Effects of in ovo exposure to PCBs 126 and 77 on mortality, deformities and post-hatch immune function in chickens

3,3',4,4'-tetrachlorobiphenyl (PCB77) enhances human Kv1.3 channel currents and alters cytokine production

Polychlorinated biphenyls (PCBs) were once used throughout various industries; however, because of their persistence in the environment, exposure remains a global threat to the environment and human health. The Kv1.3 and Kv1.5 channels have been implicated in the immunotoxicity and cardiotoxicity of PCBs, respectively. We determined whether 3,3',4,4'-tetrachlorobiphenyl (PCB77), a dioxin-like PCB, alters human Kv1.3 and Kv1.5 currents using the Xenopus oocyte expression system. Exposure to 10 nM PCB77 for 15 min enhanced the Kv1.3 current by approximately 30.6%, whereas PCB77 did not affect the Kv1.5 current at concentrations up to 10 nM. This increase in the Kv1.3 current was associated with slower activation and inactivation kinetics as well as right-shifting of the steady-state activation curve. Pretreatment with PCB77 significantly suppressed tumor necrosis factor-α and interleukin-10 production in lipopolysaccharide-stimulated Raw264.7 macrophages. Overall, these data suggest that acute exposure to trace concentrations of PCB77 impairs immune function, possibly by enhancing Kv1.3 currents.

Old World Vultures Reflect Effects of Environmental Pollutants Through Human Encroachment

African wildlife face challenges from many stressors including current and emerging contaminants, habitat and resource loss, poaching, intentional and unintentional poisoning, and climate-related environmental change. The plight of African vultures exemplifies these challenges due to environmental contaminants and other stressors acting on individuals and populations that are already threatened or endangered. Many of these threats emanate from increasing human population size and settlement density, habitat loss from changing land use for agriculture, residential areas, and industry, and climate-related changes in resource availability. Environmental chemicals that are hazardous include legacy chemicals, emerging chemicals of concern, and high-volume-use chemicals that are employed as weed killers and in other agricultural applications. Furthermore, there are differences in risk for species living in close proximity to humans or in areas affected by habitat loss, climate, and industry. Monitoring programs are essential to track the status of nesting pairs, offspring survival, longevity, and lifetime productivity. This is important for long-lived birds, such as vultures, that may be especially vulnerable to chronic exposure to chemicals as obligate scavengers. Furthermore, their position in the food web may increase risk due to biomagnification of chemicals. We review the primary chemical hazards to Old World vultures and the interacting stressors affecting these and other birds. Habitat is a major consideration for vultures, with tree-nesters and cliff-nesters potentially experiencing different risks of exposure to environmental chemicals. The present review provides information from long-term monitoring programs and discusses a range of these threats and their effects on vulture populations. Environ Toxicol Chem 2022;41:1586-1603. © 2022 SETAC.

An overview of organic contaminants in indoor dust, their health impact, geographical distribution and recent extraction/analysis methods

People spend a substantial proportion of their time indoors; therefore, exposure to contaminants in indoor dust is persistent and profuse. According to the findings of recent studies, contaminants such as flame retardants (FRs), organochlorines (OCs), and phthalate esters (PAEs) are more prevalent in indoor dust. The discrepancy in the geographical distribution of these chemicals indicates country-specific applications. However, many studies have revealed that chlorophosphates, polychlorinated biphenyls (PCBs) and di-2-ethylhexyl phthalate are frequently detected in indoor dust throughout the world. Although some chemicals (e.g., OCs) were banned/severely restricted decades ago, they have still been detected in indoor dust. These organic contaminants have shown clear evidence of carcinogenic, neurotoxic, immunogenic, and estrogenic activities. Recent extraction methods have shown their advantages, such as high recoveries, less solvent consumption, less extraction time and simplicity of use. The latest separation techniques such as two-dimensional gas/liquid chromatography, latest ionization techniques (e.g., matrix-assisted laser desorption/ionization (MALDI)), and modern techniques of mass spectrometry (e.g., tandem mass spectrometry (MS/MS), time-of-flight (TOF) and high-resolution mass spectrometry (HRMS)) improve the detection limits, accuracy, reproducibility and simultaneous detection of organic contaminants. For future perspectives, it is suggested that the importance of the study of dust morphology for comprehensive risk analysis, introducing standard reference materials to strengthen the analytical methods, adopt common guidelines for comparison of research findings and the importance of dust analysis in the developing world since lack of records on the production and usage of hazardous substances. Such measures will help to evaluate the effectiveness of prevailing legislations and to set up new regulations.

