Effects of polychlorobiphenyls, polybromodiphenylethers, organochlorine pesticides and their metabolites on vitamin A status in lactating grey seals

Effects of organochlorine pesticides on human and rat 17β-hydroxysteroid dehydrogenase 1 activity: Structure-activity relationship and in silico docking analysis

The objective of this study was to examine the effect of 11 organochlorine pesticides on human and rat 17β-Hydroxysteroid dehydrogenase 1 (17β-HSD1) in human placental and rat ovarian microsome and on estradiol production in BeWo cells. The results showed that the IC50 values for endosulfan, fenhexamid, chlordecone, and rhothane on human 17β-HSD1 were 21.37, 73.25, 92.80, and 117.69 μM. Kinetic analysis revealed that endosulfan acts as a competitive inhibitor, fenhexamid as a mixed/competitive inhibitor, chlordecone and rhothane as a mixed/uncompetitive inhibitor. In BeWo cells, all insecticides except endosulfan significantly decreased estradiol production at 100 μM. For rats, the IC50 values for dimethomorph, fenhexamid, and chlordecone were 11.98, 36.92, and 109.14 μM. Dimethomorph acts as a mixed inhibitor, while fenhexamid acts as a mixed/competitive inhibitor. Docking analysis revealed that endosulfan and fenhexamid bind to the steroid-binding site of human 17β-HSD1. On the other hand, chlordecone and rhothane binds to a different site other than the steroid and NADPH-binding site. Dimethomorph binds to the steroid/NADPH binding site, and fenhexamid binds to the steroid binding site of rat 17β-HSD1. Bivariate correlation analysis showed a positive correlation between IC50 values and LogP for human 17β-HSD1, while a slight negative correlation was observed between IC50 values and the number of HBA. ADMET analysis provided insights into the toxicokinetics and toxicity of organochlorine pesticides. In conclusion, this study identified the inhibitory effects of 3-4 organochlorine pesticides and binding mechanisms on human and rat 17β-HSD1, as well as their impact on hormone production.

Alternative and legacy flame retardants in marine mammals from three northern ocean regions

Flame retardants are globally distributed contaminants that have been linked to negative health effects in humans and wildlife. As top predators, marine mammals bioaccumulate flame retardants and other contaminants in their tissues which is one of many human-imposed factors threatening population health. While some flame retardants, such as the polybrominated diphenyl ethers (PBDE), have been banned because of known toxicity and environmental persistence, limited data exist on the presence and distribution of current-use alternative flame retardants in marine mammals from many industrialized and remote regions of the world. Therefore, this study measured 44 legacy and alternative flame retardants in nine marine mammal species from three ocean regions: the Northwest Atlantic, the Arctic, and the Baltic allowing for regional, species, age, body condition, temporal, and tissue comparisons to help understand global patterns. PBDE concentrations were 100-1000 times higher than the alternative brominated flame retardants (altBFRs) and Dechloranes. 2,2',4,5,5'-pentabromobiphenyl (BB-101) and hexabromobenzene (HBBZ) were the predominant altBFRs, while Dechlorane-602 was the predominant Dechlorane. This manuscript also reports only the second detection of hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO) in marine mammals. The NW Atlantic had the highest PBDE concentrations followed by the Baltic and Arctic which reflects greater historical use of PBDEs in North America compared to Europe and greater industrialization of North America and Baltic countries compared to the Arctic. Regional patterns for other compounds were more complicated, and there were significant interactions among species, regions, body condition and age class. Lipid-normalized PBDE concentrations in harbor seal liver and blubber were similar, but HBBZ and many Dechloranes had higher concentrations in liver, indicating factors other than lipid dynamics affect the distribution of these compounds. The health implications of contamination by this mixture of compounds are of concern and require further research.

