Introduction : Les polybromodiphényléthers, connus sous l'acronyme de PBDE, sont abondamment utilisés en industrie (textile, plastiques, électronique) pour leurs propriétés ignifugeantes. Bien qu'elles soient utiles, ces nouvelles substances s'accumulent dans l'environnement. Des études animales et récemment chez l'humain ont montré que ces substances sont susceptibles d'interférer avec le métabolisme des hormones thyroïdiennes. Les PBDE sont des substances lipophiles et sont mobilisés largement pendant la grossesse. Cette mobilisation de polluants accumulés depuis des années dans le tissu adipeux maternel explique une exposition foetale importante. Selon notre hypothèse, les niveaux élevés des PBDE chez les femmes enceintes peuvent interférer avec le métabolisme des hormones thyroïdiennes et, par conséquence, altérer le développement psychomoteur ultérieur des enfants. Objectifs: (i) Déterminer les concentrations plasmatiques des PBDE dans une population des femmes enceintes; (ii) Examiner la relation entre les concentrations des PBDE et les niveaux circulant en hormones thyroïdiennes dans le sérum maternel. Matériel et Méthodes : Il s'agit d'une étude transversale portant sur un groupe de 195 femmes enceintes recrutées au début de la grossesse (<20 semaines). Lors de l'entrevue, après la signature du consentement, un échantillon de sang et d'urine maternels ont été prélevés et un questionnaire a été proposé à chaque participante. Les PBDE (congénères BDE-47, -99, -100, -153) ont été déterminés par la chromatographie en phase gazeuse (GC-MS). La TSH et les hormones thyroïdiennes (T4 et T3 libres et totales) ont été déterminées dans les échantillons sanguins. Les BPC, les lipides, le sélénium et le mercure sanguins ainsi que l'iode urinaire ont été mesurés afin de contrôler les facteurs confondants potentiels. Résultats : L'âge moyen des femmes était de 28±4.7 ans. Le BDE-47 a été détecté dans tous les échantillons. Les médianes des quatre congénères de PBDE les plus prévalents sont de 16.21 ng/g (max: 177,47 ng/g lipides), 1,09 ng/g (max: 74,58 ng/g lipides), 1,76 ng/g (max: 105,76 ng/g lipides), 1,14 ng/g (max: 63,66 ng/g lipides), respectivement pour le BDE-47, BDE-99, BDE-100, BDE-153. D'une façon générale, les concentrations de PBDE sont faibles et celles des hormones thyroïdiennes se situaient pour la plupart dans les intervalles des valeurs de référence. Dans les modèles de régression multiples, le BDE-47 était positivement associé à l'âge et l'âge gestationnel. Nous avons trouvé des associations positives entre la T3 et T4 totales et le BDE-47 ainsi que la somme des PBDE. Conclusion : Ces résultats suggèrent que, même à de faibles niveaux d'exposition, ces contaminants environnementaux persistants et émergents pourraient interférer avec le statut thyroïdien pendant la grossesse en augmentant les concentrations de la T3 et T4 totales. Il est peu probable que l'interférence avec les hormones thyroïdiennes au début de grossesse pourrait expliquer les effets neurotoxiques des PBDE observé chez l'enfant en développement.

