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No. of bitstreams: 1 biancasartinidoespiritosanto.pdf: 3527781 bytes, checksum: c9a6ba355ca58ea44e1eb59dcc0ca070 (MD5) Previous issue date: 2012-02-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No presente estudo foi avaliada a influência da poluição orgânica sobre a composição e estrutura da comunidade de ciliados peritríqueos em ambientes lóticos no município de Juiz de Fora, Minas Gerais sujeitos a diferentes níveis de poluição orgânica, bem como os aspectos ecológicos da relação epibiótica entre esses ciliados e moluscos gastrópodes. A presente dissertação está dividida em duas seções. Na primeira seção foram analisadas a composição e estrutura da taxocenose de protistas ciliados peritríqueos encontrados em nove córregos afluentes do rio Paraibuna, Juiz de Fora, MG, que recebem diferentes cargas de esgoto doméstico. Além disso, foi avaliado o potencial destes microorganismos como indicadores da qualidade da água desses ambientes. Os ciliados peritríqueos foram obtidos com o emprego de substratos artificiais em cinco coletas, com intervalos mensais, realizadas entre junho e outubro de 2010. Amostras de água foram coletadas para avaliar os parâmetros físico-químicos: condutividade elétrica, oxigênio dissolvido, pH e nutrientes. No laboratório, os peritríqueos foram quantificados em microscópio com contraste interferencial diferencial e fixados para realização de técnicas identificação por impregnação pela prata. Foram registradas 19 espécies de ciliados peritríqueos nas estações amostrais analisadas. A espécie Carchesium polypinum (Linné, 1785) ocorreu com maior freqüência e abundância nos ambientes com grande quantidade de poluição sendo considerada como indicadora desses ambientes. Foi observada correlação positiva entre a concentração de nutrientes e a abundância e densidade de peritríqueos. Os valores mais elevados de dominância, densidade e abundância de espécies ocorreram em ambientes com altos níveis de poluição orgânica enquanto que, os maiores valores de riqueza e diversidade foram observados nas estações com níveis intermediários de poluição orgânica. Na segunda seção, foi realizada a avaliação da composição e estrutura da comunidade e a distribuição espacial de peritríqueos epibiontes sobre a concha de moluscos da espécie Physa acuta (Draparnaud, 1805) coletados em um dos nove córregos analisados na seção 1. Dos 140 moluscos analisados, 60.7% estavam colonizados por pelo menos uma das sete espécies de peritríqueos epibiontes. A espécie Epistylis sp. foi considerada dominante, representando 70.4% da abundância total de epibiontes. Além disso, os epibiontes se distribuíram por toda a superfície da concha, apresentando maior abundância na superfície ventral do que na dorsal. O presente estudo contribui para a ampliação do conhecimento sobre a ecologia de protistas ciliados peritríqueos neotropicais. / In the present study, was evaluated the influence of the organic pollution on both the composition and structure of the taxocenose of peritrich ciliates found in lotic systems at Juiz de Fora, Minas Gerais State, with different loads of domestic sewage, as well the ecological aspects of the epibiotic relation between gastropods mollusks. The present dissertation is divided into two parts. In the first one, the influence of the organic pollution on both the composition and structure of the taxocenose of peritrichs ciliates found at nine tributary streams of the Paraibuna river, Juiz de Fora, MG, wich receive different levels of domestic sewage. Furthermore, the potential of these microorganisms as water quality indicators in these environments was evaluated. Peritrichs ciliates were obtained with the use of artificial substrates in five monthly sampling carried out between June and October 2010. Water samples were collected for assessment of the physico-chemical parameters: electrical conductivity, dissolved oxygen, pH and nutrients. At the laboratory, the peritrichs ciliates were quantified in microscope equipped with Differential Interferential Contrast, and then fixed to conduct identification techniques for silver impregnation. Nineteen peritrichs ciliates species were recorded at sampling stations studied. The peritrich Carchesium polypinum (Linné, 1785) was species more frequent in environments with high organic pollution load. The abundance and density of peritrichs ciliates was positively correlated with nutrients. It was also observed the highest dominance, density and abundance of species in environments with high levels of organic load, and on the other hand, the highest richness and diversity in environments with intermediary levels of organic pollution. In the second, the composition, spatial distribution and taxocenose structure of the peritrich as epibiont on the shell of the Physa acuta (Draparnaud, 1805) snail were evaluated. Of the 140 molluscs analyzed 60.7% were colonized by at least one of the seven species of peritrich epibiont. Epistylis sp. was considered as dominant species, representing 70.4% of the epibiont total abundance. In addition, the epibiont were distributed over the entire surface of the shell, with higher abundance in the ventral surface. This study contributes to the expansion of knowledge about the ecology of protists peritrichs ciliates in neotropical lotic systems.