Larval Exposure to Polychlorinated Biphenyl-126 Led to a Long-Lasting Decrease in Immune Function in Postmetamorphic Juvenile Northern Leopard Frogs, Lithobates pipiens

Amphibian populations are decreasing worldwide, and pollution is a contributing factor. Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants known to exert immunotoxicity. To assess impacts of PCBs on frogs, we exposed Lithobates pipiens tadpoles to a diet of PCB-126 (0-5 ng PCB-126/g wet food) through metamorphic climax. Postmetamorphic frogs were immunized with keyhole limpet hemocyanin (KLH); then production of KLH-specific IgY, as well as total IgY and IgM, was measured (Trial I). A second larval study (0 and 7.3 ng PCB-126/g wet food) was performed to investigate whether PCB altered antigenic responses in prometamorphic tadpoles (Gosner Stage 36-39), and to measure the innate immune response of postmetamorphic frogs (Trial II). After larval PCB-126 exposure, both KLH-specific IgY levels and complement activity were reduced. Because postmetamorphic frogs carried a body burden of PCB-126 (2.4 ng/g or less), we wanted to determine whether the effect on immune response was due to larval exposure or to the resulting body burden as frogs. To test this, we reared tadpoles under control conditions (no PCB), and limited PCB exposure to postmetamorphosis only by injecting 2-week-old frogs with 10 ng PCB-126/g (Trial III). The resulting body burden (3.4 ng/g) was similar to that of frogs in Trial I, but we no longer detected suppression of KLH-specific IgY or hemolytic activity. These results suggest life-stage-specific immune responses; however, because we administered PCB-126 differently between trials, it is premature to conclude that these differences are intrinsically life stage dependent, and further study is warranted. Regardless, our study demonstrated a long-lasting effect of larval PCB-126 exposure that persisted through metamorphosis and suppressed frog immunity. Environ Toxicol Chem 2022;41:81-94. © 2021 SETAC.

Ecotoxicology of persistent organic pollutants in birds

Considering the explosive growth of the list of persistent organic pollutants (POPs), the scientific community is combatting increasing challenges to protect humans and wildlife from the potentially negative consequences of POPs. Herein, we characterize the main aspects and progress in the ecotoxicology of POPs in avian species since 2000. The majority of previous efforts has revealed the global occurrence of high levels of various POPs in birds. Laboratory research and epidemiological studies imply that POPs exert a broad-spectrum of side-effects on birds by interfering with their endocrine, immune and neural system, reproduction, and development, and growth. However, inconsistent results suggest that the potential effects of POP exposure on the physiological parameters in birds are multifactorial, involving a multitude of biological processes, species-specific differences, gender, age and types of compounds. Great progress has been achieved in identifying the species-specific sensitivity to dioxin-like compounds, which is attributed to different amino acid residues in the ligand-binding domain of the aryl hydrocarbon receptor. Besides the conventional concentration additivity, several studies have suggested that different classes of POPs possibly act synergistically or antagonistically based on their concentration. However, ecotoxicology information is still recorded in a scattered and inadequate manner, including lack of enough avian species, limited number of POPs investigated, and insufficient geographical representation, and thus our understanding of the effects of POPs on birds remains rudimentary, although mechanistic understanding of their mode of action is progressing. Particularly, research on what happens to wild bird populations and their ecosystems under POP stress is still unavailable. Thus, our aim is to predict and trace the effects POPs at different biological organization levels, especially from the molecular, cellular and individual levels to the population, community and ecosystem levels because of the limited and scattered information, as mentioned above.

