Assessment of environmental endocrine disruptors in bald eagles of the Great Lakes

Halogenated natural products in birds associated with the marine environment: A review

Halogenated natural products (HNPs) are widespread compounds found at high concentrations in top predators such as seabirds. This paper reviews available data on methoxylated polybrominated diphenyl ethers (MeO-BDEs), heptachloro-1'-methyl-1,2'-bipyrrole (Q1) and 1,1'-dimethyl-2,2'-bipyrroles (HDBPs) in these animals. In all, 25 papers reported such HNPs in seabirds. White tailed sea eagle from Sweden was the seabird species with higher MeO-BDEs levels in eggs and blood, while in liver the European shag from Norway was the one. Regarding HDBPs, glaucous gull livers from North Water Polynya and Leach's storm petrel eggs from South Canada (NE Atlantic) showed the highest levels, while brown skua eggs presented the highest concentration of Q1. DBP-Br₄Cl₂ and DBP-Br₆ were the most abundant HDBPs in seabirds, although only one study investigated DBP-Br₆. Furthermore, 2'-MeO-BDE-68/6'-MeO-BDE-47 ratios were lower than one in mostly of the studies (91%). The main sources of methoxylated congeners found in seabirds might to be from sponges and/or associated organisms (bacteria). The scarcity of data in seabirds showed the gap in knowledge. Few studies were done especially in tropical areas and Southern Hemisphere and the most were conducted in the northwest part of the globe. This review arouses the need of knowledge about the distribution of these compounds in seabirds worldwide as well as it encourages toxicological studies to better understand the possible effects of HNPs on seabirds.

Assessing effects of environmental chemicals on neuroendocrine systems: potential mechanisms and functional outcomes

Environmental pollutants encompass a vast array of compounds. Most studies in birds have focused on toxicological effects, with little attention to non-lethal effects. Consequently, it has proven difficult to assess potential risk associated with exposure to endocrine disrupting chemicals (EDCs). Assessing potential adverse effects due to exposure is further complicated by the great variation that occurs across avian species. These include variations in reproductive strategies, life span, sexual differentiation, and migration. Differences in reproductive strategies, particularly in the developmental patterns and mechanisms for precocial and altricial chicks, predispose birds to wide variations in response to steroids and steroid-like EDCs. We have investigated the effects of EDCs in precocial birds including Japanese quail (Coturnix japonica) and mallard ducks (Anas platyrhynchos) as well as in wild altricial songbirds. Studies in Japanese quail characterized endogenous steroid hormone changes during development and have demonstrated that the developing embryo uses the yolk as a 'steroid hormone depot'. It appears that actual embryonic exposure is quantitatively lower than indicated by the treatment in egg injections and that the true amount of compound necessary for bioactivity may be quite low relative to the actual dosage delivered. Additionally, embryonic exposure to specific EDCs adversely affected sexual differentiation in quail, especially impacting male sexual behavior as well as neural systems, immune response, and thyroid hormones. Many of these studies considered single compounds; however, wild birds are exposed to complex mixtures and multiple compounds. We tested complex mixtures of polychlorinated biphenyls (PCBs) at concentrations that bracketed those found in eggs in contaminated regions. Results indicated that the predictive value of the toxic equivalency (TEQ), based on comparative activation of the aryl hydrocarbon receptor (AhR) relative to dioxin was not as accurate as expected. We discuss the potential of developing an endocrine disruption index (EDI) to bridge the inconsistencies observed between responses predicted by the TEQ and those observed in vivo following exposure to EDCs. Further, we will discuss how an EDI would complement the adverse outcome pathways analyses to consider the range of effects of endocrine disruptors in birds.

Multiple metals exposure and neurotoxic risk in bald eagles (Haliaeetus leucocephalus) from two Great Lakes states

In the present study, the authors determined concentrations of several elements (As, Cd, Co, Cu, Cr, Mn, Pb, Sb, Zn) in the brains and livers of 46 bald eagles (Haliaeetus leucocephalus) from two Great Lakes states, Michigan and Minnesota. To explore whether exposures are of neurological concern, the authors assessed their associations with neurochemical receptors (N-methyl-D-aspartate [NMDA] and γ-aminobutyric acid A [GABA(A)]) and enzymes (glutamine synthetase [GS] and glutamic acid decarboxylase [GAD]) that play critical roles in vertebrate neurobehavior and reproduction. For most elements, levels in the livers and brains did not differ between region and gender. Hepatic Pb levels averaged 33.1 ppm (dry wt), 30.4% of all carcasses exceeded proposed avian Pb thresholds (>26.4 ppm), and in 30.8% of the birds examined evidence of Pb pellets or fragments was found. Significant changes in the activities of GS and GAD were related to brain concentrations of several metals (Pb, Cd, Co, Cu, Zn). No relationships were found among any of the nine elements and NMDA or GABA(A) receptor levels. When combined with the authors' previous study on these same eagles that showed Hg-associated alterations in GS, GAD, and NMDA receptor levels, the present research suggests that bald eagles are exposed to various elements, especially Pb and Hg, that are capable of causing changes in GABAergic and glutamatergic neurotransmission. The functional significance of these neurochemical changes warrants attention.

