Novel and legacy per- and polyfluoroalkyl substances (PFAS) in freshwater sporting fish from background and firefighting foam impacted ecosystems in Eastern Canada.

Emerging PFAS were recently reported at sites impacted by aqueous film-forming foams (AFFFs) and near major manufacturing centers; however, few studies have evaluated whether these can occur far from release sites. Here, newly identified PFAS were investigated in wild sporting fish from boreal freshwater ecosystems (background sites, 2013-2014 summer seasons), compared to fish impacted by a major AFFF release (summer 2013 and autumn 2014). Different freshwater wild sporting fish species (Esox lucius, Esox masquinongy, Micropterus dolomieu, Sander vitreus, Perca flavescens, and Semotilus corporalis, n = 74) were collected from 13 ecosystems (lakes, reservoirs, and rivers) across Eastern Canada. Of 29 quantitative PFAS, 15 compounds were detected in fish from background sites, including perfluorocarboxylates (C6,8-14), perfluoroalkane sulfonates (C6,8,10), perfluorooctane sulfonamide (FOSA), 6:2 fluorotelomer sulfonate (6:2 FTSA), 7:3 fluorotelomer carboxylic acid (7:3 FTCA), and a zwitterionic PFAS-perfluorooctane sulfonamidoalkyl betaine (PFOSB). To our knowledge, this is the first report of PFOSB in biota. It is also one of the first reports of anionic fluorotelomers (6:2 FTSA, 7:3 FTCA, 9:3 FTCA) in wildlife from background sites. Long-chain fluorotelomer sulfonamidoalkyl betaines (e.g., 8:2 and 10:2 FTAB), fluorotelomer betaines (e.g., 9:3 and 9:1:2 FTB), and fluorotelomer sulfone propanoic acids (e.g., 8:2 FT(SO2)-PA, 10:2 FT(SO2)-PA)) were solely prevalent (up to 97% of summed suspect PFAS) in Smallmouth Bass (M. dolomieu) from the AFFF-impacted site. Perfluorobutane sulfonamide (FBSA), perfluorohexane sulfonamide (FHxSA), 6:2 FTSA and 7:3 FTCA were detected in at least one Smallmouth Bass sample both at the AFFF-impacted and background sites. According to the estimated chronic daily intake and current tolerable daily intake suggested by national agencies, the observed PFOS levels would not pose a health risk to anglers who might consume these wild-caught fish.

Target and Nontarget Screening of PFAS in Biosolids, Composts, and Other Organic Waste Products for Land Application in France.

Zwitterionic, cationic, and anionic per- and polyfluoroalkyl substances (PFAS) are increasingly reported in terrestrial and aquatic environments, but their inputs to agricultural lands are not fully understood. Here, we characterized PFAS in 47 organic waste products (OWP) applied in agricultural fields of France, including historical and recent materials. Overall, 160 PFAS from 42 classes were detected from target screening and homologue-based nontarget screening. Target PFAS were low in agriculture-derived wastes such as pig slurry, poultry manure, or dairy cattle manure (median ∑46PFAS: 0.66 µg/kg dry matter). Higher PFAS levels were reported in urban and industrial wastes, paper mill sludge, sewage sludge, or residual household waste composts (median ∑46PFAS: 220 µg/kg). Historical municipal biosolids and composts (1976-1998) were dominated by perfluorooctanesulfonate (PFOS), N-ethyl perfluorooctanesulfonamido acetic acid (EtFOSAA), and cationic and zwitterionic electrochemical fluorination precursors to PFOS. Contemporaneous urban OWP (2009-2017) were rather dominated by zwitterionic fluorotelomers, which represented on average 55% of ∑160PFAS (max: 97%). The fluorotelomer sulfonamidopropyl betaines (X:2 FTSA-PrB, median: 110 µg/kg, max: 1300 µg/kg) were the emerging class with the highest occurrence and prevalence in contemporary urban OWP. They were also detected as early as 1985. The study informs for the first time that urban sludges and composts can be a significant repository of zwitterionic and cationic PFAS.

Reduced bioaccumulation of fluorotelomer sulfonates and perfluoroalkyl acids in earthworms (Eisenia fetida) from soils amended with modified clays.

