High-Resolution Mass Spectrometry for Human Exposomics: Expanding Chemical Space Coverage.

In the modern "omics" era, measurement of the human exposome is a critical missing link between genetic drivers and disease outcomes. High-resolution mass spectrometry (HRMS), routinely used in proteomics and metabolomics, has emerged as a leading technology to broadly profile chemical exposure agents and related biomolecules for accurate mass measurement, high sensitivity, rapid data acquisition, and increased resolution of chemical space. Non-targeted approaches are increasingly accessible, supporting a shift from conventional hypothesis-driven, quantitation-centric targeted analyses toward data-driven, hypothesis-generating chemical exposome-wide profiling. However, HRMS-based exposomics encounters unique challenges. New analytical and computational infrastructures are needed to expand the analysis coverage through streamlined, scalable, and harmonized workflows and data pipelines that permit longitudinal chemical exposome tracking, retrospective validation, and multi-omics integration for meaningful health-oriented inferences. In this article, we survey the literature on state-of-the-art HRMS-based technologies, review current analytical workflows and informatic pipelines, and provide an up-to-date reference on exposomic approaches for chemists, toxicologists, epidemiologists, care providers, and stakeholders in health sciences and medicine. We propose efforts to benchmark fit-for-purpose platforms for expanding coverage of chemical space, including gas/liquid chromatography-HRMS (GC-HRMS and LC-HRMS), and discuss opportunities, challenges, and strategies to advance the burgeoning field of the exposome.

Fluorine Mass Balance, including Total Fluorine, Extractable Organic Fluorine, Oxidizable Precursors, and Target Per- and Polyfluoroalkyl Substances, in Pooled Human Serum from the Tromsø Population in 1986, 2007, and 2015.

Of the thousands of per- and polyfluoroalkyl substances (PFAS) known to exist, only a small fraction (≤1%) are commonly monitored in humans. This discrepancy has led to concerns that human exposure may be underestimated. Here, we address this problem by applying a comprehensive fluorine mass balance (FMB) approach, including total fluorine (TF), extractable organic fluorine (EOF), total oxidizable precursors (TOP), and selected target PFAS, to human serum samples collected over a period of 28 years (1986, 2007, and 2015) in Tromsø, Norway. While concentrations of TF did not change between sampling years, EOF was significantly higher in 1986 compared to 2007 and 2015. The ∑12PFAS concentrations were highest in 2007 compared to 1986 and 2015, and unidentified EOF (UEOF) decreased from 1986 (46%) to 2007 (10%) and then increased in 2015 (37%). While TF and EOF were not influenced by sex, women had higher UEOF compared to men, opposite to target PFAS. This is the first FMB in human serum to include TOP, and it suggests that precursors with >4 perfluorinated carbon atoms make a minor contribution to EOF (0-4%). Additional tools are therefore needed to identify substances contributing to the UEOF in human serum.

A Bad Start in Life? Maternal Transfer of Legacy and Emerging Poly- and Perfluoroalkyl Substances to Eggs in an Arctic Seabird.

In birds, maternal transfer is a major exposure route for several contaminants, including poly- and perfluoroalkyl substances (PFAS). Little is known, however, about the extent of the transfer of the different PFAS compounds to the eggs, especially for alternative fluorinated compounds. In the present study, we measured legacy and emerging PFAS, including Gen-X, ADONA, and F-53B, in the plasma of prelaying black-legged kittiwake females breeding in Svalbard and the yolk of their eggs. We aimed to (1) describe the contaminant levels and patterns in both females and eggs, and (2) investigate the maternal transfer, that is, biological variables and the relationship between the females and their eggs for each compound. Contamination of both females and eggs were dominated by linPFOS then PFUnA or PFTriA. We notably found 7:3 fluorotelomer carboxylic acid─a precursor of long-chain carboxylates─in 84% of the egg yolks, and provide the first documented finding of ADONA in wildlife. Emerging compounds were all below the detection limit in female plasma. There was a linear association between females and eggs for most of the PFAS. Analyses of maternal transfer ratios in females and eggs suggest that the transfer is increasing with PFAS carbon chain length, therefore the longest chain perfluoroalkyl carboxylic acids (PFCAs) were preferentially transferred to the eggs. The mean ∑PFAS in the second-laid eggs was 73% of that in the first-laid eggs. Additional effort on assessing the outcome of maternal transfers on avian development physiology is essential, especially for PFCAs and emerging fluorinated compounds which are under-represented in experimental studies.

