Introduction: This study aimed to examine the association of smoking status with homocysteine levels and to determine whether the association is modified by oestradiol or cholesterol. Methods: Data (N = 4580) were obtained from National Health and Nutrition Examination Survey 2003–2004 with analysis done in 2018 on adults aged ≥20 years. The outcome was homocysteine; smoking status was the exposure variable and categorized as current, former or never smoker. Generalized linear models were used to examine the associations between smoking status and homocysteine levels, while assessing the impact of oestradiol and cholesterol. Results: After adjusting for age, sex, ethnicity, education and income level, homocysteine levels did differ by smoking status ((current smokers versus never smokers: β: 0.18 CI: 0.00, 0.36), (former smokers: β: 0.10 CI: –0.09, 0.28)). The addition of oestradiol as an interaction term in adjusted models was associated with a 16.6% increase in homocysteine levels when compared to models without the interaction term. Oestradiol but not cholesterol did moderate the association between smoking status and homocysteine levels. Discussion and conclusions: Homocysteine levels did differ across smoking status after adjusting for confounders. Oestradiol did moderate the relationship between homocysteine and smoking status.

<p>Per- and polyfluoroalkyl substances (PFAS) are a group of emerging global contaminants used in a variety of industrial processes and consumer products, such as personal care products and fast-food wrappers. However, due to their carbon-fluorine bonds, these chemicals resist degradation and persist in the environment. PFAS toxicity is driven by a compound’s functional group and chain length with perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide dimer acid (GenX) being of focal concern due to their toxicity to wildlife and presence in the environment. Despite growing concern regarding these contaminants, inadequate attention has been given to evaluating what organismal characteristics influence uptake and depuration of these chemicals, such as life stage and sex. <em>Xenopus laevis</em> tadpoles are a useful model to assess the influence of sex on PFAS kinetics since they have a life history that includes a gill to lung transition. Previous studies have shown that air-breathing organisms depurate PFAS more slowly than water-breathing organisms, but this relationship has never been directly tested. Sex has been shown to be an important factor in the depuration of PFOA for rats, with female rats depurating PFOA in four hours while males depurate in four days. The early portion of bioaccumulation curves are also understudied even though tadpoles accumulate PFAS rapidly, reaching steady state within 48 hours of exposure. <em>Xenopus laevis</em> are used to study multiple endpoints for endocrine disrupting chemicals including PFAS. Despite this, toxicity reference values (TRVs) have not been described for the uptake and elimination of PFAS using <em>X. laevis</em>. To address these gaps in knowledge, I first developed TRVs for <em>X. laevis</em> tadpoles exposed to PFOA throughout metamorphosis and evaluated the influence of sex on phenotypic endpoints. Results showed a no observed effect concentration (NOEC) of 11.1 ppm for body mass at day 14 and no effect of sex on apical endpoints. Next, I described the early bioaccumulation of four PFAS with differing structure (chain lengths and functional groups). PFOS was the only chemical to bioaccumulate with a log bioconcentration factor (BCF) at 10 and 1,000 ppm of 1.33 and 1.18, respectively. PFHxS, PFOA, and GenX had BCFs less than 0. Finally, I examined the impact of life-stage and sex on <em>X. laevis</em> tadpole and juvenile depuration rates. Larval tadpoles depurated four times faster than juveniles, indicating a significant effect of life stage on elimination rates. Sex had no influence on elimination rates. These are the first studies conducted evaluating the significance of life stage and sex in toxicokinetics of PFAS in amphibians.</p>