Incubation temperature and PCB-126 exposure interactively impair shorebird embryo and post-hatch development

In oviparous wildlife, many critical physiological and behavioural components are strongly influenced by the embryonic and early post-hatch developmental environment. As such, early life stages in these species are highly vulnerable to both natural and anthropogenic stressors. For example, in birds, incubation temperature may influence the rate of egg development while also affecting contaminant metabolism and absorption in body tissues, resulting in potentially multiplicative impacts on embryonic and posthatch development. We tested the hypothesis that cumulative effects of early contaminant exposure and temperature stress can negatively affect avian development and may have interactive effects that are more detrimental than either stressor individually. Using a controlled egg injection and incubation study on killdeer (Charadrius vociferous), eggs were exposed to a known endocrine disruptor, 3,3',4,4',5-pentachlorobiphenyl (PCB-126) and incubated at either low (36 °C), intermediate (37.5 °C), or high (39 °C) temperatures. Our results indicated that eggs incubated at low temperature had earlier detection of heartbeat, longer incubation length, lower growth rate post-hatch, and higher post-hatch mortality, compared to eggs incubated under intermediate temperatures. Higher incubation temperatures resulted in shorter incubation length, earlier detection of heart rate and faster righting time. As predicted, embryo and chick mortality were greater in the PCB-dosed birds incubated at intermediate and high temperatures. Incidence of distended yolk sacs (%) also increased with PCB exposure in all temperature groups, with the largest increase in the high temperature group. Overall, our results show that low incubation temperature can cause greater adverse effects than PCB-126 exposure alone, but that negative effects of PCB-126 exposure are exacerbated by high incubation temperatures. These findings suggest that in natural settings, shorebird embryos may be more susceptible to contaminant exposure when incubated at temperatures either below or above the apparent optimum.

Comparative Lethality of In ovo Exposure to PCB 126, PCB 77, and 2 Environmentally Relevant PCB Mixtures in Japanese Quail (Coturnix japonica)

The Japanese quail (Coturnix japonica) egg bioassay was used to directly compare the toxicity of 3,3',4,4',5-pentachlorobiphenyl (PCB 126), 3,3',4,4'-tetrachlorobiphenyl (PCB 77), and 2 environmentally relevant polychlorinated biphenyl (PCB) mixtures over specified dose ranges relative to vehicle and uninjected controls. Measures included lethality and deformities. Results showed clear dose-response relationships for PCB 126 and the 2 PCB mixtures by logistic analysis of covariance using a varying threshold model because there was a low but significant slope for mortality of vehicle controls over incubation. No dose-dependent increase in mortality was observed with PCB 77 treatment. Mortality increased above baseline for PCB 126 and the 2 mixtures after embryonic day 7 (ED07) to a stable slope from ED10. Median lethal doses and thresholds for response differed for PCB 126 and the 2 PCB mixtures, with the mixtures having lower initial toxicity and all showing progressively greater toxicity over the course of development. Further, the lethality of the PCB mixtures appeared to involve both aryl hydrocarbon receptor (AhR) and non-AhR mechanisms. Incidence of deformities was unrelated to treatments. In summary, complex mixtures of PCBs were lethal in a dose-related manner, with sublethal effects from exposure to PCB 77. Environ Toxicol Chem 2019;38:2637-2650. © 2019 SETAC.