Expression of DNA repair genes in arctic char (Salvelinus alpinus) from Bjørnøya in the Norwegian Arctic.

High levels of organochlorines (OCs) have been measured in arctic char (Salvelinus alpinus) from Lake Ellasjøen on Bjørnøya, Norway (74.30°N, 19.0°E). In a nearby lake, Laksvatn, the OC-levels in arctic char were low. A previous study has shown that char from Ellasjøen had significantly higher levels of DNA double strand breaks (DSBs) than char from Lake Laksvatn. Even though there is increasing evidence of the genotoxic effects of OCs, little is known about the effects of OCs on the DNA repair system. The aim of the present study was to determine if the two main DNA DSB repair mechanisms, homologous recombination (HR) and non-homologous end-joining (NHEJ), are affected by the higher OC and DSB level in char from Ellasjøen. This was analysed by comparing the transcript level of 11 genes involved in DNA DSB repair in char liver samples from Ellasjøen (n = 9) with char from Laksvatn (n = 12). Six of the investigated genes were significantly upregulated in char from Ellasjøen. As the expression of DNA DSB repair genes was increased in the contaminant-exposed char, it is likely that the DNA DSB repair capacity is induced in these individuals. This induction was positively correlated with the DNA DSB and negatively correlated with one or several OCs for four of these genes. However, the strongest predictor variable for DNA repair genes was habitat, indicating genetic differences in repair capacity between populations. As char from Ellasjøen still had significantly higher levels of DSBs compared to char from Laksvatn, it is possible that chronic exposure to OCs and continued production of DSB has caused selective pressure within the population for fixation of adaptive alleles. It is also possible that DSB production was exceeding the repair capacity given the prevailing conditions, or that the OC or DSB level was above the threshold value of inhibition of the DNA repair system resulting in the rate of DNA damage exceeding the rate of repair.

Plague: Clinics, Diagnosis and Treatment.

Plague still poses a significant threat to human health and as a reemerging infection is unfamiliar to the majority of the modern medical doctors. In this chapter, the plague is described according to Dr. Nikiforov's experiences in the diagnosis and treatment of patients, and also a review of the relevant literature on this subject is provided. The main modern methods and criteria for laboratory diagnosis of plague are briefly described. The clinical presentations include the bubonic and pneumonic form, septicemia, rarely pharyngitis, and meningitis. Early diagnosis and the prompt initiation of treatment reduce the mortality rate associated with bubonic plague and septicemic plague to 5-50 %; although a delay of more than 24 h in the administration of antibiotics and antishock treatment can be fatal for plague patients. Most human cases can successfully be treated with antibiotics.

Management of pharmaceutical substances in the environment: Lithuanian case study.

Investigation on the sources, discharges and related risks for the environment of the pharmaceutical substance (PhS) diclofenac (DCF) was performed in Lithuania, a country of the Baltic Sea region, for the first time. The investigation only refers to DCF as a PhS for human use; emissions from animal husbandry were not considered. In the first stage of the research, the main sources and pathways of DCF via substance flow analysis were identified within the country. During the second stage, DCF flows along the wastewater treatment plants (WWTPs) in two different cities were measured in order to assess the current levels of pharmaceutical residues in the environment. Furthermore, environmental risk assessment was carried out by taking into account the parameters of consumption data and elimination rate in WWTPs. Then, the assessment of different technical and managerial removal approaches was accomplished in an environmental management model of wastewater containing PhS, based on the framework of environmental systems theory.

Does contaminant exposure disrupt maternal hormones deposition? A study on per- and polyfluoroalkyl substances in an Arctic seabird.

