Polycyclic aromatic compounds (PACs) in the Canadian environment: Exposure and effects on wildlife

Exploring avian exposure to parent polycyclic aromatic hydrocarbons (PAHs): Using the common eider Somateria mollissima in a global context

Compared to other organic contaminants, birds are rarely studied for their exposure to polycyclic aromatic hydrocarbons (PAHs), mainly due to their effective metabolization of parent PAHs. However, as some studies suggest, exposure to PAHs may result in adverse health effects including decreased survival, especially following oil spills. In the present study, we analyzed samples from a sea duck, the common eider Somateria mollissima including feathers, preen oil, blood, liver and bile, to evaluate whether non- lethally collected samples could be reliably used for avian biomonitoring strategies. Phenanthrene was the only individual PAH detected across sample types, with the highest concentration found in preen gland and the lowest in blood. Significant differences in concentrations were observed between bile vs preen gland and liver vs preen gland, while for most compounds neither blood nor feathers showed detectable levels of parent PAHs. Therefore, the utility of those sample types for PAH exposure assessment may be limited and should be interpreted with caution, moreover as several physiological factors may affect them. Additionally, we also provide a comparison with the available literature to review current avian PAH exposure assessment and outline future research focused needs.

It's time to reevaluate the list of priority polycyclic aromatic compounds: Evidence from a large urban shallow lake

Monitoring only 16 priority PAHs (Pri-PAHs) may greatly underestimate the pollutant load and toxicity of polycyclic aromatic compounds (PACs) in aquatic environments. There is an urgent need to reevaluate the list of priority PACs. To determine which PACs deserve priority monitoring, the occurrence, sources, and toxicity of 78 PACs, including 24 parent PAHs (Par-PAHs), 49 alkylated PAHs (Alk-PAHs), 3 oxygenated PAHs (OPAHs), carbazole, and dibenzothiophene were investigated for the first time in Lake Chaohu sediments, China. Concentrations of ∑Par-PAHs, ∑Alk-PAHs, and ∑OPAHs ranged from 35 to 165, 3.4-26, and 7.7-26 ng g-1, respectively. Concentrations of 16 Pri-PAHs have decreased by 1-2 orders of magnitude compared to a decade ago, owing to the effective implementation of PAHs emission control measures. Comparisons with the sediment quality guidelines indicated that 16 Pri-PAHs have negligible adverse effects on benthic organisms. Positive matrix factorization (PMF) model results showed that coal combustion was the major source of PACs (accounting for 23.5 %), followed by traffic emissions (23.4 %), petroleum volatilization (21.9 %), wood/biomass combustion (18.2 %), and biological/microbial transformation (13.1 %). The toxicity of PACs was assessed by calculating the BaP toxic equivalent concentrations (TEQBaP) and toxic units. It was found that Par-PAHs were the predominant toxic substances. In addition, monomethyl-BaPs, OPAHs, BeP, and 7,12-DMBaA should be prioritized for monitoring due to their noticeable contributions to overall toxicity. The contributions of different sources to the toxicity of PACs were determined based on PMF model results and TEQBaP values, which revealed that combustion sources mainly contributed to the comprehensive toxicity of PACs in Lake Chaohu sediments.

Interactions between phenanthrene exposure and historical chemical stress: Implications for fitness and ecological resilience of the sentinel species Daphnia magna

Polycyclic aromatic hydrocarbons (PAHs) arise from incomplete combustion of oil, coal, and gasoline, with lipophilic properties facilitating their widespread distribution and persistence. Due to their biochemical attributes, PAHs can accumulate in animal tissues, potentially causing mutagenic and carcinogenic effects. Since the industrial revolution, PAH concentrations in the environment have risen, with lakes showing levels from 0.159 to 33,090 μg/kg sediment. Despite acute toxicity studies showing adverse effects on freshwater organisms, the long-term impacts and synergistic interactions with other pollutants remain largely unexplored. This study investigates the impact of phenanthrene (PHE), a prominent PAH found in aquatic environments, on Daphnia magna, a species of significant ecological importance in freshwater ecosystems globally, being both a sentinel species for chemical pollution and a keystone organism in freshwater aquatic ecosystems. Leveraging the dormancy of D. magna, which spans decades or even centuries, we exposed strains with diverse histories of chemical contaminant exposure to environmentally relevant concentrations of PHE. Initially, acute exposure experiments were conducted in accordance with OECD guidelines across 16 Daphnia strains, revealing substantial variation in acute toxic responses, with strains naïve to chemical pollutants showing the lowest toxicity. Utilizing the median effect concentration EC10 derived from acute exposures, we assessed the impacts of chronic PHE exposure on life history traits and ecological endpoints of the 16 strains. To elucidate how historical exposure to other environmental stressors may modulate the toxicity of PHE, temporal populations of D. magna resurrected from a lake with a well-documented century-spanning history of environmental impact were utilized. Our findings demonstrate that PHE exposure induces developmental failure, delays sexual maturation, and reduces adult size in Daphnia. Populations of Daphnia historically exposed to chemical stress exhibited significantly greater fitness impacts compared to naïve populations. This study provides crucial insights into the augmented effects of PAHs interacting with other environmental stressors.

Polycyclic aromatic compounds in a northern freshwater ecosystem: Patterns, sources, and the influences of environmental factors

Polycyclic aromatic compounds (PACs) - a large group of organic chemicals naturally present in petroleum deposits (i.e., petrogenic) or released into the environment by incomplete combustion of organic materials (i.e., pyrogenic) - represent a potential risk to the health of aquatic ecosystems. In high latitude freshwater ecosystems, concentrations of PACs may be increasing, yet there are limited studies in such systems to assess change and to understand threats. Using 10 years of contemporary data from passive samplers deployed across five regions (n = 43 sites) in the Mackenzie River Basin, we (i) describe baseline levels of PACs, (ii) assess spatiotemporal patterns, and (iii) evaluate the extent to which environmental factors (fire, snowmelt, and proximity to oil infrastructure) influence concentrations in this system. Measured concentrations were low, relative to those in more southern systems, with mixtures primarily being dominated by non-alkylated, low molecular weight compounds. Concentrations were spatially consistent, except for two sites near Norman Wells (an area of active oil extraction) with increased levels. Similarly, observed annual variation was minimal, with 2014 having generally higher levels of PACs. We did not detect effects of fire, snowmelt, or oil infrastructure on concentrations. Taken together, our findings suggest that PACs in the Mackenzie River are currently at low levels and are primarily petrogenic in origin. They further indicate that ongoing monitoring and testing of environmental drivers (especially at finer spatial scales) are needed to better predict how ecosystem change will influence PAC levels in the basin and in other northern systems.

Association between single and mixed exposure to polycyclic aromatic hydrocarbons and biological aging

Background

Aging is one of the most important public health issues. Previous studies on the factors affecting aging focused on genetics and lifestyle, but the association between polycyclic aromatic hydrocarbons (PAHs) and aging is still unclear.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2003-2010. A total of 8,100 participants was used to construct the biological age predictors by using recent advanced algorithms Klemera-Doubal method (KDM) and Mahalanobis distance. Two biological aging indexes, recorded as KDM-BA acceleration and PhenoAge acceleration, were used to investigate the relationship between single PAHs and biological age using a multiple linear regression analysis, and a weighted quantile sum (WQS) model was constructed to explore the mixed effects of PAHs on biological age. Finally, we constructed the restricted cubic spline (RCS) model to assess the non-linear relationship between PAHs and biological age.

Results

Exposure to PAHs was associated with PhenoAge acceleration. Each unit increase in the log10-transformed level of 1-naphthol, 2-naphthol, and 2-fluorene was associated with a 0.173 (95% CI: 0.085, 0.261), 0.310 (95% CI: 0.182, 0.438), and 0.454 (95% CI: 0.309, 0.598) -year increase in PhenoAge acceleration, respectively (all corrected P < 0.05). The urinary PAH mixture was relevant to KDM-BA acceleration (β = 0.13, 95% CI: 0, 0.26, P = 0.048) and PhenoAge acceleration (β = 0.59, 95% CI: 0.47, 0.70, P < 0.001), and 2-naphthol had the highest weight in the weighted quantile sum (WQS) regression. The RCS analyses showed a non-linear association between 2-naphthol and 2-fluorene with KDM-BA acceleration (all P < 0.05) in addition to a non-linear association between 1-naphthol, 2-naphthol, 3-fluorene, 2-fluorene, and 1-pyrene with PhenoAge acceleration (all P < 0.05).

