Effects of perinatal exposure to low doses of PCB 153 and PCB 126 on lymphocyte proliferation and hematology in goat kids

Thyroid function and immune status in perch (Perca fluviatilis) from lakes contaminated with PFASs or PCBs

The environment contains a multitude of man-made chemicals, some of which can act as endocrine disruptors (EDCs), while others can be immunotoxic. We evaluated thyroid disruption and immunotoxic effects in wild female perch (Perca fluviatilis) collected from two contaminated areas in Sweden; one site contaminated with per- and polyfluoroalkyl substances (PFASs) and two sites contaminated with polychlorinated biphenyls (PCBs), with one reference site included for each area. The hepatic mRNA expression of thyroid receptors α and β, and the thyroid hormone metabolising iodothyronine deiodinases (dio1, dio2 and dio3) were measured using real-time PCR, while the levels of thyroid hormone T3 in plasma was analysed using a radioimmunoassay. In addition, lymphocytes, granulocytes, and thrombocytes were counted microscopically. Our results showed lower levels of T3 as well as lower amounts of lymphocytes and granulocytes in perch collected from the PFAS-contaminated site compared to reference sites. In addition, expressions of mRNA coding for thyroid hormone metabolising enzymes (dio2 and dio3) and thyroid receptor α (thra) were significantly different in these fish compared to their reference site. For perch collected at the two PCB-contaminated sites, there were no significant differences in T3 levels or in expression levels of the thyroid-related genes, compared to the reference fish. Fish from one of the PCB-contaminated sites had higher levels of thrombocytes compared with both the second PCB lake and their reference lake; hence PCBs are unlikely to be the cause of this effect. The current study suggests that lifelong exposure to PFASs could affect both the thyroid hormone status and immune defence of perch in the wild.

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

Body Burden of Dichlorodiphenyl Dichloroethene (DDE) and Childhood Pulmonary Function

Longitudinal studies have shown that early life exposure to dichlorodiphenyl dichloroethene (DDE) can lead to growth reduction during childhood and adolescence. In addition, DDE exposure has been linked to respiratory tract infections and an increased risk of asthma in children. Our aim was to understand the relationships between DDE exposure and pulmonary function in children, and, particularly, whether associations are mediated by the height of the children. We used data from an environmental epidemiologic study conducted in central Germany in children aged 8-10 years. The pulmonary function (forced vital capacity, FVC, and forced expiratory volume in one second, FEV1) were measured in three consecutive years. Blood DDE levels were measured at 8 and 10 years. We used linear mixed models for repeated measurements and path analyses to assess the association between blood levels of DDE and pulmonary function measurements. All models were adjusted for confounders. Linear mixed approaches and modelling concurrent effects showed no significant associations. The path analytical models demonstrated that DDE measured at eight years had significant, inverse, indirect, and total effects on FVC at ten years (n = 328; −0.18 L per μg/L of DDE) and FEV1 (n = 328; −0.17 L per μg/L of DDE), mediated through effects of DDE on height and weight. The DDE burden reduces pulmonary function through its diminishing effects on height and weight in children. Further studies are required to test these associations in other samples, preferably from a region with ongoing, high DDT application.

The Increasing Prevalence in Intersex Variation from Toxicological Dysregulation in Fetal Reproductive Tissue Differentiation and Development by Endocrine-Disrupting Chemicals

An increasing number of children are born with intersex variation (IV; ambiguous genitalia/hermaphrodite, pseudohermaphroditism, etc.). Evidence shows that endocrine-disrupting chemicals (EDCs) in the environment can cause reproductive variation through dysregulation of normal reproductive tissue differentiation, growth, and maturation if the fetus is exposed to EDCs during critical developmental times in utero. Animal studies support fish and reptile embryos exhibited IV and sex reversal when exposed to EDCs. Occupational studies verified higher prevalence of offspring with IV in chemically exposed workers (male and female). Chemicals associated with endocrine-disrupting ability in humans include organochlorine pesticides, poly-chlorinated biphenyls, bisphenol A, phthalates, dioxins, and furans. Intersex individuals may have concurrent physical disorders requiring lifelong medical intervention and experience gender dysphoria. An urgent need exists to determine which chemicals possess the greatest risk for IV and the mechanisms by which these chemicals are capable of interfering with normal physiological development in children.

A Birth Cohort Study of Maternal and Infant Serum PCB-153 and DDE Concentrations and Responses to Infant Tuberculosis Vaccination

BACKGROUND

Reasons for the highly variable and often poor protection conferred by the Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine are multifaceted and poorly understood.

OBJECTIVES

We aimed to determine whether early-life exposure to PCBs (polychlorinated biphenyls) and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] reduces 6-month infant BCG vaccine response.

METHODS

Data came from families participating in a prospective birth cohort in eastern Slovakia. At birth, maternal and cord blood were collected for chemical analyses, and infants were immunized with BCG. Blood was collected from infants for chemical analyses and to determine 6-month BCG-specific immunoglobulin (Ig) G and IgA levels. Multivariable linear regression models were fit to examine chemical-BCG associations among approximately 500 mother-infant pairs, with adjustment for confounders.

RESULTS

The median 6-month infant concentration of the prevalent congener PCB-153 was 113 ng/g lipid [interquartile range (IQR): 37-248], and 388 ng/g lipid (IQR: 115-847) for DDE. Higher 6-month infant concentrations of PCB-153 and DDE were strongly associated with lower 6-month BCG-specific antibody levels. For instance, BCG-specific IgG levels were 37% lower for infants with PCB-153 concentrations at the 75th percentile compared to the 25th percentile (95% CI: -42, -32; p < 0.001). Results were similar in magnitude and precision for DDE. There was also evidence of PCB-DDE additivity, where exposure to both compounds reduced anti-BCG levels more than exposure to either compound alone.