The crosstalk effects of polybrominated diphenyl ethers on the retinoic acid and thyroid hormone signaling pathway

The toxicological and pathological influences of polybrominated diphenyl ethers (PBDEs) on the animal central nervous system have attracted worldwide attention. However, their mechanism of action has not been completely elucidated. Given that retinoic acid (RA) and thyroid hormone (TH) signaling pathway are closely related to neurodevelopment, the crosstalk between the two signaling pathways at the levels of metabolite conversion, gene expression and ligand-receptor interaction after exposure to two representative PBDE congeners (BDE-47 and BDE-209) using zebrafish larvae, dual reporter gene assay, and docking simulation was studied. Our results clarified that BDE-47 could disrupt the transport and metabolism of retinoids, induce changes in expression of key genes, bind with the seven nuclear receptors, and activate RA signaling pathway. BDE-47 exhibited more effects on the indicators of the two signaling pathways than BDE-209. Furthermore, BDE-47 may disrupt TH signaling pathway by disrupting RA signaling pathway, indicating that RA signal is priorly influenced than TH signal. This work offered a new perspective to elucidate TH signal disruption mechanism induced by PBDEs from RA signaling pathway, which is of great significance to elucidate the health effects of PBDEs.

Persistent organic pollutant exposure and associations with gene expression in northern fur seals (Callorhinus ursinus) from St. Paul Island, Alaska

Persistent organic pollutants (POPs) are highly lipophilic compounds that accumulate at increased concentrations in high tropic level organisms like marine mammals. Marine mammals' reliance on blubber makes them susceptible to accumulating POPs at potentially toxic concentrations. In this study, we analyzed POP concentrations, (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and methoxylated-BDE (MeOBDE), in the blubber of 16 subsistence harvested sub-adult, male northern fur seals as well as assessed changes in mRNA gene expression of nine relevant biomarkers including the aryl hydrocarbon receptor, thyroid receptor-α, and adiponectin. PBDE and MeOBDE concentrations were significantly lower than PCB and OCP concentrations. A negative relationship was observed between percent lipid in the blubber and contaminant concentrations, both individual and sum. Expression changes in eight biomarkers were correlated with individual and sum contaminant concentrations. This study shows that contaminant concentrations measured are correlated to changes in expression of genes from different physiological systems, metabolism and endocrine, that are important for the regulation of blubber metabolism. Northern fur seals are reliant on blubber as an energy source during times of low food intake. Potential contaminant induced changes in blubber metabolism pathways could have significant impacts on the health of individuals during critical periods.

Spatiotemporal Trends of Legacy and Alternative Flame Retardants in Harbor Seals from the Coasts of California, the Gulf of Maine, and Sweden

Temporal trends of polybrominated diphenyl ethers (PBDEs) have been extensively studied in various environmental compartments globally. However, despite the increasing use of alternative flame retardants following PBDE bans, the spatiotemporal trends of these replacements have rarely been studied, and the available results are often inconsistent. In the present study, we retrospectively investigated the spatiotemporal trends of PBDEs and a suite of alternative brominated FRs (aBFRs) and chlorinated FRs (i.e., dechloranes or DECs) in three harbor seal (Phoca vitulina) populations from the coasts of California, the Gulf of Maine, and southern Sweden during 1999-2016. We observed significantly decreasing trends of ΣPBDEs in all the three populations at an annual rate of 9-11%, which were predominantly driven by the declining concentrations of tetra- and penta-BDEs. The levels of ΣaBFRs decreased significantly in seals from California (mainly 1,3,5-tribromobenzene) and Sweden (mainly hexabromobenzene), while no trend was observed for those from Maine. By contrast, DECs (dominated by DEC 602) did not decrease significantly in any population. Compared with the consistent PBDE congener profiles across regions, aBFRs and DECs exhibited varying compositional profiles between regions, likely indicating region-specific sources of these alternative FR mixtures. Spatial analysis also revealed regional differences in the concentrations of PBDEs, aBFRs, and DECs in harbor seals. Our reconstructed spatiotemporal trends suggest the effective regulation of commercial penta-BDE mix in these regions and warrant further monitoring of the higher brominated BDEs and alternative FRs.