Conclusion

Exposure to mixed PAHs is associated with increased aging, with 2-naphthol being a key component of PAHs associated with aging. This study has identified risk factors in terms of PAH components for aging.

Sources-attributed contributions to health risks associated with PM2.5-bound polycyclic aromatic hydrocarbons during the warm and cold seasons in an urban area of Eastern Asia

Despite the well-established recognition of the health hazards posed by PM2.5-bound PAHs, a comprehensive understanding of their source-specific impact has been lacking. In this study, the health risks associated with PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and source-specific contributions were investigated in the urban region of Taipei during both cold and warm seasons. The levels of PM2.5-bound PAHs and their potential health risks across different age groups of humans were also characterized. Diagnostic ratios and positive matrix factorization analysis were utilized to identify the sources of PM2.5-bound PAHs. Moreover, potential source contribution function (PSCF), concentration-weighted trajectory (CWT) and source regional apportionment (SRA) analyses were employed to determine the potential source regions. Results showed that the total PAHs (TPAHs) concentrations ranged from 0.08 to 2.37 ng m-3, with an average of 0.69 ± 0.53 ng m-3. Vehicular emissions emerged as the primary contributor to PM2.5-bound PAHs, constituting 39.8 % of the TPAHs concentration, followed by industrial emissions (37.6 %), biomass burning (13.8 %), and petroleum/oil volatilization (8.8 %). PSCF and CWT analyses revealed that industrial activities and shipping processes in northeast China, South China Sea, Yellow Sea, and East China Sea, contributed to the occurrence of PM2.5-bound PAHs in Taipei. SRA identified central China as the primary regional contributor of ambient TPAHs in the cold season and Taiwan in the warm season, respectively. Evaluations of incremental lifetime cancer risk demonstrated the highest risk for adults, followed by children, seniors, and adolescents. The assessments of lifetime lung cancer risk showed that vehicular and industrial emissions were the main contributors to cancer risk induced by PM2.5-bound PAHs. This research emphasizes the essential role of precisely identifying the origins of PM2.5-bound PAHs to enhance our comprehension of the related human health hazards, thus providing valuable insights into the mitigation strategies.

Assessing the ecological impacts of polycyclic aromatic hydrocarbons petroleum pollutants using a network toxicity model

Polycyclic aromatic hydrocarbons (PAHs) are significant petroleum pollutants that have long-term impacts on human health and ecosystems. However, assessing their toxicity presents challenges due to factors such as cost, time, and the need for comprehensive multi-component analysis methods. In this study, we utilized network toxicity models, enrichment analysis, and molecular docking to analyze the toxicity mechanisms of PAHs at different levels: compounds, target genes, pathways, and species. Additionally, we used the maximum acceptable concentration (MAC) value and risk quotient (RQ) as an indicator for the potential ecological risk assessment of PAHs. The results showed that higher molecular weight PAHs had increased lipophilicity and higher toxicity. Benzo[a]pyrene and Fluoranthene were identified as core compounds, which increased the risk of cancer by affecting core target genes such as CCND1 in the human body, thereby influencing signal transduction and the immune system. In terms of biological species, PAHs had a greater toxic impact on aquatic organisms compared to terrestrial organisms. High molecular weight PAHs had lower effective concentrations on biological species, and the ecological risk was higher in the Yellow River Delta region. This research highlights the potential application of network toxicity models in understanding the toxicity mechanisms and species toxicity of PAHs and provides valuable insights for monitoring, prevention, and ecological risk assessment of these pollutants.

Benzo[a]pyrene disrupts LH/hCG-dependent mouse Leydig cell steroidogenesis through receptor/Gαs protein targeting

Steroidogenesis of gonadal cells is tightly regulated by gonadotropins. However, certain polycyclic aromatic hydrocarbons, including Benzo[a]pyrene (BaP), induce reproductive toxicity. Several existing studies have considered higher than environmentally relevant concentrations of BaP on male and female steroidogenesis following long-term exposure. Also, the impact of short-term exposure to BaP on gonadotropin-stimulated cells is understudied. Therefore, we evaluated the effect of 1 nM and 1 µM BaP on luteinizing hormone/choriogonadotropin (LH/hCG)-mediated signalling in two steroidogenic cell models, i.e. the mouse tumor Leydig cell line mLTC1, and the human primary granulosa lutein cells (hGLC) post 8- and 24-h exposure. Cell signalling studies were performed by homogeneous time-resolved fluorescence (HTRF) assay, bioluminescence energy transfer (BRET) and Western blotting, while immunostainings and immunoassays were used for intracellular protein expression and steroidogenesis analyses, respectively. BaP decreased cAMP production in gonadotropin-stimulated mLTC1 interfering with Gαs activation. Therefore, decrease in gonadotropin-mediated CREB phosphorylation in mLTC1 treated with 1 μM BaP was observed, while StAR protein levels in gonadotropin-stimulated mLTC1 cells were unaffected by BaP. Further, BaP decreased LH- and hCG-mediated progesterone production in mLTC1. Contrastingly, BaP failed to mediate any change in cAMP, genes and proteins of steroidogenic machinery and steroidogenesis of gonadotropin-treated hGLC. Our results indicate that short-term exposure to BaP significantly impairs steroidogenic signalling in mLTC1 interfering with Gαs. These findings could have a significant impact on our understanding of the mechanism of reproductive toxicity by endocrine disruptors.

Polycyclic aromatic hydrocarbons (PAHs) in coal preparation plant products: A contributor to environmental pollution

Coal and coal gangue are petrogenic sources of polycyclic aromatic hydrocarbons (PAHs), which cause adverse impacts on the environment. Raw coal, cleaned coal, slime, slack gangue, and lump gangue from the Pingshuo No. 1 Coal Preparation Plant, China, were analyzed to determine the concentrations and compositions of 16 priority parent PAHs (16PAHs) and their alkylated derivatives (aPAHs). The ∑16PAH and ∑aPAH concentrations in the samples ranged from 18.7 to 139.2 mg/kg and 22.2 to 262.3 mg/kg, respectively, and ranked as follows: cleaned coal > raw coal > slime > lump gangue > slack gangue. Coal gangues had a higher proportion and lower degree of alkylation of 4-6-ring PAHs than coals. A summary analysis of references related to coal and coal gangue diagnostic ratios showed that their ratios could not be used to differentiate them from other PAH sources, indicating that the release of particulate coal and coal gangue would increase the uncertainty of environmental PAH identification results. The diagnostic ratios of coal gangue were relatively concentrated, and comparing the ratio distribution could reveal the coal gangue source PAHs. The toxicity risk of slack gangue was higher than that of lump gangue based on the benzo[a]pyrene-equivalent concentration; hence, more attention should be given to its escape to the environment.

Mediterranean springs: Keystone ecosystems and biodiversity refugia threatened by global change

Mediterranean spring ecosystems are unique habitats at the interface between surface water and groundwater. These ecosystems support a remarkable array of biodiversity and provide important ecological functions and ecosystem services. Spring ecosystems are influenced by abiotic, biotic, and anthropogenic factors such as the lithology of their draining aquifers, their climate, and the land use of their recharge area, all of which affect the water chemistry of the aquifer and the spring discharges. One of the most relevant characteristics of spring ecosystems is the temporal stability of environmental conditions, including physicochemical features of the spring water, across seasons and years. This stability allows a wide range of species to benefit from these ecosystems (particularly during dry periods), fostering an unusually high number of endemic species. However, global change poses important threats to these freshwater ecosystems. Changes in temperature, evapotranspiration, and precipitation patterns can alter the water balance and chemistry of spring water. Eutrophication due to agricultural practices and emergent pollutants, such as pharmaceuticals, personal care products, and pesticides, is also a growing concern for the preservation of spring biodiversity. Here, we provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems. We then describe their ecological value and biodiversity patterns and highlight the main risks these ecosystems face. Moreover, we identify existing knowledge gaps to guide future research in order to fully uncover the hidden biodiversity within these habitats and understand the main drivers that govern them. Finally, we provide a brief summary of recommended actions that should be taken to effectively manage and preserve Mediterranean spring ecosystems for future generations. Even though studies on Mediterranean spring ecosystems are still scarce, our review shows there are sufficient data to conclude that their future viability as functional ecosystems is under severe threat.