Maternal effects are thought to be essential tools for females to modulate offspring development. The selective deposition of avian maternal hormones could therefore allow females to strategically adjust the phenotype of their offspring to the environmental situation encountered. However, at the time of egg formation, several contaminants are also transferred to the egg, including per- and polyfluoroalkyl substances (PFAS) which are ubiquitous organic contaminants with endocrine disrupting properties. It is, however, unknown if they can disrupt maternal hormone deposition. In this study we explored relationships between female PFAS burden and maternal deposition in the eggs of steroids (dihydrotestosterone, androstenedione and testosterone), glucocorticoids (corticosterone) and thyroid hormones (triiodothyronine and thyroxine) in a population of the Arctic-breeding black-legged kittiwake (Rissa tridactyla). Egg yolk hormone levels were unrelated to female hormone plasma levels. Second-laid eggs had significantly lower concentrations of androstenedione than first-laid eggs. Triiodothyronine yolk levels were decreasing with increasing egg mass but increasing with increasing females' body condition. Testosterone was the only transferred yolk hormone correlated to maternal PFAS burden: specifically, we found a positive correlation between testosterone in yolks and circulating maternal perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDcA) and perfluoroundecanoic acid (PFUnA) in first-laid eggs. This correlative study provides a first insight into the potential of some long-chain perfluoroalkyl acids to disrupt maternal hormones deposition in eggs and raises the question about the consequences of increased testosterone deposition on the developing embryo.

Targeted PFAS analyses and extractable organofluorine - Enhancing our understanding of the presence of unknown PFAS in Norwegian wildlife.

With the current possible presence of thousands of PFAS compounds in industrial emissions, there is an increasing need to assess the impacts of PFAS regulation of conventional PFAS on one hand and the exposure to emerging and yet unknown PFAS on the other. Today's analytical methodologies using targeted approaches are not sufficient to determine the complete suite of PFAS present. To evaluate the presence of unknown PFAS, we investigated in this study the occurrence of an extended range of target PFAS in various species from the marine and terrestrial Norwegian environment, in relation to the extractable organofluorine (EOF), which yields the total amount of organofluorine. The results showed a varying presence of extractable fluorinated organics, with glaucous gull eggs, otter liver and polar bear plasma showing the highest EOF and a high abundance of PFAS as well. The targeted PFAS measurements explained 1% of the organofluorine for moose liver as the lowest and 94% for otter liver as the highest. PFCAs like trifluoroacetic acid (TFA, reported semi-quantitatively), played a major role in explaining the organic fluorine present. Emerging PFAS as the perfluoroethylcyclohexane sulfonate (PFECHS), was found in polar bear plasma in quantifiable amounts for the first time, confirming earlier detection in arctic species far removed from emission sources. To enable a complete organic fluorine mass balance in wildlife, new approaches are needed, to uncover the presence of new emerging PFAS as cyclic- or ether PFAS together with chlorinated PFAS as well as fluorinated organic pesticides and pharmaceuticals.

Occurrence and backtracking of microplastic mass loads including tire wear particles in northern Atlantic air.

Few studies report the occurrence of microplastics (MP), including tire wear particles (TWP) in the marine atmosphere, and little data is available regarding their size or sources. Here we present active air sampling devices (low- and high-volume samplers) for the evaluation of composition and MP mass loads in the marine atmosphere. Air was sampled during a research cruise along the Norwegian coast up to Bear Island. Samples were analyzed with pyrolysis-gas chromatography-mass spectrometry, generating a mass-based data set for MP in the marine atmosphere. Here we show the ubiquity of MP, even in remote Arctic areas with concentrations up to 37.5 ng m-3. Cluster of polyethylene terephthalate (max. 1.5 ng m-3) were universally present. TWP (max. 35 ng m-3) and cluster of polystyrene, polypropylene, and polyurethane (max. 1.1 ng m-3) were also detected. Atmospheric transport and dispersion models, suggested the introduction of MP into the marine atmosphere equally from sea- and land-based emissions, transforming the ocean from a sink into a source for MP.

Total oxidizable precursors assay for PFAS in human serum.

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals including over 4700 substances. As a limited number of PFAS is routinely analyzed in human serum, complementary analytical methods are required to characterize the overlooked fraction. A promising tool is the total oxidizable precursors (TOP) assay to look for precursors by oxidation to perfluoroalkyl acids (PFAA). The TOP assay was originally developed for large volumes of water and had to be adapted for 250 µL of human serum. Optimization of the method was performed on serum samples spiked with model precursors. Oxidative conditions similar to previous TOP assay methods were not sufficient for complete oxidation of model precursors. Prolonged heating time (24 h) and higher oxidant amount (95 mg of Na2S2O8 per 225 µL of serum) were needed for complete conversion of the model precursors and accomplishing PFAA yields of 35-100 %. As some precursors are not fully converted to PFAA, the TOP assay can only provide semi-quantitative estimates of oxidizable precursors in human serum. However, the TOP assay can be used to give indications about the identity of unknown precursors by evaluating the oxidation products, including perfluoroalkyl sulfonic acids (PFSA) and perfluoroalkyl ether carboxylic acids (PFECA). The optimized TOP assay for human serum opens the possibility for high-throughput screening of human serum for undetected PFAA precursors.