Soils contaminated by per- and polyfluoroalkyl substances (PFAS) pose long-term sources to adjacent water bodies and soil invertebrates. The study investigated the stabilization using a modified clay adsorbent (FLUORO-SORB100®) in reducing the bioaccumulation of 13 anionic PFAS by earthworms (Eisenia fetida), as compared to coal-based granular activated carbon. The target PFAS included four perfluoroalkyl sulfonates such as perfluorooctane sulfonate (PFOS), six perfluoroalkyl carboxylates (e.g., perfluorooctanoate PFOA), and three (X:2) fluorotelomer sulfonates. Laboratory-spiked surface soil and the soil collected from a site contaminated by aqueous film-forming foams were examined. Both adsorbents resulted in reduced earthworm PFAS body burdens at the end of the 28-day uptake phase. The highest adsorbent amendment concentration (4 w/w%) was most effective, achieving >95% reduction of PFAS body burden. Soil leaching tests indicated better immobilization performance by the clay adsorbent for most analytes; in comparison, the activated carbon performed better at reducing total PFAS body burdens, possibly owing to the avoidance of larger-sized particles by earthworms. Strong positive logarithm relationships were observed between leachate concentrations and earthworm body burdens for most PFAS in the spiked soil. The study demonstrated that stabilization of PFAS using modified clay adsorbents can achieve concurrent benefits of lowering leachability and reducing bioaccumulation.

Trophic transfer of polybrominated diphenyl ethers in a recently modified freshwater food web from the St. Lawrence River, Canada.

Introduction of invasive species can have a profound impact on food web structure and therefore on trophic transfer of contaminants. In the St. Lawrence River (Canada), 20 years after its first detection in the system, invasive round goby (Neogobius melanostomus) has become the main prey for several piscivorous species. To evaluate the accumulation, trophic transfer, and the ecological risk of polybrominated diphenyl ethers (PBDEs) in this recently modified freshwater food web, samples of sediment, invertebrates, fish and aquatic bird eggs and plasma were collected. Sampling sites were located upstream and at two locations downstream of the Montreal wastewater treatment plant outfall. The results suggest that the influence of the WWTP effluent on PBDEs concentrations varied among the various compartments of this recently modified freshwater food web. The results also suggest that although predatory fish have switched to consuming round goby as a prey item instead of native yellow perch, this new feeding behaviour is not expected to have important impacts on the level of transfer of PBDE within this food web. The biota-sediment accumulation factors (BSAFs) ranged from 0.6 to 436, whereas biomagnification factors (BMFs) varied between 0.2 and 475. Despite our conservative method of risk assessment, we calculated an important risk for piscivorous fish and gull eggs within this study area.

Bioaccumulation of Zwitterionic Polyfluoroalkyl Substances in Earthworms Exposed to Aqueous Film-Forming Foam Impacted Soils.

Critical knowledge gaps remain regarding the fate and effects of zwitterionic, cationic, and anionic perfluoroalkyl and polyfluoroalkyl substances (PFASs), including assessment of their bioaccumulation potential. Here, biota soil accumulation factors (BSAFs) were assessed in earthworms (Eisenia fetida) exposed to soil microcosms amended with zwitterionic fluorotelomers and anionic perfluoroalkyl acids. The 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB) bioaccumulated in earthworms [BSAF ∼ 2.5-5.4 (gdw,worm/gdw,soil)-1] but to a lesser extent than perfluorooctane sulfonate (PFOS: BSAF ∼ 21-29). The BSAF of perfluorocarboxylates increased from ∼2.0 for C4-C6 analogues to ∼92 for perfluorotridecanoate (C13). In earthworms exposed to Ansulite and Arctic Foam aqueous film-forming foams (AFFFs), the BSAF was related to perfluorinated chain length for n:3 fluorotelomer betaines (FtBs), n:1:2 FtB, and n:2 FTAB. Earthworms were also collected in situ from a fire-equipment testing site at a major Canadian airport. Summed PFAS concentrations were between 65 000 and 830 000 ng g-1 wet weight, possibly the highest burden recorded in terrestrial biota. Fluorotelomer sulfonates (6:2 FTS, 8:2 FTS, and 10:2 FTS) and FtB were particularly prevalent. Field worms also displayed elevated concentrations of n:3 acids (n = 3-11), but not those from laboratory microcosms exposed to fluorotelomer-based AFFFs. The findings provide an important confirmation to recent data suggesting that fluorotelomer compounds may accumulate in invertebrate species with limited metabolization.