Atmospheric Transport of Polycyclic Aromatic Hydrocarbons into Three Alpine Valleys: Influence of Local-Scale Wind Patterns and Chemical Partitioning

Current understanding of atmospheric transport of polycyclic aromatic hydrocarbons (PAHs) is limited in alpine areas due to complex meteorology and topography. To better understand atmospheric transport in these areas, we measured 16 PAHs in lichens, biomonitors of atmospheric PAHs, along three transects extending from a highway into otherwise remote alpine valleys. While the valleys neighbored one another and were morphologically similar, they differed in their orientation relative to regional winds. In the valley characterized by regional winds oriented up-valley, PAH concentrations in lichens remained consistent across the transect. In the other two valleys, where regional winds were oriented down or across the valley, 3-6 ring PAHs declined rapidly with increasing distance from the highway, and PAH concentrations in the lichens declined more rapidly for higher molecular weight PAHs than lower molecular weight PAHs. We hypothesize that this trend was driven by differences in gas-particle partitioning and vegetative scavenging between PAH congeners. These results illustrate the importance of both physical transport and chemical partitioning in alpine areas where small differences in topography can lead to significant differences in chemical transport.

Determination of sediment sources following a major wildfire and evaluation of the use of color properties and polycyclic aromatic hydrocarbons (PAHs) as tracers

Purpose

This research aimed to determine if a severe wildfire caused changes in the source of sediment being delivered to downstream aquatic systems and evaluate the use of polycyclic aromatic hydrocarbons (PAHs) and color properties as tracers.

Methods

Sediment samples were collected from 2018 to 2021 in three tributaries impacted by the 2018 Shovel Lake wildfire and from two sites on the mainstem of the Nechako River, British Columbia. Source samples were collected from burned and unburned soils as well as from channel banks and road-deposited sediment. Samples were analyzed for color properties and for the 16 US Environmental Protection Agency priority PAHs. After statistical tests to determine the conservatism and ability to discriminate between sources by the tracers, the MixSIAR unmixing model was used, and its outputs were tested using virtual mixtures.

Result

In the tributaries, burned topsoil was an important contributor to sediment (up to 50%). The mainstem Nechako River was not influenced as significantly by the fires as the greatest contributor was banks (up to 89%). The color properties provided more realistic results than those based on PAHs.

Conclusion

In smaller watersheds, the wildfire had a noticeable impact on sediment sources, though the impacts of the fire seemed to be diluted in the distal mainstem Nechako River. Color tracers behaved conservatively and discriminated between contrasting sources. Due to their low cost and reliability, they should be considered more widely. While PAHs did not work in this study, there are reasons to believe they could be a useful tracer, but more needs to be understood about their behavior and degradation over time.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11368-023-03565-0.

New insights into the bioremediation of petroleum contaminants: A systematic review

Petroleum product is an essential resource for energy, that has been exploited by wide range of industries and regular life. A carbonaceous contamination of marine and terrestrial environments caused by errant runoffs of consequential petroleum-derived contaminants. Additionally, petroleum hydrocarbons can have adverse effects on human health and global ecosystems and also have negative demographic consequences in petroleum industries. Key contaminants of petroleum products, primarily includes aliphatic hydrocarbons, benzene, toluene, ethylbenzene, and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), resins, and asphaltenes. On environmental interaction, these pollutants result in ecotoxicity as well as human toxicity. Oxidative stress, mitochondrial damage, DNA mutations, and protein dysfunction are a few key causative mechanisms behind the toxic impacts. Henceforth, it becomes very evident to have certain remedial strategies which could help on eliminating these xenobiotics from the environment. This brings the efficacious application of bioremediation to remove or degrade pollutants from the ecosystems. In the recent scenario, extensive research and experimentation have been implemented towards bio-benign remediation of these petroleum-based pollutants, aiming to reduce the load of these toxic molecules in the environment. This review gives a detailed overview of petroleum pollutants, and their toxicity. Methods used for degrading them in the environment using microbes, periphytes, phyto-microbial interactions, genetically modified organisms, and nano-microbial remediation. All of these methods could have a significant impact on environmental management.

Abiotic and biotic constituents of oil sands process-affected waters

The oil sands in Northern Alberta are the largest oil sands in the world, providing an important economic resource for the Canadian energy industry. The extraction of petroleum in the oil sands begins with the addition of hot water to the bituminous sediment, generating oil sands process-affected water (OSPW), which is acutely toxic to organisms. Trillions of litres of OSPW are stored on oil sands mining leased sites in man-made reservoirs called tailings ponds. As the volume of OSPW increases, concerns arise regarding the reclamation and eventual release of this water back into the environment. OSPW is composed of a complex and heterogeneous mix of components that vary based on factors such as company extraction techniques, age of the water, location, and bitumen ore quality. Therefore, the effective remediation of OSPW requires the consideration of abiotic and biotic constituents within it to understand short and long term effects of treatments used. This review summarizes selected chemicals and organisms in these waters and their interactions to provide a holistic perspective on the physiochemical and microbial dynamics underpinning OSPW .

iGEM as a human iPS cell-based global epigenetic modulation detection assay provides throughput characterization of chemicals affecting DNA methylation

Chemical-induced dysregulation of DNA methylation during the fetal period is known to contribute to developmental disorders or increase the risk of certain diseases later in life. In this study, we developed an iGEM (iPS cell-based global epigenetic modulation) detection assay using human induced pluripotent stem (hiPS) cells that express a fluorescently labeled methyl-CpG-binding domain (MBD), which enables a high-throughput screening of epigenetic teratogens/mutagens. 135 chemicals with known cardiotoxicity and carcinogenicity were categorized according to the MBD signal intensity, which reflects the degree of nuclear spatial distribution/concentration of DNA methylation. Further biological characterization through machine-learning analysis that integrated genome-wide DNA methylation, gene expression profiling, and knowledge-based pathway analysis revealed that chemicals with hyperactive MBD signals strongly associated their effects on DNA methylation and expression of genes involved in cell cycle and development. These results demonstrated that our MBD-based integrated analytical system is a powerful framework for detecting epigenetic compounds and providing mechanism insights of pharmaceutical development for sustainable human health.

State of polycyclic aromatic hydrocarbon (PAH) contamination in the Saint John Harbour, New Brunswick, Canada

This study examined the concentrations and compositions of polycyclic aromatic hydrocarbon (PAH) contaminants in the surficial sediments of the Saint John Harbour (SJH) and assessed PAH exposure to local aquatic biota. Our findings suggest that sedimentary PAH contamination is heterogeneous and widespread in the SJH, with several sites exceeding the Canadian and NOAA recommended guidelines for the protection of aquatic life. Despite high concentrations of PAHs at some sites, there was no indication that local nekton was affected. Lack of a biological response may be due in part to a low bioavailability of sedimentary PAHs, presence of confounding factors (e.g., trace metals), and/or adaptation of local wildlife to the historic PAH contamination in this region. Overall, although no indication of effects to wildlife was observed with the data collected in the present study, continued efforts should be made to remediate highly contaminated areas and reduce the prevalence of these compounds.

Legacy and emerging contaminants in flamingos' chicks' blood from the Ebro Delta Natural Park

The Ebro Delta is a wetland of international importance for waterbird conservation but severally affected by intensive agriculture, toxic waste discharges from a past chloro-alkali industry and affluence of tourism. The discharge of contaminants associated to these activities pose waterbirds breeding in the Ebro Delta at risk. The aim of this study is to evaluate the exposure of 91 emerging and legacy micropollutants in flamingo chicks (Phoenicopterus roseus), an emblematic species of the area. Fifty chicks of 45-60 days were captured, biometric parameters measured and whole blood collected. Compounds analyzed included perfluoroalkyl substances (PFASs), pharmaceuticals, organophosphate esters (OPEs), in-use pesticides, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), and polycyclic aromatic hydrocarbons (PAHs). The results indicate a multi-exposure of flamingo's chicks from a very young age. PFASs were the most ubiquitous compounds with ∑PFASs ranging from 9.34 to 576 ng/mL, being PFOA, PFOS and PFHxS detected in all samples. ∑PAHs ranged from 0.19 to 423 ng/mL, ∑PCBs from 0.5 to 15.6 ng/mL and ∑OCs from 1.35 to 37.8 ng/mL. Pharmaceuticals, OPEs and in-use pesticides were not detected. The flamingo's filtering behavior on mud and maternal ovo-transference are the more likely routes of exposure of organic micropollutants to flamingos' chicks. The reported levels of micropollutants were not associated with any alteration in the body condition of chicks. This is the first study to describe flamingos chicks' exposure to multiple contaminants, highlighting the importance of biomonitoring for wildlife conservation and biodiversity preservation.