Intestinal microbiome changes in an infant with right atrial isomerism and recurrent necrotizing enterocolitis: A case report and review of literature.

BACKGROUND: Necrotizing enterocolitis (NEC) is a multifactorial disease that predominantly affects premature neonates. Intestinal dysbiosis plays a critical role in NEC pathogenesis in premature neonates. The main risk factor for NEC in term infants is mesenteric hypoperfusion associated with ductal-dependent congenital heart disease (CHD) that eventually leads to intestinal ischemia. The incidence of NEC in neonates with critical CHD is 6.8%-13%. However, the role of the intestinal microbiome in NEC pathogenesis in infants with ductal-dependent CHD remains unclear. CASE SUMMARY: A male term neonate with right atrial isomerism underwent modified Blalock-Taussig shunt placement on the 14th day of life and had persistent mesenteric hypoperfusion after surgery. The patient had episodes of NEC stage IIA on the 1st and 28th days after cardiac surgery. Fecal microbial composition was analyzed before and after cardiac surgery by sequencing region V4 of the 16S rRNA gene. Before surgery, species belonging to genera Veillonella and Clostridia and class Gammaproteobacteria were detected, Bifidobacteriaceae showed a low abundance. The first NEC episode was associated with postoperative hemodynamic instability, intestinal ischemia-reperfusion injury during cardiopulmonary bypass, and a high abundance of Clostridium paraputrificum (Clostridium sensu stricto I) (56.1%). Antibacterial therapy after the first NEC episode resulted in increased abundance of Gammaproteobacteria, decreased abundance of Firmicutes, and low alpha diversity. These changes in the microbial composition promoted the growth of Clostridium sensu stricto I (72.0%) before the second NEC episode. CONCLUSION: A high abundance of Clostridium sensu stricto I and mesenteric hypoperfusion may have contributed to NEC in the present case.

3D-printing in preoperative planning in neonates with complex congenital heart defects.

The application of the 3D printing approach in medicine is currently becoming increasingly popular. The management of fetuses and newborns with congenital heart defects is often difficult, primarily due to the complexity of the anatomy. Here we report a newborn with a complex congenital malformation (absent pulmonary valve syndrome associated with tetralogy of Fallot), which could be clinically interpreted in different ways. 3D printing allowed to elucidate the exact anatomy more precisely and direct the cardiosurgeon to a definitive treatment.

An actionable annotation scoring framework for gas chromatography-high-resolution mass spectrometry.

Omics-based technologies have enabled comprehensive characterization of our exposure to environmental chemicals (chemical exposome) as well as assessment of the corresponding biological responses at the molecular level (eg, metabolome, lipidome, proteome, and genome). By systematically measuring personal exposures and linking these stimuli to biological perturbations, researchers can determine specific chemical exposures of concern, identify mechanisms and biomarkers of toxicity, and design interventions to reduce exposures. However, further advancement of metabolomics and exposomics approaches is limited by a lack of standardization and approaches for assigning confidence to chemical annotations. While a wealth of chemical data is generated by gas chromatography high-resolution mass spectrometry (GC-HRMS), incorporating GC-HRMS data into an annotation framework and communicating confidence in these assignments is challenging. It is essential to be able to compare chemical data for exposomics studies across platforms to build upon prior knowledge and advance the technology. Here, we discuss the major pieces of evidence provided by common GC-HRMS workflows, including retention time and retention index, electron ionization, positive chemical ionization, electron capture negative ionization, and atmospheric pressure chemical ionization spectral matching, molecular ion, accurate mass, isotopic patterns, database occurrence, and occurrence in blanks. We then provide a qualitative framework for incorporating these various lines of evidence for communicating confidence in GC-HRMS data by adapting the Schymanski scoring schema developed for reporting confidence levels by liquid chromatography HRMS (LC-HRMS). Validation of our framework is presented using standards spiked in plasma, and confident annotations in outdoor and indoor air samples, showing a false-positive rate of 12% for suspect screening for chemical identifications assigned as Level 2 (when structurally similar isomers are not considered false positives). This framework is easily adaptable to various workflows and provides a concise means to communicate confidence in annotations. Further validation, refinements, and adoption of this framework will ideally lead to harmonization across the field, helping to improve the quality and interpretability of compound annotations obtained in GC-HRMS.