[pt] O intenso crescimento dos centros urbanos provocou aumento considerável da emissão de poluentes atmosféricos, conferindo destaque à poluição atmosférica. A qualidade do ar de uma determinada região pode ser afetada por fatores como tipos e quantidades de fontes de emissão, meteorologia e topografia, o que confere complexidade para essa área de estudo. Os principais poluentes legislados no Brasil são SO2, NO2, CO, O3 e o material particulado (MP). Dentre esses, o MP pode ser considerado como uma das mais importantes classes de poluentes devido sua composição heterogênea, que pode causar efeitos adversos à saúde e ao meio ambiente. O monitoramento dos poluentes atmosféricos para fins de fiscalização pode ser realizado utilizando métodos padronizados que incluem equipamentos capazes de determinar a concentração dos poluentes em tempo real. No Rio de Janeiro, as principais redes de monitoramento da qualidade do ar pertencem ao Instituto Estadual do Meio Ambiente (INEA) e à prefeitura do Rio de Janeiro, que dispõem de estações automáticas em diversas regiões da cidade e do estado. Entretanto, o monitoramento tradicional da poluição atmosférica demanda altos investimentos para compra e manutenção desses equipamentos, diminuindo as áreas passíveis de monitoramento. O biomonitoramento, por sua vez, que utiliza organismos vivos para avaliar mudanças ambientais, é considerado uma abordagem adequada para ampliar as áreas monitoradas e avaliar os impactos causados pela poluição. Assim, o objetivo deste estudo foi avaliar a qualidade do ar no Rio de Janeiro através do biomonitoramento ativo utilizando Tillandsia usneoides e Tillandsia stricta como biomonitores, investigando o estresse oxidativo causado pela exposição aos metais. Considerando o efeito das fontes de emissão na qualidade do ar, buscou-se também avaliar a qualidade do ar no Rio de Janeiro durante os primeiros meses da pandemia de COVID-19, quando a mobilidade urbana foi alterada consideravelmente. Nessa avaliação foi considerada ainda a influência das condições meteorológicas por meio da comparação com dados obtidos para os mesmos períodos do ano anterior. O biomonitoramento ativo foi realizado entre julho de 2019 e novembro de 2020 em cinco locais do Rio de Janeiro com diferentes características quanto a emissão de poluentes: Ramos, Urca, Niterói, Duque de Caxias e Santa Cruz. As plantas foram removidas de um local rural e instaladas nos locais de monitoramento em julho de 2019 e coletadas em outubro de 2019, janeiro e novembro de 2020. A avaliação do estresse oxidativo foi realizada através da quantificação dos biomarcadores Metalotioneína (MT), Glutationa Reduzida (GSH), H2O2 e Peroxidação Lipídica, medida pela concentração de malondialdeído (MDA). Para avaliar a fração biodisponível dos metais presente no tecido das plantas foi realizada distribuição subcelular através do procedimento de purificação da metalotioneína, que fornece três frações nas quais os elementos foram quantificados por espectrometria de massas com plasma indutivamente acoplado (ICP-MS), bem como a quantificação dos metais totais realizada em extratos ácidos dos tecidos das plantas. Na avaliação da qualidade do ar durante a pandemia, os dados de concentração de NO2, SO2, CO e O3 e variáveis meteorológicas foram fornecidos pelo INEA para março e abril de 2020 e usados para avaliar mudanças na qualidade do ar em comparação com o ano anterior e a contribuição das condições meteorológicas. A prefeitura do Rio de Janeiro forneceu dados de CO, O3 e PM10 e variáveis meteorológicas para o período entre março e setembro que foram usados para uma avaliação que considerou o impacto das medidas de distanciamento social na qualidade do ar através do acompanhamento desde o primeiro decreto de restrição até a abertura econômica total. Nos dois casos, os dados foram submetidos a destes estatísticos e análises temporais. O biomonitoramento da qualidade do ar indicou que os principais elementos encontrados nos biomonitores foram Fe, Na, K, Ca, Mg and Al. Elementos relacionados ao tráfego veicular, como Pb, Cr, Cu and V também foram encontrados em concentrações expressivas. A T. usneoides apresentou maiores concentrações em comparação com a T. stricta, entretanto, o enriquecimento das duas espécies em relação à amostra de referência foi similar, indicando que ambas são adequadas para o biomonitoramento. Duque de Caxias e Santa Cruz apresentaram os maiores enriquecimentos, o que pode estar relacionado com a contribuição das emissões industriais. A avaliação da distribuição subcelular dos metais demonstrou que Cr, Co, Cu, Cd, Mn, Ni, Se and Zn foram encontrados na fração termoestável da purificação da metalotioneína, o que indica que as plantas estão em processo de destoxificação desses elementos. A T. stricta apresentou maiores percentuais da fração não