Combustion of crude oil during in-situ burning can introduce polycyclic aromatic compounds (PACs) into small-scale freshwater systems

In-situ burning (ISB) is the controlled combustion of an oil slick to remove large quantities of spilled oil from the aquatic environment. Prior to employing ISB as a remediation technique, an oil slick must often be corralled by physical or chemical means to achieve a sufficient thickness (typically >1 mm) for ignition. While ISB is an effective means to remove oil mass, less is known about the potential for ISB to mobilize polycyclic aromatic compounds (PACs) into the aquatic environment. The PACs are primary contaminants of concern in crude oil due to their environmental persistence and toxicity. We examined the potential for ISB to mobilize PACs into underlying waters in a series of small-scale burns conducted across a gradient of oil slick thicknesses (0-7 mm). Concentrations of PACs in underlying waters were evaluated and compared to reference conditions using an equivalent gradient of oil slick thicknesses that were not ignited. At thinner slick thicknesses (i.e. 0 - 4 mm) ISB enhanced the mobilization of total PACs, likely a result of heat transfer to underlying waters; this effect increased as slick thickness increased. Among thicker slicks (i.e. 4 - 7 mm), pyrogenic PACs became more prevalent and greater concentrations of 4-ring PACs were detected in underlying waters. The potential for PAC mobilization needs to be considered in scenarios where ISB may be the only viable oil spill remediation option (e.g. wetlands, marshes, or where oil is entrained) and in shallow systems susceptible to temperature changes.

Monitoring ocean water quality by deployment of lumpfish (Cyclopterus lumpus) eggs: In situ bioaccumulation and toxicity in embryos

Fish embryos can bioaccumulate and are particularly sensitive to a wide range of contaminants, which makes them suitable sentinels for environmental biomonitoring. However, fish embryos are very rarely utilized in environmental monitoring surveys, possibly due to their fragility and seasonality. In the present work, we assessed the applicability of caged lumpfish (Cyclopterus lumpus) eggs for in situ biomonitoring of exposure and effects of organic contaminants focusing on polyaromatic hydrocarbons and phenolic compounds. Fertilized eggs (1 dpf) were transplanted for 17-19 days at different locations that differed in terms of contaminant load, depths and weather conditions, namely at three stations close to the city of Trondheim (two harbour areas and a one in the Fjord) and three stations at a coastal aquaculture facility. High survival upon retrieval after deployment showed that lumpfish eggs are relatively robust and survive encaging in different environments. Bioaccumulation of organic contaminants (PAHs and phenolic compounds) was measured and potential effects on hatching, development, survival and larvae morphometry were determined. Chemical analyses showed that especially PAHs were effectively accumulated in eggs in contaminated sites, with concentrations of ƩPAHs being 15 - 25 times higher in harbour areas compared to those at the aquaculture facility. A higher incidence of embryonic deformations was observed in the most polluted deployment location, but larvae morphometry revealed no evidence of toxicity related to pollutant body burden. In conclusion, the in-situ exposure method was proven to work well, making it attractive for implementations in environmental monitoring programs.

Vanillic acid attenuates cell proliferation, xenobiotic enzyme activity, and the status of pulmonary mitochondrial enzymes in lung carcinoma

The purpose of the study is to determine the anti-proliferative and mitochondrial status of benzo(a)pyrene-induced lung cancer in Swiss albino mice, as well as the modulatory effect of vanillic acid on it. B(a)P had altered levels of lysosomal enzymes, xenobiotic-metabolizing enzymes, cell proliferation, inflammation, and mitochondrial abnormalities, whereas treatment with VA treatment significantly reversed the aforementioned activities. According to the findings, VA greatly reduces lung carcinogenesis by restoring antioxidants and xenobiotic-enzyme levels, consequently proving to be an anti-proliferative and anti-inflammatory drug against lung cancer in mice. PRACTICAL APPLICATIONS: As we all know, lung cancer is on the rise all over the world. A recent study demonstrated that vanillic acid protects against B(a)P in experimental mice. According to the findings, VA considerably suppresses lung carcinogenesis by restoring lysosomal enzyme levels, xenobiotic-metabolizing enzyme levels, and mitochondrial activities, effectively functioning as an anti-proliferative and anti-inflammatory therapy against lung cancer. According to the most recent study, vanillic acid can be used as a defensive medicine in the treatment of lung cancer.

Alkylation of Benz[a]anthracene Affects Toxicity to Early-Life Stage Zebrafish and In Vitro Aryl Hydrocarbon Receptor 2 Transactivation in a Position-Dependent Manner

Polycyclic aromatic hydrocarbons (PAHs) are structurally diverse organic chemicals that can have adverse effects on the health of fishes through activation of aryl hydrocarbon receptor 2 (AhR2). They are ubiquitous in the environment, but alkyl PAHs are more abundant in some environmental matrices. However, relatively little is known regarding the effects of alkylation on the toxicity of PAHs to fishes in vivo and how this relates to potency for activation of AhR2 in vitro. Therefore, the objectives of the present study were to determine the toxicity of benz[a]anthracene and three alkylated homologs representing various alkylation positions to early life stages of zebrafish (Danio rerio) and to assess the potency of each for activation of the zebrafish AhR2 in a standardized in vitro AhR transactivation assay. Exposure of embryos to each of the PAHs caused a dose-dependent increase in mortality and malformations characteristic of AhR2 activation. Each alkyl homolog had in vivo toxicities and in vitro AhR2 activation potencies different from those of the parent PAH in a position-dependent manner. However, there was no statistically significant linear relationship between responses measured in these assays. The results suggest a need for further investigation into the effect of alkylation on the toxicity of PAHs to fishes and greater consideration of the contribution of alkylated homologs in ecological risk assessments. Environ Toxicol Chem 2022;41:1993-2002. © 2022 SETAC.

Decadal differences in polycyclic aromatic compound (PAC) concentrations in two seabird species in Arctic Canada

Seabirds are exposed to a variety of environmental contaminants in the Arctic. While the persistence, bioaccumulation, and toxicity of some groups of contaminants have been well-studied in seabirds since the 1970s, there is less known about polycyclic aromatic compounds (PACs). With increased vessel traffic, and potential oil and gas development in the Arctic region, there is a need to understand existing PAC exposure in biota against which to compare potential effects of anticipated increases of PACs in the marine region. Thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) collected in the Baffin Bay - Davis Strait region during the International Polar Year (IPY; 2007-08), and during a recent Strategic Environmental Assessment (2018; SEA) were examined for hepatic PAC concentrations. We found that fulmars generally had higher concentrations of PACs than the murres, but murres and fulmars sampled in 2007/08 had higher concentrations of most groups of PACs compared to birds from 2018. The one exception to this pattern was that the sum of the alkylated congeners of the heterocyclic aromatic compounds containing a sulfur atom (dibenzothiophene; ΣAHET) was significantly higher in murres in the more recent sampling period (2018) as compared to 2007/08. ΣAHETs likely reflect recent exposure to more refined petroleum products associated with small boats, such as diesel, gasoline and motor oil. This work highlights the need for longitudinal studies on PAC concentrations in biota for us to gain a better understanding of how Arctic biota are exposed to this group of contaminants, and the potential deleterious effects associated with PACs.

An Emerging Cross-Species Marker for Organismal Health: Tryptophan-Kynurenine Pathway

Tryptophan (TRP) is an essential dietary amino acid that, unless otherwise committed to protein synthesis, undergoes metabolism via the Tryptophan-Kynurenine (TRP-KYN) pathway in vertebrate organisms. TRP and its metabolites have key roles in diverse physiological processes including cell growth and maintenance, immunity, disease states and the coordination of adaptive responses to environmental and dietary cues. Changes in TRP metabolism can alter the availability of TRP for protein and serotonin biosynthesis as well as alter levels of the immune-active KYN pathway metabolites. There is now considerable evidence which has shown that the TRP-KYN pathway can be influenced by various stressors including glucocorticoids (marker of chronic stress), infection, inflammation and oxidative stress, and environmental toxicants. While there is little known regarding the role of TRP metabolism following exposure to environmental contaminants, there is evidence of linkages between chemically induced metabolic perturbations and altered TRP enzymes and KYN metabolites. Moreover, the TRP-KYN pathway is conserved across vertebrate species and can be influenced by exposure to xenobiotics, therefore, understanding how this pathway is regulated may have broader implications for environmental and wildlife toxicology. The goal of this narrative review is to (1) identify key pathways affecting Trp-Kyn metabolism in vertebrates and (2) highlight consequences of altered tryptophan metabolism in mammals, birds, amphibians, and fish. We discuss current literature available across species, highlight gaps in the current state of knowledge, and further postulate that the kynurenine to tryptophan ratio can be used as a novel biomarker for assessing organismal and, more broadly, ecosystem health.