Organochlorine residues in blood of cinereous vultures and Eurasian griffon vultures in a northeastern Mediterranean area of nature conservation

In the National Park of Dadia-Lefkimi-Soufli Forest (Dadia NP, Greece), seven "target" PCBs and 16 organochlorine pesticides (OCs) were analysed in blood samples of cinereous vultures (Aegypius monachus) and Eurasian griffon vultures (Gyps fulvus). PCB congeners 138, 153 and 180 predominated in both species' blood samples. In both species, no differences were detected in congener levels between successive age classes, but in cinereous vulture, there were significant differences between adult and nestling in levels of PCB 28, 52, 101, 118 and between nestling and immature in levels of PCB 101. Regarding pesticides, p,p'-DDE dominated in both vultures followed by β-HCH, lindane and endosulfan sulphate, but ∑OCs were higher in griffon vulture. Significant differences were detected only between nestling and sub-adult cinereous vultures in heptachlor levels and between nestling and adult in p,p'-DDT. The origin of pollutants differs between the two vulture species and pollution patterns may not reflect those at Dadia NP.

Incidence of organochlorine pesticides and the health condition of nestling ospreys (Pandion haliaetus) at Laguna San Ignacio, a pristine area of Baja California Sur, Mexico

We identified and quantified organochlorine (OC) pesticide residues in the plasma of 28 osprey (Pandion haliaetus) nestlings from a dense population in Laguna San Ignacio, a pristine area of Baja California Sur, Mexico, during the 2001 breeding season. Sixteen OC pesticides were identified and quantified. α-, β-, δ- and γ-hexachlorocyclohexane, heptaclor, heptachlor epoxide, endosulfan I and II, endosulfan-sulfate, p,p'-DDE, p,p'-DDD, aldrin, dieldrin, endrin, endrin aldehyde, and endrin ketone were the OCs found in the plasma of nestlings, ranging from 0.002 to 6.856 pg/μl (parts per billion). No differences were found in the concentration of pesticides between genders (P > 0.05). In our work, the concentrations detected in the plasma were lower than those reported to be a threat for the species and that affect the survival and reproduction of birds. The presence of OC pesticides in the remote Laguna San Ignacio osprey population is an indication of the ubiquitous nature of these contaminants. OCs are apparently able to travel long distances from their source to the study area. A significant relationship between hemoglobin and mean corpuscular hemoglobin concentrations and OC concentrations were found suggesting that a potential effect on the health of chicks may exist in this osprey population caused by the OC, e.g. anemia. The total proteins were positively correlated with α-BHC, endosulfan I, and p,p'-DDD. It has been suggested that OC also affects competitive interactions and population status over the long term in vertebrate species, and our results could be used as reference information for comparison with other more exposed osprey populations.

Contaminantes ambientais e os interferentes endócrinos

A toxicidade de diversos poluentes ambientais em seres humanos e demais espécies tem sido habitualmente investigada quanto aos seus efeitos teratogênicos e cancerígenos. Nas últimas décadas, muitos contaminantes têm demonstrado efeitos adversos sobre o sistema endócrino. Atualmente, cerca de onze milhões de substâncias químicas são conhecidas em todo mundo, sendo três mil delas produzidas em larga escala. Numerosos compostos químicos de uso doméstico, industrial e agrícola possuem comprovada atividade hormonal. Entre os produtos químicos com atividade estrogênica, destacam-se hormônios presentes em cosméticos, anabolizantes utilizados em rações animais, fitoestrógenos e poluentes orgânicos persistentes (POPs). Esses agentes que estão presentes nos efluentes industriais, residenciais e das estações de tratamento de água e esgoto representam uma importante fonte de contaminação ambiental. O Programa Internacional de Segurança Química (International Programme on Chemical Safety - IPCS) define como interferente endócrino substâncias ou misturas presentes no ambiente capazes de interferir nas funções do sistema endócrino, causando efeitos adversos em um organismo intacto ou na sua prole. No presente artigo, os autores apresentam uma revisão da literatura atual sobre o papel desses elementos nas doenças endócrinas e metabólicas, os prováveis mecanismos de ação envolvidos, discutindo-se perspectivas futuras em termos de investigação e estratégias para prevenção e redução dos seus possíveis danos.