CONCLUSIONS

The associations observed in this study indicate that environmental exposures may be overlooked contributors to poorer responses to BCG vaccine. The overall association between these exposures and tuberculosis incidence is unknown.

CITATION

Jusko TA, De Roos AJ, Lee SY, Thevenet-Morrison K, Schwartz SM, Verner MA, Palkovicova Murinova L, Drobná B, Kočan A, Fabišiková A, Čonka K, Trnovec T, Hertz-Picciotto I, Lawrence BP. 2016. A birth cohort study of maternal and infant serum PCB-153 and DDE concentrations and responses to infant tuberculosis vaccination. Environ Health Perspect 124:813-821; http://dx.doi.org/10.1289/ehp.1510101.

Endocrine effects of real-life mixtures of persistent organic pollutants (POP) in experimental models and wild fish

A series of studies have assessed the occurrence, levels, and potential adverse effects of persistent organic pollutants (POP) in fish from Lake Mjøsa. In this lake, high levels of various POP were detected in biota. Fish from the nearby Lake Losna contain background levels of POP and served as reference (controls) in these studies. Significantly higher prevalence of mycobacteriosis and pathological changes were documented in burbot (Lota lota) from Mjøsa compared to burbot from Losna. Further, transcriptional profiling identified changes in gene expression in burbot from Mjøsa compared to burbot from Losna associated with drug metabolism enzymes and oxidative stress. POP extracted from burbot liver oil from the two lakes was used to expose zebrafish (Danio rerio) during two consecutive generations. During both generations, POP mixtures from both lakes increased the rate of mortality, induced earlier onset of puberty, and skewed sex ratio toward males. However, opposite effects on weight gain were found in exposure groups compared to controls during the two generations. Exposure to POP from both lakes was associated with suppression of ovarian follicle development. Analyses of genome-wide transcription profiling identified functional networks of genes associated with weight homeostasis, steroid hormone functions, and insulin signaling. In human cell studies using adrenocortical H295R and primary porcine theca and granulosa cells, exposure to lake extracts from both populations modulated steroid hormone production with significant difference from controls. The results suggest that POP from both lakes may possess the potential to induce endocrine disruption and may adversely affect health in wild fish.

Effects of PCBs and PBDEs on thyroid hormone, lymphocyte proliferation, hematology and kidney injury markers in residents of an e-waste dismantling area in Zhejiang, China

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are two typical categories of contaminants released from e-waste dismantling environments. In China, the body burdens of PCBs and PBDEs are associated with abnormal thyroid hormones in populations from e-waste dismantling sites, but the results are limited and contradictory. In this study, we measured the serum levels of PCBs and PBDEs and the thyroid hormone free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) in 40 residents in an e-waste dismantling area and in 15 residents in a control area. Additionally, we also measured some lymphocyte proliferation indexes, hematologic parameters and kidney injury markers, including white blood cells, neutrophils, monocytes, lymphocytes, hemoglobin, platelets, serum creatinine and beta 2-microglobulin (β2-MG). The results indicated that the mean level of ΣPCBs in the exposure group was significantly higher than that in the control group (964.39 and 67.98 ng g(-1), p<0.0001), but the mean level of ΣPBDEs in the exposure group was not significantly higher than that in the controls (139.32 vs. 75.74 ng g(-1), p>0.05). We determined that serum levels of FT3, FT4, monocytes and lymphocytes were significantly lower, whereas the levels of neutrophils, hemoglobin, platelets and serum creatinine were significantly higher in the exposed group (p<0.05). The mean level of ΣPCBs was negatively correlated with levels of FT3, FT4, monocytes and lymphocytes (p<0.05) and positively correlated with levels of neutrophils, hemoglobin, serum creatinine and β2-MG (p<0.05). Additionally, the mean level of ΣPBDEs was positively correlated with levels of white blood cells, hemoglobin and platelets (p<0.05). Our data suggest that exposure to an e-waste dismantling environment may increase the body burdens of PCBs and the specific PBDEs congeners in native residents and that the contaminants released from e-waste may contribute to abnormal changes in body levels of thyroid hormone, hematology and kidney injury markers.

Prenatal exposure to DDE and PCB 153 and respiratory health in early childhood: a meta-analysis

BACKGROUND

Persistent organic pollutants may affect the immune and respiratory systems, but available evidence is based on small study populations. We studied the association between prenatal exposure to dichlorodiphenyldichloroethylene (DDE) and polychlorinated biphenyl 153 (PCB 153) and children's respiratory health in European birth cohorts.

METHODS

We included 4608 mothers and children enrolled in 10 birth cohort studies from 7 European countries. Outcomes were parent-reported bronchitis and wheeze in the first 4 years of life. For each cohort, we performed Poisson regression analyses, modeling occurrences of the outcomes on the estimates of cord-serum concentrations of PCB 153 and DDE as continuous variables (per doubling exposure) and as cohort-specific tertiles. Summary estimates were obtained through random-effects meta-analyses.

RESULTS

The risk of bronchitis or wheeze (combined variable) assessed before 18 months of age increased with increasing DDE exposure (relative risk [RR] per doubling exposure = 1.03 [95% confidence interval = 1.00-1.07]). When these outcomes were analyzed separately, associations appeared stronger for bronchitis. We also found an association between increasing PCB 153 exposure and bronchitis in this period (RR per doubling exposure = 1.06 [1.01-1.12]) but not between PCB 153 and wheeze. No associations were found between either DDE or PCB 153 and ever-wheeze assessed after 18 months. Inclusion of both compounds in the models attenuated risk estimates for PCB 153 tertiles of exposure, whereas DDE associations were more robust.

CONCLUSION

This large meta-analysis suggests that prenatal DDE exposure may be associated with respiratory health symptoms in young children (below 18 months), whereas prenatal PCB 153 levels were not associated with such symptoms.