biodisponível, o que indica que essa espécie é mais resistente aos efeitos tóxicos causados pelos metais. Foi observado ainda que em períodos secos a absorção das plantas é menor, devido ao metabolismo ácido das crassuláceas (CAM), que favorece o controle hídrico em condições de baixa umidade mantendo as organelas responsáveis pelas trocas gasosas fechadas durante o dia, período no qual se registram maiores concentrações de poluentes. Os biomarcadores de estresse oxidativo indicaram que as duas espécies estão em condições semelhantes de estresse oxidativo, pois suas concentrações não apresentaram diferença significativa entre as espécies na maioria dos casos. As correlações entre os biomarcadores indicaram que a principal função da GSH é no sistema antioxidante, embora em alguns caso ela tenha atuado auxiliando a MT na destoxificação de metais. As correlações de H2O2 com MT e GSH indicam que a exposição de metais estimula e produção de espécies reativas de oxigênio (ROS), como H2O2, cuja concentração pode ser regulada pela ação da GSH, entretanto, a correlação com MDA indica que o sistema antioxidante não está sendo eficiente na prevenção do estresse oxidativo. A avaliação da qualidade do ar durante a pandemia revelou que a redução de até 85 por cento na mobilidade urbana foi a principal responsável pela melhora da qualidade do ar, principalmente nos primeiros meses de isolamento social. Foi registrada diminuição na concentração dos poluentes primários e aumento da concentração de O3, um poluente secundário. Esse mesmo comportamento também foi registrado em outras cidades ao redor do mundo e é atribuído aos complexos processos de formação de ozônio, que dependem da concentração de alguns poluentes primários. Embora as concentrações de ozônio tenham aumentando, o índice de qualidade do ar durante a pandemia foi melhor do que em períodos com a rotina normal das cidades. A contribuição das condições meteorológicas não apresentou muita influência, uma vez que se mostrou semelhante ao mesmo período do ano anterior. A avaliação da qualidade do ar no Rio de Janeiro revelou que as emissões veiculares são as principais fontes de poluentes atmosféricos, e que a mudança no fluxo de veículos pode melhorar a qualidade do ar, embora empreendimentos industriais também apresentem expressiva contribuição. A poluição urbana pode causar desequilíbrio ambiental, uma vez que a vegetação está em constante exposição. Podese destacar ainda que o estado do Rio de Janeiro abriga importantes remanescentes de mata atlântica, o que demanda constante fiscalização visando a garantia da preservação ambiental. / [en] The intense growth of urban centers has caused a considerable increase in atmospheric pollutant emission, which can lead to human health and ecosystem risks. The air quality monitoring network in Brazil is limited, covering not even half of the states. Biomonitoring employing plants is, thus, an alternative to increase the monitored areas and still allow the ecotoxicological evaluations concerning air pollution exposure. In this sense, this study sought to evaluate the air quality of the metropolitan region of Rio de Janeiro using official atmospheric pollutant concentration data and biomonitoring efforts aiming to investigate oxidative stress in the bromeliad species used as biomonitors. During the social isolation period established as a contingency measure against the spread of the coronavirus, air quality was improved overall, although ozone concentrations increased relative to the previous year and the period preceding the lockdown. This change was attributed to an urban mobility reduction of up to 85 percent. The biomonitoring assessments indicate that the main elements taken up by the plants were those related to vehicular traffic. The correlation of these elements with oxidative stress biomarkers indicate that air pollution exposure represents a risk to local ecosystems. Tillandsia stricta and Tillandsia usneoides displayed similar behavior regarding metal accumulation, albeit presenting different detoxification processes. Although Rio de Janeiro has one of the most widespread air quality monitoring networks, studies aimed to assess the environmental air pollution impacts are required, considering that the state is home to important and endangered Atlantic Forest remnants. In additions, vehicular emission control can contribute to air pollution reduction, considering that this is one of the main pollutant sources.