Are vitamins A and E associated with persistent organic pollutants and fatty acids in the blubber of highly contaminated killer whales (Orcinus orca) from Greenland?

We quantified blubber concentrations of vitamins A (retinol) and E (α-tocopherol) and evaluated associations with persistent organic pollutants (ΣPOPs) in 14 highly-contaminated killer whales (Orcinus orca) sampled in Greenland from 2012 to 2014. We considered the influence of blubber depth, sex/age class and diet (based on biomass % of major fatty acids) in these relationships. Blubber concentrations of vitamin A averaged 34.1 ± 4.7 μg g^-1 wet weight (ww) and vitamin E averaged 35.6 ± 4.4 μg g^-1 ww. Although overall vitamin A concentrations did not vary between inner (closer to the muscle) and outer (closer to the skin) blubber layer or between sub-adults and adult females, concentrations in the outer layer of sub-adults were lower compared to the outer layer of adult females (p = 0.03). Outer layer may therefore reflect age accumulation of vitamin A, while in the more active inner layer, age effects might be masked by metabolic needs such as lactation. Neither diet nor ΣPOPs affected vitamin A variation, suggesting this vitamin is highly regulated in the body. Given the high exposures in these killer whales, vitamin A might not be a sensitive biomarker for POPs adverse effects. Vitamin E concentrations were significantly higher in inner compared to outer layer (p < 0.001), likely associated with blubber composition, suggesting that biopsies may not fully represent vitamin E concentrations in blubber. Age-accumulation of vitamin E also occurred with higher concentrations in adult females compared to sub-adults, independent of blubber depth (p < 0.01). Diet, ΣPOPs, and an interaction between these two variables significantly affected vitamin E variation in inner blubber, explaining 91% of this variation. The negative relationship between ΣPOPs (especially Σdichlorodiphenyltrichloroethane (DDT) and Σchlordanes in outer layers) and vitamin E was observed only in killer whales with a diet poorer in polyunsaturated fatty acids, suggested that killer whales feeding more consistently on marine mammals in Arctic environments over a fish-based diet, may be at higher risk of POP-induced disruption in vitamin E homeostasis. Considering diet is therefore important to understand the potential effects of elevated contaminant exposures on levels of certain essential nutrients, i.e., vitamin E, in killer whales.

4-Bromodiphenyl Ether Causes Adrenal Gland Dysfunction in Rats during Puberty

Polybrominated diphenyl ethers (PBDEs) are a group of flame retardants with two or more bromines attached. They are endocrine disruptors. PBDEs photodegrade into 4-bromodiphenyl ether (BDE3). Whether BDE3 impairs adrenal cortical cell function during postnatal development still remains unknown. The aim of the current study was to investigate the influence of BDE3 on adrenal cortical cell function. Sprague-Dawley rats (35 days of age, male) were orally administered with BDE3 (0, 50, 100, and 200 mg/kg/day body weight) for 21 days. BDE3 significantly increased serum aldosterone and corticosterone levels at 200 mg/kg without affecting adrenocorticotropic hormone level. Further study showed that BDE3 up-regulated Cyp11b1 at 100 and 200 mg/kg and Scarb1, Star, Cyp11b2, Cyp21, and Nr5a1 mRNA levels in the 200 mg/kg group. BDE3 also decreased the phosphorylation of AMP-activated protein kinase (AMPK) at 200 mg/kg and increased PGC-1α and phosphorylated cyclic AMP-responsive element-binding protein (CREB)/CREB at 200 mg/kg. Taken together, these findings demonstrate that BDE3 stimulates adrenal cell function likely through decreasing phosphorylation of AMPK and increasing phosphorylation of CREB.

