While in vitro cell systems as a suitable alternative model for animal testings are used to support hazard characterization and identify mechanisms involved in the toxicity, effectively using in vitro data for risk assessment is challenging. As part of a large interdisciplinary effort to assess the human health risk of a complex pesticide mixture, we aimed to evaluate in vitro assays that could be used in a human health risk assessment format. PubMed, Web of Science (ISI), and Medline were systematically searched for studies that assessed the toxicity of pesticides on human cell lines. The IC50s derived from the evaluated endpoints were compared to NOEL/NOAELs and ADIs using Spearman correlation and linear regression models. Out of 2362, 66 studies met the inclusion criteria. In total, our database included 108 pesticides evaluated at four endpoints on ten human-derived cell types. While human neuroblastoma cells (SH-SY5Y) were the most sensitive, HepG2 was the most used cell line in evaluating the toxicity of pesticides. The IC50s derived from SH-SY5Y cells, using MTT-24 & 48 h (the most used assay) showed significant correlations (ρ = 0.56 - 0.79; p <0.05) with ADIs and NOEL/NOAELs. From all the used cell lines only SH-SY5Y cells showed a significant correlation with in vivo guidelines. The high sensitivity of SH-SY5Y cells suggests that they could be appropriate cells to assess pesticide toxicity. Further research is needed to investigate the toxicity of more pesticides on SH-SY5Y cells to ensure their usefulness for predicting in vivo risk guidelines.

The use of firefighting water additives has greatly increased over past decades in both wildland and residential fires in order to increase extinguishing efficacy. Fluorinated fire-fighting additives were used extensively in the past, however, due to their bioaccumulative potential and persistence in the environment they are no longer permitted in Canada for forest and residential applications. With greater concern of the environmental fate of firefighting water additives, new formulations have been developed that are meant to be “eco- friendly” alternatives for fire suppression. There currently exists very little data on the toxicity of additives in current use with respect to terrestrial and aquatic biota. This study will assess the toxic effects of nine different types of firefighting water additives on terrestrial and aquatic species. This will include acute lethality testing of the aquatic species Daphnia magna. The terrestrial portion will include chronic testing for the springtail species Folsomia candida and germination and emergence tests for three plant species (Picea glauca, Agropyron cristatum, and Raphanus sativus). The D. magna portion of the study revealed considerable risk for all tested products with the exception of Eco-gel and TetraKO. The F. candida tests revealed relative sensitivity to all products with the exception of TetraKO.and Bio FOR N. Picea glauca and A. cristatum germination tests showed relatively high sensitivity at the lowest administered concentrations for all tested products, whereas R. sativus showed relatively low sensitivity to all tested products with the exception of LC95A. Finally, emergence tests with R. sativus also showed relatively high sensitivity to LC95A. The results of this study highlight the potential hazard that firefighting water additives pose to aquatic and terrestrial organisms.

Groundwater containing a complex mixture of known and unknown contaminants was collected from an industrial site for characterization of toxic effects. An oral exposure to a single concentration (0.05% v/v) of groundwater compared to control (7, 14, 28, and 56 days exposure) in male Sprague Dawley rats (n=10/group). A transient, significant increase in white blood cell count was seen in the day-7 experimental group compared to the control. Blood smears showed occasional lymphocytosis and neutrophilia, but these did not differ significantly with treatment at any time-point. Moreover, 40% of the experimental rats at all time points had bite cells. Bone marrow smears showed hypercellularity after 56 days contaminated drinking water consumption compared to control. While gross behaviour appeared normal, a novel object exploratory test showed an increased duration and number of interactions in the 56 day-exposed rats. In summary, this study provides a framework for future studies of unknown, complex mixtures to characterize a broad range of toxic effects and target organs. The evidence of immunotoxicity, hematotoxicity, and neurological toxic effects, that will be explored in more mechanistic detail with a targeted dose-response experiment in the second tier of experiments.

Environmental Impact Assessment (EIA) is a process that considers positive and negative aspects of a development project to determine if it should be approved and with what mitigation. To assist in the decision-making process, the Ecosystem Services (ES) concept was developed to describe the ecosystem attributes that create benefits for human well-being. In Canada, a dominant aspect of the environmental protection process requires meeting the needs of the Fisheries Act, which requires that fish, fish habitat, and the use of fish are protected. The challenge, as in many countries, is that the regulatory processes and evaluation procedures for environmental risk assessment, environmental assessment, cumulative effects assessment, and post-operational impact assessments are disjointed and poorly aligned, which creates ineffective monitoring programs filled with a discord of different approaches and metrics. It is possible that re-orienting the Canadian environmental assessment process along the lines of critical needs and benefits from the perspectives of the Fisheries Act could serve to better align risk, development, and monitoring assessment processes. We will present the critical ecosystem functions from a fish perspective and suggest how a fish-oriented ES approach could be incorporated into the design of monitoring programs to better align pre-development, development, and post-operational monitoring programs.