Embryonic effects of an environmentally relevant PCB mixture in the domestic chicken

Studies were conducted to develop methods to assess the effects of a complex mixture of polychlorinated biphenyls (PCBs) in the domestic chicken (Gallus domesticus). Treatments were administered by egg injection to compare embryonic effects of an environmentally relevant PCB congener mixture in the domestic chicken over a range of doses. Chicken eggs were injected with the PCB mixture with a profile similar to that found in avian eggs collected on the upper Hudson River, New York, USA, at doses that spanned 0 to 98 μg/g egg. Eggs were hatched in the laboratory to ascertain hatching success. In the domestic chicken, the median lethal dose was 0.3 μg/g. These data demonstrate adverse effects of an environmentally relevant PCB mixture and provide the basis for further work using in vitro and other models to characterize the potential risk to avian populations. Environ Toxicol Chem 2018;37:2513-2522. © 2018 SETAC.

Differential expression of hepatic genes with embryonic exposure to an environmentally relevant PCB mixture in Japanese quail (Coturnix japonica)

The upper Hudson River was contaminated with polychlorinated biphenyls (PCB) Aroclor mixtures from the 1940s until the late 1970s. Several well-established biomarkers, such as induction of hepatic cytochrome P450 monooxygenases, were used to measure exposure to PCBs and similar contaminants in birds. In the present study, Japanese quail eggs were injected with a PCB mixture based upon a congener profile found in spotted sandpiper eggs at the upper Hudson River and subsequently, RNA was extracted from hatchling liver tissue for hybridization to a customized chicken cDNA microarray. Nominal concentrations of the mixture used for microarray hybridization were 0, 6, 12, or 49 μg/g egg. Hepatic gene expression profiles were analyzed using cluster and pathway analyses. Results showed potentially useful biomarkers of both exposure and effect attributed to PCB mixture. Biorag and Ingenuity Pathway Analysis® analyses revealed differentially expressed genes including those involved in glycolysis, xenobiotic metabolism, replication, protein degradation, and tumor regulation. These genes included cytochrome P450 1A5 (CYP1A5), cytochrome b5 (CYB5), NADH-cytochrome b5 reductase, glutathione S-transferase (GSTA), fructose bisphosphate aldolase (ALDOB), glycogen phosphorylase, carbonic anhydrase, and DNA topoisomerase II. CYP1A5, CYB5, GSTA, and ALDOB were chosen for quantitative real-time polymerase chain reaction confirmation, as these genes exhibited a clear dose response on the array. Data demonstrated that an initial transcriptional profile associated with an environmentally relevant PCB mixture in Japanese quail occurred.

Effects of in ovo exposure to 3,3',4,4'-tetrachlorobiphenyl (PCB 77) on heart development in tree swallow (Tachycineta bicolor)

Tree swallow (Tachycineta bicolor) eggs from 2 uncontaminated sites, the Patuxent Research Refuge (Laurel, MD, USA) and the Cobleskill Reservoir (Cobleskill, NY, USA) were dosed with polychlorinated biphenyl (PCB) 77 to evaluate effects on the developing cardiovascular system. To ensure embryonic viability, treatments were administered into the air cell at embryonic day 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1000 ng/g egg. Eggs were dosed in the field with 0.2 μL/egg, returned to the nest, collected at embryonic day 13, hatched in the laboratory, and necropsied. The PCB 77-treated hatchlings were compared with uninjected, vehicle-injected, and environmentally exposed hatchlings collected from a PCB-contaminated Upper Hudson River (NY, USA) site. The PCB 77-treated embryos showed no effects on hatching success or hatchling mortality, heart index, or morphological measures of 4 distinct heart layers (heart width, length, septal thickness, total and ventricular cavity area) compared with controls. Hatchlings that had received PCB 77 exhibited increased incidence of a cardiomyopathy and absence of the ventricular heart wall compact layer (Chi square test; p < 0.001); environmentally exposed embryos showed no apparent effects. The compact layer is essential in development and overall heart function for ventricular cardiomyocyte proliferation and normal heart contraction. The finding that in ovo exposure to PCB 77 resulted in distinct cardiomyopathy has implications for long-term individual fitness. Environ Toxicol Chem 2018;37:116-125. © 2017 SETAC.