No description available.

<p>Animal movement has had a long history of study in the fields of behavioural ecology and toxicology, but rarely is the ecological context of behaviour in toxicology directly addressed. To explore how movement might be influenced by both sex differences and habitat contamination, I conducted studies on the round goby, an invasive fish, in a highly polluted part of Lake Ontario. In the first half of my dissertation I examined the reproductive biology of this species, finding evidence of multiple male reproductive tactics, and extended this to predict sex differences in goby movement. I showed that male fish were more exploratory in the laboratory, and over multiple years moved further in the field than females. This difference may predict variation in sex ratio along a round goby invasion front. Second, I accumulated multiple lines of evidence for contaminant exposure in these fish, validating their utility as a contaminant sentinel species in the field. With the same battery of behavioural tests, I revealed that round goby collected from cleaner sites were more exploratory than fish from highly contaminated sites in the laboratory, but moved similar distances in the field. Although changes in activity level are the most frequently used behavioural measure of contaminant exposure, the ecological relevance of change was not apparent in this study. These results challenge the utility of movement as an integrated biomarker of contaminant exposure beyond the laboratory.<strong></strong></p> / Doctor of Philosophy (PhD)

Wastewater effluent is a major source of aquatic pollution, discharging a continuous and complex mix of contaminants into the environment. The physiological impacts of exposure to individual contaminants are well characterized in fish, but less is known about the consequences of complex mixtures that typify wastewater effluent in the environment. This thesis explores the metabolic and respiratory effects of in situ wastewater exposure on bluegill sunfish (Lepomis macrochirus). By assessing multiple levels of biological organization, I provide evidence that wastewater exposure invoked a metabolic cost in bluegill, which was associated with physiological adjustments to enhance oxygen uptake, delivery, and utilization. These findings broaden our understanding of how fish tolerate life in effluent-dominated waters and support the emergence of metabolic and respiratory physiology as biomarkers in ecotoxicology. / Thesis / Master of Science (MSc)

MSc Thesis - The effect of wastewater effluent on the gut microbiome of rainbow darter / The microbiome plays an important role in host physiology and can be influenced by species, diet, and environment. Municipal wastewater effluent contains a mixture of chemicals including antibiotics and antimicrobials that may affect the gut microbiome of fish living downstream of these discharges. Thus, this study examines the effect of wastewater treatment plant (WWTP) effluent on the gut microbiome of wild rainbow darter (Etheostoma cearuleum), and examines how the gut microbiome of wild fish changes in the lab. Fish were collected from sites upstream and downstream of 2 major WWTPs along the central Grand River and gut contents were aseptically sampled. After extracting gDNA, nested PCR of the V3-V4 region of the 16S rRNA gene, and Illumina sequencing were performed. The gut microbiome of exposed fish had increased bacterial diversity and was dominated by Proteobacteria, which has been linked to altered health outcomes in mammals. Next, rainbow darters were collected from a reference site on the Grand River. Fish were sampled in the field, after a 14 day lab acclimation, and after a 28 day exposure to environmental stressors (WWTP effluent or triclosan, an antimicrobial found in WWTP effluent). Surprisingly, there were no changes in the microbiome after exposure to environmental stressors. Major changes were observed between the field and laboratory fish suggesting that environment and diet are important factors influencing the gut microbiome. Changes in the gut microbiome continued up to 42 days in the lab, indicating longer acclimation periods may be needed. This study showed that effluents altered the gut microbiome of fish in the field, but not in the laboratory for unknown reasons. Laboratory studies indicated that transitioning to a new environment may require greater than 14 days before achieving a stable microbiome. / Thesis / Master of Science (MSc) / Wastewater is the largest source of pollution affecting Canada’s aquatic ecosystems; effluents contain antibiotics and antimicrobials that can affect fish and other aquatic life. The gut microbiome of fish is influenced by host species, its diet, and the environment, and thus contaminants released via wastewater effluents may alter the gut microbiome of fishes in receiving waters. This study found that the gut microbiota of rainbow darter fish exposed to wastewater effluents in the central Grand River (Waterloo/Kitchener, Ontario) were dominated by Proteobacteria and had increased diversity. Wild fish transitioned to the lab were dominated by Firmicutes and had decreased bacterial diversity in the gut compared to those in the wild. Altogether, these results suggest that wild fish exposed to wastewater effluents had altered gut microbiomes; transitions to new environments and laboratory acclimation periods are important considerations when studying the fish gut microbiome.

