrations seems unlikely. Environ Toxicol Chem 2019;00:1-12. © 2019 SETAC.

Ecological risk assessment of perfluooroctane sulfonate to aquatic fauna from a bayou adjacent to former fire training areas at a US Air Force installation

Per- and polyfluoroalkyl substances (PFASs) continue to receive significant attention, with particular concern for PFASs such as perfluorooctane sulfonate (PFOS), which was a constituent of aqueous film-forming foam used widely as a fire suppressant for aircraft since the 1970s. We were interested in the potential for risk to ecological receptors inhabiting Cooper Bayou, which is adjacent to 2 former fire-training areas at Barksdale Air Force Base (LA, USA). Previous research showed higher PFOS concentrations in surface water and biota from Cooper Bayou compared to reference sites. To estimate risk, we compared surface water concentrations from multiple sites within Cooper Bayou with several PFOS chronic toxicity benchmarks for freshwater aquatic organisms (∼0.4-5.1 μg PFOS/L) and showed probability of exceedances from 0.04 to 0.5, suggesting a potential for adverse effects in the most contaminated habitats. A tissue-residue assessment similarly showed some exceedance of benchmarks but with a lower probability (maximum = 0.17). Both fire-training areas have been inactive for more than a decade, so exposures (and, thus, risks) are expected to decline. Several uncertainties limit confidence in our risk estimates including highly dynamic surface water concentrations and limited chronic toxicity data for relevant species. Also, we have little data concerning organisms higher in the food chain which may receive higher lifetime exposures given the potential for PFOS to bioaccumulate and the longevity of many of these organisms. Overall, the present study suggests that PFOS can occur at concentrations that may cause adverse effects to ecological receptors, although additional, focused research is needed to reduce uncertainties. Environ Toxicol Chem 2018;37:2198-2209. © 2018 SETAC.

The toxic exposure of flamingos to per- and Polyfluoroalkyl substances (PFAS) from firefighting foam applications in Bonaire

In 2010 an oil terminal next to nature reservation Saliña Goto (Bonaire) caught fire. Firefighting resulted in elevated per- and polyfluoroalkyl substances (PFAS) concentrations in the salt lake. Within months flamingo abundance in Goto dropped to near complete absence. After statistical analysis, rainfall was deemed an unlikely cause for this decline. Toxicological effects on abundance of prey are likely the main cause for the flamingo absence. This reduced PFAS exposure via food and thus risk towards flamingos during the first years after the fires. Although the sediment is still polluted with persistent PFAS, flamingos returned, and started to feed on organisms with PFAS levels that exceed safety thresholds, placing the birds and other wildlife at risk. Monitoring bird populations is advised to assess potential toxic effects on birds and their offspring. This case suggests that applying persistent chemicals to reduce incident impacts may be more harmful than the incident itself.

First report of perfluoroalkyl substances in South African Odonata

Perfluorinated substances are global and ubiquitous pollutants. However, very little is known about these substances in invertebrates, and even less in terrestrial invertebrates in particular. We analysed adult male dragonflies from six sites in South Africa for perfluoroalkyl substances (PFASs), including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluro-n-undecanoic acid (PFUnA), perfluoro-n-dodecanoic acid (PFDoA), perfluorohexanoic acid (PFHxA), and perfluorohexane sulfonic acid (PFHxS). PFOS was detected in all individuals, with less quantifiable occurrences of the other substances. The dragonflies from the three northern sites located in farming areas had significantly lower ΣPFASs concentrations than the southern sites located closer to industrial areas (median ΣPFASs of 0.32 ng/g wm (wet mass) for North, and 9.3 ng/g wm for South). All substances except PFOS occurred at similar concentrations at all six sites when quantifiable, but PFOS dominated in the Southern sites. The highest median concentration was from Bloemhof Dam (ΣPFASs = 21 ng/g wm), which is known to be polluted by PFOS. Perfluorinated substances are not known to be manufactured in South Africa, therefore the residues detected are likely to have been derived from imported products. Odonata play a significant role in freshwater ecology. Any impacts on these aquatic and aerial predators are likely to have effects on aquatic and associated ecosystems. Further studies are required over a much larger geographic region and to investigate sources.

Strong Delayed Interactive Effects of Metal Exposure and Warming: Latitude-Dependent Synergisms Persist Across Metamorphosis

As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species' ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and low-latitude populations. By integrating these mechanisms into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies. These results highlight that a more complete life-cycle approach that incorporates the possibility of delayed interactions between contaminants and warming in a geographical context is crucial for a more realistic risk assessment in a warming world.