Endocrine disruption in the context of life cycles: perception and transduction of environmental cues

Environmental and social stresses have major impacts on the life cycles of organisms. Furthermore, habitat disturbance/destruction, global climate change, and existence of endocrine disrupting chemicals (EDCs) due to human activities are increasingly likely to pose additive and synergistic stresses that could have potential deleterious effects on physiological function in vertebrates. Central to an organism's life cycle is the ability to respond to environmental cues, physical and social. Environmental signals may act directly on endocrine tissues, but most act through neural pathways, and neuroendocrine and endocrine secretions that affect changes in morphology, physiology and behavior. While most investigations focus on endocrine secretions and their effects, we know much less about perception and transduction of environmental signals. Additionally, some populations of vertebrates, from fish to mammals, temporarily resist environmental and social stresses, and breed successfully. However, many show varying degrees of failure, sometimes resulting in marked population decline. There is potential for EDCs to act at all levels of the response systems to environmental cues. Because animals live in diverse habitats, there is variation in susceptibility to disruption of response systems to environmental cues. Although this may be partly due to genetic differences at a level of receptors and/or metabolism, fundamental differences in how species perceive environmental cues and respond to them may also be major factors. Here we discuss how EDCs may interact with the perception and transduction of environmental cues that are important for all organisms in their natural world. This may introduce a new perspective on the effects of environmental endocrine disruptors.

Biologically directed environmental monitoring, fate, and transport of estrogenic endocrine disrupting compounds in water: A review

Endocrine disrupting compounds (EDCs) are contaminants that may be hormonally active at low concentrations and are emerging as a major concern for water quality. Estrogenic EDCs (e-EDCs) are a subclass of EDCs that, when organisms are exposed to them, function as estrogens. Given that there are numerous e-EDCs that can negatively affect humans and wildlife, general screening techniques like biologically based assays (BBAs) may provide major advantages by estimating the total estrogenic effects of many e-EDCs in the environment. These techniques may potentially be adapted for field portable biologically directed sampling and analyses. This article summarizes available BBAs used to measure estrogenic e-EDCs in the environmental samples and also presents results relating to fate and transport of e-EDCs. Estrogenic EDCs appear to be almost ubiquitous in the environment, despite low solubility and high affinity of organic matter. Potential transport mechanisms may include: (1) transport of more soluble precursors, (2) colloid facilitated transport, (3) enhanced solubility through elevated pH, and (4) the formation of micelles by longer-chain ethoxylates. Due to their persistent and ubiquitous nature, source control strategies for e-EDCs may reduce influent concentration to wastewater treatment plants so that the post treatment effluent will decrease concentrations to estrogenically inactive levels. Alternatively if source reduction is not possible, then more testing is needed on tertiary treatment technologies and treatment efficiencies for e-EDCs. There is still a need for research on remediation and restoration approaches for habitats disturbed by elevated e-EDC concentrations.

Effects of tributyltin and 17β-estradiol on immune and lysosomal systems of the Asian clam Corbicula fluminea (M.)

Freshwater clams Corbicula fluminea were experimentally exposed to a range of tributyltin (TBT) (50, 250 and 500ng Sn/L) and 17β-estradiol (20, 200, 2000ng/L) for 30 days. After 15 and 30 days, phagocytosis activity of haemocytes and lysosomal structural changes in the digestive cells were assayed. 17β-Estradiol exerted a higher inhibition on phagocytosis than tributyltin. This would suggest the existence of estrogen receptors, influencing the immune function. The stereological parameters measured for lysosomal structural changes in animals exposed to tributyltin varied as observed in other studies. Tributyltin is then depurated as other contaminants via digestive cell lysosomal compartment. This experiment emphasized a possible approach on the influence of endocrine disrupting compounds on a hermaphroditic species for environmental surveys.