Assessing anthropogenic pressure in the St. Lawrence River using traits of benthic macroinvertebrates.

This study aims to evaluate the anthropogenic pressure in the St. Lawrence River by assessing the relationships between chemical contamination of sediments and benthic community structure with the trait-based approach. Organic and inorganic contaminants as well as other sediment variables (sediment grain size, total organic carbon, nutrients, etc.) and benthic invertebrate assemblages were determined in 59 sites along the river. Biological and ecological traits of taxa were coded, taking into account regional climate and ecosystem conditions. The aims of this study were to (1) describe the relationships between traits and macroinvertebrate taxa and identify homogeneous clusters of taxa with the same combinations of functional traits, (2) describe spatial patterns in traits of macroinvertebrates in the St. Lawrence River, (3) link trait-based metrics and site groups to sediment quality and (4) define a trait-based strategy for diagnosing the ecological quality of the St. Lawrence River. Seven groups of taxa sharing similar trait-category attributes were defined. Moreover, four groups of sites were identified using the 'K-mean' non-hierarchical clustering approach. The 'IndVal' method enabled us to specifically defined trait categories corresponding to site groups on the basis of their indicator value. The relative abundances of taxa from five functional groups significantly varied among site groups. For example, some indicator traits such as multivoltine cycle, long life span, fixed clutches, tegumental respiration, asexual reproduction, and collector/gatherer feeding habit were associated to the most heavily polluted sites located in the Montreal harbour which showed the highest sediment concentrations in Pb, Zn and Cu. Three trait-based pressure-specific models were built, based on the random forest approach, for respectively (1) heavy metals, (2) BPCs and PAHs, and (3) TBTs occurring in the environment. These models could be applied to assess sediment quality using macroinvertebrate assemblages in a large Canadian river.

Accumulation and sublethal effects of triclosan and its transformation product methyl-triclosan in the earthworm Eisenia andrei exposed to environmental concentrations in an artificial soil.

Municipal biosolids are increasingly used as a low-cost fertilizer in agricultural soil. Biosolids are contaminated by low concentrations (nanograms per gram dry wt range) of a large variety of organic contaminants, such as triclosan. The effect of exposure to low concentrations of organic contaminants on soil biota remains largely undocumented. We evaluated the sublethal effects of triclosan on the earthworm Eisenia andrei using an artificial soil amended with a nominal concentration of triclosan of 50 ng g-1 dry weight soil. Using a 56-d reproduction test, we monitored the effect of triclosan exposure on adult earthworm survival, growth, and reproduction. The bioaccumulation of triclosan in earthworm tissue (adults and juveniles) and degradation of triclosan were monitored. The genotoxicity of triclosan was evaluated using a comet assay (DNA damage) on adult earthworm coelomocytes. Exposure to a low concentration of triclosan had no significant effects on adult earthworm survival and DNA damage but significantly stimulated growth (p < 0.05) by 2-fold compared with controls. It also significantly affected E. andrei reproduction parameters (p < 0.05), as evidenced by an increase in the number of cocoons and juveniles and a decrease in the mean dry weight of juveniles. The bioaccumulation of triclosan in earthworms was moderate (bioaccumulation factor ∼2). In biosolid-borne trials, the bioaccumulation of methyl-triclosan in earthworm tissues was higher than that of the parent compound triclosan. We conclude that exposure to low concentrations of triclosan in artificial soil can significantly affect the growth and reproductive performance of earthworms (i.e., E. andrei). More research is required with natural soils to assess triclosan bioavailability for earthworms. Environ Toxicol Chem 2018;37:1940-1948. © 2018 SETAC.

Field biomonitoring using the zebra mussel Dreissena polymorpha and the quagga mussel Dreissena bugensis following immunotoxic reponses. Is there a need to separate the two species?