<p>Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs) that have been heavily used in consumer products such as furniture foams, plastics, and textiles since the mid-1970’s. BFRs are added to products in order to meet state flammability standards intended to increase indoor safety in the event of a fire. The three commercial PBDE mixtures, Penta-, Octa-, and DecaBDE, have all been banned in the United States, however, limited use of DecaBDE is still permitted. PBDEs were phased out of production and added to the Stockholm Convention due to concerns over their environmental persistence and toxicity. Human exposure to PBDEs occurs primarily through the inadvertent ingestion of contaminated house dust, as well as though dietary sources. Despite the phase-out and discontinued use of PBDEs, human exposure to this class of chemicals is likely to continue for decades due to the continued use of treated products and existing environmental reservoirs of PBDEs. Extensive research over the years has shown that PBDEs disrupt thyroid hormone (TH) levels and neurodevelopmental endpoints in rodent and fish models. Additionally, there is growing epidemiological evidence linking PBDE exposure in humans to altered TH homeostasis and neurodevelopmental impairments in children. Due to the importance of THs throughout gestation, there is a great need to understand the effects of BFRs on the developing fetus. Specifically, the placenta plays a critical role in the transport, metabolism, and delivery of THs to the fetal compartment during pregnancy and is a likely target for BFR bioaccumulation and endocrine disruption. The central hypothesis of this dissertation research is that BFRs disrupt the activity of TH sulfotransferase (SULT) enzymes, thereby altering TH concentrations in the placenta.</p><p>In the first aim of this dissertation research, the concentrations of PBDEs and 2,4,6-TBP were measured in a cohort of 102 placenta tissue samples from an ongoing pregnancy cohort in Durham, NC. Methods were developed for the extraction and analysis of the BFR analytes. It was found that 2,4,6-TBP was significantly correlated with all PBDE analytes, indicating that 2,4,6-TBP may share common product applications with PBDEs or that 2,4,6-TBP is a metabolite of PBDE compounds. Additionally, this was the first study to measure 2,4,6-TBP in human placenta tissues.</p><p>In the second aim of this dissertation research, the placenta tissue concentrations of THs, as well as the endogenous activity of deiodinase (DI) and TH SULT enzymes were quantified using the same cohort of 102 placenta tissue samples. Enzyme activity was detected in all samples and this was the first study to measure TH DI and SULT activity in human placenta tissues. Enzyme activities and TH concentrations were compared with BFR concentrations measured in Aim 1. There were few statistically significant associations observed for the combined data, however, upon stratifying the data set based on infant sex, additional significant associations were observed. For example, among males, those with the highest concentrations of BDE-99 in placenta had T3 levels 0.80 times those with the lowest concentration of BDE-99 (95% confidence interval (CI): 0.59, 1.07). Whereas females with the highest concentrations of BDE-99 in placenta had T3 levels 1.50 times those with the lowest concentration of BDE-99 (95% CI: 1.10, 2.04). Additionally, all BFR analyte concentrations were higher in the placenta of males versus females and they were significantly higher for 2,4,6-TBP and BDE-209. 3,3’-T2 SULT activity was significantly higher in female placenta tissues, while type 3 DI activity was significantly higher in male placenta tissues. This research is the first to show sex-specific differences in the bioaccumulation of BFRs in human placenta tissue, as well as differences in TH concentrations and endogenous DI and SULT activity. The underlying mechanisms of these observed sex differences warrant further investigation. </p><p>In the third aim of this dissertation research, the effects of BFRs were examined in a human choriocarcinoma placenta cell line, BeWo. Michaelis-Menten parameters and inhibition curves were calculated for 2,4,6-TBP, 3-OH BDE-47, and 6-OH BDE-47. 2,4,6-TBP was shown to be the most potent inhibitor of 3,3’-T2 SULT activity with a calculated IC50 value of 11.6 nM. It was also shown that 2,4,6-TBP and 3-OH BDE-47 exhibit mixed inhibition of 3,3’-T2 sulfation in BeWo cell homogenates. Next, a series of cell culture exposure experiments were performed using 1, 6, 12, and 24 hour exposure durations. Once again, 2,4,6-TBP was shown to be the most potent inhibitor of basal 3,3’-T2 SULT activity by significantly decreasing activity at the high and medium dose (1 M and 0.5 M, respectively) at all measured time points. Interestingly, BDE-99 was also shown to inhibit basal 3,3’-T2 SULT activity in BeWo cells following the 24 hour exposure, despite exhibiting no inhibitory effects in the BeWo cell homogenate experiments. This indicates that