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Mercury (Hg) pollution poses a significant threat to the environment, particularly in the form of methylmercury (MeHg). However, little is known about the distribution and influencing factors of Hg in deep-sea (>200m) fish, which is crucial for assessing potential health risks to fish and humans. In Canada, the deepwater redfish (Sebastes mentella) has been designated as an endangered species. After a 25-year fishing moratorium, the redfish population in the St. Lawrence Estuary and Gulf is recovering, and resuming of commercial fishing and human consumption are expected. This study aimed to investigate the distribution of MeHg and total Hg (THg) in the muscle of redfish, as well as the factors influencing its distribution, and to assess the potential human health risks associated with redfish consumption. The redfish samples (n = 123) were collected by Fisheries and Oceans Canada in 2019. The concentrations of THg and MeHg in redfish muscle were determined to be 93.3 ± 183 ng/g (mean ± SD, wet weight) and 78.2 ± 149 ng/g, respectively. Large redfish (>30 cm) accumulated 20 to 30 times more Hg than small redfish (17–30 cm). Small redfish from the Estuary-Western Gulf had higher levels of MeHg and THg than those from the Laurentian Channel and the Northeast Gulf, but the Hg availability to redfish among the three areas were similar. Significant predictors of MeHg concentrations in redfish muscle were determined to be fish length, muscle moisture, δ 15N, and N%. MeHg consumption by the general population with an average fish consumption rate is not anticipated to have adverse effects. This study establishes a baseline for future Hg monitoring in the deep water environments in this region. Further research is required to elucidate the cause-effect relationships between various environmental/biological parameters and Hg accumulation in deep-sea biota. [Display omitted] • Large redfish (>30 cm) showed 20–30 times higher levels of Hg than small individuals. • Spatial variations of Hg levels were observed in small but not in large redfish. • Hg levels in redfish can be predicted by fish size, muscle moisture, δ 15N, and N%. • No health risk is expected from consuming redfish for the general population. [ABSTRACT FROM AUTHOR]

Thirty-five sewage sludge samples collected across Canada were analyzed for 18 polycyclic aromatic hydrocarbons (PAHs), 17 congeners of polychlorinated biphenyls (PCBs) and seven selected chlorinated compounds. Samples were prepared by accelerated solvent extraction and standard column cleanup procedures using silica gel and Florisil. Gas chromatography with electron-capture detection was used for the determination of PCBs. Gas chromatography/mass spectrometry with electron-impact ionization and methane negative ion chemical ionization were used for the detection of PAHs and the chlorinated compounds, respectively. PAHs were detected in nearly all samples, with a total concentration ranging from 0.14 to 209 μg/g (median 3.65 μg/g) on a dry weight basis. Phenanthrene, fluoranthene and pyrene were present at the highest concentrations, with medians ranging from 0.56 to 0.58 μg/g. PCBs were also found in all samples, with a total PCB concentration ranging from 31 to 323 μg/g. The most abundant PCBs (congeners 52, 101 and 110) had median concentrations of 12 ng/g or above. While pentachlorobenzene and hexachlorobenzene were observed in all sludge, at low ng/g levels, no other less chlorinated benzenes have been detected in the same samples. Octachlorostyrene was only found in the Ontario samples, with concentrations ranging from 0.3 to 11.5 ng/g (median 0.9 ng/g). For the chlorinated insecticides, only p,p′-DDE, α- and γ-chlordane were found on a more regular basis, with median concentrations of 12.0, 0.4 and 0.8 ng/g, respectively. These results suggest that the above toxic chemicals are occurring in Canadian sewage samples and are persistent enough to survive the existing sewage treatment processes. [ABSTRACT FROM AUTHOR]

The concentrations of 23 polycyclic aromatic hydrocarbons (PAHs; 16 parent PAHs and 7 alkyl-PAHs) were determined in 45 surface sediment and 7 basal sediment box core samples retrieved from the Estuary and Gulf of St. Lawrence in eastern Canada. The concentration sums of 16 priority PAHs (Σ 16 PAHs) in the surface sediments (representing modern times or at least younger than the last decade) ranged from 71 to 5672 ng g−1. Σ 16 PAHs in the basal sediments ranged from 93 to 172 ng g−1 among the pre-industrial samples (pre-1900 common era or CE) and from 1216 to 1621 ng g−1 among the early post-industrial samples (~1930s and ~1940s CE). The highest Σ 16 PAH values occurred in samples retrieved from the Baie-Comeau-Matane area, an area affected by intense industrial anthropogenic activities. Source-diagnostic PAH ratios suggest a predominance of pyrogenic sources via atmospheric deposition, with a minor contribution of petrogenic seabed pockmark sources. The PAH concentrations in the sediments from the study areas reveal low ecological risks to benthic or other organisms living near the water-sediment interface. • The PAH contents are similar to those in other well-urbanized estuarine systems. • The PAH contents between 1930s and 1940s are 2.5 times higher than modern values. • PAHs mainly originate from pyrogenic sources with little petrogenic influence. • A few urbanized sector samples exhibit a possible ecological risk to organisms. [ABSTRACT FROM AUTHOR]