American Electric Power's (AEP) coal-fired Clinch River Plant, a power-generating facility in Carbo, Russell County, Virginia (USA), has impaired Clinch River biota through toxic spills in 1967 and 1970, and effluent copper (Cu) concentrations that were reported to have exceeded water quality criteria from 1985-1989. These impacts have provided impetus for many research projects addressing the absence of bivalves, including federally protected species of native mussels (Unionoidea), from sites influenced by CRP effluent. Modifications in CRP effluent during 1987 and 1993 drastically reduced Cu levels and warranted the present study, which assessed long-term biological recovery in Clinch River biota near the CRP. In 2000-2001, surveys of benthic macroinvertebrate communities and instantaneous measures of effluent toxicity did not foretell significant reductions in survivorship and growth of field-caged Asian clams (Corbicula fluminea) at sites downstream of the CRP. More importantly, these results indicated renewed toxicity in CRP effluent. Additional transplant studies using two enclosure types were conducted to isolate effects attributable to CRP effluent from the potentially confounding effects of substrate variability among study sites. While it was found that mean growth of clams was greatest in the enclosure that minimized substrate variability (p=0.0157), both enclosure types clearly distinguished significant impairment of survivorship and growth at sites downstream of the CRP discharge, and strengthened the association between impairment and CRP effluent. An intensive field investigation was undertaken to determine whether impairment observed in transplant studies extended to resident bivalves. During 2001-2002, densities and age structures of C. fluminea and distributions of mussels suggested that impairment indeed extended to resident bivalves for a distance of 0.5 to 0.6 km downstream of the CRP discharge. Impairment of bivalves was less evident below (1) a fly ash landfill and (2) coal mining activities and low-volume leachate from a bottom ash settling pond. With respect to long-term recovery, modifications in CRP effluent treatment have reduced Cu concentrations from an average of 436 mg/L in 1985-1989 to 13 mg/L in 1991-2002. Subsequently, Cu body burdens of Asian clams (Corbicula fluminea) transplanted within CRP influence have decreased from 442% of levels accumulated at reference sites in 1986, to 163% of these levels in 2002. The reduction in effluent Cu largely explains recovery of most benthic macroinvertebrate community parameters (e.g., richness, diversity) at influenced sites from levels that were typically less than 70% of reference levels, to levels that frequently range from 80 to greater than 100% of reference levels. Nevertheless, bivalves remain impaired downstream of the CRP; survivorship and growth of C. fluminea transplanted to CRP-influenced sites have typically been less than 40 and 20% of reference values, respectively. Furthermore, C. fluminea has seldom been encountered within CRP influence for nearly two decades. Likewise, native mussels remain absent within CRP influence, but recent surveys suggest their downstream distributions are more proximate to the CRP discharge than has been reported previously. A preliminary assessment of factors potentially contributing to toxicity revealed that (1) water reclaimed from settling basins for discharge with CRP effluent significantly impaired fecundity of ceriodaphnids at concentrations of 50%, (2) LC50 values for industrial treatment chemicals were misrepresented on Material Safety Data Sheets and consequently, were subject to misapplication by operators, (3) Cu concentrations of 96 mg/L significantly impaired growth of Asian clams in artificial stream testing, and (4) effluent Al exceeded acute and chronic water quality criteria, suggesting this ion should receive further consideration in future studies. / Master of Science