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-02-16T16:40:03Z No. of bitstreams: 1 DISSERTAÇÂO FELIPPE BRAGA.pdf: 3584465 bytes, checksum: 5a6e3d3041992e9cdde4fba139fbe982 (MD5) / Made available in DSpace on 2017-02-16T16:40:04Z (GMT). No. of bitstreams: 1 DISSERTAÇÂO FELIPPE BRAGA.pdf: 3584465 bytes, checksum: 5a6e3d3041992e9cdde4fba139fbe982 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências- Geoquímica Ambiental. Niterói, RJ / Bivalves marinhos podem acumular altas concentrações de metais disponíveis no ambiente. Como consequência, eles têm sido utilizados como biomonitores de contaminação costeira. No presente estudo, bivalves marinhos da espécie Anomalocardia brasiliana coletados na Baía de Sepetiba (Rio de Janeiro, Brasil), foram aclimatados e submetidos a um conjunto de experimentos realizados em sistema fechado onde foram expostos à radiotraçadores por até 10 dias no Laboratório de Radioisótopos Aplicados ao Meio Ambiente (LARAMAM) na Universidade Federal Fluminense. A fim de avaliar a cinética de incorporação e de depuração de metais-traço foi adicionada concentração conhecida dos radioisótopos 54Mn, 57Co e 65Zn na água do mar coletada. Os radiotraçadores foram analisados por espectrometria da radiação γ. Neste estudo foi investigado o uso potencial da Anomalocardia brasiliana como biomonitor em eventos agudos de contaminação, uma vez que pouco se sabe sobre a dinâmica de acumulação de metais nesta espécie. Esta avaliação teve como finalidade fornecer subsídios para a futura aplicação desta abordagem metodológica no monitoramento de eventos de real contaminação por metais no Brasil. Os resultados observados mostraram que é possível aplicar esta metodologia para avaliar a dinâmica de depuração dos metais nesta espécie de bivalve, essencialmente em casos de contaminação aguda. Foi observado que o intervalos de tempo adotados para a amostragem, com base na literatura, não foram suficientes para a obtenção da cinética de incorporação dos radiotraçadores por esta espécie, além disso, observou-se que esta espécie foi capaz de depurar assim que a atividade de radioisótopos na água atingiu o equilíbrio. Em termos da distribuição dos radioisótopos na coluna sedimentar, as maiores concentrações de 57Co, 54Mn e 65Zn foram encontradas nas camadas mais superficiais dos sedimentos. / Marine bivalves can accumulate high metal concentration from the surrounding environment. Consequently, they have been used as biomonitors in processes of coastal contamination. In the present work marine bivalves from Anomalocardia brasiliana species were collected from the Sepetiba Bay (Rio de Janeiro State, Brazil), acclimated in laboratory conditions and exposed to radiotracers in a closed system experiment during 10 days. The experimental procedure was developed in the Laboratory of radioisotopes applied to the environment at the Fluminense Federal University (LARAMAM/UFF). The main objectives of this work were to evaluate the uptake and downtake kinetics of trace metals through the addition of 54Mn, 57Co and 65Zn to the collected sea water. The radiotracers were measured using gamma radiation spectrometry. In the present study the potential use of Anomalocardia brasiliana a biomonitor in events of contamination was investigated, since little is known the metal accumulation dynamics for such species. This evaluation had the objective of providing subsides for the future application of this methodology for monitoring actual metal contamination events in Brazil. The results have shown that it is possible to apply such methodology to evaluate the depuration dynamics in this bivalve species, essentially in acute contamination. It was observed that the time intervals adopted for the sampling based on literature were not enough for obtaining the radiotracers incorporation kinetics for this species. Also, it was able to depurate as soon as the water activity reached the equilibrium. In terms of radioisotpes distribution within the sedimentation column the highest concentrations of 57Co, 54Mn e 65Zn were found in the top layers.