Immunoendocrinology: faulty hormonal imprinting in the immune system

Hormonal imprinting is an epigenetic process which is taking place perinatally at the first encounter between the developing hormone receptors and their target hormones. The hormonal imprinting influences the binding capacity of receptors, the hormone synthesis of the cells, and other hormonally regulated functions, as sexual behavior, aggressivity, empathy, etc. However, during the critical period, when the window for imprinting is open, molecules similar to the physiological imprinters as synthetic hormone analogs, other members of the hormone families, environmental pollutants, etc. can cause faulty imprinting with life-long consequences. The developing immune system, the cells of which also have receptors for hormones, is very sensitive to faulty imprinting, which causes alterations in the antibody and cytokine production, in the ratio of immune cells, in the defense against bacterial and viral infections as well as against malignant tumors. Immune cells (lymphocytes, monocytes, granulocytes and mast cells) are also producing hormones which are secreted into the blood circulation as well as are transported locally (packed transport). This process is also disturbed by faulty imprinting. As immune cells are differentiating during the whole life, faulty imprinting could develop any time, however, the most decisive is the perinatal imprinting. The faulty imprinting is inherited to the progenies in general and especially in the case of immune system. In our modern world the number and amount of artificial imprinters (e.g. endocrine disruptors and drugs) are enormously increasing. The effects of the faulty imprinters most dangerous to the immune system are shown in the paper. The present and future consequences of the flood of faulty imprintings are unpredictable however, it is discussed.

Brucella pinnipedialis hooded seal (Cystophora cristata) strain in the mouse model with concurrent exposure to PCB 153

Brucellosis, a worldwide zoonosis, is linked to reproductive problems in primary hosts. A high proportion of Brucella-positive hooded seals (Cystophora cristata) have been detected in the declined Northeast Atlantic stock. High concentrations of polychlorinated biphenyls (PCBs) have also been discovered in top predators in the Arctic, including the hooded seal, PCB 153 being most abundant. The aim of this study was to assess the pathogenicity of Brucella pinnipedialis hooded seal strain in the mouse model and to evaluate the outcome of Brucella spp. infection after exposure of mice to PCB 153. BALB/c mice were infected with B. pinnipedialis hooded seal strain or Brucella suis 1330, and half from each group was exposed to PCB 153 through the diet. B. pinnipedialis showed a reduced pathogenicity in the mouse model as compared to B. suis 1330. Exposure to PCB 153 affected neither the immunological parameters, nor the outcome of the infection. Altogether this indicates that it is unlikely that B. pinnipedialis contribute to the decline of hooded seals in the Northeast Atlantic.

Reactive oxygen species alteration of immune cells in local residents at an electronic waste recycling site in northern China

The health effects of exposure to pollutants from electronic waste (e-waste) pose an important issue. In this study, we explored the association between oxidative stress and blood levels of e-waste-related pollutants. Blood samples were collected from individuals living in the proximity of an e-waste recycling site located in northern China, and pollutants, as well as reactive oxygen species (ROS), were measured in comparison to a reference population. The geometric mean concentrations of PCBs, dechlorane plus, and 2,2',4,4',5,5'-hexabromobiphenyl in plasma from the exposure group were 60.4, 9.0, and 0.55 ng g(-1) lipid, respectively, which were 2.2, 3.2, and 2.2 times higher than the corresponding measurement in the reference group. Correspondingly, ROS levels in white blood cells, including in neutrophil granulocytes, from the exposure group were significantly higher than in those from the reference group, suggesting potential ROS related health effects for residents at the e-waste site. In contrast, fewer ROS were generated in the respiratory burst of neutrophil granulocytes for the exposure group, indicating a depressed innate immune function for the individuals living at the e-waste site. These findings suggest a potential linkage between exposure to pollutants from e-waste recycling and both elevated oxidative stress and altered immune function.

High prevalence of infections and pathological changes in burbot (Lota lota) from a polluted lake (Lake Mjøsa, Norway)

The aim of the present study was to investigate whether exposure to high levels of persistent organic pollutants (POPs) affected a fish population in Lake Mjøsa. Lake Mjøsa is known to be contaminated by polybrominated diphenyl ethers (PBDEs), a subgroup of brominated flame retardants from local industrial activities. Fish from Lake Losna, a less contaminated lake located close to Lake Mjøsa, was used as reference (control). The sampling of burbot (Lota lota) was carried out between 2005 and 2008. Hepatic levels of POPs were analysed in burbot from the two lakes, and the fish were examined for bacterial- and parasite infection and histopathological changes. The levels of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and PBDEs were about 10, 15 and 300 times higher in fish from Lake Mjøsa compared to fish from Lake Losna. Mycobacterium salmoniphilum was present in 7% and 35% of the fish from Lake Losna and Lake Mjøsa respectively. Significantly higher number of external and visceral macroscopic lesions, histopathological diffuse changes and granulomas were seen in fish from Lake Mjøsa compared to Lake Losna. Furthermore the parasite infection was higher and the hepatic lipid content was significantly lower in burbot from Lake Mjøsa. The results of the present study suggest that the high level of contamination in Lake Mjøsa could have a negative impact on the health status of wild fish inhabiting the lake.