Dietary Aroclor 1254-Induced Toxicity on Antioxidant Capacity, Immunity and Energy Metabolism in Chinese Mitten Crab Eriocheir sinensis: Amelioration by Vitamin A

Effects of dietary Polychlorinated biphenyl (PCB) exposure and dietary vitamin A supplementation on Chinese mitten crab Eriocheir sinensis were studied with the aim to explain dietary PCB toxicity and toxic alleviation by vitamin A intake in crab. Four diets were used including three experimental diets containing 0, 80000 or 240000 IU/kg vitamin A with each experimental diet containing 10 mg PCB/kg diet, and a control diet (without vitamin A and PCB supplementation) in 56 days feeding trial. Crabs fed the PCB-only diet had significantly lower weight gain than those fed the control diet. No significant difference was observed in crab survival among all groups. Crabs fed the PCB-only diet had a significantly higher malondialdehyde content and antioxidase superoxide dismutase activity in the serum and hepatopancreas, and higher erythromycin N-demethylase and glutathione S-transferase activities in the hepatopancreas than those fed the control diet. However, supplementation of dietary vitamin A decreased the levels of all these parameters. The hepatopancreatic cytochrome P450 2 and 4 (CYP2, CYP4), fatty acid binding proteins 3 and 10 (FABP3, FABP10) and intracellular lipolytic enzyme (IL) Messenger Ribonucleic Acid (mRNA) levels in the PCB-only group were significantly higher than those in the control group, and dietary 240000 IU/kg vitamin A supplementation decreased hepatopancreatic CYP4, FABP3, FABP10 and IL enzyme mRNA level. The crabs fed 80000 IU/kg vitamin A supplementation diet had the highest level of retinoid X receptor mRNA in the hepatopancreas. The structure of the hepatopancreas was damaged and the deposit of lipid droplets decreased with dietary PCB exposure. Both levels of vitamin A supplementation alleviated the damage and increased lipid droplets in the hepatopancreas. Dietary PCB exposure significantly reduced total hemocyte count (THC), and phenoloxidase, acid phosphatase activities in the serum. Post-challenge survival of crab in the experimental PCB-only diet group was low compared with that in the control. Supplementation of 240000 IU/kg vitamin A significantly increased the THC and phenoloxidase activity in the serum and post-challenge survival compared with those in the PCB-only group. This study indicates that dietary vitamin A can improve the antioxidant capacity, immune response, detoxification enzymes activities, energy metabolism and hepatopancreas tissue structure of Chinese mitten crab fed PCB contaminated diets.

Linking pollutant exposure of humpback whales breeding in the Indian Ocean to their feeding habits and feeding areas off Antarctica

Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ¹³C and δ¹⁵N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs > CHLs > HCHs > PCBs > PBDEs > MeO-BDEs. HCB (median: 24 ng g^-1 lw) and DDTs (median: 7.7 ng g^-1 lw) were the predominant compounds in all whale biopsies. Among DDT compounds, p,p'-DDE was the major organohalogenated pollutant, reflecting its long-term accumulation in humpback whales. Significantly lower concentrations of HCB and DDTs were found in females than in males (p < 0.001). Other compounds were similar between the two genders (p > 0.05). Differences in the HCB and DDTs suggested gender-specific transfer of some compounds to the offspring. POP concentrations were lower than previously reported results for humpback whales sampled near the Antarctic Peninsula, suggesting potential influence of their nutritional status and may indicate different exposures of the whales according to their feeding zones. Further investigations are required to assess exposure of southern humpback whales throughout their feeding zones.