The zebra mussel, Dreissena polymorpha constitutes an extensively used sentinel species for biomonitoring in European and North American freshwater systems. However, this invasive species is gradually replaced in freshwater ecosystem by Dreissena bugensis, a closely related dreissenid species that shares common morphological characteristics but possess some physiological differences. However, few are known about differences on more integrated physiological processes that are generally used as biomarkers in biological monitoring studies. Declining of zebra mussel populations raises the question of the sustainability of using one or both species indifferently to maintain the quality of environmental pollution monitoring data. In our study, we performed a field comparative study measuring immune-related markers and bioaccumulation of PCBs, PAHs and PBDEs in sympatrically occurring mussel populations from three sites of the St. Lawrence River. For tested organisms, species were identified using RFLP analysis. Measurement of bioaccumulated organic compounds indicated a higher accumulation of PCBs and PBDEs in D. bugensis soft tissues compared to D. polymorpha while no differences were noticed for PAHs. Results of hemocytic parameters highlighted that differences of hemocyte distributions were associated to modulations of phagocytic activities. Moreover, marked differences occurred in measurement of hemocytic oxidative activity, indicating divergences between the two species for ROS regulation strategies. This physiological characteristic may deeply influence species responses facing environmental or pollution related stress and induce bias if the two species are not differentiated in further biomarker or bioaccumulation measurement-based studies.

Worldwide drinking water occurrence and levels of newly-identified perfluoroalkyl and polyfluoroalkyl substances.

In the last decade or so, concerns have arisen with respect to the widespread occurrence of perfluoroalkyl acids (PFAAs) in the environment, food, drinking water, and humans. In this study, the occurrence and levels of a large range of perfluoroalkyl and polyfluoroalkyl substances (PFASs) were investigated in drinking water (bottled and tap water samples) from various locations around the world. Automated off-line solid phase extraction followed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry was used to analyze PFASs of various chain lengths and functional groups. In total, 29 target and 104 suspect-target PFASs were screened in drinking water samples (n=97) from Canada and other countries (Burkina Faso, Chile, Ivory Coast, France, Japan, Mexico, Norway, and the USA) in 2015-2016. Out of the 29 PFASs quantitatively analyzed, perfluorocarboxylates (PFCAs: C4/14), perfluoroalkane sulfonates (PFSAs: C4, C6, C8), and perfluoroalkyl acid precursors (e.g., 5:3 fluorotelomer carboxylate (5:3 FTCA)) were recurrently detected in drinking water samples (concentration range:

Synthetic hospital wastewater treatment by coupling submerged membrane bioreactor and electrochemical advanced oxidation process: Kinetic study and toxicity assessment.

In this work, the combination of membrane bioreactor (MBR) and electro-oxidation (EO) process was studied for the treatment of a synthetic hospital wastewater fortified with four pharmaceutical pollutants namely carbamazepine (CBZ), ibuprofen (IBU), estradiol (E-E) at a concentration of 10 µg L-1 venlafaxine (VEN) at 0.2 µg L-1. Two treatment configurations were studied: EO process as pre-treatment and post-treatment. Wastewater treatment with MBR alone shows high removal percentages of IBU and E-E (∼90%). Unlikely for CBZ and VEN, a low elimination percentage (∼10%) was observed. The hydraulic and the solid retention times (HRT and SRT) were 18 h and 140 d respectively, while the biomass concentration in the MBR was 16.5 g L-1. To enhance pharmaceuticals elimination, an EO pretreatment was conducted during 40 min at 2 A. This configuration allowed a 92% removal for VEN, which was far greater than both treatments alone, with lower than 30% and 50% for MBR and EO, respectively. The MBR-EO coupling (EO as post-treatment) allows high removal percentages (∼97%) of the four pharmaceutical pollutants after 40 min of treatment at a current intensity of 0.5 A with Nb/BDD as electrodes. This configuration appears to be very effective compared to the first configuration (EO-MBR) where EO process is used as a pre-treatment. Toxicity assessment showed that the treated effluent of this configuration is not toxic to Daphnia magna except at 100% v/v. The MBR-EO coupling appears to be a promising treatment for contaminated hospital effluents.

Selective bioaccumulation of neonicotinoids and sub-lethal effects in the earthworm Eisenia andrei exposed to environmental concentrations in an artificial soil.

In this study, we evaluated the bioaccumulation of neonicotinoid insecticides in the earthworm Eisenia andrei exposed to environmental concentrations (<200 ng g-1 dry weight, nominal concentration) in an artificial soil. We tested the selectivity for neonicotinoids by exposing earthworms to 7 neonicotinoids alone and in more complex mixtures of 54 pesticides then 69 organic contaminants (OCs) (54 pesticides and 15 pharmaceuticals). We applied long-term (56-day) toxicity tests to further evaluate the effect of OCs on earthworms. We monitored adult survival, adult DNA damage using a comet assay on earthworm coelomocyte cells, and reproduction performance (i.e. number of cocoons and number and dry weight of juveniles). A selective bioaccumulation of neonicotinoid insecticides in adult and juvenile earthworms was found. This bioaccumulation is concomitant with a significant increase in adult DNA damage and significant effects on reproduction when earthworms were exposed to neonicotinoid insecticides alone. This study reveals a new potential point of entry of neonicotinoid insecticides into the wildlife food chain and also shows that E. andrei reproduction could be affected by long-term exposure to environmental concentrations of OCs.