The effects of dissolved petroleum hydrocarbons on benthic organisms: Chironomids and amphipods

The oil sands industry in Canada, produces heavy unconventional oils, diluted for transport and called diluted bitumen. However, despite advances in our knowledge of the ecotoxicological risk that these products represent, their effects on benthic organisms following a spill are still largely unknown. In order to fill these gaps, this study aims to determine the lethal and sublethal effects of two diluted bitumens (Bluesky and Cold Lake) and one conventional oil (Lloydminster) for two freshwater benthic invertebrates: Chironomus riparius and Hyalella azteca. The objective of this study is to assess the toxicity of dissolved hydrocarbons, resulting from the physical dispersion of oil, immediately after a spill on the benthic invertebrates. To this end, organisms were exposed for 7 days for chironomids and 14 days for amphipods to a fraction containing soluble hydrocarbons (WAF: water accommodated fraction; 10 g/L, 18 h of agitation, followed by 6 h of sedimentation) with natural or artificial sediment. After exposure, the effects of hydrocarbons were determined using size, mortality, and antioxidant capacities. Dissolved hydrocarbons induced mortality for both species, but these hydrocarbons disappeared very quickly from the water column, regardless of the oil type. The amphipods were sensitive to both types of oil while the chironomids were only sensitive to diluted bitumens. The presence of a natural sediment seems to provide a protective role against dissolved hydrocarbons. The antioxidant enzymes measured (CAT, SOD and GPx) do not appear to be relevant biomarkers for the exposure of these organisms to diluted bitumen.

The effects of polycyclic aromatic compounds (PACs) on mammalian ovarian function

•

Toxicity of polycyclic aromatic compounds (PACs) is limited to a subset of PACs.

•

Exposure to these compounds impact major processes necessary for ovarian function.

•

PAC exposure causes follicle loss and aberrant steroid production and angiogenesis.

•

PAC exposure may increase the risk for impaired fertility and ovarian pathologies.

•

The study of PACs as ovarian toxicants should include additional compounds.

Polycyclic aromatic compounds (PACs) are a broad class of contaminants ubiquitously present in the environment due to natural and anthropogenic activities. With increasing industrialization and reliance on petroleum worldwide, PACs are increasingly being detected in different environmental compartments. Previous studies have shown that PACs possess endocrine disruptive properties as these compounds often interfere with hormone signaling and function. In females, the ovary is largely responsible for regulating reproductive and endocrine function and thus, serves as a primary target for PAC-mediated toxicity. Perturbations in the signaling pathways that mediate ovarian folliculogenesis, steroidogenesis and angiogenesis can lead to adverse reproductive outcomes including polycystic ovary syndrome, premature ovarian insufficiency, and infertility. To date, the impact of PACs on ovarian function has focused predominantly on polycyclic aromatic hydrocarbons like benzo(a)pyrene, 3-methylcholanthrene and 7,12-dimethylbenz[a]anthracene. However, investigation into the impact of substituted PACs including halogenated, heterocyclic, and alkylated PACs on mammalian reproduction has been largely overlooked despite the fact that these compounds are found in higher abundance in free-ranging wildlife. This review aims to discuss current literature on the effects of PACs on the ovary in mammals, with a particular focus on folliculogenesis, steroidogenesis and angiogenesis, which are key processes necessary for proper ovarian functions.

Microsatellite mutation frequencies in river otters (Lontra Canadensis) from the Athabasca Oil Sands region are correlated to polycyclic aromatic compound tissue burden

Mining activities in the Athabasca oil sands region (AOSR) have contributed to an increase of polycyclic aromatic compounds (PACs) locally. However, many PACs found in the AOSR, and the combined effects of PAC mixtures have not been evaluated for genotoxicity in wildlife. Here, we examine whether mutation frequencies in AOSR river otters are correlated to PAC tissue burdens. We used single-molecule polymerase chain reaction (SM-PCR) to measure the mutant frequency of unstable DNA microsatellite loci in the bone marrow of wild river otters (n = 11) from the AOSR. Microsatellite mutation frequencies were regressed against liver PAC burden (total, low/high molecular weight [LMW/HMW], and parent/alkylated PACs), and to the distances from where the samples were collected to nearby bitumen upgraders. We found that microsatellite mutation frequency was positively correlated with total liver PAC burden. LMW and alkylated PACs were detected at higher levels and had a stronger positive relationship with mutation frequency than HMW (alkylated and parent) PACs. There were no significant relationships detected between mutation frequency and LMW parent PACs or the distance from bitumen upgraders. Furthermore, pyrogenic and petrogenic signatures suggest PACs in animals with high mutation frequencies were associated with combustion processes; although further investigation is warranted, due to limitations of diagnostic ratio determination with biotic models. Our findings support the hypothesis that PACs found in the AOSR increase mutation frequency in wildlife. Further investigation is required to determine if the elevated PAC levels associated with higher mutation frequency are due to natural exposure or elevated human activity.

Resilience of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from naturally weathered diluted bitumen in a boreal lake

The risks to aquatic wildlife from spills of diluted bitumen (dilbit) into inland waters are poorly understood. In this paper, we describe the response of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from experimental spills of dilbit in a temperate boreal lake. To simulate a wide range of environmentally relevant oil spill scenarios, different volumes of Cold Lake Winter Blend dilbit (0, 1.5, 2.9, 5.5, 18, 42, 82, and 180 L) were added to 10 m diameter in-lake limnocorrals. Larvae (n = 360) were reared (from Gosner Stage (GS) 25 to ∼42) in land-based aquatic microcosms, where they were first exposed to clean water during a 2-week baseline phase, and then (at GS ∼30), to contaminated water withdrawn from the limnocorrals for 3 weeks. We observed no statistically significant trends in survival, growth, or development of larvae as a consequence of exposure to the chemical compounds released from naturally weathered dilbit. Likewise, neither cytochrome P450 1A biomarkers nor levels of thyroid hormones in wood frogs near metamorphic climax were significantly related to volume of the oil spills. However, there was a modest statistically significant decrease in larval activity (up to 8.7% relative to the control), but no change in other behavioral metrics (i.e., sociality or space use). Our work adds to the limited body of literature on the effects of unconventional oils on aquatic wildlife and helps to inform risk assessments regarding pipeline projects.

High resolution Orbitrap mass spectrometry analysis of oxidized hydrocarbons found in freshwater following a simulated spill of crude oil

Negative ion electrospray Orbitrap mass spectrometry was used to analyze water samples taken from a pilot-scale spill tank test of conventional crude oil on freshwater. A 56-day spill test was performed, and water samples were taken at regular intervals throughout the test to determine what changes in water chemistry occur with time. Orbitrap mass spectrometry was used to measure oxidized species in water samples, and oxidized species are analyzed by carbon number, double bond equivalent and hydrocarbon class. Emphasis is placed on changes with time over the course of the spill test, to examine changes by weathering processes that could occur naturally in a field spill scenario. Results demonstrate that while the concentrations of polycyclic aromatic hydrocarbons decrease in the water phase over time, the concentrations of total organic carbon and oxidized species in the water increase with time, where quantities of O2 and O3 species have the highest abundance. Measurement of increasing concentrations and changing relative abundances of these oxidized compounds can be used to assess how oil behaves in a freshwater aquatic environment after a spill.

Metabolomic profiles in relation to benchmark polycyclic aromatic compounds (PACs) and trace elements in two seabird species from Arctic Canada

While exposure of birds to oil-related contaminants has been documented, the related adverse effects this exposure has on Arctic marine birds remain unexplored. Metabolomics can play an important role to explore biologically relevant metabolite biomarkers in relation to different stressors, even at benchmark levels of contamination. The aim of this study was to characterize the metabolomics profiles in relation to polycyclic aromatic compounds (PACs) and trace elements in the liver of two seabird species in the Canadian Arctic. In July 2018, black guillemots (Cepphus grylle) and thick-billed murres (Uria lomvia) were collected by hunters from a region where natural oil seeps occur in the seabed near Qikiqtarjuaq, Nunavut, Canada. A total of 121 metabolites were identified in liver tissue samples using reversed phase and hydrophilic interaction liquid chromatography coupled to high resolution mass spectrometry platforms to detect non-polar and polar metabolites, respectively. Sixty-nine metabolites showed excellent repeatability and linearity and were used to examine possible effects of oil-related contaminants exposure (PACs and trace elements). Metabolites including 3-hydroxy anthranilic acid, adenine, adenosine, adenosine mono-phosphate, ascorbic acid, butyrylcarnitine, cholic acid, guanosine, guanosine mono-phosphate, inosine, norepinephrine and threonine showed significant differences (more than two fold) between the two species. Elevated adenine and adenosine, along with decreased reduced/oxidized glutathione ratio, highlighted the potential for oxidative stress in murres. Lipid peroxidation and superoxide dismutase activity assays also confirmed these metabolomic findings. These results will help to characterize the baseline metabolomic profiles of Arctic seabird species with different foraging behaviour and trace element burden.