BDE-99 must act through a pathway other than direct enzyme inhibition. Following exposures, the TH concentrations in the cell culture growth media and mRNA expression of TH-related genes were also examined. There was no observed effect of BFR treatment on these endpoints. Future work should focus on determining the downstream biological effects of TH SULT disruption in placental cells, as well as the underlying mechanisms of action responsible for reductions in basal TH SULT activity following BFR exposure. </p><p>This was one of the first studies to measure BFRs in a cohort of placenta tissue samples from the United States and the first study to measure THs, DI activity, and SULT activity in human placenta tissues. This research provides a novel contribution to our growing understanding of the effects of BFRs on TH homeostasis within the human placenta, and provides further evidence for sex-specific differences within this important organ. Future research should continue to investigate the effects of environmental contaminants on TH homeostasis within the placenta, as this represents the most critical and vulnerable stage of human development.</p> / Dissertation

A grande evolução tecnológica tem sido responsável pela introdução de diferentes contaminantes no ambiente, dentre os quais estão os éteres difenílicos polibromados (PBDEs). Os PBDEs representam uma importante classe de retardantes de chama adicionada aos diversos bens de consumo da vida moderna com a finalidade de retardar o processo de ignição e impedir a propagação de chamas. Atualmente, a crescente presença desses compostos em compartimentos ambientais e em amostras de fluídos biológicos tem levantado preocupações relacionadas com os possíveis efeitos tóxicos à saúde, no entanto tais efeitos são incertos devido à baixa disponibilidade de dados relacionados com a ação direta sobre o organismo humano. Desta forma, esse trabalho objetivou investigar os efeitos dos principais representantes de PBDEs: congênere PBDE-209, PBDE-99 e PBDE-47 sobre células de hepatoblastoma humano (HepG2) na faixa de concentração de 0.1-25µmol/L, em períodos de 24 e 48 horas, como uma alternativa de esclarecer os efeitos tóxicos dos PBDEs sobre a saúde humana, bem como correlacionar os efeitos entre os diferentes congêneres. As células HepG2 foram escolhidas devido as semelhanças com o metabolismo das células hepáticas normais. Também foi investigado o potencial dos três congêneres em induzir a morte celular após exposição aos PBDEs, sendo demonstrado potencial citotóxico diferenciado de acordo com o congênere investigado. Pela avaliação de ensaios de proliferação celular (SRB) e viabilidade celular (MTT) foi obtido que o congênere PBDE-209 induz morte celular em altas concentrações (10µmol/L, 25µmol/L) sendo esses efeitos iniciados primeiramente, por mecanismos citostáticos em concentrações menores. Enquanto isso, os PBDE-99 e PBDE-47 demonstraram elevado potencial citotóxico de forma concentração dependente, apresentando diferenças nas intensidades das concentrações avaliadas, relacionando-as com a facilidade de absorção e com os possíveis metabólitos formados. A investigação dos mecanismos citotóxicos foi realizada pelos ensaios de avaliação do potencial de membrana mitocondrial, exposição da fosfatidilserina na membrana externa celular e fragmentação nuclear. Esses ensaios evidenciaram que os congêneres investigados agem por indução de mecanismos apoptóticos, sendo os maiores resultados relacionados com os menores congêneres investigados. A avaliação dos mecanismos por vias necróticas foi realizada pela avaliação da atividade da LDH devido ao rompimento da membrana celular característico de mecanismos necróticos, não sendo obtidos resultados significativos. A avaliação do acúmulo de EROs ocasionado pela exposição aos congêneres demonstrou que os compostos investigados apresentam elevado potencial para induzir o estresse oxidativo, sendo inclusive relacionado com os efeitos citostáticos preliminares do congênere PBDE-209. A diferença dos resultados obtidos entre os três congêneres foi relacionada com as diferenças estruturais, as quais facilitam a absorção dos menores congêneres e com os possíveis metabólitos oriundos formados. Concluindo, estes resultados mostram os efeitos tóxicos dos PBDEs em células hepáticas e sugere a presença de efeitos adversos à saúde. Além disso, embora os congêneres PBDE-99 e PBDE-47 apresentem os maiores potenciais tóxicos, o efeito do congênere PBDE-209 não deve ser ignorado uma vez que o mesmo pode se intensificado com a exposição prolongada / Technologic demand has increased the different pollutants released in the environment. Polybrominated diphenyl ether (PBDE) is an important class of the flame retardants added in several good products with a wide range of toxic effects on biotic and abiotic systems. These compounds are release into environment through the loss during manufacture and of products containing PBDEs. Their toxic mechanisms on biologic systems still have not understood due to the existence