Catbirds are the New Chickens: High Sensitivity to a Dioxin-like Compound in a Wildlife Species

Dioxins and dioxin-like compounds (DLCs) are highly toxic and persistent global pollutants with extremely large differences in sensitivity across taxonomic groups. The chicken has long been considered uniquely sensitive to DLCs among avian species; but DLC toxicity in nondomesticated birds is largely untested, and the relevance of the chicken as an ecological model is uncertain. New approaches that use genotyping of the AHR1 ligand binding domain to screen for DLC sensitivity among avian species predicted that the gray catbird, a relevant wildlife species, is also highly sensitive. We tested this prediction using egg injections of a dioxin-like PCB (PCB-126) and found that the catbird is at least as sensitive as the chicken to DLCs, based on both embryotoxicity and mRNA induction of phase I metabolizing enzymes (CYP1A4/5). This study is the first to confirm that there are wildlife species as sensitive as the chicken and demonstrates how using predictive genotyping methods and targeted bioassays can focus toxicity assessments on ecologically relevant species.

Amino acid sequence of the AhR1 ligand-binding domain predicts avian sensitivity to dioxin like compounds: in vivo verification in European starlings

Research has demonstrated that the sensitivity of avian species to the embyrotoxic effects of dioxin-like compounds can be predicted by the amino acid identities at two key sites within the ligand-binding domain of the aryl hydrocarbon receptor 1 (AhR1). The domestic chicken (Gallus gallus domesticus) has been established as a highly sensitive species to the toxic effects of dioxin-like compounds. Results from genotyping and in vitro assays predict that the European starling (Sturnus vulgaris) is also highly sensitive to dioxin-like compound toxicity. The objective of the present study was to test that prediction in vivo. To do this, we used egg injections in field nesting starlings with 3,3',4,4',5-pentachlorobiphenyl (PCB-126), a dioxin-like polychlorinated biphenyl. Eggs were dosed with either the vehicle control or 1 of 5 doses (1.4, 7.1, 15.9, 32.1, and 52.9 ng PCB-126/g egg). A dose-dependent increase in embryo mortality occurred, and the median lethal dose (LD50; 95% confidence interval [CI]) was 5.61 (2.33-9.08) ng/g. Hepatic CYP1A4/5 messenger RNA (mRNA) expression in hatchlings also increased in a dose-dependent manner, with CYP1A4 being more induced than CYP1A5. No effect of dose on morphological measures was seen, and we did not observe any overt malformations. These results indicate that, other than the chicken, the European starling is the most sensitive species to the effects of PCB-126 on avian embryo mortality reported to date, which supports the prediction of relative sensitivity to dioxin-like compounds based on amino acid sequence of the AhR1.

Toxicity reference values for protecting aquatic birds in China from the effects of polychlorinated biphenyls

PCBs are typical of persistent, bioaccumulative and toxic compounds (PBTs) that are widely distributed in the environment and can biomagnify through aquatic food webs, because of their stability and lipophilic properties. Fish-eating birds are top predators in the aquatic food chain and may suffer adverse effects from exposure to PCB concentrations. In this review, we address the toxicity of PCBs to birds and have derived tissue residue guidelines (TRGs) and toxic reference values (TRVs) for PCBs for protecting birds in China. In deriving these protective indices, we utilized available data and three approaches, to wit: species sensitivity distribution (SSD), critical study approach (CSA) and toxicity percentile rank method (TPRM). The TRGs and TRVs arrived at by using these methods were 42.3, I 0. 7, 4.3 pg TEQs/g diet wm and 16.7, 15.5, and 5.5 pg TEQs/g tissue wm for the CSA SSD and TPRM approaches, respectively. These criteria values were analyzed and compared with those derived by others. The following TRG and TRY, derived by SSD, were recommended as avian criteria for protecting avian species in China: 10.7 pg TEQs/g diet wm and 15.5 pg TEQs/g tissue wm, respectively. The hazard of PCBs to birds was assessed by comparing the TRVs and TRGs derived in this study with actual PCB concentrations detected in birds or fish. The criteria values derived in this study can be used to evaluate the risk of PCBs to birds in China, and to provide indices that are more reasonable for protecting Chinese avian species. However, several sources of uncertainty exists when deriving TRGs and TRVs for the PCBs in birds, such as lack of adequate toxicity data for birds and need to use uncertainty factors. Clearly, relevant work on PCBs and birds in China are needed in the future. For example, PCB toxicity data for resident avian species in China are needed. In addition, studies are needed on the actual PCB levels in birds and fish in China. Such information is needed to serve as a more firm foundation for future risk assessments.