Parental exposure to natural mixtures of POPs reduced embryo production and altered gene transcription in zebrafish embryos

Determination of toxicity of complex mixtures has been proposed to be one of the most important challenges for modern toxicology. In this study we performed genome wide transcriptome profiling to assess potential toxicant induced changes in gene regulation in zebrafish embryos following parental exposure to two natural mixtures of persistent organic pollutants (POPs). The mixtures used were extracted from burbot (Lota lota) liver originating from two lakes (Lake Mjøsa and Lake Losna) belonging to the same freshwater system in Norway. The dominating groups of contaminants were polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane metabolites (DDTs). Because both mixtures used in the present study induced similar effects, it is likely that the same toxicants are involved. The Mjøsa mixture contains high levels of PBDEs while this group of pollutants is low in the Losna mixture. However, both mixtures contain substantial concentrations of PCB and DDT suggesting these contaminants as the predominant contributors to the toxicity observed. The observed effects included phenotypic traits, like embryo production and survival, and gene transcription changes corresponding with disease and biological functions such as cancer, reproductive system disease, cardiovascular disease, lipid and protein metabolism, small molecule biochemistry and cell cycle. The changes in gene transcription included genes regulated by HNF4A, insulin, LH, FSH and NF-κB which are known to be central regulators of endocrine signaling, metabolism, metabolic homeostasis, immune functions, cancer development and reproduction. The results suggest that relative low concentrations of the natural mixtures of POPs used in the present study might pose a threat to wild freshwater fish living in the lakes from which the POPs mixtures originated.

The Relationship Between Noncoplanar PCB-Induced Immunotoxicity and Hepatic CYP1A Induction in a Fish Model

Abundant literature exists demonstrating the immunomodulating effects of polychlorinated biphenyls (PCBs). To date, most of the research has focused on dioxin-like coplanar PCB congeners because of their high affinity for the aryl hydrocarbon receptor (AhR) and cytochrome P450-inducing capability. For this study, the impact of two structurally different PCB congeners on the immune responsiveness of bluegill sunfish (Lepomis macrochirus) was examined to evaluate the immunotoxic potential of each congener (as separate entities) and to relate effects on immune function with hepatic CYP1A induction. Fish received a single intraperitoneal injection of the: coplanar congener, PCB 126 (0.01 or 1.0 mug/g BW); noncoplanar PCB 153 (5.0 or 50.0 mug/g BW); or, the corn oil vehicle. PCB-induced effects on innate and cell-mediated immune parameters, and on hepatic CYP1A protein induction were evaluated in fish sacrificed 1, 3, 7, 14 or 21 days post-injection. In the absence of CYP1A induction, PCB 153 increased kidney phagocyte-mediated superoxide production 3 d post-injection, and at the highest dose suppressed B- and T-lymphocyte proliferation after 3 and 7 days, respectively. Treatment of fish with PCB 126 had no effect on oxyradical production, but altered B-lymphocyte proliferation after 1 day, also in the absence of CYP1A induction. Hepatic CYP1A was only induced in fish exposed to the highest PCB 126 dose; protein induction appeared at 3 d post-injection and persisted for up to 21 days. Taken together, these results demonstrate that exposure to different PCB congeners can alter immune function in the absence of CYP1A induction, suggesting that mechanisms other than the AhR pathway may play a role in PCB-induced immunotoxicity, particularly for the noncoplanar congeners.

Current status of the epidemiologic evidence linking polychlorinated biphenyls and non-hodgkin lymphoma, and the role of immune dysregulation

BACKGROUND

Although case-control studies conducted to date have largely affirmed the relationship between polychlorinated biphenyls (PCBs) and non-Hodgkin lymphoma (NHL), occupational cohort studies of PCB-exposed workers have been generally interpreted as negative, thereby raising doubts about a potential causal association. A common theme of immune dysregulation unifies many of NHL's strongest risk factors, and several authors have posited that subclinical immune dysregulation may increase NHL risk by decreasing host resistance, reducing control of cellular proliferation and differentiation, and diminishing tumor surveillance mechanisms.

OBJECTIVES

The goals of this review were a) to evaluate the epidemiological research examining the association between PCB exposure and NHL and discuss the contribution to the weight of evidence of case-control studies and occupational cohort studies; and b) to summarize the evidence for immune dysregulation as a means by which PCBs may cause NHL.

METHODS

We performed a literature search using PubMed and seven additional online biomedical and toxicological referencing libraries to identify literature published through August 2011.

DISCUSSION AND CONCLUSIONS

Overall, we conclude that the weight of evidence supports a causal role of PCBs in lymphomagenesis. The strongest epidemiological evidence for the relationship between PCBs and NHL comes from case-control studies conducted among the general population. Epidemiological and toxicological data demonstrating immunosuppressive and inflammatory effects of PCBs further contribute to the weight of evidence by providing a plausible explanation for how PCBs can cause NHL through immune dysregulation.

Global gene expression and Ingenuity biological functions analysis on PCBs 153 and 138 induced human PBMC in vitro reveals differential mode(s) of action in developing toxicities

Several reports have indicated that low level of polychlorinated biphenyl (PCB) exposure can adversely affect a multitude of physiological disorders and diseases in in vitro, in vivo, and as reported in epidemiological studies. This investigation is focused on the possible contribution of two most prevalent PCB congeners in vitro in developing toxicities. We used PCBs 138 and 153 at the human equivalence level as model agents to test their specificity in developing toxicities. We chose a global approach using oligonucleotide microarray technology to investigate modulated gene expression for biological effects, upon exposure of PCBs, followed by Ingenuity Pathway Analysis (IPA), to understand the underlying consequence in developing disease and disorders. We performed in vitro studies with human peripheral blood mononuclear cells (PBMC), where PBMC cells were exposed to respective PCBs for 48 h. Overall, our observation on gene expression indicated that PCB produces a unique signature affecting different pathways, specific for each congener. While analyzing these data through IPA, the prominent and interesting disease and disorders were neurological disease, cancer, cardiovascular disease, respiratory disease, as well as endocrine system disorders, genetic disorders, and reproductive system disease. They showed strong resemblances with in vitro, in vivo, and in the epidemiological studies. A distinct difference was observed in renal and urological diseases, organisimal injury and abnormalities, dental disease, ophthalmic disease, and psychological disorders, which are only revealed by PCB 138 exposure, but not in PCB 153. The present study emphasizes the challenges of global gene expression in vitro and was correlated with the results of exposed human population. The microarray results give a molecular mechanistic insight and functional effects, following PCB exposure. The extent of changes in genes related to several possible mode(s) of action highlights the changes in cellular functions and signaling pathways that play major roles. In addition to understanding the pathways related to mode of action for chemicals, these data could lead to the identification of genomic signatures that could be used for screening of chemicals for their potential to cause disease and developmental disorders.