of several different congeners, with different chemical and biological characteristics in the environment, and absence of their effects on the body. Therefore, in this study we examine effects of congeners PBDE-209, PBDE-99 and PBDE-47 on HepG2 cell line in order to understand their mechanism of action and their effects on the human health. Firstly, we evaluated citotoxic mechanism by SRB assay followed by MTT assay. This way, we showed that all tested PBDEs seem to cause cell death although PBDE-209 also causes cystostatic mechanism in lower concentration. The cytotoxic mechanism was observed in higher concentrations and it was suggested be evidences of apoptosis. Apoptotic mechanism was investigated by mitochondrial membrane potential, phosphatidyl serine exposure and nuclear fragmentation. Our results showed that all tested congeners were able to decrease mitochondrial membrane potential, to cause phosphatidyl serine exposure and a nuclear fragmentation with higher results found for BDE-99 and BDE-47 due structural difference that may facilities their absorption and their toxic metabolites Exclusion of necrotic mechanism was performed by LDH release assay. We evaluated reactive oxygen species (ROS) production and it was showed that apoptotics mechanisms is followed by oxidative stress in all congeners tested and suggest cytostatic mechanism is also mediated by ROS. These results are evidences of toxic effects of PBDEs on the cell line and health

<p>Brominated flame retardants (BFRs) has for many years been used in products to reduce their</p><p>flammability, mainly in electronic products, textiles and construction materials.</p><p>In 2003, Sweden imported 300 tons of brominated flame retardants.</p><p>Leakage of these compounds has polluted natural environments. Fishes has shown increased</p><p>contents of these substances, especially fat fish, since brominated flame retardants tends to</p><p>accumulate in fatty tissues.</p><p>They are also regarded as persistent and that gives them the ability to travel long distances.</p><p>What also is really scary is that increased levels of brominated flame retardants have been</p><p>detected in human breast milk.</p><p>The knowledge of the brominated flame retardants is limited and not so much research has been</p><p>done in this field. There are many reasons though, to keep the research going. Partly their</p><p>structural resemblance to well-known toxics as PCB, but also their ability to accumulate in</p><p>biological systems and enrich in food chains.</p><p>In which way they affect humans we really don’t know yet. Experiments on mice have been done</p><p>and behavioural disturbances were observed as well as a decrease in learning capacity.</p><p>The BRFs chosen for this study are hexabromocyclododecan (HBCD) and a polybrominated</p><p>diphenyl ether (PBDE) called pentabromodiphenylether (BDE 99).</p><p>About 25 % of the flame retardants produced in the world every year, consists of the brominated</p><p>ones. If we look at the PBDEs it’s mainly tetrabromodiphenylether (BDE 47),</p><p>pentabromodiphenylether (BDE 99), octabromodiphenylether (BDE 205) and</p><p>decabromodiphenylether (BDE 209) that are common flame retardants.</p><p>As from July 1st 2006, PBDE was forbidden in electric and electronic products (15).</p><p>January 1st 2007, a Swedish prohibition concerning the use of BDE-209 was established. BDE-</p><p>209 is not allowed on the Swedish market if the content of substance exceed 0,1 percent of weight</p><p>(23).</p><p>BDE-99 is classified as environmentally dangerous and a healthrisk. It´s not only toxic for</p><p>waterliving organisms but also for humans if exposed during a long time (19).</p><p>We shall develop a well functioning, reproducible and economic method to analyse HBCD and</p><p>PBDE in sediment. It includes extraction, cleanup and sample analyses with a ECD (electron</p><p>capture detector) equipped capillary gas chromatograph.</p><p>Several analyses of adequate diluted standards has been analysed in a GC-ECD to find suitable</p><p>temperature gradients. Then we produced spiked sediment samples with known amounts of</p><p>standards. To homogenize the spiked samples we used a mixer. As a first step in the extraction we</p><p>used acetone as a solvent. Then we used cyclohexane and NaCl (2%) to separate the nonpolar and</p><p>polar substances from each other. Cleanup with concentrated sulphuric acid was done and for</p><p>some samples we also used Florisil. To concentrate the extract it was evaporated with N2(g).The</p><p>extract was then analysed in a GC-ECD and then the results was compared with the standards.</p><p>The result of this project showed that our method of extraction is useful. We managed to extract</p><p>50 % HBCD, 30 % BDE-99 and 60 % BDE-99 (dried sediment).</p>