Magister Scientiae - MSc / The aim of this study was to use plants to determine the degree of heavy metal contamination in water and sediments in order to effectively monitor and provide possible recommendation to improve the water quality in the aquatic ecosystem of the Bottelary River.

Alterações antrópicas em ecossistemas aquáticos exigem medidas de recuperação dos ambientes degradados, destacando-se projetos de restauração ecológica. Uma das etapas cruciais nesses projetos é a fase de monitoramento, sendo que o uso de macroinvertebrados como bioindicadores apresenta-se como uma importante ferramenta, por eles oferecerem vantagens sobre outros métodos de avaliação. Assim, o objetivo foi verificar os efeitos do assoreamento, antes e depois do rompimento da barragem de um pequeno reservatório em um riacho tropical, sobre a assembleia de macroinvertebrados aquáticos e avaliar a resposta da estrutura da comunidade após a implementação de um projeto de restauração ecológica. A pesquisa foi conduzida no riacho da Campininha, que passou por diversas alterações antrópicas, destacando-se aqui o rompimento de uma barragem e posteriormente a todos esses distúrbios pela implementação de um projeto de restauração ecológica. Foi realizada revisões da literatura para verificação da aplicabilidade da comunidade de macroinvertebrados como bioindicadores de sedimentação e na avaliação de projetos de restauração ecológica. Foram coletados dados pré-existentes antes e após o acidente e realizadas campanhas amostrais dois anos após o início da implantação do projeto de restauração. A comunidade de macroinvertebrados foi avaliada pela aplicação de índices ecológicos estruturais e funcionais alimentares e os resultados analisados por meio de ferramentas de estatística uni e multivariada. A análise da literatura mostrou que a aplicação de índices ecológicos tradicionais, tais como riqueza e diversidade, podem não ser sensíveis o suficiente para indicar impactos relacionados à sedimentação e implementação de projetos de restauração ecológica. Sendo, assim, necessária a utilização de índices que considerem a composição da comunidade, a sensibilidade dos organismos e a utilização de grupos funcionais alimentares e suas relações. Antes do rompimento da barragem a comunidade de macroinvertebrados já apresentava-se empobrecida pelo assoreamento do trecho represado e do canal fluvial. O rompimento da estrutura implicou na perda de importantes grupos e na mudança da composição da comunidade, além da perda de grupos funcionais alimentares, com consequente perda de funções ambientais. Após a implementação do projeto de restauração houve o aparecimento de 20 famílias, no entanto, os índices ecológicos tradicionais não foram capazes de identificar mudanças na comunidade. Métricas de composição e de grupos alimentares apontaram para um processo de recuperação da área. As características do sedimento tiveram um alto poder explicativo da comunidade, mostrando que a recuperação do habitat bentônico é um dos fatores que leva à uma melhor resposta da comunidade, mesmo esse não tendo sido o foco da aplicação do projeto de restauração avaliado. O relativo curto período transcorrido após a implementação do projeto já foi suficiente para indicar melhorias na qualidade ambiental. Tais resultados contrapõe a maioria dos estudos verificados na revisão da literatura. No entanto destaca-se que os mesmos foram conduzidos principalmente em ambientes temperados, indicando que em ambientes tropicais a dinâmica de recuperação é diferente. Assim aponta-se a necessidade da intensificação da implantação de projetos e monitoramento dos mesmos para a criação de um arcabouço teórico para auxiliar gestores e projetistas na sua elaboração. / Anthropic alterations in aquatic ecosystems demand the implementation of recuperation actions, highlighting ecological restoration projects. The monitoring is an important step to these projects, and the macroinvertebrates application as bioindicators is an important tool, because they are advantageous in comparison to another assessment methods. Thus, the goal was verify the effects of silting, and dam rupture in macroinvertebrate community, in a tropical stream, and assess the answer to an ecological restoration project implementation. The research was conducted in the Campininha stream, that was impacted by anthropic alterations, featured a dam rupture and after all this disturbances was implemented an ecological restoration project. A literature review was conducted to verification of the applicability of macroinvertebrates as bioindicators of silting and in ecological restoration projects assessment. Data was collected before and after the dam rupture, and samplings were done two years after the project implementation began. The macroinvertebrates community was assessed by application of structural and functional feeding indexes and the results analyzed by univariate and multivariate statistic. The literature review showed that the traditional indexes application may be not sensible to indicate impacts related to silting and ecological restoration projects implementation, and it is necessary the utilization of indexes that consider the community composition, organisms sensibility and functional feeding groups and your relations. Before the dam rupture, the macroinvertebrate community was already poor by the silting of the lake and fluvial channel. The dam rupture leaded to the loss of important groups and in the change of the macroinvertebrate community composition, also loss of functional feeding groups and consequently environmental functions. After the ecological restoration project implementation were found another 20 families, however, the traditional indexes were not sensible to indicate changes in macroinvertebrates community. Composition and functional feeding groups indexes showed the stream recuperation process. The sediment characteristics had a community high explanative power showing that the benthic habitat recovery is a factor that guide to a better community answer, even this was not the goal of the restoration project application. The relative short time after the project implementation was enough to point a environmental quality recovery, in contrast with the literature review. However the most studies analyzed was conducted in temperate environments, showing that in tropical environments the recovery dynamics is different. Thus, is necessary a intensification of restoration projects implementation and monitoring to a creation of data bases to guide managers and professionals responsible by the projects elaboration in decision make.