Relationships between persistent organic pollutants and circulating immunoglobulin-Y in black-legged kittiwakes and Atlantic puffins

Have Although persistent organic pollutants (POPs) may affect the immune system, few field studies actually examined this effect. There are indications that POP exert effects on the immune system; however, in the Arctic ecosystem data are scarce. The aim of this study was to examine immune functions in two medium trophic-positioned seabirds, the black-legged kittiwakes (Rissa tridactyla) and Atlantic puffins (Fratercula arctica). Overall POP concentrations were higher in kittiwakes than puffins and males had significantly higher concentrations than females. Mean concentrations of total polychlorinated biphenyls (ΣPCB9) were 4700 ± 200 and 9600 ± 1400 ng/g lipid weight and 2800 ± 180 and 3900 ± 200 ng/g lipid weight in female and male kittiwake and puffin blood, respectively. Levels of immunoglobulin-Y (IgY) in blood of kittiwakes were not markedly affected by concentrations of POP. Similarly, the primary IgY response to tetanus toxoid was not affected by POP concentrations in a subsample of immunized kittiwakes. In puffins, there were significant correlations between the IgY-response and some of the POPs, but with low explanatory values. These results suggest that POPs concentrations were lower than, or just at the threshold level for effects of the proposed IgY biomarker. It is also conceivable that the IgY levels are not a suitable endpoint for evaluating perturbation of the immune system in free-living seabirds.

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

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

Effects of an environmentally relevant polychlorinated biphenyl (PCB) mixture on embryonic survival and cardiac development in the domestic chicken

A 58-congener polychlorinated biphenyl (PCB) mixture based on contaminant analysis of spotted sandpiper eggs collected along the upper Hudson River, New York, USA, in 2004 was used to study in ovo PCB effects on cardiac development in the domestic chicken. Fertile eggs were injected prior to incubation with the following doses of the PCB mixture: untreated, sham, 0, 0.03, 0.08, 0.3, 0.5, 0.7, and 2.06 µg PCBs/g egg weight (toxic equivalent quotient [TEQ] range of 0.004-0.266 ng/g). In addition, there were untreated and sham-control groups. Embryonic development was monitored throughout incubation and chicks were necropsied at hatch. Hatchability followed a dose-dependent curve with significant (p < 0.05) mortality above the 0.5 µg PCBs/g egg weight treatment compared with controls. The median lethal dose (LD50) of this PCB mixture in hatchling chicks was estimated as 0.4 µg/g egg weight (0.052 ng TEQ/g egg wt) based on the lethality curve. Cardiac arrhythmia was observed at embryonic day 14 of development in embryos treated at concentrations of 0.5 µg/g egg weight and above. Histological analysis was utilized to characterize any cardiac abnormalities. Cardiomyopathies increased across treatments in a dose-dependent manner compared with control groups. Identified abnormalities included the absence of the trabeculated layer of the ventricular wall, ventricular dilation, thinning of the ventricular walls, malformation of the septal wall, and most commonly, absence of the compact layer of the ventricular wall. Chick heart width, depth, total area, compact layer depth, septal width, chamber area, and ventricular wall dimensions did not differ across treatments. The present study supports prior reports of adverse developmental effects of PCBs on cardiovascular systems in birds. Although the eggs hatched, measured cardiomyopathies suggest potential deleterious long-term impacts on individual health and fitness.