Brominated flame retardants (BFRs) has for many years been used in products to reduce their flammability, mainly in electronic products, textiles and construction materials. In 2003, Sweden imported 300 tons of brominated flame retardants. Leakage of these compounds has polluted natural environments. Fishes has shown increased contents of these substances, especially fat fish, since brominated flame retardants tends to accumulate in fatty tissues. They are also regarded as persistent and that gives them the ability to travel long distances. What also is really scary is that increased levels of brominated flame retardants have been detected in human breast milk. The knowledge of the brominated flame retardants is limited and not so much research has been done in this field. There are many reasons though, to keep the research going. Partly their structural resemblance to well-known toxics as PCB, but also their ability to accumulate in biological systems and enrich in food chains. In which way they affect humans we really don’t know yet. Experiments on mice have been done and behavioural disturbances were observed as well as a decrease in learning capacity. The BRFs chosen for this study are hexabromocyclododecan (HBCD) and a polybrominated diphenyl ether (PBDE) called pentabromodiphenylether (BDE 99). About 25 % of the flame retardants produced in the world every year, consists of the brominated ones. If we look at the PBDEs it’s mainly tetrabromodiphenylether (BDE 47), pentabromodiphenylether (BDE 99), octabromodiphenylether (BDE 205) and decabromodiphenylether (BDE 209) that are common flame retardants. As from July 1st 2006, PBDE was forbidden in electric and electronic products (15). January 1st 2007, a Swedish prohibition concerning the use of BDE-209 was established. BDE- 209 is not allowed on the Swedish market if the content of substance exceed 0,1 percent of weight (23). BDE-99 is classified as environmentally dangerous and a healthrisk. It´s not only toxic for waterliving organisms but also for humans if exposed during a long time (19). We shall develop a well functioning, reproducible and economic method to analyse HBCD and PBDE in sediment. It includes extraction, cleanup and sample analyses with a ECD (electron capture detector) equipped capillary gas chromatograph. Several analyses of adequate diluted standards has been analysed in a GC-ECD to find suitable temperature gradients. Then we produced spiked sediment samples with known amounts of standards. To homogenize the spiked samples we used a mixer. As a first step in the extraction we used acetone as a solvent. Then we used cyclohexane and NaCl (2%) to separate the nonpolar and polar substances from each other. Cleanup with concentrated sulphuric acid was done and for some samples we also used Florisil. To concentrate the extract it was evaporated with N2(g).The extract was then analysed in a GC-ECD and then the results was compared with the standards. The result of this project showed that our method of extraction is useful. We managed to extract 50 % HBCD, 30 % BDE-99 and 60 % BDE-99 (dried sediment).

El Decabromodifenil èter (BDE-209) és un retardant de la flama àmpliament utilitzat i font de preocupació a causa de la toxicitat mostrada per altres Difenil Èters Polibromats (PBDEs). La presència de PBDEs en la llet materna fa preocupant la seva exposició durant el desenvolupament. Pensem que l’exposició primerenca a BDE-209 pot produir efectes a llarg termini i interactuar amb factors genètics, com el genotip de l’ApolipoproteinaE. Ratolins portadors de les diferents isoformeshumanes de l’ApoE foren tractats amb una dosi oral aguda de 0, 10 o 30 mg / kg de BDE-209 en el dia postnatal 10 i van ser avaluats per neurocomportament durant el desenvolupament, a l'edat adulta i la vellesa. L’exposició a BDE-209 indueix un retard en el desenvolupament físic i neuromotor i en la compactació de la mielina en els ratolins ApoE2, disminueix els nivells de tiroxina lliure en les femelles adultes i disminueix l'activitat en ratolins ApoE4. Els efectes més consistents durant tota la vida s'observen en ratolins ApoE3 i consisteixen en problemes d'aprenentatge als 4 mesos, i problemes d'aprenentatge i memòria i un augment de l'ansietat als 12 mesos. / Decabromodiphenyl Ether (BDE-209) is a flame retardant widely used and source of concern because ofthe toxicity showed by other Polibrominateddiphenyl ethers (PBDEs). The presenceof PBDEs in human’s breast milkmakes worrying its exposure during development. We hypothesised that an early exposure to BDE-209 can induce long-term impairments and interact with genetic factors, such as ApolipoproteinE genotype. Mice carrying the different Human ApoE isoforms treated with an acute oral dose of 0, 10 or 30 mg/kg of BDE-209 on postnatal day 10 were assessed for neurobehaviourduring development, in young adulthood and old age. BDE-209 exposure inducesadelay in physic and neuromotordevelopment and in myelin compaction in ApoE2 mice, decreases the levels of free thyroxin in adult femalesand decreases activity in ApoE4 mice. The most consistent effects across the lifespan are observed in ApoE3 mice and consist of impaired learning at 4 months, and impaired learning and memory and increased anxiety at 12 months.