Hydrolysis of FTOH precursors, a simple method to account for some of the unknown PFAS.

There is a growing concern over a suspected presense of unknown perfluoroaliphatic substances (PFAS) in consumer goods and in the environment. Such unknown substances, possibly with high molecular weight, might be precursors of hazardous or controlled known PFAS. Recent studies confirmed that total organic fluorine (TOF) content often can not be explained by the measured target PFAS. One of the suspected classes of such unknowns are polymers with fluorotelomer alcohol (FTOH) residues in a side chain. In this report we suggest hydrolysis of precursors, as a complementary method to account for the unknown PFAS. It was shown here that hydrolysis allows to preserve structural information on the perlfuorinated parts of the precursors, which can be an advantage for the purpose of accurate risk assessment or source identification. A convenient procedure for hydrolysis with 4% sodium hydroxide in water-methanol mixture (1:9) at 60 °C for 16 h was shown to convert model substances - FTOH acrylate, methacrylate and isobutyrate esters as well as FTOH phenylcarbamate to free FTOHs. Analysis of extracts of textile samples with preliminary hydrolysis and without it showed up to 1300-fold higher level of "hidden" FTOHs.

Reducing sampling artifacts in active air sampling methodology for remote monitoring and atmospheric fate assessment of cyclic volatile methylsiloxanes.

Active sampling methodology for atmospheric monitoring of cyclic volatile methylsiloxanes (cVMS) was improved to reduce sampling artifacts. A new sorbent, ABN Express (ABN), was evaluated for storage stability and measurement accuracy. Storage stability of cVMS on ABN showed less than 1% degradation of the individual 13C-labelled octamethylcyclotetrasiloxane (13C4-D4), decamethylcyclopentasiloxane (13C5-D5) and dodecamethylcyclohexasiloxane (13C6-D6) after 14 days storage at room temperature and at -20 °C whereas significant degradation was observed on ENV+ sorbent at room temperature (37-62 %) and -20 °C (9-16 %). 13C4-D4 formed on ENV+ spiked with 13C5-D5, and both 13C4-D4 and 13C5-D5 formed on ENV+ spiked with 13C6-D6. However, this was not observed on the ABN sorbent. Performance of ABN was compared to ENV+ through an 8-month Arctic sampling campaign at the Zeppelin Observatory (Ny Ålesund, Svalbard). Good agreement between ABN and ENV+ was observed for D4 in the spring/summer months. However, D5 and D6 was found to be consistently higher on the ABN sorbent during this time period with D6 showing the greatest deviation. During the winter months, larger deviations were observed between ABN and ENV+ sorbents with a factor of 4 times higher atmospheric concentrations of both D5 and D6 found on ABN; indicating sorbent related degradation on ENV+. Our findings show that the ABN sorbent provides greater stability and accuracy for atmospheric monitoring of cVMS. Implications of these improvements towards atmospheric fate processes will be discussed.

Long-range atmospheric transport of three toxaphene congeners across Europe. Modeling by chained single-box FATEMOD program.