Accumulation and effects of natural mixtures of persistent organic pollutants (POP) in Zebrafish after two generations of exposure

Effects of exposure to environmentally realistic mixtures of persistent organic pollutants (POP) harvested from aquatic ecosystems in Norway were studied in an in vivo zebrafish model. POP were extracted from burbot (Lota lota) liver from two separate lakes, Lake Losna and Lake Mjøsa, and exposed to zebrafish through the diet in a two-generation study. Effects on survival, growth, sex ratio, and timing of puberty were investigated. In addition, the biomarkers 7-ethoxyresorufin O-deethylase (EROD) and vitellogenin (Vtg) were measured. The ratios of contaminant levels in extracts collected from Lake Mjøsa:Lake Losna were 6, 10, and 270 for polychlorinated biphenyls (PCB), dichlorodiphenyltrichloroethanes (DDT), and polybrominated diphenyl ethers (PBDE), respectively. The concentration range of POP measured in zebrafish was lower than in burbot originating from Lake Mjøsa, but comparable to concentrations previously reported in humans and wildlife. The results showed that exposure to environmentally realistic mixtures of POP exerted a negative effect on survival of fish in both generations. The marked drop in survival during 9-20 days post fertilization (dpf) suggested that this period may be a critical window for development. In both generations an earlier onset of puberty was observed and a higher proportion of males than females was noted in exposed fish compared to controls. Suprising effects of exposure were found on body weight. In the first generation (F(0)), body weight was significantly higher in both exposure groups compared to controls, while in the next generation (F(1)) the same exposures were associated with a decrease in body weight. Zebrafish exposed to relatively low quantities of POP showed a significant induction of biomarkers (EROD and Vtg), while fish exposed to higher exposure doses did not demonstrate induction.

In vitro cytokine release from human peripheral blood mononuclear cells in the assessment of the immunotoxic potential of chemicals

Alternative methods to the use of animals in testing of chemicals are needed. We investigated if the immunotoxic potential of 12 dietary toxicants could be predicted from effects on cytokine release from human peripheral blood mononuclear cells (PBMC) after in vitro exposure. Nine cytokines were selected to reflect different types of immune responses. The toxicants were classified as immunotoxic or non-immunotoxic substances according to the published in vivo data. Isolated human PBMC were exposed for 20 h to three concentrations of each of the 12 substances in the presence of human liver S9 fraction. After further incubation of PBMC in fresh medium containing the mitogen phytohemagglutinin (PHA, 10 μg/ml) for 48 h, release of the nine selected cytokines into the supernatant as well as cell proliferation were measured by Luminex technology™ and the BrdU incorporation assay, respectively. All 12 substances investigated affected the release of one or more cytokines, and each of the substances showed different cytokine release patterns. Within the limitations of the study design, the present study suggests that the effect of the substances on mitogen-induced cytokine release from PBMC cannot predict their immunotoxic potential, but may be useful in mechanistic studies.

Trans-generational and neonatal humoral immune responses in West Greenland sledge dogs (Canis familiaris) exposed to organohalogenated environmental contaminants

Previous investigations in the Arctic have suggested OHC (organohalogen contaminant) induced immune toxic effects on e.g. polar bears (Ursus maritimus). We therefore studied the dietary impact from minke whale blubber (Balaenoptera acutorostrata), rich in polyunsaturated fatty acids and OHCs, on the humoral immunity of 7 captive West Greenland sledge dog (Canis familiaris) bitches and their 4 pups constituting a sentinel model species for polar bears. A control group was composed of 8 bitches and their 5 pups all fed pork (Suis scrofa) fat. The study included serum IgG measurements (bitches and pups) and specific immune responses towards tetanus toxoid (bitches) and diphtheria toxoid (pups) as well as influenza virus (pups). The analyses showed that IgG concentrations were non-significantly lowest in exposed bitches and pups (t-test: all p>0.05). In addition, significant lower antibody response was detected in exposed pups immunized with influenza virus at age 3 months (t-test: both p<0.05). No clear group differences were found for tetanus toxoid in bitches and diphtheria toxoid in pups. The results suggest that the humoral immune system of sledge dogs may be suppressed by the dietary blubber composition of OHCs and polyunsaturated fatty acids while a larger follow-up study is recommended in order to investigate this relationship further.

PCB congener specific oxidative stress response by microarray analysis using human liver cell line

In this study we have examined the effect of exposure to different congeners of PCBs and their role in oxidative stress response. A metabolically competent human liver cell line (HepG2) was exposed with two prototype congeners of PCBs: coplanar PCB-77 and non-coplanar PCB-153. After the predetermined times of exposure (0-24h) at 70 μM concentration, the HepG2 cells showed significant apoptotic changes by fluorescent microscopy after 12h of exposure. Gene set enrichment analysis (GSEA) identified oxidative stress as the predominant enrichment. Further, paraquat assay showed that PCB congeners lead to oxidative stress to different extents, PCB-77 being more toxic. This study, with emphasis on all recommended microarray quality control steps, showed that apoptosis was one of the most significant cellular processes as a result of oxidative stress, but each of these congeners had a unique signature gene expression, which was further validated by Taqman real time PCR and immunoblotting. The pathways involved leading to the common apoptotic effect were completely different. Further in-silico analysis showed that PCB-153 most likely acted through the TNF receptor, leading to oxidative stress involving metallothionein gene families, and causing apoptosis mainly by the Fas receptor signaling pathway. In contrast, PCB-77 acted through the aryl hydrocarbon receptor. It induced oxidative stress through the involvement of cytochrome P450 (CYP1A1) leading to apoptosis through AHR/ARNT pathway.