Serum POP concentrations are highly predictive of inner blubber concentrations at two extremes of body condition in northern elephant seals

Long-lived, upper trophic level marine mammals are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Internal tissues may accumulate and mobilize POP compounds at different rates related to the body condition of the animal and the chemical characteristics of individual POP compounds; however, collection of samples from multiple tissues is a major challenge to ecotoxicology studies of free-ranging marine mammals and the ability to predict POP concentrations in one tissue from another tissue remains rare. Northern elephant seals (Mirounga angustirostris) forage on mesopelagic fish and squid for months at a time in the northeastern Pacific Ocean, interspersed with two periods of fasting on land, which results in dramatic seasonal fluctuations in body condition. Using northern elephant seals, we examined commonly studied tissues in mammalian toxicology to describe relationships and determine predictive equations among tissues for a suite of POP compounds, including ΣDDTs, ΣPCBs, Σchlordanes, and ΣPBDEs. We collected paired blubber (inner and outer) and blood serum samples from adult female and male seals in 2012 and 2013 at Año Nuevo State Reserve (California, USA). For females (N = 24), we sampled the same seals before (late in molting fast) and after (early in breeding fast) their approximately seven month foraging trip. For males, we sampled different seals before (N = 14) and after (N = 15) their approximately four month foraging trip. We observed strong relationships among tissues for many, but not all compounds. Serum POP concentrations were strong predictors of inner blubber POP concentrations for both females and males, while serum was a more consistent predictor of outer blubber for males than females. The ability to estimate POP blubber concentrations from serum, or vice versa, has the potential to enhance toxicological assessment and physiological modeling. Furthermore, predictive equations may illuminate commonalities or distinctions in bioaccumulation across marine mammal species.

Relationships between concentrations of selected organohalogen contaminants and thyroid hormones and vitamins A, E and D in Faroese pilot whales

Pilot whales (Globicephala melas) from the Faroe Islands, North-East Atlantic, have high body concentrations of organohalogenated compounds (OHCs), such as polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and brominated flame retardants (BFRs). The aim of the present study was to examine if and to what extent blood plasma and liver concentrations of several groups of these OHCs are related to concentrations of relevant nutritional and hormonal biomarkers in pilot whales. Thyroid hormones (THs: total and free thyroxine and total and free triiodothyronine) and vitamin A (retinol), D (25-hydroxyvitamin D3) and E (α-tocopherol) were analysed in plasma (n=27) and vitamin A (total vitamin A, retinol and retinyl palmitate) and E (α- and γ-tocopherol) were analysed in liver (n=37) of Faroe Island pilot whales. Correlative relationships between the biomarkers and OHC concentrations previously analysed in the same tissues in these individuals were studied. The TH concentrations in plasma were significantly higher in juveniles than in adults. Vitamin D concentrations in plasma and α- and γ-tocopherol in liver were higher in adults than in juveniles. Multivariate statistical modelling showed that the age and sex influenced the relationship between biomarkers and OHCs. Some significant positive relationships were found between OHCs and thyroid hormone concentrations in the youngest juveniles (p<0.05). In plasma of juvenile whales α-tocopherol was also positively correlated with all the OHCs (p<0.05). Only few significant correlations were found between single OHCs and retinol and vitamin D in plasma within the age groups. There were significant negative relationships between hepatic PBDE concentrations and retinol (BDE-47) and γ-tocopherol (BDE-49, -47, -100, -99, -153) in liver. The relationships between OHCs and THs or vitamins suggest that in pilot whales OHCs seem to have minor effects on TH and vitamin concentrations.

Effect of enrofloxacin and chlorpyrifos on the levels of vitamins A and E in Wistar rats

This study investigates the effects of enrofloxacin and chlorpyrifos, and their combination on vitamin A and E concentrations in the liver of rats. Results of this study indicated a reduction in the contents of vitamins A and E in the liver, which persisted for the entire period of the experiment. Vitamins A and E concentrations were slightly decreased (2-7%) in enrofloxacin-treated rats. In the group of rats intoxicated with chlorpyrifos, a significant decrease in the level of vitamin A was observed up to the 24th hour, and for vitamin E up to the 3rd day from the discontinuation of intoxication with the compounds under study. In the enrofloxacin-chlorpyrifos co-exposure group reduced vitamins A and E level was also noted. The greatest fall in vitamin A level was observed after 3h, while the contents of vitamin E decreased progressively up to the 3rd day. Changes in this group were less pronounced in comparison to the animals intoxicated with chlorpyrifos only.