Genotoxicity evaluation of two metallic-insecticides using Allium cepa and Tradescantia pallida: A new alternative against leaf-cutting ants

In order to combat leaf-cutting ants, the pesticide sulfluramid used to be the most widely utilized active ingredient. However, its use was banned in 2009 by the Stockholm Convention, although some countries were allowed to continue using it. As an effective alternative to its replacement, researchers developed a metallic-insecticide system, which is a natural product linked to metal complexes. Thus, the aim of this study was to evaluate the ability of these new metallic-insecticides in change the genetic material of non-target organisms. The tests were performed utilizing chromosomal aberrations and micronucleus tests in the Allium cepa test system and the Trad-MCN test in Tradescantia pallida. To better understand the results, one of the components of the formula, 5-methyl-phenanthroline, was also analyzed according to the same parameters. To A. cepa, the results showed that one of the metallic insecticides induced cytotoxicity and genotoxicity at different concentrations, while the other metallic-insecticide showed chromosomal instability only at the highest concentration. The analysis of 5-methyl-phenanthroline revealed that it can be related with the positive results, since genotoxic effects were induced. In the Trad-MCN test, none of the metallic-insecticides showed genotoxic activity, although one of them induced more micronucleus formation.

Perfluorooctane sulfonate exposure causes gonadal developmental toxicity in Caenorhabditis elegans through ROS-induced DNA damage

Perfluorooctane sulfonate (PFOS), a common persistent organic pollutant, has been reported to show potential developmental toxicity in many animal studies. However, little was known about its effects on reproductive tissues, especially in the germ line. In the present study, Caenorhabditis elegans was used as an in vivo experimental model to study the developmental toxicity caused by PFOS exposure, especially in the gonads. Our results showed that PFOS exposure significantly retarded gonadal development, as shown by the increased number of worms that remained in the larval stages after hatched L1-stage larvae were exposed to PFOS for 72 h. Investigation of germ line proliferation following PFOS exposure showed that the number of total germ cells reduced in a dose-dependent manner when L1-stage larvae were exposed to 0-25.0 μM PFOS. PFOS exposure induced transient mitotic cell cycle arrest and apoptosis in the germ line. Quantification of DNA damage in proliferating germ cells and production of reactive oxygen species (ROS) showed that distinct foci of HUS-1:GFP and ROS significantly increased in the PFOS-treated groups, whereas the decrease in mitotic germ cell number and the enhanced apoptosis induced by PFOS exposure were effectively rescued upon addition of dimethyl sulfoxide (DMSO) and mannitol (MNT). These results suggested that ROS-induced DNA damage might play a pivotal role in the impairment of gonadal development indicated by the reduction in total germ cells, transient mitotic cell cycle arrest, and apoptosis.

Developmental retardation, reduced fecundity, and modulated expression of the defensome in the intertidal copepod Tigriopus japonicus exposed to BDE-47 and PFOS

2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and perfluorooctane sulfonate (PFOS) are widely dispersed persistent organic pollutants (POPs) in the marine ecosystem. However, their toxic effects on marine organisms are still poorly understood. In this study, we investigated the effects of BDE-47 and PFOS on development and reproduction at the organismal level and reactive oxygen species (ROS) production and gene expression patterns of the defensome at the cellular level in the intertidal copepod Tigriopus japonicus. In copepods exposed to BDE-47 and PFOS, we observed developmental retardation and reduced fecundity, suggesting repercussions on in vivo endpoints through alterations to the normal molting and reproduction system of T. japonicus. BDE-47 and PFOS increased levels of ROS in T. japonicus in a concentration-dependent manner, indicating that POPs can induce oxidative stress through the generation of ROS. Additionally, transcript profiles of genes related to detoxification (e.g., CYPs), antioxidant functions (e.g., GST- sigma, catalase, MnSOD), apoptosis (e.g., p53, Rb), and cellular proliferation (e.g., PCNA) were modulated over 72h in response to BDE-47 (120μg/L) and PFOS (1000μg/L). These findings indicate that BDE-47 and PFOS can induce oxidative stress-mediated DNA damage repair systems with transcriptional regulation of detoxification, antioxidant, and apoptosis-related genes, resulting in developmental retardation and reduced fecundity in the copepod T. japonicus.

Partial life-cycle and acute toxicity of perfluoroalkyl acids to freshwater mussels

Freshwater mussels are among the most sensitive aquatic organisms to many contaminants and have complex life-cycles that include several distinct life stages with unique contaminant exposure pathways. Standard acute (24-96 h) and chronic (28 d) toxicity tests with free larva (glochidia) and juvenile mussels are effective at generating data on contaminant effects at two discrete life stages but do not incorporate effects on brooded glochidia. We developed a novel partial life-cycle assay that incorporates exposures to brooding adult female mussels and used this method in combination with acute toxicity tests to assess adverse effects of perfluoroctanesulfonic acid (PFOS) and perfluoroctanoic acid (PFOA) on freshwater mussels. Fatmucket (Lampsilis siliquoidea) were exposed to PFOS at two life stages: brooding glochidia (in marsupia) for 36 d and free glochidia in water for 24 h. In standard acute tests with glochidia (24-48 h exposures) and juveniles (48-96 h exposures) of fatmucket and black sandshell (Ligumia recta), glochidia were 8 to 25 times more sensitive than juveniles. Perfluoroctanesulfonic acid significantly reduced the duration of glochidia viability and reduced probability of metamorphosis at concentrations 3,000 times lower than the most sensitive acute endpoint (24-h EC50). The partial life-cycle test is adaptable to a variety of endpoints and research objectives and is useful for identifying adverse effects at contaminant concentrations below those required for an acute lethal response.