Ore processing techniques used in Yellowknife’s largest mining operation, Giant Mine, is responsible for the atmospheric release of approximately 20,000 tonnes of particulate arsenic trioxide and other heavy metal(loids). This rapid deposition of heavy metal(loids) is thought to have caused ecological disturbances to aquatic food webs. Here we examine lake sediment cores from 20 lakes within a 50km radius of Yellowknife. These cores were dated by 210Pb and 137Cs, and metal(loid) concentrations were determined in each. Toxicity of sediment intervals to aquatic biota were assessed using palaeotoxicity modelling. We found that metal(loid) profiles in sediment peaked during the height of mining operations. These peak metal(loid) concentrations were highest in lakes near the mine’s roaster stack, and decreased with distance from the stack. Temporal analysis of lakes closest to the mine, and in the predominant wind direction, show probable adverse effects to biota even prior to the onset of mining operations. However, these risks increased substantially during the period of gold mine operations in the region. In recent years, the toxicological risk has decreased in some lakes. Although our results show a pattern of recovery in the region, the results indicate that aquatic ecosystems in Yellowknife continue to have lingering effects to aquatic biota despite the closure of the mine two decades ago.

The objectives of this study were 1) to characterize the exposure of aquatic ecosystems in Southern Ontario to pesticides by constructing environmental exposure distributions (EEDs) including censored data; 2) use the EEDs to predict the probability of exceeding regulatory guidelines; and 3) assess whether crop types in catchments of sampling sites correlate with the pesticide(s) detected. Surface water samples were collected from the Great Lakes and its associated tributaries over a 15-year period by Environment and Climate Change Canada (ECCC). The dataset contained 167 compounds, sampled across 114 individual sites, and had a total of 2,213 distinct samples. There were 67,920 total data observations: 55,058 non-detects (81%), and 12,862 detects (19%). We ultimately focused on two compounds, atrazine and glyphosate. Atrazine had an overall detection frequency of 91.4%. The maximum observed concentration of atrazine-river or stream (18,600 ngL-1) and 4.3% of the samples in the generated EED exceed the regulatory acute guideline (1,000 ngL-1). However, the calculated 99th centile of the EED (4,067 ngL-1) indicates that these are rare occurrences in streams. Regression analysis between the annual average atrazine concentrations and percent land coverage of corn was performed and showed a significant relationship (r2 = 0.26, p = 0.05). Glyphosate (n = 427) was the 11th most detected compound (33.3% detection). The modelled 50th centile concentrations indicated glyphosate-Pond (2,004 ngL-1), and glyphosate-River or stream (383 ngL-1) had the two highest “average” concentrations of the dataset, with measured maximum concentrations smaller than their 99th centiles, potentially pointing to the existence of higher peak concentrations missed in sampling. Overall, both the data and generated models for glyphosate had <0.01% chance of exceeding of acute benchmarks. This study provides important insight into the risk that pesticide compounds can pose to aquatic ecosystems in southern Ontario, and the approach taken here could be modelled in other jurisdictions.

Mechanistic toxicology approaches are increasingly considered as tools to address limitations of traditional risk assessment methods that are time and resource intensive and heavily rely on live animal testing. However, the adoption of such approaches is still limited. The objective of this systematic review was to evaluate the current evidence supporting the inclusion of molecular mechanistic responses in regulatory risk assessment based on their potential to establish causal relationships between toxicant exposure and adverse apical outcomes in fish. We searched four databases to conduct three systematic literature searches according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. The studies selected were included in two lines of evidence either focusing on molecular effects analyses alone (LOE1) or on both molecular and apical outcomes analyses in fish (LOE2). These were then evaluated against the nine principles of the Bradford Hill criteria to quantitatively determine the weight-of-evidence for the use of molecular data for regulatory purposes. During this review, a lack of information about the “specificity”, “temporality” and “consistency” of the association between exposure and effect in fish were noticed in a majority of studies considered under each LOE. Thus, “specificity” and “temporality” criteria were not met by both LOEs and “consistency” criterion was not met by LOE1. However, as the other principles were met by both LOES, this review was considered as strongly supportive for the inclusion of molecular responses in regulatory risk assessments. Nevertheless, future efforts to standardize molecular effects testing such as transcriptomics, proteomics and metabolomics analyses would be necessary to increase their applicability for regulatory risk assessments.