A synthetic review of terrestrial biological research from the Alberta oil sands region: 10 years of published literature

In the past decade, a large volume of peer-reviewed papers has examined the potential impacts of oil and gas resource extraction in the Canadian oil sands (OS). A large proportion focuses on terrestrial biology: wildlife, birds, and vegetation. We provide a qualitative synthesis of the condition of the environment in the oil sands region (OSR) from 2009 to 2020 to identify gaps and progress cumulative effects assessments. Our objectives were to (1) qualitatively synthesize and critically review knowledge from the OSR; (2) identify consistent trends and generalizable conclusions; and (3) pinpoint gaps in need of greater monitoring or research effort. We visualize knowledge and terrestrial monitoring foci by allocating papers to a conceptual model for the OS. Despite a recent increase in publications, focus has remained concentrated on a few key stressors, especially landscape disturbance, and a few taxa of interest. Stressor and response monitoring is well represented, but direct monitoring of pathways (linkages between stressors and responses) is limited. Important knowledge gaps include understanding effects at multiple spatial scales, mammal health effects monitoring, focused monitoring of local resources important to Indigenous communities, and geospatial coverage and availability, including higher attribute resolution in human footprint, comprehensive land cover mapping, and up-to-date LiDAR coverage. Causal attribution based on spatial proximity to operations or spatial orientation of monitoring in the region is common but may be limited in the strength of inference that it provides. Integr Environ Assess Manag 2022;18:388-406. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Effects of diluted bitumen exposure on the survival, physiology, and behaviour of zebra finches (Taeniopygia guttata)

Diluted bitumen (dilbit) is an unconventional crude petroleum increasingly being extracted and transported to market by pipeline and tanker. Despite the transport of dilbit through terrestrial, aquatic, and coastal habitat important to diverse bird fauna, toxicity data are currently only available for fish and invertebrates. We used the zebra finch (Taeniopygia guttata) as a tractable, avian model system to investigate exposure effects of lightly weathered Cold Lake blend dilbit on survival, tissue residue, and a range of physiological and behavioural endpoints. Birds were exposed via oral gavage over 14-days with dosages of 0, 2, 4, 6, 8, 10, or 12 mL dilbit/kg bw/day. We identified an LD₅₀ of 9.4 mL/kg/d dilbit, with complete mortality at 12 mL/kg/d. Mortality was associated with mass loss, external oiling, decreased pectoral and heart mass, and increased liver mass. Hepatic ethoxyresorufin-O-deethylase activity (EROD) was elevated in all dilbit-dosed birds compared with controls but there was limited evidence of sublethal effects of dilbit on physiological endpoints at doses < 10 mL/kg/d (hematocrit, hemoglobin, total antioxidants, and reactive oxygen metabolites). Dilbit exposure affected behavior, with more dilbit-treated birds foraging away from the feeder, more birds sleeping or idle at low dilbit doses, and fewer birds huddling together at high dilbit doses. Naphthalene, dibenzothiophene, and their alkylated congeners in particular (e.g. C2-napthalene and C2-dibenzothiophene) accumulated in the liver at greater concentrations in dilbit-treated birds compared to controls. Although directly comparable studies in the zebra finch are limited, our mortality data suggest that dilbit is more toxic than the well-studied MC252 conventional light crude oil with this exposure regime. A lack of overt sublethal effects at lower doses, but effects on body mass and composition, behaviour, high mortality, and elevated PAC residue at doses ≥ 10 mL/kg/d suggest a threshold effect.

Ecotoxicological impacts of oil sand mining activity to endemic caged mussels Pyganodon grandis

The intense mining extraction of oil sand (OS) has increased over the last few decades, raising concerns about the release of OS contaminants and toxicity in resident aquatic organisms in the Athabasca River (Alberta, Canada). To address this, endemic Pyganodon grandis mussels were caged for 6 weeks at various upstream and downstream sites of industrial OS mining activities. Post-exposure mussels were then analyzed for light/medium/heavy polyaromatic hydrocarbons (PAHs) in tissues, general health (weight to length ratio, growth rate, air survival time), biotransformation (cytochrome P4501A and 3A and glutathione S-transferase activities), oxidative stress/inflammation (lipid peroxidation-LPO and arachidonate cyclooxygenase-COX), genotoxicity (DNA strand breaks), and gonad status (triglycerides, GSI and vitellogenin-like proteins). The following effects significantly differed between OS mining area and natural/background sites: health condition, growth rate, air survival time, COX (immune/inflammation) activity, P4501A/GST activity, LPO and DNA breaks in the digestive gland and vitellogenin-like proteins in the gonad. Correlation analysis revealed that the biochemical responses were scaled to at least one of the following impacts at the individual level: air survival time, weight to length ratio, growth rate and vitellogenin-like proteins. These indices were therefore identified as key adverse outcome pathways of mussels impacted by OS mining activities. Based on the relative levels of light/medium/heavy PAHs in tissues, the observed effects appears to be associated rather to the disturbance of OS in this area than contamination from OS tailing ponds leaching into the aquatic environment.

Effects of Avian Eggshell Oiling With Diluted Bitumen Show Sublethal Embryonic Polycyclic Aromatic Compound Exposure

Breeding birds that become oiled may contaminate the shells of their eggs, and studies of conventional crude oil suggest that even small quantities can be absorbed through the eggshell and cause embryotoxicity. Unconventional crude oils remain untested, so we evaluated whether a major Canadian oil sands product, diluted bitumen (dilbit), would be absorbed and cause toxicity when applied to eggshells of two species, domestic chicken (Gallus gallus domesticus) and double-crested cormorant (Nannopterum auritum). We artificially incubated eggs and applied lightly weathered dilbit (Cold Lake blend) to the eggshells (0.015-0.15 mg g^-1 egg in chicken; 0.1-0.4 mg g^-1 egg in cormorant) at various points during incubation before sampling prehatch embryos. Polycyclic aromatic compound (PAC) residue in cormorant embryos was elevated only at the highest dilbit application (0.4 mg g^-1 egg) closest (day 16) to sampling on day 22. In contrast, cormorant liver cytochrome P450 1a4 (Cyp1a4) mRNA expression (quantitative polymerase chain reaction assay) was elevated only in embryos treated with the earliest and lowest dilbit application (0.1 mg g^-1 egg on day 4). These results confirm that dilbit can cross through the eggshell and be absorbed by embryos, and they imply rapid biotransformation of PACs and a nonmonotonic Cyp1a4 response. Despite evidence of exposure in cormorant, we found no detectable effects on the frequency of survival, deformity, and gross lesions, nor did we find effects on physiological endpoints indicative of growth and cardiovascular function in either chicken or cormorant. In ovo dilbit exposure may be less toxic than well-studied conventional crude oils. The effects of an oil spill scenario involving dilbit to bird embryos might be subtle, and PACs may be rapidly metabolized. Environ Toxicol Chem 2022;41:159-174. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Biodegradation of 4-hydroxybenzoic acid by Acinetobacter johnsonii FZ-5 and Klebsiella oxytoca FZ-8 under anaerobic conditions

4-Hydroxybenzoic acid (4-HBA) is a common organic compound that is prevalent in the environment, and the persistence of 4-HBA residues results in exertion of pollution-related detrimental effects. Bioremediation is an effective method for the removal of 4-HBA from the environment. In this study, two bacterial strains FZ-5 and FZ-8 capable of utilizing 4-HBA as the sole carbon and energy source under anaerobic conditions were isolated from marine sediment samples. Phylogenetic analysis identified the two strains FZ-5 and FZ-8 as Acinetobacter johnsonii and Klebsiella oxytoca, respectively. The strains FZ-5 and FZ-8 degraded 2000 mg·L^-1 4-HBA in 72 h with degradation rates of 71.04% and 80.10%, respectively. The optimum culture conditions for degradation by the strains and crude enzymes were also investigated. The strains FZ-5 and FZ-8 also exhibited the ability to degrade other lignin-derived compounds, such as protocatechuic acid, cinnamic acid, and vanillic acid. Immobilization of the two strains showed that they could be used for the bioremediation of 4-HBA in an aqueous environment. Soils inoculated with the strains FZ-5 and FZ-8 showed higher degradation of 4-HBA than the uninoculated soil, and the strains could survive efficiently in anaerobic soil. This is the first report of 4-HBA-degrading bacteria, belonging to the two genera, which showed degradation ability under anaerobic conditions. This study expound the strains could efficiently degrade 4-HBA in anaerobic soil and will help in the development of 4-HBA anaerobic bioremediation systems.