Non-coplanar polychlorinated biphenyl (PCB)-induced immunotoxicity is coincident with alterations in the serotonergic system

Attention to non-coplanar polychlorinated biphenyl (PCB) congeners in immunotoxicological research is increasing. However, the exact mechanism by which these congeners may induce immune dysfunction is still undefined. Because the serotonergic nervous system has been shown to be involved in the regulation of some immune responses, and also serves as a sensitive target for PCBs, the relationship (if any) between non-coplanar PCB exposure, immune responsiveness and the neurotransmitter serotonin (5-HT) was examined. Using bluegill sunfish (Lepomis macrochirus) as a model, changes in brain 5-HT levels, 5-HT synthesis and metabolism, and innate and cell-mediated immune parameters were evaluated following a single intraperitoneal injection of PCB 153 (5.0 or 50 μg/g body weight). Results revealed that 3 d following administration, PCB exposure decreased brain 5-HT levels (in the absence of effects on some enzymes involved in 5-HT synthesis and metabolism), increased oxyradical production by kidney phagocytes, and reduced splenic T- and B-lymphocyte proliferation. In vivo treatment of PCB-exposed fish with 5-hydroxy-L-tryptophan (the immediate precursor to 5-HT) ameliorated the observed PCB-induced immunotoxicity; in vitro treatment of immune cells from PCB-exposed fish with 5-HT failed to reverse the effects. Taken together, results from this study could suggest a link between PCB-induced alterations of brain 5-HT levels and subsequent immune dysfunction. These studies highlight the importance of indirect mechanisms of immunotoxicity, and, specifically, suggest a role for the neuroimmune axis in non-coplanar PCB-induced immune alterations.

Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish

Persistent organic pollutants (POPs) encompass an array of anthropogenic organic and elemental substances and their degradation and metabolic byproducts that have been found in the tissues of exposed animals, especially POPs categorized as organohalogen contaminants (OHCs). OHCs have been of concern in the circumpolar arctic for decades. For example, as a consequence of bioaccumulation and in some cases biomagnification of legacy (e.g., chlorinated PCBs, DDTs and CHLs) and emerging (e.g., brominated flame retardants (BFRs) and in particular polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanic acid (PFOA) found in Arctic biota and humans. Of high concern are the potential biological effects of these contaminants in exposed Arctic wildlife and fish. As concluded in the last review in 2004 for the Arctic Monitoring and Assessment Program (AMAP) on the effects of POPs in Arctic wildlife, prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects in relation to OHC exposure, and attempts to assess known tissue/body compartment concentration data in the context of possible threshold levels of effects to evaluate the risks. This review concentrates mainly on post-2002, new OHC effects data in Arctic wildlife and fish, and is largely based on recently available effects data for populations of several top trophic level species, including seabirds (e.g., glaucous gull (Larus hyperboreus)), polar bears (Ursus maritimus), polar (Arctic) fox (Vulpes lagopus), and Arctic charr (Salvelinus alpinus), as well as semi-captive studies on sled dogs (Canis familiaris). Regardless, there remains a dearth of data on true contaminant exposure, cause-effect relationships with respect to these contaminant exposures in Arctic wildlife and fish. Indications of exposure effects are largely based on correlations between biomarker endpoints (e.g., biochemical processes related to the immune and endocrine system, pathological changes in tissues and reproduction and development) and tissue residue levels of OHCs (e.g., PCBs, DDTs, CHLs, PBDEs and in a few cases perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs)). Some exceptions include semi-field studies on comparative contaminant effects of control and exposed cohorts of captive Greenland sled dogs, and performance studies mimicking environmentally relevant PCB concentrations in Arctic charr. Recent tissue concentrations in several arctic marine mammal species and populations exceed a general threshold level of concern of 1 part-per-million (ppm), but a clear evidence of a POP/OHC-related stress in these populations remains to be confirmed. There remains minimal evidence that OHCs are having widespread effects on the health of Arctic organisms, with the possible exception of East Greenland and Svalbard polar bears and Svalbard glaucous gulls. However, the true (if any real) effects of POPs in Arctic wildlife have to be put into the context of other environmental, ecological and physiological stressors (both anthropogenic and natural) that render an overall complex picture. For instance, seasonal changes in food intake and corresponding cycles of fattening and emaciation seen in Arctic animals can modify contaminant tissue distribution and toxicokinetics (contaminant deposition, metabolism and depuration). Also, other factors, including impact of climate change (seasonal ice and temperature changes, and connection to food web changes, nutrition, etc. in exposed biota), disease, species invasion and the connection to disease resistance will impact toxicant exposure. Overall, further research and better understanding of POP/OHC impact on animal performance in Arctic biota are recommended. Regardless, it could be argued that Arctic wildlife and fish at the highest potential risk of POP/OHC exposure and mediated effects are East Greenland, Svalbard and (West and South) Hudson Bay polar bears, Alaskan and Northern Norway killer whales, several species of gulls and other seabirds from the Svalbard area, Northern Norway, East Greenland, the Kara Sea and/or the Canadian central high Arctic, East Greenland ringed seal and a few populations of Arctic charr and Greenland shark.