Orientador: Maria Aparecida Marin-Morales / Resumo: O crescente aumento das atividades antrópicas vem promovendo um aumento nos impactos causados ao meio ambiente. Dentre essas atividades humanas, a mineração, realizada no Brasil desde o século XVII e persistindo até os dias atuais, tem se destacado, quanto à sua potencialidade de causarem danos ambientais. O estado de Minas Gerais é um grande produtor de ouro e nele está localizado o município de Paracatu, onde se encontra a mina Morro do Ouro, que é considerada uma grande lavra a céu aberto, situada a poucos metros do perímetro urbano. Diante deste cenário, o presente estudo tem por objetivo avaliar a biodisponibilidade dos metais presentes nas amostras, as fontes poluidoras envolvidas com a contaminação desses metais e os riscos que esses metais promovem ao meio ambiente, por meio das análises químicas, extrações sequenciais e cálculos de Fator de Enriquecimento (EF), Índice de geoacumulução (Igeo) e Avaliação de Risco (RAC) e o potencial tóxico das amostras, por meio de bioensaios in vivo (Allium cepa e Lactuca sativa) e in vitro (cultura celular humana – HepG2/C3A). Para a avaliação do comprometimento dos rios que recebem influência da mineradora, foram coletadas amostras de água superficiais e de sedimentos de 3 regiões distintas: 1) jusante da mina Morro do Ouro, onde está localizado o município de Paracatu (P1, P2 e P3); 2) jusante da barragem de rejeitos da mina Morro do Ouro (P4, P5 e P6) e 3) rio de captação de água para abastecimento público de Paracatu (P7) e água... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The increase of anthropic activities has been promoting an impact increase to the environment. Among these human activities, mining, conducted in Brazil since the XVII century, has stood out for its potential to cause environmental damage. The Morro do Ouro mine, located in Paracatu (state of Minas Gerais, considered a major gold producer) is a large open mining located a few meters from the urban perimeter. According to this scenario, the present study aims to evaluate the bioavailability of the metals present in the samples, the polluting sources involved with the contamination of these metals and the risks that these metals promote to the environment by chemical analysis, sequential extractions and calculations of Enrichment Factor (EF), Geoaccumulation Index (Igeo) and Risk Assessment (RAC) and the toxic potential of samples by in vivo (Allium cepa and Lactuca sativa) and in vitro bioassays (human cell culture - HepG2 / C3A).To evaluate the impact of rivers that receive influence from the mining company, surface water and sediment samples were collected from 3 different regions: 1) downstream of the Morro do Ouro mine, located in Paracatu (P1, P2 and P3); 2) downstream of the Morro do Ouro tailings dam (P4, P5 and P6) and 3) Paracatu water supply river (P7) and water supply provided by Paracatu WTS (Water Treatment Station) (P8). Afterwards, two extracts of eachcollected sediments (solubilized and leached) were prepared. The results demonstrated that this region is highly... (Complete abstract click electronic access below) / Doutor

Les milieux côtiers subissent de fortes pressions dues aux activités anthropiques. Ces pressions vont parfois impacter les écosystèmes benthiques. En Europe, des réglementations internationales, telle que la Directive Cadre sur l’Eau (DCE), ont vu le jour. La DCE a fixé un cadre pour obtenir le retour et le maintien d’un bon état écologique pour les masses d’eau côtières, jusqu’à un mile de la côte. Pour vérifier si ce bon état écologique est atteint, des outils de mesure adaptés et performants sont nécessaires. L’utilisation d’indices biotiques basés sur les faunes de foraminifères benthiques est un des moyens pour mesurer l’état des écosystèmes. Ces indices basés sur les faunes de foraminifères sont en pleine expansion, notamment en Méditerranée. En termes de méthodologie, nous avons pu améliorer une technique de concentration des foraminifères benthiques par séparation par densité, qui accélère le traitement des