Bioaccumulation of hydroxylated polychlorinated biphenyls and pentachlorophenol in the serum of northern elephant seal pups (Mirounga angustirostris)

Northern elephant seals (NES) (Mirounga angustirostris) from the Año Nuevo State Reserve (CA, USA) were sampled at 1-, 4-, 7- and 10-week post-weaning. Concentrations of hydroxylated polychlorinated biphenyls (HO-PCBs) and their parent PCBs were measured in the serum of each individual. The ΣHO-PCB concentrations in the serum increased significantly between early and late fast (from 282 ± 20 to 529 ± 31 pg/mL). This increase might result from a mobilisation of HO-PCBs transferred from the mother during gestation and/or lactation and stored in the pup's liver. Food deprivation has been shown to exacerbate biotransformation capacities in mammals, birds and fish. The HO-penta-CBs was the predominant homologue group, followed by HO-hexa-CBs and HO-hepta-CBs. No preferential pathway for the metabolism of HO-PCBs (HO-direct insertion or NIH-shift of a chlorine atom) could be evidenced. The concentrations of pentachlorophenol (PCP) in the serum of weaned NES increased from 103 ± 7 pg/mL at early fast to 246 ± 41 pg/mL at late fast, which is within the range of PCP concentrations usually encountered in marine mammals.

Human health risk associated with brominated flame-retardants (BFRs)

The purposes of this review are to assess the human exposure and human and experimental evidence for adverse effects of brominated flame-retardants (BFRs) with specific focus on intake from seafood. The leakage of BFRs from consumer products leads to exposure of humans from fetal life to adulthood. Fish and fish products contain the highest levels of BFRs and dominate the dietary intake of frequent fish eaters in Europe, while meat, followed by seafood and dairy products accounted for the highest US dietary intake. House dust is also reported as an important source of exposure for children as well as adults. The levels of BFRs in the general North American populations are higher than those in Europe and Japan and the highest levels are detected in infants and toddlers. The daily intake via breast milk exceeds the RfD in 10% of US infants. BFRs including PBDEs, HBCDs and TBBP-A have induced endocrine-, reproductive- and behavior effects in laboratory animals. Furthermore, recent human epidemiological data demonstrated association between exposure to BFRs and similar adverse effects as observed in animal studies. Fish including farmed fish and crude fish oil for human consumption may contain substantial levels of BFRs and infants and toddlers consuming these products on a daily basis may exceed the tolerable daily intake suggesting that fish and fish oil alone represent a risk to human health. This intake comes in addition to exposure from other sources (breast milk, other food, house dust). Because potential harmful concentrations of BFRs and other toxicants occur in fish and fish products, research on a wider range of products is warranted, to assess health hazard related to the contamination of fish and fish products for human consumption.

Ruthenium/base-catalyzed ortho-selective C–H arylation of acylarenes with halogenated arylboronates

Ruthenium-catalyzed ortho-selective C–H arylation of acylarenes with halogenated arylboronates was promoted by the catalytic amount of bases and provided desired halogenated biaryls in excellent yields under 0.2–1 mol% ruthenium catalyst loading.