Effects of the endocrine disruptors atrazine and PCB 153 on the protein expression of MCF-7 human cells

Polychlorinated biphenyls (PCBs) and a number of pesticides can act as endocrine disrupting compounds (EDCs). These molecules exhibit hormonal activity in vivo, and can therefore interact and perturb normal physiological functions. Many of these compounds are persistent in the environment, and their bioaccumulation may constitute a significant threat for human health. Physiological abnormalities following exposure to these xenobiotic compounds go along with alterations at the protein level of individual cells. In this study, MCF-7 cells were exposed to environmentally relevant concentrations of atrazine, PCB153 (100 ppb, respectively), 17-beta estradiol (positive control, 10 nM) and a negative control (solvent) for t = 24 h (n = 3 replicates/exposure group). After trizol extraction and protein solubilization, protein expression levels were studied by 2D-DIGE. Proteins differentially expressed were excised, trypsin-digested, and identified by MALDI-ToF-ToF, followed by NCBInr database search. 2D-DIGE experiments demonstrated that 49 spots corresponding to 29 proteins were significantly differentially expressed in MCF-7 cells (>1.5-fold, P < 0.05, Student's paired t test). These proteins belonged to various cellular compartments (nucleus, cytosol, membrane), and varied in function; 88% of proteins were down-regulated during atrazine exposure, whereas 75% of proteins were up-regulated by PCB153. Affected proteins included those regulating oxidative stress such as superoxide dismutase and structural proteins such as actin or tropomyosin, which may explain morphological changes of cells already observed under the microscope. This study highlights the susceptibility of human cells to compounds with endocrine disrupting properties.

Altered stress-induced cortisol levels in goats exposed to polychlorinated biphenyls (PCB 126 and PCB 153) during fetal and postnatal development

Short-term stress exposure is associated with activation of the hypothalamic-pituitary-adrenal (HPA) axis and a consequent rise in blood glucocorticoids and catecholamines, from the adrenal cortex and medulla, respectively. The HPA axis is a potential target for some persistent organic pollutants, among which polychlorinated biphenyls (PCB) were found to be modulators of the mammalian endocrine system. PCB are distributed globally in the environment, in food chains, and are transferred to the fetuses of pregnant animals and via mother's milk to suckling offspring. In the present study it was postulated that intrauterine and lactational exposure to either of two single congeners of PCB (PCB 153 and PCB 126, respectively) might affect basal cortisol concentrations, and also the cortisol response to short-term stress in adulthood. Thus, pregnant goats were orally exposed to one of these PCB congeners from d 60 of gestation until delivery, and their offspring studied. Low-dose exposure to PCB 153 and PCB 126 resulted in significantly lower mean basal cortisol concentrations in goat offspring during certain periods of pubertal development and their first breeding season. Male goat kids exposed to either PCB congener showed a greater and more prolonged rise in plasma cortisol levels than controls when animals were subjected to mild stress at 9 mo of age using frequent blood sampling. Neither the basal maternal cortisol plasma level nor goat kid adrenal masses were affected by PCB exposure.

The toxic effects of multiple persistent organic pollutant exposures on the post-hatch immunity maturation of glaucous gulls

This study tested whether the immune system of the glaucous gull (Larus hyperboreus) chicks became affected by existing environmental contaminants. An experimental group was given food that mimicked the natural contaminant mixture found in food from the North Atlantic marine environment, while the control group was given the equivalent of nearly clean food. All chicks were immunized with herpes virus (EHV), reovirus (REO), influenza virus (EIV), and tetanus toxoid (TET) in order to test their ability to respond to foreign specific antigens. At 8 wk, the experimental group had 3- to 13-fold higher concentrations of hexachlorobenzene (HCB), oxychlordane, p,p'-DDE, and total polychlorinated biphenyls (Sigma PCB) than did the control. The experimental group produced significantly lower antibody titer against EIV and had lower concentrations of immunoglobulin-G (IgG) and -M (IgM) in blood. Hematocrit percent and leukocyte numbers did not differ between the two groups. The ability of lymphocytes to proliferate in vitro was tested with three mitogens, phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM), and three antigens, keyhole limpet hemocyanin (KLH), TET, and Mycobacterium avium subsp. paratuberculosis tuberculin purified protein derivative (PPD). The experimental group had a significantly higher peripheral blood lymphocyte response to PHA and to spleen lymphocytes in vitro stimulated with Con A and PCB congeners 99 or 153, while the Con A, PWM, KLH, TET, PPD, and Con A plus PCB-156 or -126 showed nonsignificant differences between groups. Data indicate that the combined effect of multiple persistent organic pollution exposures occurring naturally in the Arctic negatively affect the immune system of the glaucous gull chick.

Perinatal exposure to PCB 153, but not PCB 126, alters bone tissue composition in female goat offspring

The aim of this study was to investigate if environmentally relevant doses of the putative estrogenic non dioxin-like PCB 153 and the dioxin-like PCB 126 caused changes in bone tissue in female goat offspring following perinatal exposure. Goat dams were orally dosed with PCB 153 in corn oil (98 microg/kg body wt/day) or PCB 126 (49 ng/kg body wt/day) from day 60 of gestation until delivery. The offspring were exposed to PCB in utero and through mother's milk. The suckling period lasted for 6 weeks. Offspring metacarpal bones were analysed using peripheral quantitative computed tomography (pQCT) after euthanisation at 9 months of age. The diaphyseal bone was analysed at a distance of 18% and 50% of the total bone length, and the metaphyseal bone at a distance of 9%. Also, biomechanical three-point bending of the bones was conducted, with the load being applied to the mid-diaphyseal pQCT measure point (50%). PCB 153 exposure significantly decreased the total cross-sectional area (125 mm(2)+/-4) versus non-exposed (142 mm(2)+/-5), decreased the marrow cavity (38 mm(2)+/-4) versus non-exposed (50 mm(2)+/-3) and decreased the moment of resistance (318 mm(3)+/-10) versus non-exposed (371 mm(3)+/-20) at the diaphyseal 18% measure point. At the metaphyseal measure point, the trabecular bone mineral density (121 mg/cm(3)+/-5) was increased versus non-exposed (111 mg/cm(3)+/-3). PCB 126 exposure did not produce any observable changes in bone tissue. The biomechanical testing of the bones did not show any significant changes in bone strength after PCB 153 or PCB 126 exposure. In conclusion, perinatal exposure to PCB 153, but not PCB 126, resulted in altered bone composition in female goat offspring.