Ecological risk assessment of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in marine environment using Isochrysis galbana, Paracentrotus lividus, Siriella armata and Psetta maxima

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are anthropogenic substances classified as persistent bioaccumulative compounds and are found in various environmental compartments throughout the world, from industrialized regions to remote zones far from areas of production. In this study, we assessed the effects of PFOA and PFOS on early life stages of marine test species belonging to three different trophic levels: one microalga (Isochrysis galbana), a primary consumer (Paracentrotus lividus) and two secondary consumers (Siriella armata and Psetta maxima). Acute EC(50) values for PFOS were 0.11 mg L(-1) in P. maxima, 6.9 mg L(-1) in S. armata, 20 mg L(-1) in P. lividus and 37.5 mg L(-1) in I. galbana. In the case of PFOA, the toxicity was lower but the ranking was the same; 11.9 mg L(-1) in P. maxima, 15.5 mg L(-1) in S. armata, 110 mg L(-1) in P. lividus and 163.6 mg L(-1) in I. galbana. The Predicted No Effect Concentration (PNEC) for PFOS and PFOA in marine water derived from these acute toxicity values are 1.1 μg L(-1) for PFOS and 119 μg L(-1) for PFOA. This study established a baseline dataset of toxicity of PFOS and PFOA on saltwater organisms. The data obtained suggest that PFOA pose a minor risk to these organisms through direct exposure. In the perspective of risk assessment, early life stage (ELS) endpoints provide rapid, cost-effective and ecologically relevant information, and links should be sought between these short-term tests and effects of long-term exposures in more realistic scenarios.

Aquatic predicted no-effect-concentration derivation for perfluorooctane sulfonic acid

Perfluorooctane sulfonic acid (PFOS), a representative perfluorinated surfactant, is an anthropogenic pollutant detected in various environmental and biological matrices. Some laboratory and field work has been conducted to assess the aquatic toxicity of PFOS, but little is known regarding its toxicity threshold to the aquatic ecosystem. In the present study, predicted no-effect concentrations (PNECs) were derived by four different approaches. The interspecies correlation estimation (ICE) program and final acute-to-chronic ratio (FACR) were applied to the development of PNEC based on the toxic mode of action (MOA) of PFOS. By comparison of the different PNECs, the recommended aquatic toxicity thresholds for PFOS are in the range of 0.61 to 6.66 µg/L. Based on comparison of PNEC values, microcosm results, and reported environmental concentrations, PFOS appears not to pose a serious threat to aquatic organisms. The present results demonstrate that MOA is an important consideration for the derivation of reliable PNECs; moreover, the ICE-based species sensitivity distribution (SSD) method can be used to derive PNECs when toxicological data are limited. The application of MOA and ICE for deriving PNEC values in the present study may facilitate studies on using a combination of quantitative structure-activity relationship (QSAR) models and ICE to estimate PNECs.

Impact of a perfluorinated organic compound PFOS on the terrestrial pollinator Bombus terrestris (Insecta, Hymenoptera)

Perfluorinated organic chemicals like perfluorooctane sulfonic acid (PFOS) are persistent environmental pollutants that have been measured in a great diversity of wildlife worldwide, especially in the aquatic compartment. However, little information is available on the presence and effects of PFOS in the terrestrial compartment. Therefore, we investigated in this project the risks for effects, bioaccumulation and potential mechanisms of activity of PFOS in the bumblebee Bombus terrestris L. (Hymenoptera: Apidae) that is an important worldwide pollinator in the terrestrial compartment of wildflowers and cultivated crops. The exposure to PFOS occurred orally via the drinking of treated sugar water in a wide range from 1 μg/l up to 10 mg/l, containing environmentally relevant as well as high concentrations, and this was done with use of microcolonies of B. terrestris in the laboratory. A chronic toxicity assay demonstrated high bumblebee worker mortality (up to 100%) with an LC(50) of 1.01 mg/l (R(2) = 0.98). In addition, PFOS posed strong detrimental reproductive effects, and these concerted with a dramatic reduction in ovarian size. HPLC-MS demonstrated a bioaccumulation factor of 27.9 for PFOS in bumblebee workers fed with sugar water containing 100 μg/l PFOS during 5 weeks (2184 ± 365 ng/g BW). Finally, potential mechanisms of activity were investigated to explain the significant impact of PFOS on survival and reproduction capacity of B. terrestris. Exposure of bumblebee workers to PFOS resulted in a significant decrease in mitochondrial electron transport activity (p = 0.035) and lipid amounts (p = 0.019), while the respective p-values were 0.58 and 0.12 for protein and glucose amounts. Hence, addition of PFOS to ecdysteroid responsive Drosophila melanogaster S2 cells resulted in a strong antagonistic action on the EcR-b.act.luc reporter construct, demonstrating that PFOS may exert its effects partially through an endocrine disrupting action via the insect molting hormone or ecdysteroid receptor.