Impacts of NCP-priority chemicals on endocrine function, energetics, and behavior, in conjunction with changing ice conditions, will be examined in thick-billed murres (Coats Island) where climate change is impacting their health. When ice breaks up earlier, energetics of adult murres is increased, they obtain less food, and nestling growth is slowed. Endocrine changes from e.g., chemical exposure, may decouple relationships between corticosterone, thyroid hormones, energy expenditure, and behavior. Specifically, because high energy expenditure is necessary to access food when ice is far away versus when ice is near, chemical disruption of these relationships may explain the inappropriate foraging behavior responses of some birds to changing ice conditions.

There is a need to estimate effect thresholds for the lanthanides, and in particular, using natural soils relevant to Canada. Prior research to address these data gaps specific to soil media have included the evaluation of cerium and lanthanum in forest soils, and the effect of aging and leaching on toxicity over time (EC, 2014). The study demonstrated low risk of these metals to the plant species assessed, but did demonstrate increased sensitivity to the soil invertebrate species, which then decreased with aging of the soil for ten months (EC, 2014). This study proposal aims to widen the applicability of soil toxicity assays to other priority metals, where such data is lacking. The project objectives are: • To provide soil effects data for four (4) lanthanide REEs: Praseodymium (Pr); Samarium (Sm); Terbium (Tb); and Erbium (Er). Specifically, effects data will be derived using a natural boreal forest and test organisms (soil invertebrates and indigenous microorganisms) representative of Canadian boreal ecozones; and • To provide soil effects data for the impact of aging on two toxic lanthanide rare earthworm elements • To develop a Species Sensitivity Distribution (SSD) based on the point estimate results generated for each rare earth element The lanthanides can be divided into two groups: the ‘light’ lanthanides (e.g., Pr, Nd, Pm and Sm) and ‘heavy’ lanthanides (e.g., Tb, Dy and Er). It has been hypothesized that the heavy lanthanides will be more toxic, however, given the limited data available, no trend has been identified with certainty (Gonzalez et al., 2014). Also, given that REES are readily bound to soil (Sheppard et al., 2009), the bioavailability may be low resulting in reduced toxicity. As a result, the effects of the lanthanide REEs on the proposed test organisms and soil microbial communities will be evaluated to determine whether these proposed trends exist across the metals and species studied.

This project sheet is for the last year of an OMOECC and ECCC agreement, on the toxicity of neonicotinoids. Half of the money was split with Stacey Robinson (20K). This portion of the work for this project was to assess the hazard of these pesticides to mussels and benthic invertebrates, along with scientists from ACRD, at CCIW.

Snapping turtles have been used by the EC since the early 1980s to determine spatial and temporal trends in PCB (and other organochlorine) concentrations, and have furthermore been used extensively for assessing AOCs. There is some concern, however, that their longevity may pose problems in interpreting body burdens. Given that Chelydra can live for over 50 years, individuals would be exposed to temporally varying levels of PCBs over their lifetime. Assessment of their body burdens, either through eggs, plasma, or other tissues, will indicate the temporal integration of PCBs over their lifetime, with the caveat that the proportion of PCBs from any given time period to the current burden will decline over time. The objective is to estimate depuration rates of PCBs in turtles to determine how much contribution past exposures have on the current tissue burden. In addition, there is very little information on the toxicity of PCBs to turtles. This project will assess toxicity, using genetic biomarkers (e.g. P450, oxidative stress, heat shock proteins, thyroid, and others), of PCB exposure to snapping turtles exposed through diet.

The Chemicals Management Plan (CMP) requires information for risk evaluation of novel CMP3-Priority flame retardants (FRs), whose occurrence and potential toxic effects on birds is unknown. Research will determine concentrations of CMP-priority FRs in terrestrial birds (e.g., peregrine falcons) and evaluate in vivo effects of ≤ 4 Priority FRs utilizing captive quail (McGill). Thus, pending the extent of funding, we will conduct research in the context of an avian AOP that supports CMP3’s current themes: exposure and toxicity, provide novel avian exposure and toxicity data for substances to inform CEPA risk assessment, and support the development of future environmental scientists and risk assessors (e.g., post-doctoral fellow, Melanie Guigueno; graduate student).

The tumor suppressor gene (TP53) is a biomarker of exposure and toxicity of PAHs, or other mutagens and genotoxins. The TP53 pathway regulates gene repair, cellular growth, and apoptosis, following induced genetic damage. We will be using avian (double crested cormorant) models from laboratory egg injection studies to develop these assays. Our goal is to assess the effects of PAH containing mixtures to cormorants in ovo (egg injections), by examining transcriptomics of the TP53 pathway in the embryo. Cormorant eggs will be injected with the PAH mixture, and at pipping. embryos will be sacrificed, genomic DNA extracted from tissues, and sequenced for mRNA to evaluate the TP53 signalling pathway, and the up- or down-regulation of key promoter and regulator genes such as P21, BAX, GADD45, P53R2, and MDM2.