Firefighters experience above average risks of cancer and other serious illness. Their exposures to combustion emissions, including polycyclic aromatic hydrocarbons (PAHs), are a concern. To reduce dermal exposure, cleaning of firefighters’ skin immediately after firefighting is often implemented. However, such efforts lack scientific evidence. To assess the ability of dermal cleaning methods to reduce firefighters’ exposures, PAHs and subsequent genetic damage was measured and compared between participants following current decontamination protocols (i.e., no dermal decontamination) and those who added a dermal decontamination step using skin cleaning wipes or soap and water (i.e., the intervention groups). During training fires, we collected (1) personal air samplers; (2) wipe samples of skin before and after the fire, and after a dermal decontamination; and (3) urine samples before and after the fire. We measured PAHs in the air and wipes of skin, and PAH metabolites and mutagenicity in urine. Firefighters experienced significantly elevated concentrations of urinary PAH metabolites in their urine and PAHs on their skin (p<0.05). Soap and water was the only intervention to remove a significant amount of PAHs from the skin (p<0.05). However, fold changes of urinary PAH metabolites were not affected by implementing a dermal cleaning step. These data suggest that despite on-site attempts to remove PAHs from firefighters’ skin, it does not reduce the overall dose received. Mutagenicity analyses will be conducted in the future to reveal if exposures to other mutagens are influenced by dermal decontamination efforts.

Plastic debris polluting our waterways has been a concern for decades. Recently increased attention has been placed on microplastics (MPs) contamination of aquatic ecosystems. These small particles of plastics (<5 mm) have been observed in marine and freshwater ecosystems all over the Earth. Although effects of MPs ingestion on important marine invertebrate species have been demonstrated, little is known on the effect of microplastics on freshwater species. To date, freshwater studies have focused on the presence and/or concentration of microplastics in surface waters, but in order to assess their risk, there is a need to compare the environmental concentrations of microplastics to concentrations that cause adverse effects. Freshwater mussels are a group of filter-feeding organisms that have experienced a global decline due to habitat destruction and declines in water quality and they are under-represented in microplastics research. In this study, standard methods were used to conduct acute (48 h) toxicity tests with glochidia (larvae) of Lampsilis fasciola, a species of special concern. Tests were performed with pristine microplastic spheres of varying polymer types and sizes. Polystyrene (6 and 90 μm), polyethylene (75-90 μm), and cellulose acetate (1000 μm) spheres were used in treatment concentrations spanning 50-300,000 MP/L. Glochidia viability (i.e., the ability to close valves) was used as a surrogate for survival. L. siliquoidea glochidia were insensitive to each type of microsphere tested with effect concentrations being >300,000 MP/L for polystyrene and polyethylene and >1000 MP/L for cellulose acetate. This data will help inform the risk assessment of microplastics to freshwater biota.

The ongoing industrial development of the oil sands region in Alberta Canada has raised concerns about potential impacts it may have on the local environment. Trout-perch are monitored as proxy variables for the overall health of aquatic ecosystem. Fish health has previously been modeled using categorical variables such as year and site. This research seeks to improve upon existing models by replacing the general explanatory variables with year-site specific water quality measures. We employ the lasso and elastic net procedures to select a subset of variables for modeling. We find that the use of water quality measures paired with regularization techniques greatly improves the predictive accuracy over the traditional regression models. Additionally, we find that some of the variables selected by the regularization techniques are not being actively monitored in the Athabasca River suggesting that current monitoring programs and protective regulations may not be sufficient in scope.

Federal Environmental Quality Guidelines (FEQGs) provide thresholds of acceptable quality in the ambient environment in support of various federal activities including risk assessment, risk management, and environmental quality monitoring. Where the FEQG is met there is low likelihood of adverse effects from the chemical on aquatic life directly exposed via the water or sediment or through the diet for chemicals that may bioaccumulate in wildlife that consume aquatic life (e.g. birds and mammals). Draft FEQGs will soon be published for a 60-day public comment period for three substances; aluminium (water quality guideline), siloxane D4 (water, sediment, tissue, and wildlife diet guidelines), and selenium (fish tissue and bird egg guidelines). This presentation will provide a brief introduction to environmental quality guidelines and a summary of the new draft guidelines. Aluminium- The draft FEQG for water follows the current CCME (2007) derivation protocol and uses a multiple linear regression (MLR) approach allowing for the incorporation of toxicity modifying factors pH, DOC, and water hardness for site-specific application. Selenium- CEPA Risk Assessment (2017) predicted no effect concentrations (PNECs) have been adopted as draft fish tissue FEQGs and the draft bird egg FEQG is adopted from the USEPA (2019). Siloxane D4- The PNEC from the CEPA Risk Assessment for D4 (2008) has been adopted as the draft FEQG for water. Additional guideline values for sediment and wildlife diet were developed according to CCME protocols (1995, 1998) while the aquatic biota tissue guideline was developed using the target lipid model.