Concerns regarding the persistence, bioaccumulation, long-range transport, and adverse health effects of polybrominated dipheyl ethers (PBDEs) have recently come to light. PBDEs are quickly becoming a ubiquitous pollutant and have been found globally in sediment, aquatic mammals, fish, bird eggs, human milk, serum, and adipose tissue. Due to their persistence and lipophilicity, PBDEs may biomagnify through the food chain and could pose a danger to those who consume these contaminated animals. Many First Nation communities in the James Bay region rely in part on a subsistence diet; therefore, these communities have the potential to carry high levels of PBDEs. Additionally, PBDEs have been shown to be preferentially deposited in the sub-Arctic, making this contaminant of particular interest to the James Bay region of northern Ontario and Quebec, Canada. By analyzing PBDE body burden (plasma), this contaminant was characterized with regards to its latitudinal variation and concentration. The study established a baseline PBDE level in the communities of the James Bay region and determined concentrations in the traditional foods of the First Nation communities located in the Mushkegowuk Territory of sub-Arctic Canada, to examine potential routes of exposure. The PBDE body burden was found to be low in the Mushkegowuk communities when compared to more northern communities in Canada. Similarly, PBDE body burden in the US and southern Canada is higher than those of the James Bay region. The body burdens of the James Bay Cree are similar to Japanese and Swedish levels. Analysis of traditional foods shows relatively elevated levels of PBDEs in certain game species such as whitefish (Coregonus clupeaformis), mallard duck (Anas platyrhynchos), and moose (Alces alces) compared to other traditional foods from the same area. Data in this thesis can be used for human biomonitoring purposes and the animal data can be combined with consumption data in order to assess the contribution of PBDEs to body burden from a First Nation diet as well as provide guidance when developing safety guidelines for the consumption of traditional foods. While the sub-arctic has been identified as an environmental sink for PBDEs, the levels found in this study indicate that long-range transportation and dietary biomagnification of the contaminant may not be the primary exposure pathway. This may be due to low bioavailability of the contaminant, rapid metabolism, or alternate sources of exposure and should be investigated in future studies.

Concerns regarding the persistence, bioaccumulation, long-range transport, and adverse health effects of polybrominated dipheyl ethers (PBDEs) have recently come to light. PBDEs are quickly becoming a ubiquitous pollutant and have been found globally in sediment, aquatic mammals, fish, bird eggs, human milk, serum, and adipose tissue. Due to their persistence and lipophilicity, PBDEs may biomagnify through the food chain and could pose a danger to those who consume these contaminated animals. Many First Nation communities in the James Bay region rely in part on a subsistence diet; therefore, these communities have the potential to carry high levels of PBDEs. Additionally, PBDEs have been shown to be preferentially deposited in the sub-Arctic, making this contaminant of particular interest to the James Bay region of northern Ontario and Quebec, Canada. By analyzing PBDE body burden (plasma), this contaminant was characterized with regards to its latitudinal variation and concentration. The study established a baseline PBDE level in the communities of the James Bay region and determined concentrations in the traditional foods of the First Nation communities located in the Mushkegowuk Territory of sub-Arctic Canada, to examine potential routes of exposure. The PBDE body burden was found to be low in the Mushkegowuk communities when compared to more northern communities in Canada. Similarly, PBDE body burden in the US and southern Canada is higher than those of the James Bay region. The body burdens of the James Bay Cree are similar to Japanese and Swedish levels. Analysis of traditional foods shows relatively elevated levels of PBDEs in certain game species such as whitefish (Coregonus clupeaformis), mallard duck (Anas platyrhynchos), and moose (Alces alces) compared to other traditional foods from the same area. Data in this thesis can be used for human biomonitoring purposes and the animal data can be combined with consumption data in order to assess the contribution of PBDEs to body burden from a First Nation diet as well as provide guidance when developing safety guidelines for the consumption of traditional foods. While the sub-arctic has been identified as an environmental sink for PBDEs, the levels found in this study indicate that long-range transportation and dietary biomagnification of the contaminant may not be the primary exposure pathway. This may be due to low bioavailability of the contaminant, rapid metabolism, or alternate sources of exposure and should be investigated in future studies.