échantillons. L’indice TSI-Med a la particularité d’apporter une correction pour l’état trophique naturel, c’est-à-dire le taux d’enrichissement naturel en matière organique, sur la base de la granulométrie du sédiment. Nos données suggèrent néanmoins que cette correction est encore insuffisante. Nous avons également comparé plusieurs indices biotiques basés sur les faunes de foraminifères benthiques le long des côtes méditerranéennes françaises. Les indices basés sur la diversité, notamment l’exp(H’bc), ne sont pas adaptés à notre zone d’étude oligotrophe. Les indices basés sur les groupes écologiques d’espèces que nous avons testés (TSI-Med, Foram-AMBI et FSI) sont plutôt bien corrélés. Le principal facteur qui va induire des différences entre ces indices est la liste d’assignation écologique des espèces. Trop d’espèces n’ont pas encore été assignées et l’assignation de plusieurs espèces majeures est problématique. Néanmoins, nous avons montré que ces indices sont efficaces à détecter l’impact d’un enrichissement en matière organique diffus et/ou provenant de source ponctuelle, telle que les rejets de stations d’épuration (côte israélienne). Pour perfectionner ces indices, des efforts de caractérisation écologique des espèces doivent être poursuivis. / Coastal environments suffer from anthropogenic activities. Various types of pressure can have large impacts on benthic ecosystems. In Europe, international regulations, such as the Water Framework Directive (WFD), have been implemented. The WFD aims to attain and sustain a good ecological status for all coastal waters, up to one mile from the coast. To verify whether this good status has been reached, adapted and efficient measuring tools are needed. The use of biotic indices based on foraminiferal faunas are a mean to assess the ecosystem status. The use of indices based on foraminiferal faunas rapidly increases, especially in the Mediterranean. In terms of methodology, we were able to improve a method to concentrate benthic foraminifera by density separation, which accelerates the sample treatment. The TSI-Med index includes a correction to take into account the natural trophic state, i.e., the natural enrichment rate in organic matter, on the basis of sediment grain size. However, our data suggest that the applied correction is still insufficient. We also compared several biotic indices based on benthic foraminiferal faunas along the French Mediterranean coast. Indices based on diversity, such as the exp(H’bc), are not suited for our oligotrophic study area. The results of three tested indices based on ecological groups (TSI-Med, Foram-AMBI, FSI) are well correlated. The main factor inducing differences between the indices is the list of ecological assignments for the various species. In general, too many species have not yet been assigned to ecological categories and the assignment of several major species is problematic. Nevertheless, we show that the indices are already efficient in detecting the impact of diffusive organic matter enrichment or enrichment from point sources, such as sewage outlets (Israelian coast). To further perfection the foraminiferal indices, the efforts of ecological assignments of species have to be continued

Mit der vorliegenden Broschüre werden die Ergebnisse des Sächsischen Landesamtes für Umwelt, Landwirtschaft und Geologie, des Staatsbetriebes Sachsenforst und der Staatlichen Betriebsgesellschaft für Umwelt und Landwirtschaft gemeinsam vorgestellt. Aus mehrjährigen acker- und pflanzenbaulichen sowie forstlichen Untersuchungen liegen umfangreiche Ergebnisse zu Stickstoffdüngung, -aufnahme, -bilanz und -dynamik unter sächsischen Bedingungen vor. Die zusammenfassende Darstellung der Ergebnisse zeigt, dass regelmäßige Auswertungen der in den verschiedenen Messnetzen erhobenen Parameter und Messreihen die Plattform für ein integriertes und ressortübergreifendes Stickstoffmonitoring bilden können. Die Broschüre liefert einen Beitrag zur Bewertung der Stickstoffbelastung und enthält Handlungsempfehlungen für Flächenbewirtschafter sowie für die Verwaltung.