Reduced antibody responses to vaccinations in children exposed to polychlorinated biphenyls

BACKGROUND

Developmental exposure to polychlorinated biphenyls (PCBs) has been implicated as a possible cause of deficient immune function in children. This study was designed to assess whether prenatal and postnatal exposure to PCBs impacts on antibody response to childhood immunizations.

METHODS AND FINDINGS

Two birth cohorts were formed in the Faroe Islands, where exposures vary widely, because traditional diets may include whale blubber contaminated with PCBs. Prenatal exposure was determined from maternal concentrations of PCBs in pregnancy serum and milk. Following routine childhood vaccinations against tetanus and diphtheria, 119 children were examined at 18 mo and 129 children at 7 y of age, and their serum samples were analyzed for tetanus and diphtheria toxoid antibodies and for PCBs. The antibody response to diphtheria toxoid decreased at age 18 mo by 24.4% (95% confidence interval [CI], 1.63-41.9; p = 0.04) for each doubling of the cumulative PCB exposure at the time of examination. The diphtheria response was lower at age 7 y and was not associated with the exposure. However, the tetanus toxoid antibody response was affected mainly at age 7 y, decreasing by 16.5% (95% CI, 1.51-29.3; p = 0.03) for each doubling of the prenatal exposure. Structural equation analysis showed that the early postnatal exposure was the most important predictor of a decreased vaccination response.

CONCLUSIONS

Increased perinatal exposure to PCBs may adversely impact on immune responses to childhood vaccinations. The clinical implications of insufficient antibody production emphasize the need for prevention of immunotoxicant exposures.

Perinatal exposure to low doses of PCB 153 and PCB 126 affects maternal and neonatal immunity in goat kids

Pregnant does (10 goats/group) were dosed orally either with polychlorinated biphenyl (PCB) 153 (98 microg/kg body weight/d) or PCB 126 (ng/kg body weight/d) dissolved in corn oil or with corn oil only (control group) from gestation day (GD) 60 until delivery. An additional group (n = 5) of pregnant does received the synthetic estrogen diethylstilbestrol (DES; 0.4 microg/kg body weight/d) by intramuscular injection using the same treatment schedule as for the PCB groups. Blood samples for immune analysis were collected at wk 0, 1, 2, 4, 6, and 8 of age. The effects of perinatal PCB exposure on postnatal humoral immune responses were examined by assessing the levels of total immunoglobulin G (IgG) and immunoglobulins to specific microbes at wk 0, 1, 2, 4, 6, and 8 of age, and immune responses following immunization of kids at 2 wk of age. PCB 153 exposure suppressed maternal and neonatal immunity, as demonstrated by reduced transfer of maternal IgG and specific antibodies to the environmental microbes Arcanobacterium pyogenes, Mannheimia haemolytica, and reovirus (REO-1). Furthermore, PCB 153 reduced the level of maternal antibodies to Mycobacterium avium paratuberculosis and equine influenza virus (EIV-1) in the newborn kids. The antibody response against EIV-1 was significantly higher in PCB 153-exposed kids 2 wk following immunization. PCB 126 exposure reduced the levels of maternal antibodies to REO-1. In contrast, gestational exposure to PCB 126 increased the concentrations of maternal antibodies to tetanus toxoid. No differences from controls in plasma total IgG levels at birth or colostrum IgG concentrations were observed in the PCB 126-treated does. However, a significant reduction in IgG levels from GD 60 until delivery was found in this group. Gestational exposure to DES reduced the concentrations of maternal antibodies against A. pyogenes, M. haemolytica, M. avium Paratuberculosis, and REO-1. These results suggest that perinatal exposure to low doses of PCB 126 and PCB 153 affects the maternal immunity in kids. The difference in responses between PCB 126 and PCB 153 treatment groups may strengthen the hypothesis that PCBs mediate immunotoxic effects through both AhR-dependent and -independent mechanisms. The observation that the effects produced by PCB 153 resembled those produced by DES raises the question of whether this congener may modulate immunity by estrogenic mechanisms.

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part II: Possible effect of OCs on mitogen- and antigen-induced lymphocyte proliferation

Previous studies have reported alarmingly high levels of organochlorines (OCs), particularly polychlorinated biphenyls (PCBs), in free-ranging polar bears (Ursus maritimus). In this study plasma concentration of PCBs ranged from 14.8 to 200 ng/g wet weight. The aim of the study was to investigate associations between OCs and lymphocyte proliferation after in vitro stimulation with different mitogens and antigens. In 1998 and 1999, 26 and 30 free-ranging polar bears from Svalbard and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated tetanus toxoid and hemocyanin from keyhole limpets (KLH) to sensitize lymphocytes. At recapture, blood was sampled for determination of plasma levels of PCBs and organochlorine pesticides (OCPs) and lymphocyte proliferation after in vitro stimulation with specific mitogens--phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (Con A), lipopolysaccharide (LPS), and purified protein derivative of Mycobacterium avium subsp. paratuberculosis (PPD)--and antigens: tetanus toxoid and KLH. The combinations of sum(PCBs) (sum of 12 individual PCB congeners), sum(OCPs) (sum of 6 OCPs), and their interactions contributed up to 15% of the variations in the lymphocyte responses. By using multiple regression analyses, followed by classical mathematic function analyses, thresholds for immunomodulation were estimated. Depending on the lymphocyte proliferation response studied, the estimated thresholds for significant immunomodulation were within the concentration ranges 32-89 ng/g wet weight (ww) and 7.8-14 ng/g ww for sum(PCBs) and sum(OCPs), respectively. Thus, this study demonstrated that OC exposure significantly influences specific lymphocyte proliferation responses and part of the cell-mediated immunity, which also is associated with impaired ability to produce antibodies (Lie et al., 2004).