Environmental profile, distributions and potential sources of halogenated polycyclic aromatic hydrocarbons

Halogenated polycyclic aromatic hydrocarbons (HPAHs) are high lipophilic and degradation-resistant, which have been detected in the air, water, sediment and biota. HPAHs tend to have strong adverse effects on animals and humans. Although we have realized HPAHs are emerging contaminants which needs to be paid attention, there is still a lack of their individual commercial standards. This makes it difficult for understanding HPAHs comprehensively. This review is devoted to collect all the results have reported, and give a systemic look of their global distributions, influence factors and sources. Compared with air, studies on other environmental matrices (water and sediment) are more limited. The researches on organisms are fewest. Comparing the studied congeners, there are more studies on ClPAHs than BrPAHs. Human activities contribute mostly to their occurrence. Further, we then also introduce the toxicity and analytical methods to better understand HPAHs. The future research directions are also provided. Through this review, we can conclude there is an urgent need to develop analysis methods and ecologic risk assessment for better exploring HPAHs. Effective methods should be done to control HPAHs. Therefore, this review can provide a good basis for researchers to understand and control global pollution.

Polycyclic aromatic compounds in the Canadian Environment: Aquatic and terrestrial environments

Polycyclic aromatic compounds (PACs) are ubiquitous across environmental media in Canada, including surface water, soil, sediment and snowpack. Information is presented according to pan-Canadian sources, and key geographical areas including the Great Lakes, the Alberta Oil Sands Region (AOSR) and the Canadian Arctic. Significant PAC releases result from exploitation of fossil fuels containing naturally-derived PACs, with anthropogenic sources related to production, upgrading and transport which also release alkylated PACs. Continued expansion of the oil and gas industry indicates contamination by PACs may increase. Monitoring networks should be expanded, and include petrogenic PACs in their analytical schema, particularly near fuel transportation routes. National-scale roll-ups of emission budgets may not expose important details for localized areas, and on local scales emissions can be substantial without significantly contributing to total Canadian emissions. Burning organic matter produces mainly parent or pyrogenic PACs, with forest fires and coal combustion to produce iron and steel being major sources of pyrogenic PACs in Canada. Another major source is the use of carbon electrodes at aluminum smelters in British Columbia and Quebec. Temporal trends in PAC levels across the Great Lakes basin have remained relatively consistent over the past four decades. Management actions to reduce PAC loadings have been countered by increased urbanization, vehicular emissions and areas of impervious surfaces. Major cities within the Great Lakes watershed act as diffuse sources of PACs, and result in coronas of contamination emanating from urban centres, highlighting the need for non-point source controls to reduce loadings.

New approaches to reduce sample processing times for the determination of polycyclic aromatic compounds in environmental samples

This study validates two approaches to streamlining the processing of sediment and biota for a suite of polycyclic aromatic compounds (PACs) with a wide range of chemical properties, including polycyclic aromatic hydrocarbons (PAHs) and alkyl-PAHs (APAHs), and a new class of environmental contaminants, halogenated PAHs (HPAHs). One method is based on one-step in situ extraction/cleanup using accelerated solvent extraction (ASE) in which a mixture of copper, deactivated alumina and silica gel were added directly to the ASE cell along with sample; the second technique is based on dispersive solid phase extraction (dSPE) using alumina/silica for cleanup of biota samples to augment conventional ASE extraction combined with gel permeation chromatography. Validation protocols were performed in accordance with the ISO/IEC 17025 guidelines, whereby method performance characteristics, i.e., accuracy, precision, linearity, limits of detection and ruggedness, were evaluated. Accuracies generally ranged from 70 to 120% for the in situ ASE method and 70-100% for the dSPE technique. Limits of detection/quantitation for the 45 target analytes for in situ ASE and dSPE methods were determined to be < 2.5/8 pg μL^-1, and < 20/60 pg μL^-1, respectively. Intra- and inter-day repeatability for both methods were < 25% except for 1 APAH which had an inter-day precision of 35% using the dSPE method. Neither method was affected by any of the purposeful changes attempted which implies that both methods are robust. Results of our validation studies showed excellent data quality for both methods in addition to achieving a reduction in sample processing times.

Isotopic Analyses Fingerprint Sources of Polycyclic Aromatic Compound-Bearing Dust in Athabasca Oil Sands Region Snowpack

Fugitive dust associated with surface mining activities is one of the principal vectors for transport of airborne contaminants in Canada's Athabasca oil sands region (AOSR). Effective environmental management requires quantitative identification of the sources of this dust. Using natural abundance radiocarbon (Δ¹⁴C) and dual (δ¹³C, δ²H) compound-specific isotope analysis (CSIA), this study investigated the sources of dust and particulate-bound polycyclic aromatic compounds (PACs) deposited in AOSR lake snowpack. Lower Δ¹⁴C values, higher particulate and PAC loadings, and lower δ¹³C values for phenanthrene and C1-alkylated phenanthrenes/anthracenes (C1-Phen) at sites closer to the mining operations indicated unprocessed oil sand and/or petroleum coke (petcoke-a byproduct of bitumen upgrading) as major sources of anthropogenic fugitive dust. However, a Bayesian isotopic mixing model that incorporated both δ¹³C and δ²H could discriminate petcoke from oil sand, and determined that petcoke comprised between 44 and 95% (95% credibility intervals) of a C1-Phen isomer at lakes <25 km from the heart of the mining operations, making it by far the most abundant source. This study is the first to demonstrate the potential of CSIA to provide accurate PAC source apportionment in snowpack and reveals that petcoke rather than oil sand is the main source of mining-related particulate PACs deposited directly to AOSR lakes.

Alkylated polycyclic aromatic hydrocarbons are the largest contributor to polycyclic aromatic compound concentrations in traditional foods of the Bigstone Cree Nation in Alberta, Canada

Rising global demand for energy promotes extensive mining of natural resources, such as oil sands extractions in Alberta, Canada. These extractive activities release hazardous chemicals into the environment, such as polycyclic aromatic compounds (PACs), which include the parent polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and sulfur-containing heterocyclic dibenzothiophenes (DBTs). In areas adjacent to industrial installations, Indigenous communities may be exposed to these PACs through the consumption of traditional foods. Our objective was to evaluate and compare the concentrations of total PACs (∑PAC), expressed as the sum of the 16 U.S. EPA priority PAHs (∑PAH), 49 alkylated PAHs (∑alkyl-PAH), and 7 DBTs (∑DBT) in plant and animal foods collected in 2015 by the Bigstone Cree Nation in Alberta, Canada. We analyzed 42 plant tissues, 40 animal muscles, 5 ribs, and 4 pooled liver samples. Concentrations of ∑PAC were higher in the lichen, old man's beard (Usnea spp.) (808 ± 116 ng g^-1 w.w.), than in vascular plants, and were also higher in smoked moose (Alces alces) rib (461 ± 120 ng g^-1 w.w.) than in all other non-smoked animal samples. Alkylated-PAHs accounted for between 63% and 95% of ∑PAC, while the concentrations of ∑PAH represented 4%-36% of ∑PAC. Contributions of ∑DBT to ∑PAC were generally lowest, ranging from <1% to 14%. While the concentrations of benzo(a)pyrene (B[a]P) and ∑PAH4 (∑benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and B[a]P) in all samples were below guideline levels for human consumption as determined by the European Commission, guideline levels for the more prevalent alkylated PAHs are not available. Given the predominance of alkylated PAHs in all food samples and the potentially elevated toxicity relative to parent PAHs of this class of PACs, it is critical to consider a broader range of PACs other than just parent PAHs in research conducted close to oil sands mining activities.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Ambient air and deposition