Characterization of microbial communities found in the human vagina by analysis of terminal restriction fragment length polymorphisms of 16S rRNA genes

To define and monitor the structure of microbial communities found in the human vagina, a cultivation-independent approach based on analyses of terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes was developed and validated. Sixteen bacterial strains commonly found in the human vagina were used to construct model communities that were subsequently used to develop efficient means for the isolation of genomic DNA and an optimal strategy for T-RFLP analyses. The various genera in the model community could best be resolved by digesting amplicons made using bacterial primers 8f and 926r with HaeIII; fewer strains could be resolved using other primer-enzyme combinations, and no combination successfully distinguished certain species of the same genus. To demonstrate the utility of the approach, samples from five women that had been collected over a 2-month period were analyzed. Differences and similarities among the vaginal microbial communities of the women were readily apparent. The T-RFLP data suggest that the communities of three women were dominated by a single phylotype, most likely species of Lactobacillus. In contrast, the communities of two other women included numerically abundant populations that differed from Lactobacillus strains whose 16S rRNA genes had been previously determined. The T-RFLP profiles of samples from all the women were largely invariant over time, indicating that the kinds and abundances of the numerically dominant populations were relatively stable throughout two menstrual cycles. These findings show that T-RFLP of 16S rRNA genes can be used to compare vaginal microbial communities and gain information about the numerically dominant populations that are present.

Chlorinated hydrocarbon contaminants in blood of black and turkey vultures from Savannah River Site, South Carolina, USA

Blood of adult and juvenile black and turkey vultures in the Savannah River Site of South Carolina, USA was analyzed for the presence of 2,3,7,8-chlorine substituted polychlorinated dibenzo-p-dioxins (2,3,7,8-PCDDs), dibenzofurans (2,3,7,8-PCDFs), -dioxin-like and -di-ortho polychlorinated biphenyls. Concentration ranges of 2,3,7,8-PCDD/DFs in blood of black and turkey vultures were 14.2-34.6 and 8.7-56.2 pg/ml wet wt., respectively. Dioxin-like PCBs were in the ranges of 815-4627 and 753-3611 pg/ml wet wt. respectively, in black and turkey vultures. Considerable concentrations of two congeners of di-ortho PCBs were noticed in the ranges of 1415-10325 and 663-7500 pg/ml respectively, in black and turkey vultures. Comparatively, greater toxic equivalency (TEQ) were observed in blood of turkey vultures with the ranges of 3.2-20, whereas black vulture contained 1.8-8.4 pgTEQ/ml wet wt. basis. The species-specific accumulation profiles of PCDD/DFs and dioxin-like PCBs may reflect the different feeding habits, ecology, metabolic capacity and migratory movements of these two scavenging species.

Concentrations and hazard assessment of PCBs, organochlorine pesticides and mercury in fish species from the Upper Thames: river pollution and its potential effects on top predators

Aquatic environmental contamination levels of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and heavy metals in the Upper Thames catchment area, UK were assessed on the basis of fish muscle analysis in wet weight, and their effects on top predators were assessed. The contamination levels of lead, cadmium, dichloro-diphenyl-trichloroethane (DDT) and its metabolites were found to be low (undetectable) in the area. Average mercury contamination level varied between 55 and 342 microg/kg, dieldrin between less than 0.09 and 36.8, lindane between < 0.08 and 4.94, and PCBs between < 0.77 and 3.32. Eels (Anguilla anguilla) had always much higher concentration of OCPs compared to the other fishes from the same monitoring sites. The environmental contamination level of PCBs may be partly associated with industrial and human activities, however, it was difficult to find such associations for mercury level. The hazard indices (HI) of both dieldrin and PCBs were below 1 for mink (Mustela vison). However, the HI of mercury of the all fish species from all monitoring sites are above 1 for mink. These contamination levels may be less harmful to polecats (Mustela putorius), but more so to otters (Lutra lutra) as their diets are dominated by aquatic prey.

Gene expression patterns predict exposure to PCBs in developing Xenopus laevis tadpoles

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that pose global ecological and human health problems. Although it is well established that PCBs are associated with a variety of adverse health effects in wildlife and in humans, it is often difficult to determine direct cause-and-effect relationships between exposure and specific health outcomes. In this study, gene expression signatures were used to relate exposure to PCBs with altered physiological responses and/or specific health effects. Real-time PCR was used to measure gene expression levels for 10 genes in Xenopus laevis tadpoles (18 days postfertilization, PF) after acute exposure (2 days) to the PCB mixture Aroclor 1254. Specific gene expression signatures correlated with exposure and were predictive of adverse health effects. Exposure to low levels of Aroclor 1254 (5-50 ppb) significantly increased expression of six genes, independent of any health effects; exposure to midlevel concentrations (300-400 ppb) significantly decreased expression levels of two genes, NGF and beta-actin, prior to the onset of observable health effects; exposure to higher doses (500-700 ppb) significantly decreased NGF and beta-actin expression concomitant with the appearance of gross morphological abnormalities, behavioral deficits, and a statistically significant decrease in survival. This study expands upon our previous work that demonstrated an age-dependent susceptibility to Aroclor 1254 in Xenopus laevis tadpoles and that defined specific gene expression signatures as useful bioindicators of exposure and as predictors of overt or impending health effects.