Retinoid metabolism in invertebrates: when evolution meets endocrine disruption

Recent genomic and biochemical evidence in invertebrate species pushes back the origin of the retinoid metabolic and signaling modules to the last common ancestor of all bilaterians. However, the evolution of retinoid pathways are far from fully understood. In the majority of non-chordate invertebrate lineages, the ongoing functional characterization of retinoid-related genes (metabolism and signaling pathways), as well as the characterization of the endogenous retinoid content (precursors and active retinoids), is still incomplete. Despite limited, the available data supports the presence of biologically active retinoid pathways in invertebrates. Yet, the mechanisms controlling the spatial and temporal distribution of retinoids as well as their physiological significance share similarities and differences with vertebrates. For instance, retinol storage in the form of retinyl esters, a key feature for the maintenance of retinoid homeostatic balance in vertebrates, was only recently demonstrated in some mollusk species, suggesting that such ability is older than previously anticipated. In contrast, the enzymatic repertoire involved in this process is probably unlike that of vertebrates. The suggested ancestry of active retinoid pathways implies that many more metazoan species might be potential targets for endocrine disrupting chemicals. Here, we review the current knowledge about the occurrence and functionality of retinoid metabolic and signaling pathways in invertebrate lineages, paying special attention to the evolutionary origin of retinoid storage mechanisms. Additionally, we summarize existing information on the endocrine disruption of invertebrate retinoid modules by environmental chemicals. Research priorities in the field are highlighted.

Polybrominated diphenyl ether (PBDE) exposure in children: possible associations with cardiovascular and psychological functions

BACKGROUND

Polybrominated diphenyl ethers (PBDE) have been used widely in consumer products and are currently found at detectable levels in the blood of humans and animals across the globe. In stark contrast to this widespread exposure to PBDEs, there is relatively little research on potential adverse health effects of exposure of children to these chemicals.

OBJECTIVES

We performed this cross-sectional study to determine if blood PBDE levels (for 4 congeners) are associated with cardiovascular stress responses and psychological states in children.

METHODS

Levels of 4 PBDE congeners (BDE-28, -47, -99, and -100) in whole blood were measured in children (N=43). These levels were analyzed in relation to cardiovascular disease risk factors, including cardiovascular responses to acute stress and relevant psychological variables, namely, hostility and depression.

RESULTS

Higher levels of blood PBDEs were associated with significantly greater sympathetic activation during acute psychological stress and greater anger, as evidenced by significant associations with 3 different measures of this psychological variable.

CONCLUSIONS

This study suggests an association between PBDE exposure and children's cardiovascular responses to stress as well as parental and self-reported anger in the child. These variables are particularly important as they may be of potential relevance to the future development of cardiovascular disease (CVD). Although intriguing, there is a need for further investigation and replication with a larger sample of children.

Characterization of estrogen receptor α activities in polychlorinated biphenyls by in vitro dual-luciferase reporter gene assay

Polychlorinated biphenyls (PCBs) are thought to cause adverse health effects, particularly endocrine disruption. However, results on the estrogenic activities of a large set of PCB congeners through hormone receptors have not been fully studied. In this study, we evaluated the anti/estrogenic effects of 20 PCBs using an in vitro dual-luciferase reporter gene assay. PCB 18, 28, 49, 52, 99, 101, 103, 110, and 128 exhibited estrogenic effects, whereas PCB 118, 138, 163, 170, 180, 187, 194, 199 and 203 behaved as anti-estrogens. In particular, PCB 30 and 44 exhibited both agonistic and antagonistic activities in the dual-luciferase reporter gene assay. The results obtained from the dual-luciferase reporter gene assay, yeast two-hybrid assay and E-SCREEN were compared, suggesting that the dual-luciferase reporter gene assay is a useful approach for high-throughput screening. We also predicted the possible relationship between the chemical structures and the estrogenic effects of PCBs.

Contamination levels of polychlorinated biphenyls in wild versus cultivated samples of female and male mussels (Mytilus sp.) from the Northwest Coast of Iberian Peninsula--new application for QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methodology

A newly analytical method based on QuEChERS extraction followed by gas chromatography with mass spectrometry (GC-MS) analysis was developed and validated for the quantification of 18 PCBs in wild (from Matosinhos Beach, Portugal) and cultivated (from Ria de Arousa, Spain) mussel samples, pooled by sex. Wild animals showed higher PCB levels than cultivated mussels, with males from both origins, presenting an upper contamination profile comparing with females. This fact seems to be correlated with few biometric parameters, but other interdependencies, not addressed herein, such as distinct lipid contents between sexes, as a consequence of the gametogenic stage, may also explain this data. Overall, data reiterate the importance of investigating the presence of PCBs in marine biological samples, which can act both as bioindicators of environmental contamination, either as food quality controls for human health.