Bioconcentration factor (BCF) is one of the most common endpoints in chemical risk assessment, informing bioaccumulation status. While BCF as determined from in-vivo whole fish exposures is still considered the gold standard to inform this criterion, there is growing concern in academia, governments, and industries about the suitability and reproducibility of this test, especially for chemicals that are biotransformed. Alternative approaches using in-vitro biotransformation assays based on hepatocytes or liver sub-cellular fractions in combination with in-vitro in-vivo extrapolation (IVIVE) models have been developed as potential replacements. However, extrapolation to BCF is complicated by confounding factors, e.g., extrahepatic biotransformation and quality issues with experimental BCFs. Therefore, there is a need for an ex-situ model at an intermediate level of biological organization. A recently developed method is that of the rainbow trout isolated perfused liver, seeking to reduce uncertainty in IVIVE of clearance rates of chemicals. The present study seeks to obtain hepatic clearance data of four environmental contaminants of interest within the isolated perfused trout liver and cross-validate with prior standardized in-vitro methods. Livers of sexually immature rainbow trout were cannulated via the hepatic portal vein and perfused for six hours with a physiological buffer spiked at varying concentrations of pyrene, 4-nonylphenol, deltamethrin, and methoxychlor. Afferent and efferent samples were taken in 15-minute intervals across the perfusion period. Samples were analyzed using high-performance-liquid-chromatography with fluorescence detection (HPLC-FLD) and gas-chromatography (GC) to calculate hepatic extraction fraction and clearance. Results demonstrate that this experimental method can be used to validate IVIVE models, as illustrated by the excellent fit of predicted versus measured hepatic clearance values. This study has the potential to settle an important debate in this field and enables scientists to focus on other factors to allow for confident predictions of bioconcentration in fish.

PFAS are a class of chemicals that are highly persistent in the environment and pose an array of threats to the health of humans and biota. PFAS are widely used in industrial processes and in consumer products due to their oil and water-repelling properties. Despite increasing scientific evidence linking adverse health effects to PFAS exposure, this class of chemicals is poorly regulated in many parts of the world, including Canada which has implemented controls on only a few of the many PFAS. The goal of our study is to determine the prevalence of PFAS in Canadian and US fast-food packaging, including paper bags, compostable bowls and other food-contact materials from popular restaurants. Results showed the prevalence of PFAS in specific items, notably in paper donut bags, bagasse paper (“compostable”) takeout bowls and popcorn bags. For example, total fluorine analysis of fast-food packaging revealed 2235 ppm fluorine in a “compostable” bagasse takeout container and 783 ppm F in a paper bakery bag. Inclusion of these containers in the recycling stream can contaminate paper products with PFAS and disposal to landfills leads to accumulation of PFAS in landfill leachate, ultimately entering the environment. The joint Canadian-US project now seeks to understand the breadth of products sold in Canada that contain PFAS and to estimate the fate of this PFAS.

Treatment of groundwater for removal of salts by several processes leaves residual wastewater that is elevated in sulphate and chloride. At our client’s industrial site, it mixes with site runoff in a reservoir prior to discharge to the Conestogo River. Expansion of plant capacity required an amended Environmental Compliance Approval with discharge limits for the two major ions. Detailed understanding of in-plant waste streams allowed collection of a series of composite and ion-specific samples for acute toxicity testing and chemical characterisation. This provided hardness-modified lethal thresholds for the joint action of chloride and sulphate exposures which were used to recommend effluent limits. Assimilation analysis of the receiver showed no impacts from past discharges or predicted impacts from discharges at the limits of 640 mg/L for Cl and 5140 mg/L sulphate. Monitoring protocols were developed for episodic discharges, for discharges after drought periods with no runoff to dilute the process water and to separate the role of uncontrolled road salt runoff from that of controllable inputs of process water in determining discharge characteristics.