BACKGROUND, AIMS, AND SCOPE: Since toxaphene (polychlorocamphene, polychloropinene, or strobane) mixtures were applied for massive insecticide use in the 1960s to replace the use of DDT, some of their congeners have been found at high latitudes far away from the usage areas. Especially polychlorinated bornanes have demonstrated dominating congeners transported by air up to the Arctic areas. Environmental fate modeling has been applied to monitor this phenomenon using parallel zones of atmosphere around the globe as interconnected environments. These zones, shown in many meteorological maps, however, may not be the best way to configure atmospheric transport in air trajectories. The latter could also be covered by connecting a chain of simple model boxes. We aim to study this alternative approach by modeling the trajectory chain using catchment boxes of our FATEMOD model. Polychlorobornanes analyzed in biota of the Barents Sea offered one case to study this modeling alternative, while toxaphene has been and partly still is used massively at southern East Europe and around rivers flowing to the Aral Sea. MATERIALS AND METHODS: Pure model substances of three polychlorobornanes (toxaphene congeners P26, P50, and P62) were synthesized, their environmentally important thermal properties measured by differential scanning calorimetry, as evaluated from literature data, and their temperature dependences estimated by the QSPR programs VPLEST, WATSOLU, and TDLKOW. The evaluated property parameters were used to model their atmospheric long-range transport from toxaphene heavy usage areas in Ukraine and Aral/SyrDarja/AmuDarja region areas, through East Europe and Northern Norway (Finnmarken) to the Barents Sea. The time period used for the emission model was June 1997. Usual weather conditions in June were applied in the model, which was constructed by chaining FATEMOD model boxes of the catchment's areas along assumed maximal air flow trajectories. Analysis of the three chlorobornanes in toxaphene mixtures function as a basis for the estimates of emission levels caused by its usage. High estimate (A) was taken from contents in a Western product chlorocamphene and low estimate (B) from mean contents in Russian polychloroterpene products to achieve modeled water concentrations. Bioaccumulation to analyzed lipid of aquatic biota at the target region was estimated by using statistical calculation for persistent organic pollutants in literature. RESULTS: The results from model runs A and B (high and low emission estimate) for levels in sea biota were compared to analysis results of samples taken in August 1997 at Barents Sea. The model results (ng g(-1) lw): 4-95 in lipid of planktovores and 7-150 in lipid of piscivores, were in fair agreement with the analysis results from August 1997: 21-31 in Themisto libellula (chatka), 26-42 in Boreocadus saida (Polar cod), and 5-27 in Gadus morhua (cod) liver. DISCUSSION: The modeling results indicate that the application of chained simple multimedia catchment boxes on predicted trajectory is a useful method for estimation of volatile airborne persistent chemical exposures to biota in remote areas. For hazard assessment of these pollutants, their properties, especially temperature dependences, must be estimated by a reasonable accuracy. That can be achieved by using measurements in laboratory with pure model compounds and estimation of properties by thermodynamic QSPR methods. The property parameters can be validated by comparing their values at an environmental temperature range with measured or QSPR-estimated values derived by independent methods. The chained box method used for long-range air transport modeling can be more suitable than global parallel zones modeling used earlier, provided that the main airflow trajectories and properties of transported pollutants are predictable enough. CONCLUSIONS: Long-range air transport modeling of persistent, especially photo-resistant organic compounds using a chain of joint simple boxes of catchment's environments is a feasible method to predict concentrations of pollutants at the target area. This is justified from model results compared with analytical measurements in Barents Sea biota in August 1997: three of six modeled values were high and the other three low compared to the analysis results. The order of magnitude level was similar in both modeled (planktovore and piscivore) and observed (chatka and polar cod) values of lipid samples. The obtained results were too limited to firm validation but are sufficient to justify feasibility of the method, which prompts one to perform more studies on this modeling system. RECOMMENDATIONS AND PERSPECTIVES: For assessment of the risk of environmental damages, chemical fate determination is an essential tool for chemical control, e.g., for EU following the REACH rules. The present conclusion of applicability of the chained single-box multimedia modeling can be validated by further studies using analyses of emissions and target biota in various other cases. To achieve useful results, fate models built with databases having automatic steps for most calculations and outputs accessible to all chemical control professionals are essential. Our FATEMOD program catchments at environments and compound properties listed in the database represent a feasible tool for local, regional, and, according our present test results, for global exposure predictions. As an extended use of model, emission estimates can be achieved by reversed modeling from analysis results of samples corresponding to the target area.

Occurrence of PCDD/PCDFs, dioxin-like PCBs, and PBDEs in surface sediments from the Neva River and the Eastern Gulf of Finland (Russia).