Vitamin A and E profiles as biomarkers of PCB exposure in beluga whales (Delphinapterus leucas) from the western Canadian Arctic

We evaluated the utility of vitamin A and E profiles as biomarkers of contaminant exposure in beluga whales (Delphinapterus leucas; n=66) harvested by the Inuvialuit in the Beaufort Sea. Blubber was an important repository for these vitamins, accounting for 76.8±2.6% of the total body store of vitamin A, and 98.5±0.4% of total vitamin E. While the free alcohol form of vitamin A (retinol) appeared highly regulated, the vitamin A esters were influenced by several biological factors including age, body condition and length. Vitamin E concentrations in liver and blubber were related to age, condition, length and feeding ecology, as described δ(15)N and δ(13)C. Despite the influence of these factors, collective results from univariate statistics, best fit multiple regressions, and principal component analysis (PCA) identified polychlorinated biphenyls (PCBs) as important determinants of vitamin concentrations and profiles in beluga tissues. Blubber PCB concentrations best explained variation of the first principal component in a PCA of hepatic vitamins (r(2)=0.13, p=0.014), and regression models found that vitamin A concentrations were negatively correlated with PCB levels in liver (esters: r(2)=0.19, p=0.001), but positively in plasma (retinol: r(2)=0.20, p=0.06) and blubber (retinol: r(2)=0.22, p=0.001, esters: r(2)=0.43, p<0.001). Our analyses provide a basis to propose an integrated toxicity reference value for disruption of vitamin A and E profiles in beluga of 1.6 mg/kg lw PCBs. This disruption of vitamin profiles by moderate levels of PCBs in an arctic cetacean highlights the global reach and impact of these legacy chemicals decades after their peak use.

Stereoselective formation of mono- and dihydroxylated polychlorinated biphenyls by rat cytochrome P450 2B1

Changes in atropisomer composition of chiral polychlorinated biphenyls (PCBs) and their mono- and dihydroxylated metabolites (OH- and diOH-PCBs) via rat cytochrome P450 2B1 (CYP2B1) mediated biotransformation were investigated in vitro. Rat CYP2B1 could stereoselectively biotransform chiral PCBs to generate meta-OH-PCBs as the major metabolites after 60 min incubations. Nonracemic enantiomer fractions (EFs: concentration ratios of the (+)-atropisomer or the first-eluting atropisomer over the total concentrations of two atropisomers) of 5-OH-PCBs, were 0.17, 0.20, 0.85, 0.77, and 0.41 for incubations with PCBs 91, 95, 132, 136, and 149, respectively. CYP-mediated stereoselective formation of diOH-PCBs from OH-PCBs was observed for the first time. After 60 min stereoselective biotransformation, the EFs of both 4-OH-PCB 95 and 5-OH-PCB 95 changed from racemic (i.e., 0.50) to 0.62 and 0.46, respectively. These transformations generated statistically nonracemic 4,5-diOH-PCB 95, with EFs of 0.53 and 0.58 for 4-OH-PCB 95 and 5-OH-PCB 95 incubations, respectively. Biotransformation of PCBs 91 and 136 also generated 4,5-diOH-PCB 91 and 4,5-diOH-PCB 136, respectively. These in vitro results were consistent with that observed for stereoselective PCB biotransformation by rat liver microsomes and in vivo. Biotransformation interference between two atropisomers of PCB 136 was investigated for the first time in this study. The biotransformation process of (-)-PCB 136 was significantly disrupted by the presence of (+)-PCB 136 but not the other way around. Thus, stereoselective metabolism of chiral PCBs and OH-PCBs by CYPs is a major mechanism for atropisomer composition change of PCBs and their metabolites in the environment, with the degree of composition change dependent, at least in part, on stereoselective interference of atropisomers with each other at the enzyme level.