Novel Fluoroalkylated Surfactants in Soils Following Firefighting Foam Deployment During the Lac-Mégantic Railway Accident.

The derailment of an unmanned train carrying crude oil and subsequent fire in the town of Lac-Mégantic, Quebec, led to the use of 33 000 L of aqueous film forming foam (AFFF) concentrate. While it is known that per- and polyfluoroalkyl substances (PFASs) contained in AFFFs pose a potential environmental and health risk, critical knowledge gaps remain as regards to their environmental fate after release. The accident in Lac-Mégantic provided valuable information regarding the identity and concentration of PFASs present in the soil after the AFFF deployment, as well as their possible transformation over time. The current study analyzed four sets of samples from Lac-Mégantic: soil collected days after the accident from a heavily impacted area, soil sampled two years later from the treatment biopiles, soil collected two years after the accident from downtown Lac-Mégantic, and nonimpacted soil from a nearby area. A total of 33 PFASs were quantified in the soils. The highest observed concentrations correspond to those of 6:2 fluorotelomer sulfonamidoalkyl betaine, 6:2 and 8:2 fluorotelomer sulfonates, and short chain perfluorocarboxylic acids. The soils collected in Lac-Mégantic two years after the accident show a total PFAS concentration that is ∼50 times lower than soils collected in 2013, while the proportion of perfluoroalkyl acids in those samples shows an increase. Qualitative analysis revealed the presence in soil of 55 additional PFASs that had been previously identified in AFFF formulations. The present study highlights the need to perform detailed analysis of AFFF impacted sites, instead of focusing solely on perfluoroalkyl acids.

QuEChERS extraction for multi-residue analysis of PCBs, PAHs, PBDEs and PCDD/Fs in biological samples.

In this study, a fast and rugged method is presented for the analysis of PCBs, PAHs, PBDEs and PCDD/Fs in biological tissues using a simple Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) extraction and a clean-up by Gel Permeation Chromatography (GPC) and silica Solid Phase Extraction (SPE). Development was performed on blue mussels (Mytilus edulis) and Atlantic salmon (Salmo salar) for evaluation of two ranges of lipid and water content of biological tissues. Statistical validation was performed with Atlantic salmon samples. Forty-five PAHs were analyzed including the priority list of the US EPA and the European Union with 41 PCBs, 24 PBDEs and 17 PCDD/Fs. Instrumental analyses were performed on Gas Chromatography - High Resolution Mass Spectrometry (GC-HRMS). Accuracy was evaluated for PCBs and PCDD/Fs with a certified reference material furnished by the National Research Council Canada (NRCC) and also compared with results obtained by the conventional Soxhlet extraction. Statistical validation showed recoveries for PCBs, PAHs, PBDEs and PCDD/Fs close to 100% with average Relative Standard Deviation (RSD) lower than 10% and internal standard recoveries in the range of 70% with average RSD ranging from 5-15%. Average calculated Method Detection Limits (MDLs) were lower than 0.05µg/Kg for PCBs, 0.2µg/Kg for PAHs and PBDEs and 1ng/Kg for PCDD/Fs. The method is a faster and cheaper alternative to the time-consuming conventional method that has been used in most environmental laboratories.

Environmental Occurrence of Perfluoroalkyl Acids and Novel Fluorotelomer Surfactants in the Freshwater Fish Catostomus commersonii and Sediments Following Firefighting Foam Deployment at the Lac-Mégantic Railway Accident.