A grande evolução tecnológica tem sido responsável pela introdução de diferentes contaminantes no ambiente, dentre os quais estão os éteres difenílicos polibromados (PBDEs). Os PBDEs representam uma importante classe de retardantes de chama adicionada aos diversos bens de consumo da vida moderna com a finalidade de retardar o processo de ignição e impedir a propagação de chamas. Atualmente, a crescente presença desses compostos em compartimentos ambientais e em amostras de fluídos biológicos tem levantado preocupações relacionadas com os possíveis efeitos tóxicos à saúde, no entanto tais efeitos são incertos devido à baixa disponibilidade de dados relacionados com a ação direta sobre o organismo humano. Desta forma, esse trabalho objetivou investigar os efeitos dos principais representantes de PBDEs: congênere PBDE-209, PBDE-99 e PBDE-47 sobre células de hepatoblastoma humano (HepG2) na faixa de concentração de 0.1-25µmol/L, em períodos de 24 e 48 horas, como uma alternativa de esclarecer os efeitos tóxicos dos PBDEs sobre a saúde humana, bem como correlacionar os efeitos entre os diferentes congêneres. As células HepG2 foram escolhidas devido as semelhanças com o metabolismo das células hepáticas normais. Também foi investigado o potencial dos três congêneres em induzir a morte celular após exposição aos PBDEs, sendo demonstrado potencial citotóxico diferenciado de acordo com o congênere investigado. Pela avaliação de ensaios de proliferação celular (SRB) e viabilidade celular (MTT) foi obtido que o congênere PBDE-209 induz morte celular em altas concentrações (10µmol/L, 25µmol/L) sendo esses efeitos iniciados primeiramente, por mecanismos citostáticos em concentrações menores. Enquanto isso, os PBDE-99 e PBDE-47 demonstraram elevado potencial citotóxico de forma concentração dependente, apresentando diferenças nas intensidades das concentrações avaliadas, relacionando-as com a facilidade de absorção e com os possíveis metabólitos formados. A investigação dos mecanismos citotóxicos foi realizada pelos ensaios de avaliação do potencial de membrana mitocondrial, exposição da fosfatidilserina na membrana externa celular e fragmentação nuclear. Esses ensaios evidenciaram que os congêneres investigados agem por indução de mecanismos apoptóticos, sendo os maiores resultados relacionados com os menores congêneres investigados. A avaliação dos mecanismos por vias necróticas foi realizada pela avaliação da atividade da LDH devido ao rompimento da membrana celular característico de mecanismos necróticos, não sendo obtidos resultados significativos. A avaliação do acúmulo de EROs ocasionado pela exposição aos congêneres demonstrou que os compostos investigados apresentam elevado potencial para induzir o estresse oxidativo, sendo inclusive relacionado com os efeitos citostáticos preliminares do congênere PBDE-209. A diferença dos resultados obtidos entre os três congêneres foi relacionada com as diferenças estruturais, as quais facilitam a absorção dos menores congêneres e com os possíveis metabólitos oriundos formados. Concluindo, estes resultados mostram os efeitos tóxicos dos PBDEs em células hepáticas e sugere a presença de efeitos adversos à saúde. Além disso, embora os congêneres PBDE-99 e PBDE-47 apresentem os maiores potenciais tóxicos, o efeito do congênere PBDE-209 não deve ser ignorado uma vez que o mesmo pode se intensificado com a exposição prolongada / Technologic demand has increased the different pollutants released in the environment. Polybrominated diphenyl ether (PBDE) is an important class of the flame retardants added in several good products with a wide range of toxic effects on biotic and abiotic systems. These compounds are release into environment through the loss during manufacture and of products containing PBDEs. Their toxic mechanisms on biologic systems still have not understood