Limited human exposure and toxicity data are currently available for 4,5,6,7-Tetrabromo-2,3-dihydro-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-1H-indene (OBTMPI), a flame retardant often used for high temperature application of various polymer materials. Levels of OBTMPI in a cohort population that includes children and their co-residing parents (n = 217) in Canada were determined. Detection frequency of OBTMPI in the samples was 22.6%. OBTMPI levels were in general at sub-to low ng/g lipid weight level with a 95th percentile at 15.6 ng/g lipid weight. Compared to an earlier study conducted in 2008–2009 in the same region, results from this study show an increase in both detection frequency and concentration of OBTMPI. In silico toxicity predictions using Multicase CaseUltra and Leadscope Model Applier suggested that OBTMPI, and its possible metabolites in humans, while unlikely to be carcinogenic or mutagenic, exhibit some estrogen antagonist, androgen antagonist and estrogen binding capability reflective of possible endocrine disrupting properties. Image 1 • Possible rise in levels of emerging flame retardant OBTMPI in humans in Canada. • Exposure to OBTMPI among child, mother and father living in the same household. • In silico prediction of endocrine disruption properties for OBTMPI and metabolites. Emerging flame retardant OBTMPI is present in humans and endocrine disruption predicted by in silico is a likely adverse effect of OBTMPI. [ABSTRACT FROM AUTHOR]

The Leach's storm-petrel (Hydrobates leucorhous) is one of the most abundant and widely distributed marine birds in the North Atlantic but is under global population decline, possibly linked to marine pollution. We determined levels of ingested plastic and hepatic total mercury (THg) in recently fledged juveniles that stranded in Newfoundland and Labrador, Canada, and assessed the relationship to body condition, size and diet. Plastic prevalence was high (87.5%) but hepatic THg was relatively low (mean 486.7 ng/g dry weight) compared to other studies. Levels of neither pollutant were significantly related to body metrics of health. Our data confirm that plastic and mercury are pervasive in the western North Atlantic Ocean, prominent even in young birds. • A mass stranding event allowed recently fledged Leach's storm-petrels to be sampled. • 87.5% of recently fledged birds contained plastic pollution. • Average hepatic THg (mean 486.7 ng/g) was lower than adults. • Plastic pollution and mercury pollution were not significantly correlated with bird body condition. [ABSTRACT FROM AUTHOR]

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in soil and XAD-based passive air samples taken from a total of 22 sites along three transects (Revelstoke, Yoho, and Observation, 6–8 sites for each transect) in the mountains of Western Canada in 2003–2004. Median concentrations in air (4-ring PAHs: 33 pg/m3) were very low and comparable to those in global background regions such as the Arctic. Low median soil concentrations (16 EPA PAHs: 16 ng/g dry weight) and compositional profiles dominated by naphthalene and phenanthrene are similar to those of tropical soils, indicative of remote regions influenced mostly by PAHs from traffic and small settlements. Comparing levels and composition of PAHs in soils between and along transects indeed suggests a clear relationship with proximity to local sources. Sampling sites that are closer to major traffic arteries and local settlements have higher soil concentrations and a higher relative abundance of heavier PAHs than truly remote sites at higher elevations. This remains the case when the variability in soil organic carbon content between sites is taken into account. Both air/soil concentration ratios and fugacity fractions suggest atmospheric net deposition of four-ring PAHs to soils. [Copyright &y& Elsevier]

Organochlorine contaminant levels were compared between the native unionid Elliptio complanata and the exotic zebra mussel, Dreissena polymorpha, at four sites along the Rideau River near Ottawa in 1995. Overall, the two taxa exhibited similar bioaccumulation patterns. PCB congeners, treated individually or as classes, showed strong positive and significant correlations between the two taxa. Additionally, the ratios DDD/ΣDDT, DDE/ΣDDT and DDT/ΣDDT were not significantly different between the two taxa. Mean concentrations of ΣPCB, ΣDDT, and Σchlordane were 65.8, 14.0, 1.2 and 227.9, 10.6, 1.8 ng/g soft tissue dry weight in E. complanata and D. polymorpha, respectively. These three organochlorine groupings accounted for 98.2 and 98.7% of the organochlorine soft tissue dry weight burden in E. complanata and D. polymorpha, respectively. However, while the bioaccumulation patterns were similar in E. complanata and D. polymorpha, the ΣPCB concentration was significantly higher in D. polymorpha. The organochlorine dry weight burden was 2.0 to 5.6 times greater in D. polymorpha compared to that in E. complanata and this was mostly attributable to differences in ΣPCB. This difference may be explained in part by the relative lipid content in D. polymorpha being 1.8 times greater on average than in E. complanata. We conclude that D. polymorpha is a good alternative freshwater biomonitor for E. complanata. [ABSTRACT FROM AUTHOR]