The objective of this experiment was to expose plants to a mixture of the three most common and widely used Rare Earth Elements (REEs) in soils: lanthanum (La), neodymium (Nd) and cerium (Ce). It was hypothesized that plant sensitivity to La, Nd and Ce would be additive, and would increase with overall soil REE concentration. In addition, it was hypothesized that REE uptake would be similar for all three REEs (measured concentrations in plants would be equal) if REE soil concentrations were equal (La = Nd = Ce). Deviations in uptake would indicate potential higher risks of one REE over the others. Ny, Ce, and La were tested in soil mixture with doses based on the previously identified IC25 and IC50 values for native plant species (see Experiments 1 and 2). Doses were equal for all REEs in a given dose (i.e. 100 mg/kg Nd, Ce, and La), and followed a geometric progression. Due to the presumed influence of pH and calcium (Ca) on bioavailability and uptake, two soil pH levels (one acidic, one closer to neutral) and two Ca levels were also be tested. Two species were tested: the native common milkweed, Asclepias syriaca as well as the crop tomato, Solanum lycopersicum var. Beefsteak. The full experimental set-up was: 2 soil pH levels x 2 Ca concentrations x 4 REE doses (including controls) x 2 plant species x 6 replicates = 192 pots. The experiment was conducted in NWRC greenhouses of Environment and Climate Canada with plants tested individually in pots. Measured endpoints included germination percent and rates, aboveground and below ground biomass. In addition, to address plant accumulation rates, tissue concentrations (roots and shoots) of the REEs, as well as calcium, were measured. There was no obvious effect of treatment on the overall number of germinating seeds of A. syriaca or S. lycopersicum. Speed of germination of both species was found to be significantly affected by the soil treatments. For A. syriaca, a marginally significant main effect of soil REE dose was found but no main effects for soil pH or soil Ca; however, there was a significant soil pH x soil Ca interaction. Speed of germination of S. lycopersicum was found to be significantly affected by both soil pH and soil total REE concentration but there was no main effect of soil Ca levels, and no significant interactions were identified. Effects of soil parameters (pH, Ca, and REE) on A. syriaca and S. lycopersicum root and shoot biomass were complex. In general, a reduction in biomass was observed at high REE doses but there were multiple interactions with soil pH and Ca. The measured concentrations of each individual REE in plant tissues (both roots and shoots) were found to consistently increase with increasing soil REE dose within a given soil pH, soil Ca treatment. For all treatments, the measured concentration of a given REE was always greater in the roots than in the corresponding shoots. Measured REE soil concentrations tended to follow a consistent pattern of [Ce] > [Nd] > [La] for all soil treatment levels (soil pH, soil Ca, soil REE). However, results for the REE-dosed soils across all soil pH x soil Ca treatments consistently followed a pattern of [La] > [Ce] > [Nd] for both tissues in both species with the only exceptions found for the roots of both A. syriaca and S. lycopersicum in the high soil pH, low Ca, 150 mg REE kg-1 treatment ([Ce] > [La] > [Nd]). The overall result for REE-dosed soils appears to indicate that La may be more readily taken up by plants, followed by Ce and then Nd. All REE control soils were found to contain background levels of the three tested REEs: La (3.16 ± 0.01 mg kg-1 dry soil), Ce 6.94 ± 0.21 mg kg-1 dry soil), and Nd (3.91 ± 0.10 mg kg-1 dry soil). REE recovery rates, calculated as: (measured REE soil concentration – background level concentration)/nominal REE soil concentration, spanned from 93-117%, 98-124%, and 96-127% for La, Ce, and Nd respectively.