A total of 26 samples of surface sediments collected in the Neva River (including the St. Petersburg city area) and in the Russian part of the Gulf of Finland were analyzed for 17 polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), 12 dioxin-like polychlorinated biphenyls (dl-PCBs), and 10 polybrominated diphenyl ethers (PBDEs). The concentrations of total PCDD/Fs and dl-PCBs in sediments ranged from < 0.05 to 219 pg g-1 d.w. and from 44 to 246,600 pg g-1 d.w. respectively. The total World Health Organization toxic equivalent (WHO-TEQPCDD/F + PCB) values varied between 0.01 and 59.0 pg g-1. In the majority of cases, the PCDD/F and dl-PCB concentrations do not exceed the threshold effect level (TEL) recommended by Helsinki Commission (HELCOM) as quantitative target for the sum of PCDD/Fs and dl-PCBs. The congener profile indicates that combustion is the primary source of PCDD/Fs in most of the studied samples. For the PCBs, the historical use of technical PCB products was identified as the major source. ΣPBDE10 concentrations ranged from 0.004 to 1.8 ng g-1 d.w. The congener profile results show that BDE-47 (tetra-BDE) is the dominant congener in sediment samples. According to the sediment and water quality guidelines established in the EU (PNEC) and in Canada (FEQG), all the samples studied can be classified as lowly contaminated by PBDEs. The sediment concentrations of PCDD/Fs, dl-PCBs, and PBDEs measured in this study were comparable to or lower than those reported for other areas of the Baltic Sea.

DNA Double-Strand Breaks in Arctic Char (Salvelinus alpinus) from Bjørnøya in the Norwegian Arctic.

High levels of organochlorine contaminants (OCs) have been found in arctic char (Salvelinus alpinus) from Lake Ellasjøen, Bjørnøya (Norwegian Arctic). The aim of the present study was to investigate the potential genotoxic effect of environmental organochlorine contaminant exposure in arctic char from Ellasjøen compared with arctic char from the low-contaminated Lake Laksvatn nearby. Blood was analyzed using agarose gel electrophoresis and image data analysis to quantify the fraction of total DNA that migrated into the gel (DNA-FTM) as a relative measure of DNA double-strand breaks (DSBs). Analysis by GC-MS of muscle samples showed an average 43 times higher concentration of ΣOCs in arctic char from Ellasjøen (n = 18) compared with Laksvatn char (n = 21). Char from Lake Ellasjøen had a much higher frequency of DSBs, as measured by DNA-FTM, than char from Lake Laksvatn. Principal component analysis and multiple linear regressions show that there was a significant positive relationship between DSBs and levels of organochlorine contaminants in the char. In addition, DSBs were less frequent in reproductively mature char than in immature char. The results suggest that organochlorine contaminants are genotoxic to arctic char. Environ Toxicol Chem 2019;38:2405-2413. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Investigations on the sorption of a toxaphene model congener, the B7-1450, on marine sediments.

Sorption is a natural process that takes place in sediments or soils and changes the mobility and availability of hydrophobic organic compounds, such as toxaphene pesticide in the environment. The sorption of the 2-exo,3-endo,5-exo,8,9,10,10-heptachlorobornane (B7-1450), used as a model compound of the toxaphene heptachlorobornane congeners found in sediments, was investigated for the first time through a series of batch sorption experiments. The losses of B7-1450 due to adsorption onto glass walls and to evaporation occurring during analytical treatment steps were corrected. The study showed that these specific losses ranged from 2% to 3.5% for the glass walls adsorption and can be as high as 15% for the evaporation treatment. The sorption coefficients, K(d) and K(oc), of B7-1450 could be overestimated by >30%, particularly for low-concentration samples, if the losses were not corrected. Loss correction equations were established, validated and applied to determine sorption coefficients for the B7-1450 congener. The K(oc) values for B7-1450 determined over a gradient of concentrations ranged from 3.5x10(4) to 6.5x10(4)mlg(-1), revealing a strong affinity of B7-1450 for marine sediments.

2-exo,5-endo,8,8,10-Penta-chloro-bornane.

The title compound, C(10)H(13)Cl(5), is a polychlorinated monoterpene and a Toxaphene congener. This compound is also the only penta-chlorinated derivative of camphene formed via ionic chlorination. Previously, the title compound was thought to be 2-exo,5-endo,9,9,10-penta-chloro-bornane, but X-ray structural analysis showed it to have a different structure and rather to be 2-exo,5-endo,8,8,10-penta-chloro-bornane. The title compound shows static disorder and almost half the molecule was divided in two partitions with an occupancy ratio of 0.575 (major) to 0.425 (minor). The repulsive close contacts of Cl atoms could possibly be the cause for this disorder.