Les êtres humains sont constamment confrontés à des agents génotoxiques issus de l’environnement ou liés aux activités humaines. Ces agents induisent différents types de lésions sur l’ADN et peuvent conduire à un risque accru de développer des cancers. Pour préserver son intégrité génétique, la cellule possède divers mécanismes de réparation permettant leur élimination. L’impact de ces agents exogènes sur l’organisme a conduit à l’émergence d’un nouveau domaine, la biosurveillance. Elle vise à évaluer l’exposition des individus par l’identification d’indicateurs biologiques de l’exposition. Cependant, à ce jour, une des limites principales dans ce domaine est le manque de méthodes et de biomarqueurs disponibles. Afin de définir de nouveaux biomarqueurs, les conséquences de l’exposition de deux agents cancérigènes reconnus, le benzo[a]pyrène et le chlorure de vinyle, ainsi que leurs métabolites toxiques ont été évaluées dans deux modèles cellulaires. Pour cela, deux méthodes ont été utilisées : la chromatographie liquide haute performance couplée à la spectrométrie de masse pour la quantification des lésions formées ainsi qu’un test de mesure des activités enzymatiques de réparation développé par la société LXRepair. Cette approche permet d’appréhender de manière globale l’exposition à ces composés en étudiant différents paramètres comme le seuil de déclenchement, la variabilité ainsi que la spécificité de la réponse cellulaire. L’étude a montré la difficulté de mettre en évidence une réponse spécifique à un agent donné. Cependant, les profils de réparation obtenus ont souligné la complexité des régulations mises en jeu et permettent de soulever de nouvelles pistes de recherches. / Humans are constantly exposed to environmental genotoxic agents. These agents can induce different types of DNA damage, which have been associated with an increased risk of developing cancer. In order to maintain genomic integrity, cells have multiple DNA repair mechanisms that help protect their DNA from injury. Investigation of the impact of these exogenous genotoxic agents on individuals leads to the emergence of a new field, biomonitoring. This field allows researchers to evaluate individual exposure to genotoxic agents based on the detection of biological markers of exposure. However, up to now, the major limitations in this area are the lack of relevant biomarkers, as well as the availability of methods to detect them. In order to define new biomarkers, two cell lines were exposed to two well-known carcinogenic compounds, benzo[a]pyrene and vinyl chloride, as well as their toxic metabolites, in order to determine the consequences of these exposures. Two methods were used: DNA lesions were quantified by HPLC-MS/MS and DNA repair activities were evaluated using a microarray assay developed by the start-up company, LXRepair. This approach allowed us to gain a global understanding related to the exposure of these compounds by considering different parameters, such as the specificity of different cellular responses to a given genotoxic agent and the minimum concentration needed to observe an effect with respect to its toxicity. This study underlines the complexity to obtain specific cellular responses to a given genotoxic agent. However, DNA repair signatures bring on the intricacy of the regulations of DNA repair mechanisms and open up new research avenues.

Die Belastung von Oberflächengewässern kann mit unterschiedlichen Methoden erfasst werden. Bioteste ergänzen die Ergebnisse der chemischen Analyse. Mit dem effektbasierten Monitoring lassen sich Risikopotentiale erfassen. Es sind Rückschlüsse auf die Art der Belastung möglich. Der Bericht enthält erste Ergebnisse für ausgewählte sächsische Fließgewässer. Redaktionsschluss: 29.07.2019

Contexte : L’acide perfluorooctanoïque (PFOA) est présent dans le sang de presque tous les participants dans les études de biosurveillance. L’appréciation des risques pour la santé qui sont associés aux concentrations sanguines de PFOA est difficile, car les valeurs guides d'exposition (VGE) sont généralement exprimées en termes de dose externe. Des équivalents de biosurveillance (ÉB) compatibles avec les VGE pourraient faciliter l'interprétation des concentrations de PFOA dans le contexte du risque pour la santé. Objectifs : i) Dériver des ÉB pour le PFOA sérique ou plasmatique correspondant aux VGE de la Environmental Protection Agency des États-Unis (U.S. EPA), de la