due to the existence of several different congeners, with different chemical and biological characteristics in the environment, and absence of their effects on the body. Therefore, in this study we examine effects of congeners PBDE-209, PBDE-99 and PBDE-47 on HepG2 cell line in order to understand their mechanism of action and their effects on the human health. Firstly, we evaluated citotoxic mechanism by SRB assay followed by MTT assay. This way, we showed that all tested PBDEs seem to cause cell death although PBDE-209 also causes cystostatic mechanism in lower concentration. The cytotoxic mechanism was observed in higher concentrations and it was suggested be evidences of apoptosis. Apoptotic mechanism was investigated by mitochondrial membrane potential, phosphatidyl serine exposure and nuclear fragmentation. Our results showed that all tested congeners were able to decrease mitochondrial membrane potential, to cause phosphatidyl serine exposure and a nuclear fragmentation with higher results found for BDE-99 and BDE-47 due structural difference that may facilities their absorption and their toxic metabolites Exclusion of necrotic mechanism was performed by LDH release assay. We evaluated reactive oxygen species (ROS) production and it was showed that apoptotics mechanisms is followed by oxidative stress in all congeners tested and suggest cytostatic mechanism is also mediated by ROS. These results are evidences of toxic effects of PBDEs on the cell line and health

A região do complexo estuarino-lagunar de Cananéia-Iguape, situada no litoral sul do estado de São Paulo, é uma área de grande interesse científico. Entre um dos mamíferos marinhos existente nessa região está a Pontoporia blainvillei, a qual teve a sua gordura subcutânea (blubber) analisada para quantificação de POPs. Os valores de concentração média obtida para as 48 amostras analisadas foram, em ordem decrescente: PCBs (1532 ng g-1); DDTs (537 ng g-1); Clordanas (64,0 ng g-1); PBDEs (38,4 ng g-1); Mirex (30,7 ng g-1); Drins (25,2 ng g-1); HCB (9,51 ng g-1); HCHs (7,59 ng g-1) e Endosulfan (6,22 ng g-1). A razão DDT/PCB encontrada foi de 0,35. As concentrações dos POPs entre machos maduros e machos imaturos apresentaram diferenças significativas (com exceção do HCH), sendo os valores encontrados para os machos maduros maiores que os valores obtidos para os machos imaturos; entre os machos maduros e fêmeas imaturas, os grupos de dados foram iguais significativamente (exceção para o DDT e mirex); entre os machos imaturos e fêmeas imaturas, os grupos de dados apresentaram igualdade significativa para todos os POPs. Foi encontrada correlação entre os POPs e a idade dos indivíduos estudados, bem como correlação forte entre PCB x PBDE, PCB x DDT e PBDE x DDT. / Forty eight samples of subcutaneous fat (blubber) of Pontoporia blainvillei were analyzed for the quantitation of persistent organic pollutants (POPs). This marine mammal lives in the estuarine complex of Cananéia-Iguape, São Paulo-BR. The average concentration values of POPs was: PCBs (1532 ng g-1); DDTs (537 ng g-1); Chlordanes (64.0 ng g-1); PBDEs (38.4 ng g-1); Mirex (30.7 ng g-1); Drins (25.2 ng g-1); HCB (9.51 ng g-1); HCHs (7.59 ng g-1) e Endosulfan (6.22 ng g-1). Adult male were those with the highest concentrations of POPs. The DDT/PCBs ratio was equal to 0.35, showing an increase in concentration of PCBs in this area (compared with earlier studies). The concentrations of POPs were different (except for HCH) for mature males and immature males. Between males mature and immature females, the data were significantly (except for DDT and mirex) equal. Between immature males and immature females, data groups were significantly equal for all POPs. Moderate correlation was found between POPs and age, as well as strong correlation between PCB x PBDE, PCB x DDT and PBDE x DDT.