Form, mobility, toxicity and the eventual fate of engineered nanomaterials in environmental ecosystems are currently not well defined and are needed to improve risk assessment and legislation. The present study subjected uncoated zinc oxide (ZnO) nanoparticles (30nm and 200nm) and coated silver (Ag) nanoparticles (Paraffin: 3-8nm and citrate/PVP: 50nm) to different ionic strength media and different types of algal/bacterial extracellular-polymeric species (EPS) at long (6 months) and short (2 weeks) timescales. Changes in particle size distribution and stability were examined using a multi-method approach. Sample concentration and sample polydispersity are important factors when selecting techniques. Uncoated ZnO nanoparticles aggregated heavily in water at high concentrations (1000mg/L). However silver nanoparticles (1-10mg/L) remained stable at all ionic strengths and EPS in this study due to the steric component of their coatings. Nano-toxicological experiments involving cyanobacteria S.leopoliensis and green algae C.reinhardtii showed size-dependent toxicity from coated nanosilver particles. Smaller nanoparticles (3-8nm) showed greater dissolution over 72h and greater toxicity to both species than 50nm particles indicating silver ions are an important toxicity mechanism. Nanoparticle coatings were likely important in controlling dissolution levels. Cell viability and production of reactive oxygen species (ROS) were shown to be important mechanisms of toxicity to phycological species. Species specific effects were noted for both silver nanoparticles. EPS from S.leopoliensis were noted to remove ionic silver from suspension and different types of C.reinhardtii EPS were produced when particles underwent different levels of toxic stress indicating that EPS could both affect particle toxicity and be affected by it. This work has demonstrated that coated nanoparticles could remain stable under various ionic strengths and with exposure to algal organic matter for timescales up to 6 months. This could result in adverse effects to aquatic organisms were they to reach environmental systems and is of concern to nanomaterial risk assessors.

Amphibians are regarded as sensitive indicators of environmental change and are therefore excellent subjects for use in ecotoxicology. The Phongolo River floodplain is South Africa’s most diverse natural floodplain system and hosts more than 40 frog species. It is also a malaria endemic region and is subjected to active spraying with Dichlorodiphenyltrichloroethane (DDT) through means of indoor residual spraying over the summer months. The upper Phongolo River runs through agricultural landscape and is subjected to runoff from forest plantations, orchards and sugar cane plantations. In this study residue levels of 22 different organochlorine pesticides (OCPs) were analysed in selected amphibian species from in and around the Ndumo Nature Reserve coupled with 12 different biomarker response assays to determine environmental exposure levels and possible sublethal effects in amphibians from the lower Phongolo River floodplain. Seasonal change, direct influence of anthropogenic activity and the influence of species’ aquatic preference in habitat selection were all factors considered during this assessment. Stable Isotope analyses were performed on 11 different food web components In order to determine the food web structure pertaining to Xenopus muelleri (Müller's platanna). Samples were collected during both high and low flow seasons from inside and outside Ndumo Nature Reserve. Organochlorine pesticide bioaccumulation was analysed in whole frog samples using a GC-μECD. Results indicated significant seasonal variation in OCP levels and exposure composition. Significant differences between inside and outside sites were also noted. Dichlorodiphenyltrichloroethane in its different isomer forms and their metabolites along with the hexachlorocyclohexane (HCH) isomers was the two main contributing OCP groups detected. Total OCP levels from all sample sets ranged between 8.71 ng/g lipid and 21,399.03 ng/g lipid. An increase in OCP accumulation was observed for X. muelleri over a period of one year. Organochlorine pesticides are known to have neurotoxic effects causing imbalances in Na+, K+, and Ca+ ion exchange. Hyperactivity has been reported in Rana temporaria (European Common frog) tadpoles exposed to p,p-DDT concentrations above 110,000 ng/g lipid. Despite OCP levels measured in frogs from this study being lower than reported toxic levels, the biomarker response assays indicated definite oxidative stress responses correlating to OCP bioaccumulation, with other minor responses shown. Cellular energy allocation showed a shift in the main energy source type from proteins to lipids correlating to increased OCP bioaccumulation. A slight inhibition response was noted in the hepato-somatic index correlating to γ-HCH bioaccumulation. Stable isotope analyses indicated food web structure differences between inside and outside the reserve, with outside showing less clear distinction between trophic groups and nitrogen enrichment of primary producers. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015