On July 6th 2013, an unmanned train laden with almost 8 million liters of crude oil careened off the rails downtown Lac-Mégantic (Québec, Canada). In the aftermath of the derailment accident, the emergency response entailed the deployment of 33 000 L of aqueous film forming foam (AFFF) concentrate that contained proprietary fluorosurfactants. The present study examines the environmental occurrence of perfluoroalkyl acids (PFAAs) and newly identified per and polyfluoroalkyl substances (PFASs) in the benthic fish white sucker (Catostomus commersonii) and sediments from Lake Mégantic and Chaudière River. In sediments, PFAAs displayed relatively low concentrations (∑PFAAs = 0.06-0.5 ng g-1 dw) while the sum of fluorotelomer-based PFASs was in the range < LOD-6.2 ng g-1 dw. Notably, fluorotelomer sulfonamide betaines (8:2-FTAB and 10:2-FTAB), fluorotelomer betaines (9:3-FTB, 11:3-FTB and 9:1:2 FTB) and 6:2 fluorotelomer sulfonate (6:2-FTSA) were ubiquitously identified in the sediment samples surveyed. Levels of PFAAs remained moderate in fish muscle (e.g. , PFOS: 0.28-2.1 ng g-1 wet-weight), with little or no differences when comparing 2013 or 2014 fish samples with 2011 archived samples. In contrast, n:2-FTSAs emerged in the immediate weeks or months that followed the accident, as did several betaine-based PFASs (8:2-FTAB, 10:2-FTAB, 9:3-FTB, 11:3-FTB, 7:1:2 FTB and 9:1:2 FTB), observed for the first time in situ. Fluorotelomer thioether amido sulfonate (10:2-FTSAS) and fluorotelomer sulfoxide amido sulfonate (10:2-FTSAS-sulfoxide) were also occasionally reported after the AFFF spill. With time, levels of betaine-based PFASs gradually decreased in fish, possibly indicating attenuation by biodegradation of the fluorine-free moiety, supported by the observation of likely metabolites such as n:3-fluorotelomer carboxylates and n:2-fluorotelomer sulfonamides.

Analysis of emerging contaminants in water and solid samples using high resolution mass spectrometry with a Q Exactive orbital ion trap and estrogenic activity with YES-assay.

Trace emerging contaminants (ECs) occur in both waste and surface waters that are rich in particulates that have been found to sorb several organic contaminants. An analytical method based on off-line solid-phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS) analysis was developed for the detection and quantification of 31 ECs from surface water, wastewater, suspended particulate matter (SPM) as well as sediments. Lyophilized sediments and air-dried SPM were subjected to ultrasonic extraction. Water samples and extracts were then concentrated and cleaned-up by off-line SPE. Quantification was realized using a Q Exactive mass spectrometer in both full scan (FS) and MS2 modes. These two modes were optimized and compared to determine which one was the most suitable for each matrix studied. Yeast estrogen screen assay (YES-assay) adapted from the direct measurement of estrogenic activity without sample extraction was tested on filtered wastewater samples. An endocrine disrupting effect was detected in all effluent samples analyzed with estradiol equivalent concentrations ranging from 4.4 to 720 ng eq E2 L-1 for the WWTP-1 and 6.5-42 ng eq E2 L-1 for the WWTP-2. The analytical methods were also applied on six samples of surface water, the corresponding SPM, the sediments and thirty-nine effluent samples from two wastewater treatment plants (WWTPs) sampled over a period of five months (February to June 2014).

A review of what is an emerging contaminant.

A review is presented of how one defines emerging contaminants and what can be included in that group of contaminants which is preferably termed "contaminants of emerging concern". An historical perspective is given on the evolution of the issues surrounding emerging contaminants and how environmental scientists have tackled this issue. This begins with global lead contamination from the Romans two millennia ago, moves on to arsenic-based and DDT issues and more recently to pharmaceuticals, cyanotoxins, personal care products, nanoparticles, flame retardants, etc. Contaminants of emerging concern will remain a moving target as new chemical compounds are continuously being produced and science continuously improves its understanding of current and past contaminants.

Effects of silver nanoparticles on soil enzyme activities with and without added organic matter.