Polycyclic aromatic compounds (PACs) in Canadian air and deposition were examined at the national scale for the first time in over twenty-five years. Air concentrations spanned four orders of magnitude, and were highest near industrial emitters and lowest in the Arctic. Declines in unsubstituted PAHs were observed at locations close to industrial facilities that had reduced emissions, but trends elsewhere were modest or negligible. Retene concentrations are increasing at several locations. Ambient concentrations of benzo[a]pyrene exceeded Ontario's health-based guideline in many urban/industrial areas. The estimated toxicity of the ambient PAC mixture increased by up to a factor of six when including compounds beyond the US EPA PAHs. Knowledge of PAC deposition is limited to the Laurentian Great Lakes and Athabasca Oil Sands regions. The atmosphere remained a net source of PAHs to the Great Lakes, though atmospheric inputs were decreasing with halving times of 26-30 years. Chemical transport modelling substantially overestimated wet deposition, but model performance is unknown for dry deposition. Sources from Asia, Europe and North America contributed to Arctic and Sub-Arctic concentrations, whereas transboundary or long-range transport have not been assessed outside Canada's north. Climate-related impacts from re-emission and forest fires were implicated in maintaining air concentrations in the high Arctic that were not consistent with global emissions reductions. Industrial emission decreases were substantial at the national scale, but their influence on the environment was limited to areas near relevant facilities. When examined through the lens of ambient levels at the local scale, evidence suggested that contributions from residential wood combustion and motor vehicles were smaller and larger, respectively, than those reported in national inventories. Future work aimed at characterizing PACs beyond the EPA PAHs, improving measurement coverage, elucidating deposition phenomena, and refining estimates of source contributions would assist in reducing remaining knowledge gaps about PACs in Canada.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Sources and emissions

Twenty-five years after the first look at polycyclic aromatic compounds (PACs) in Canada, this article presents current knowledge on Canadian PAC emission sources. The analysis is based on national inventories (the National Pollutant Release Inventory (NPRI) and the Air Pollutant Emissions Inventory (APEI)), an analysis of Canadian forest fires, and several air quality model-ready emissions inventories. Nationally, forest fires continue to dominate PAC emissions in Canada, however there is uncertainty in these estimates. Though forest fire data show a steady average in the total annual area burned historically, an upward trend has developed recently. Non-industrial sources (home firewood burning, mobile sources) are estimated to be the second largest contributor (∼6-8 times lower than forest fires) and show moderate decreases (25%-65%) in the last decades. Industrial point sources (aluminum production, iron/steel manufacturing) are yet a smaller contributor and have seen considerable reductions (90% +) in recent decades. Fugitive emissions from other industrial sources (e.g. disposals by the non-conventional oil extraction and wastewater sectors, respectively) remain a gap in our understanding of total PAC emissions in Canada. Emerging concerns about previously unrecognized sources such as coal tar-sealed pavement run-off, climate change are discussed elsewhere in this special issue. Results affirm that observations at the annual/national scale are not always reflective of regional/local or finer temporal scales. When determining which sources contribute most to human and ecosystem exposure in various contexts, examination at regional and local scales is needed. There is uncertainty overall in emissions data stemming in part from various accuracy issues, limitations in the scope of the various inventories, and inventory gaps, among others.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Links to global change

In this review, global change processes have been linked to polycyclic aromatic compounds (PACs) in Canada and a first national budget of sources and sinks has been derived. Sources are dominated by wildfire emissions that affect western and northern regions of Canada disproportionately due to the location of Pacific and boreal forests and the direction of prevailing winds. Wildfire emissions are projected to increase under climate warming along with releases from the thawing of glaciers and permafrost. Residential wood combustion, domestic transportation and industry contribute the bulk of anthropogenic emissions, though they are substantially smaller than wildfire emissions and are not expected to change considerably in coming years. Other sources such as accidental spills, deforestation, and re-emission of previous industrial deposition are expected to contribute anthropogenic and biogenic PACs to nearby ecosystems. PAC sinks are less well-understood. Atmospheric deposition is similar in magnitude to anthropogenic sources. Considerable knowledge gaps preclude the estimation of environmental transformations and transboundary flows, and assessing the importance of climate change relative to shifts in population distribution and energy production is not yet possible. The outlook for PACs in the Arctic is uncertain due to conflicting assessments of competing factors and limited measurements, some of which provide a baseline but have not been followed up in recent years. Climate change has led to an increase in primary productivity in the Arctic Ocean, but PAC-related impacts on marine biota appear to be modest. The net effect of changes in ecological exposure from changing emissions and environmental conditions throughout Canada remains to be seen. Evidence suggests that the PAC budget at the national scale does not represent impacts at the local or regional level. The ability to assess future trends depends on improvements to Canada's environmental measurement strategy and biogeochemical modelling capability.

AHR canonical pathway: in vivo findings to support novel antihypertensive strategies

Essential hypertension (HTN) is a disease where genetic and environmental factors interact to produce a high prevalent set of almost indistinguishable phenotypes. The weak definition of what is under the umbrella of HTN is a consequence of the lack of knowledge on the players involved in environment-gene interaction and their impact on blood pressure (BP) and mechanisms. The disclosure of these mechanisms that sense and (mal)adapt to toxic-environmental stimuli might at least determine some phenotypes of essential HTN and will have important therapeutic implications. In the present manuscript, we looked closer to the environmental sensor aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor involved in cardiovascular physiology, but better known by its involvement in biotransformation of xenobiotics through its canonical pathway. This review aims to disclose the contribution of the AHR-canonical pathway to HTN. For better mirror the complexity of the mechanisms involved in BP regulation, we privileged evidence from in vivo studies. Here we ascertained the level of available evidence and a comprehensive characterization of the AHR-related phenotype of HTN. We reviewed clinical and rodent studies on AHR-HTN genetic association and on AHR ligands and their impact on BP. We concluded that AHR is a druggable mechanistic linker of environmental exposure to HTN. We conclude that is worth to investigate the canonical pathway of AHR and the expression/polymorphisms of its related genes and/or other biomarkers (e.g. tryptophan-related ligands), in order to identify patients that may benefit from an AHR-centered antihypertensive treatment.

Fate and Fathead Minnow Embryotoxicity of Weathering Crude Oil in a Pilot-Scale Spill Tank

For several years now, the Natural Resources Canada research facility at CanmetENERGY Devon (AB, Canada) has been performing experiments in a pilot-scale spill tank using 1200 L of river water to examine the physical and chemical behaviors of various crude oil/water mixtures under varying water temperature regimes. Because oil toxicity can be modulated by weathering of the petroleum products, the present study aimed to assess changes in fish embryotoxicity to mixed sweet blend crude oil as it weathered at air and water temperatures of 14 °C and 15 °C, respectively, for 28 d. The physicochemical behavior of the oil was also monitored. Water samples were taken from the spill tank 5 times during the 28-d experiment on days 1, 6, 14, 21, and 28 and were used to perform toxicity exposures using fathead minnow embryos (Pimephales promelas). For each water sampling day, newly fertilized embryos were exposed to a serial dilution of the spill tank water, noncontaminated river water (used in the spill tank), and a reconstituted water laboratory control. Embryos were raised until hatching. Although mortality was not significantly altered by the oil contamination over the time period, malformation occurrence and severity showed concentration-dependent responses to all contaminated water collected. The results suggest that days 14, 21, and 28 were the most toxic time periods for the fish embryos, which corresponded to increasing concentrations of unidentified oxidized organic compounds detected by a quadropole-time-of-flight system. The present study highlights a novel area for oil research, which could help us to better understand the toxicity associated with oil weathering for aquatic species. Environ Toxicol Chem 2021;40:127-138. © 2020 Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of Natural Resources Canada.

Polycyclic aromatic compounds (PACs) in the Canadian environment: A review of sampling techniques, strategies and instrumentation

A wide variety of sampling techniques and strategies are needed to analyze polycyclic aromatic compounds (PACs) and interpret their distributions in various environmental media (i.e., air, water, snow, soils, sediments, peat and biological material). In this review, we provide a summary of commonly employed sampling methods and strategies, as well as a discussion of routine and innovative approaches used to quantify and characterize PACs in frequently targeted environmental samples, with specific examples and applications in Canadian investigations. The pros and cons of different analytical techniques, including gas chromatography - flame ionization detection (GC-FID), GC low-resolution mass spectrometry (GC-LRMS), high performance liquid chromatography (HPLC) with ultraviolet, fluorescence or MS detection, GC high-resolution MS (GC-HRMS) and compound-specific stable (δ¹³C, δ²H) and radiocarbon (Δ¹⁴C) isotope analysis are considered. Using as an example research carried out in Canada's Athabasca oil sands region (AOSR), where alkylated polycyclic aromatic hydrocarbons and sulfur-containing dibenzothiophenes are frequently targeted, the need to move beyond the standard list of sixteen EPA priority PAHs and for adoption of an AOSR bitumen PAC reference standard are highlighted.