Agency for Toxic Substances and Disease Registry (ATSDR) et de Santé Canada, et ii) comparer les ÉB avec les concentrations de PFOA mesurées dans des enquêtes nationales de biosurveillance. Méthodes : En partant des points de départ à partir desquels les VGE ont été estimées, nous avons dérivé des ÉB à l'aide de données ou modèles pharmacocinétiques et de facteurs d'incertitude. À l'aide d'un modèle pharmacocinétique animal de gestation et de lactation, nous avons converti les points de départ chez les souris gestantes (U.S. EPA 2016, ATSDR) en concentrations sériques chez l’organisme en développement pour quatre mesures de dose (concentrations moyenne prénatale, moyenne postnatale, moyenne totale, et maximale). Les concentrations équivalentes chez le fœtus humain et l’enfant ont ensuite été converties en ÉB correspondants dans le sérum maternel humain au moment de la conception à l'aide d’une modèle pharmacocinétique humain de grossesse et d’allaitement. Le point de départ chez les rongeurs adultes (Santé Canada) a été converti en un ÉB dans le sérum humain adulte à l'aide de données expérimentales. Pour le point de départ basé sur l'épidémiologie (valeur provisoire de 2022 de l’U.S.EPA), un BE a été dérivé à l'aide d'un modèle pharmacocinétique humain de grossesse et d’allaitement. Les BE dérivés ont été comparés à des données de biosurveillance canadiennes et américaines. Résultats : Les ÉB étaient de 684 ng/mL pour Santé Canada, de 0.012 ng/mL pour l’U.S. EPA (valeur provisoire de 2022), et variaient de 15 à 29 ng/mL pour l’U.S. EPA (valeur de 2016) et de 6 à 10 ng/mL pour l’ATSDR. Les 95ème centiles des concentrations sériques dans l'Enquête canadienne sur les mesures de la santé (ECMS) de 2018-2019 et dans la National Health and Nutrition Examination Survey (NHANES) de 2017-2018 étaient légèrement inférieures à l’ÉB de l’ATSDR et deux ordres de grandeur plus élevées que l'ÉB pour la valeur provisoire de 2022 de l’U.S. EPA. Conclusion : Les ÉB couvraient quatre ordres de grandeur. Les concentrations de PFOA mesurés dans des enquêtes nationales de biosurveillance canadiennes et américaines étaient supérieures ou similaires à certains de ces ÉB. / Background: Perfluorooctanoic acid (PFOA) is detected in the blood of virtually everyone participating in biomonitoring studies. Assessing the health risks associated with blood PFOA levels is challenging because exposure guidance values (EGVs) are typically expressed in terms of external dose. Biomonitoring equivalents (BEs) consistent with EGVs could facilitate interpreting biomarker levels in a health risk context. Objective: To i) derive BEs for serum/plasma PFOA corresponding to the EGVs of the U.S. Environmental Protection Agency (U.S. EPA), the Agency for Toxic Substances and Disease Registry (ATSDR) and Health Canada, and ii) compare with PFOA levels measured in national biomonitoring surveys. Methods: Starting from the points of departure from which EGVs were estimated, we derived BEs using pharmacokinetic data/models and uncertainty factors. Using an animal gestational/lactational pharmacokinetic model, we converted points of departure in pregnant dams (U.S. EPA 2016, ATSDR) into serum concentrations in the developing organism for four dose metrics: average prenatal, average postnatal, average overall, and maximum concentrations. Equivalent human fetus and child concentrations were then converted into corresponding BEs in maternal serum at time of conception using a pharmacokinetic model of human gestation/lactation. The point of departure in adult rodents (Health Canada) was converted into a BE in adult serum using experimental data. For the epidemiology-based point of departure (U.S.EPA 2022, draft), a BE was derived using a human pharmacokinetic model of gestation/lactation. BEs were compared with Canadian and U.S. biomonitoring data. Results: BEs (ng/mL) were 684 for Health Canada, 0.012 for the U.S. EPA (2022 draft), and ranged from 15-29 for the U.S. EPA (2016) and from 6-10 for ATSDR. Ninety-fifth percentiles of serum levels from the 2018-2019 Canadian Health Measures Survey (CHMS) and the 2017-2018 National Health and Nutrition Examination Survey (NHANES) were slightly below the BE for the ATSDR, and two orders of magnitude above the BE for the U.S. EPA (2022 draft). Conclusion: BEs varied over four orders of magnitude. Levels measured in Canadian and U.S. national surveys were higher than or close to some of these BEs.