Fragrances such as synthetic musk compounds are commonly used as additives in a wide range of consumer and personal-care products. At the end of their life cycle, most of these compounds will end up in municipal sewage systems. In this work, we report the occurrence of selected polycyclic and nitro musk compounds in sewage sludge, influent, effluent, as well as some industrial wastewater samples collected in Canada. A newly developed supercritical carbon dioxide extraction technique was used for the extraction of residual musk fragrances in the sludge. Final analysis was performed by gas chromatography/ mass spectrometry (GC/MS) using electron-impact and methane negative ion chemical ionization techniques. The results indicated that Galaxolide® (HHCB), Tonalide® (AHTN), musk xylene (MX), and musk ketone (MK) were the most common musk compounds in the Canadian environment, as they were found in every sample in this study. In the same sludge sample, levels of HHCB and AHTN (ranging from 1.3 to 26.7 µg/g) were often found to be about 1000 times higher than those of MX and MK (ranging from 1.4 to 422 ng/g). Similarly, in the sewage influent and effluent collected in Ontario, the levels of HHCB and AHTN (ranging from 159 to 2411 ng/L) were much higher than those of MX and MK (ranging from 1 to 84 ng/L). The levels of musk compounds varied widely in industrial wastewaters. In one sample collected from a detergent manufacturer, the levels of HHCB, AHTN, MX, and MK were found to be 54,200, 13,300, 5480, and 2.2 ng/L, respectively. It was also noted that the levels of MX and MK observed in the samples collected from the commercial laundries in Toronto were significantly higher than those found in domestic sewage. [ABSTRACT FROM AUTHOR]

The occurrence of toxic or endocrine-disrupting chemicals such as nonylphenol ethoxylates (NPEO), 4-nonylphenol (NP), 4-tert-octylphenol (OP), bisphenol A (BPA), tridosan (TCS), pentachlorophenol (PCP), hexachlorophene (HCP), and tetrabromobisphenol A (TBBPA) in 35 sewage sludge samples collected from cities across Canada is documented. Samples were extracted by supercritical carbon dioxide and the phenols were converted into their acetyl derivatives using published methods. The ethoxylates were analyzed by HPLC with a fluorescence detector. The other extracts, after silica gel column cleanup, were analyzed by GC/MS in either the electron impact or negative-ion chemical ionization mode. With minor exceptions, the above-mentioned compounds were present in all samples. The levels of these contaminants varied widely in the samples. The more abundant chemicals were NP as well as its mono- and di-ethoxylates, with median concentrations of 232, 69.4, and 26.4 µg/g (dry weight), respectively. Triclosan, a common antibacterial agent, BPA, and HCP were also ubiquitous in the sludge samples, with median concentrations of 12.5, 0.45, and 0.37 µg/g, respectively. Also present, albeit at much lower concentrations, were PCP and TBBPA, with median concentrations of 27.7 and 12.4 ng/g, respectively. Except for the last two compounds, all the chemicals are components or additives in various formulations of household and industrial detergents and personal care products. The potential risk of these toxic chemicals reaching the aquatic environment as a result of land spreading of sewage sludge should be investigated. [ABSTRACT FROM AUTHOR]

Surficial sediments and blue mussels (Mytilus edulis) were collected around the perimeter of Halifax Harbour. Samples were analyzed for the presence of polychlorinated biphenyls (PCBs), ranging from mono- to decachloro congeners, and results compared to the presence of polycyclic aromatic compounds (PACs). The objective was to explore the relationship between contaminant profiles in sediments and in mussels, and the possibility of deducing their sources, patterns of deposition, circulation and bioavailability. IUPAC hexachlorobiphenyls 138/158/160/163 (unresolved) and 153/132/168 were the most abundant congeners in both sets of matrices, ranging in concentration between <0.5 to 46 and 4.5 to 25.5 ng/g (dry weight) in sediments and mussels, respectively. PCBs profiles point to a combination of commercial sources superimposed on some weathering. Biota-sediment accumulation factors (BSAF, concentration in mussels, dry weight/concentration in sediments, dry weight, and lipid/TOC normalized) varied throughout the harbour and per congener. Some similarities were observed between the most contaminated sites previously analyzed for PACs and presently analyzed for PCBs, while BSAF were highest at the entrance to the harbour, for PACs and PCBs. [ABSTRACT FROM AUTHOR]

We collected and analysed 113 leeches (Hirudinea) from 17 small lakes in the acid-stressed Muskoka region of central Ontario, Canada to examine the relationship between lake chemistry and mercury (Hg) concentrations in leeches, and thus determine whether leeches and other benthic invertebrates posed a dietary risk of Hg exposure for non-piscivorous waterfowl. Hg concentrations in leeches were generally low andonly a few-fold above the detection limit (0.78 ng g- 1 wet weight (ww)). Mean Hg concentration in the bloodsucker Macrobdelladecora was 6.94 q0.78 SE ng g-1 ww (n = 49) and was 5.98 q 0.46 ng g-1 ww (n = 64) in the scavenger Percymoorensis marmoratis. Leech Hg concentrations were correlated with calcium and dissolved organic carbon concentrations in the water, respectively. These data suggest that leeches are not suitable monitors of Hg (usually as methylmercury) biomagnification in central Ontario lakes, and do not pose a dietary risk to non-piscivorous waterfowl. [ABSTRACT FROM AUTHOR]