The objective of this experiment was to examine the effect of calcium (Ca) addition/shortage on plant sensitivity to Rare Earth Elements (REEs). It was postulated that REEs are able to exert effects on plants due to their similarity in ionic radii to Ca. As Ca is vital to many physiological processes, competition with the REEs may lead to undesirable effects on plant health. Due to the assumed link between REEs and Ca availability, it was hypothesized that plant sensitivity to REEs (as indicated by lower germination and biomass inhibition concentrations) would increase when exposed to lower soil Ca levels. Three Ca concentrations were assessed at two pH levels and three REE doses. Two species were tested: the native common milkweed, Asclepias syriaca as well as the crop tomato, Solanum lycopersicum var. Beefsteak. Experiments were conducted in NWRC greenhouses of Environment and Climate Canada with plants tested individually in pots. Three REEs were investigated in separate experiments: lanthanum (La), neodymium (Nd) and cerium (Ce). Concentrations of Ca and REEs were determined. At a given pH level, measured Ca concentrations in roots and shoots tended to increase with increasing soil Ca levels from the low Ca to the medium Ca treatment, but there was little difference between the medium Ca and high Ca soil treatments, indicating a threshold. Aboveground shoot Ca concentrations in both species were generally higher than their corresponding root measures. The worst case scenario for REE uptake and accumulation in the roots and shoots of both species would be at low soil pH and generally at low soil calcium levels. No effect of any REEs was detected on percent seed germination while some subtle and mixed effects were observed on speed of germination. There was generally a significant reduction in shoot and root biomass in both S. lycopersicum and A. syriaca due to REEs. The concentration of Ce in the soil had more of an effect on the two plant species than was observed in La and Nd experiments. There was generally an increase in biomass with addition of soil Ca. Many interactions between REE concentrations, Ca and pH were significant meaning that the relationships between these variables were not linear.

Metals, including some PGEs and REEs, seem to greatly affect pollen formation, viability and germination. Exposure to PGEs occurs largely via aerial deposition along roadsides as well as in long range transport. Plant pollen is thus extremely likely to come into contact with PGEs, including palladium (Pd) and platinum (Pt), as well as cerium (Ce), via aerial emissions. The aim of this study was to determine whether Pd, Pt and Ce affect pollen growth and development in terrestrial plants. It was hypothesized that malformations and inhibitory effects (reduced viability) on pollen would occur if pollen was exposed to these metals. Four species were selected which belonged to four different plant families: Trifolium pratense L. (Fabaceae), Brassica juncea (L.) Czernajew (Brassicaceae), Centaurea cyanus L. (Asteraceae) and Viola arvensis Murray (Violaceae). The experiment was conducted in NWRC greenhouses of Environment and Climate Change Canada. Seeds of each species were sown in a soil mixture and pollen grains were collected at maturity. The medium used for pollen germination differed between species. The basic medium comprised sucrose, boric acid and calcium nitrate in various concentrations as well as polyethylene glycol. Other compounds were added depending on the species: yeast extract, magnesium sulfate, potassium nitrate and/or iron sulfate. Pollen grains freshly collected were mixed with the medium on glass slides. In total, seven doses x six replicates were assessed. After four hour incubation, pollen grains were rated as germinated or not germinated. Pollen germination and tube length were measured on a minimum of 20 pollen grains per drop (replicate). Results showed that all species were affected by Ce exposure to different degrees. Percent germination was observed to decrease in a dose-response manner with increasing Ce concentrations. Consistent effects were observed in all trials with T. pratense and in three trials with V. arvensis. These two species germinated readily when exposed to their respective medium in control replicates. Pollen germination of C. cyanus appeared to also be a sensitive endpoint although large variability in the results was detected in all trials. As observed for C. cyanus, effect on pollen germination was only recorded in one trial for B. juncea, with the effect only present at the highest evaluated dose (24.3 mg Ce L-1). Effects on overall pollen germination in C. cyanus and B. juncea, however, remain difficult to interpret due to the overall low germination rates observed for these species. In contrast, pollen tube length provided more consistent results, and, with the exception for T. pratense, proved to be a more sensitive endpoint for several species tested with Ce. In contrast, Pd only affected T. pratense. Pd exposure did not inhibit pollen germination in any of the species tested. However, Pd did have a negative effect on pollen tube length in T. pratense in two trials. Although only EC10 and EC25 could be determined, Pd appeared to be quite toxic to the species. With regards to Pt, significant effects were found to be erratic in all experiments.

As part of the research program on the aquatic ecotoxicology of nanomaterials, a study was carried out using the invertebrate Hydra vulgaris in order to determine the influence that the shape of nanoparticles (sphere, cube and prism) have on the toxic potential of silver nanoparticles. The selection of nanoparticles of similar size and identical surface properties (polyvinylpyrrolidone) allowed to highlight the effects related to the geometrical shape. This study also contributes to the expansion of knowledge on the toxic effects of nanoparticles in relation to their geometry—a topic that has very little examination in aquatic ecotoxicology. All data are a part subject of a publication containing method details, full QA/QC, interpretation and conclusions. Citation: Auclair J, Gagné F. Shape-Dependent Toxicity of Silver Nanoparticles on Freshwater Cnidarians. Nanomaterials. 2022; 12(18):3107. doi.org/10.3390/nano12183107