The effects of silver nanoparticles (AgNPs) on terrestrial ecosystems need to be better understood and assessed. Cationic silver (Ag+) has well-documented toxicity against bacteria, but it is not clear what will be the effect of nanoscale Ag. In the present study, the potential effects of AgNPs were investigated in soils by measuring activity of the enzymes phosphomonoesterase, arylsulfatase, ß-D-glucosidase, and leucine-aminopeptidase. The toxicity of AgNPs was compared with that of ionic Ag, and the ameliorating effects of soil organic matter were evaluated. To this end, 2 soils with different organic matter contents were artificially contaminated with either AgNPs or Ag-acetate at equivalent total Ag concentrations. In general, enzyme activities were inhibited as a function of the Ag concentration in the soil. In the AgNP exposures, only a small fraction of the AgNP was actually truly dissolved (found in the <1-nm fraction), suggesting that the particulate forms of AgNPs resulted in a significant inhibition of soil enzymes. The addition of organic matter to the soils appeared to enhance enzyme activities; however, the mechanism of organic matter action is not clear given that dissolved Ag concentrations were similar in both the organic-matter­amended and unamended soils. The present study shows that the AgNP produces significant negative effects on the soil enzyme activities tested. The Ag chemical speciation measurements suggested that the AgNP caused greater toxic effects to the soil enzymes at the low Ag concentrations. For the larger concentrations of total soil Ag, causes of the negative effects on enzyme activities are less obvious but suggest that colloidal forms of Ag play a role.

High levels of adenosine deaminase on dendritic cells promote autoreactive T cell activation and diabetes in nonobese diabetic mice.

Adenosine has been established as an important regulator of immune activation. It signals through P1 adenosine receptors to suppress activation of T cells and professional APCs. Adenosine deaminase (ADA) counters this effect by catabolizing adenosine. This regulatory mechanism has not been tested in a disease model in vivo. Questions also remain as to which cell types are most sensitive to this regulation and whether its dysregulation contributes to any autoimmune conditions. We approached this issue using the NOD model. We report that ADA is upregulated in NOD dendritic cells, which results in their exuberant and spontaneous activation. This, in turn, triggers autoimmune T cell activation. NOD DCs deficient in ADA expression have a greatly reduced capacity to trigger type I diabetes. We also provide evidence that although many cell types, particularly T cells, have been implicated as the suppression targets by adenosine in an in vitro setting, DCs also seem to be affected by this regulatory mechanism. Therefore, this report illustrates a role of ADA in autoimmunity and suggests a potential target for therapeutic intervention.

Alum interaction with dendritic cell membrane lipids is essential for its adjuvanticity.

As an approved vaccine adjuvant for use in humans, alum has vast health implications, but, as it is a crystal, questions remain regarding its mechanism. Furthermore, little is known about the target cells, receptors, and signaling pathways engaged by alum. Here we report that, independent of inflammasome and membrane proteins, alum binds dendritic cell (DC) plasma membrane lipids with substantial force. Subsequent lipid sorting activates an abortive phagocytic response that leads to antigen uptake. Such activated DCs, without further association with alum, show high affinity and stable binding with CD4(+) T cells via the adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1). We propose that alum triggers DC responses by altering membrane lipid structures. This study therefore suggests an unexpected mechanism for how this crystalline structure interacts with the immune system and how the DC plasma membrane may behave as a general sensor for solid structures.

Traits-based approaches in bioassessment and ecological risk assessment: strengths, weaknesses, opportunities and threats.

We discuss the application of traits-based bioassessment approaches in retrospective bioassessment as well as in prospective ecological risk assessments in regulatory frameworks. Both approaches address the interaction between species and stressors and their consequences at different levels of biological organization, but the fact that a specific species may be less abundant in a potentially impacted site compared with a reference site is, regrettably, insufficient to provide diagnostic information. Species traits may, however, overcome the problems associated with taxonomy-based bioassessment. Trait-based approaches could provide signals regarding what environmental factors may be responsible for the impairment and, thereby, provide causal insight into the interaction between species and stressors. For development of traits-based (TBA), traits should correspond to specific types of stressors or suites of stressors. In this paper, a strengths, weaknesses, opportunities, and threats (SWOT) analysis of TBA in both applications was used to identify challenges and potentials. This paper is part of a series describing the output of the TERA (Traits-based ecological risk assessment: Realising the potential of ecoinformatics approaches in ecotoxicology) Workshop held between 7 and 11 September, 2009, in Burlington, Ontario, Canada. The recognized strengths were that traits are transferrable across geographies, add mechanistic and diagnostic knowledge, require no new sampling methodology, have an old tradition, and can supplement taxonomic analysis. Weaknesses include autocorrelation, redundancy, and inability to protect biodiversity directly. Automated image analysis, combined with genetic and biotechnology tools and improved data analysis to solve autocorrelation problems were identified as opportunities, whereas low availability of trait data, their transferability, their quantitative interpretation, the risk of developing nonrelevant traits, low quality of historic databases, and their standardization were listed as threats.