Predictors of adipose tissue concentrations of organochlorine pesticides in a general Danish population

Organochlorine pesticides are ubiquitously present in the environment and suspected of carcinogenic, neurological and immunological effects. Our objective was to identify determinants of adipose tissue levels of organochlorine pesticides experienced by a general Danish population. Adipose tissue was collected upon enrolment of 245 randomly selected persons from a prospective cohort of 57,053 persons enrolled between 1993 and 1997. We examined geography, gender, age, lactation, body mass index (BMI) and intake of nine dietary groups and tap water drinks, as potential determinants of dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene, hexachlorocyclohexane, dieldrin, hexachlorobenzene, cis-nonachlor, trans-nonachlor and oxychlordane. Living in Copenhagen city and age at enrolment showed positive associations with all compounds. BMI was positively associated with all compounds except cis-nonachlor. Fatty-fish consumption showed positive associations with cis-nonachlor, trans-nonachlor, DDT and dieldrin and fruit and vegetables were inversely associated with dieldrin. Determinant estimates of trans-nonachlor were similar to estimates of total chlordanes while cis-nonachlor and oxychlordane seemed to differ. This is one of the first studies of organochlorine pesticides predictors in adipose tissue and contributes to the ongoing debate about exposure sources of these compounds. Single determinants varied among the individual compounds, even within related chlordane residues, suggesting that organochlorine pesticides should not be treated as a homogenous group.

Early life environment and developmental immunotoxicity in inflammatory dysfunction and disease

Components of the innate immune system such as macrophages and dendritic cells are instrumental in determining the fate of immune responses and are, also, among the most sensitive targets of early life environmental alterations including developmental immunotoxicity (DIT). DIT can impede innate immune cell maturation, disrupt tissue microenvironment, alter immune responses to infectious challenges, and disrupt regulatory responses. Dysregulation of inflammation, such as that observed with DIT, has been linked with an increased risk of chronic inflammatory diseases in both children and adults. In this review, we discuss the relationship between early-life risk factors for innate immune modulation and promotion of dysregulated inflammation associated with chronic inflammatory disease. The health risks from DIT-associated inflammation may extend beyond primary immune dysfunction to include an elevated risk of several later-life, inflammatory-mediated diseases that target a wide range of physiological systems and organs. For this reason, determination of innate immune status should be an integral part of drug and chemical safety evaluation.

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.

Embryo toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to the wood duck (Aix sponsa)

We examined the sensitivity of the wood duck (Aix sponsa) embryo to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by injecting the toxicant into their eggs. Six groups of wood duck eggs (n = 35 to 211 per trial) were injected with 0 to 4600 pg TCDD/g egg between 2003 and 2005. Injections were made into yolk prior to incubation, and eggs were subsequently incubated and assessed weekly for mortality. Significant TCDD-induced mortality was not observed through day 25 (90% of incubation). Liver, heart, eye, and brain histology were generally unremarkable. Hepatic ethoxyresorufin-O-deethylase activity, a biomarker of dioxin-like compound exposure, was induced by 12-fold in the 4600 pg/g treatment relative to controls. The median lethal dose for chicken (Gallus domesticus) eggs we dosed identically to wood duck eggs was about 100 pg/g, similar to other assessments of chickens. Among dioxin-like compound embryo lethality data for 15 avian genera, the wood duck 4600 pg/g no-observed-effect level ranks near the middle. Because no higher doses were tested, wood ducks may be like other waterfowl (order Anseriformes), which are comparatively tolerant to embryo mortality from polychlorinated dibenzo-p-dioxins and dibenzofurans when exposed by egg injection.

Effect of In Ovo exposure to an organochlorine mixture extracted from double crested cormorant eggs (Phalacrocorax auritus) and PCB 126 on immune function of juvenile chickens

Organochlorine (OC) contaminants including polychlorinated biphenyls (PCBs) and p, p'-dichlorodiphenyldichloroethylene (DDE) have been associated with immune modulation in wild fish-eating birds from the Great Lakes. The objective of this study was to evaluate the immune function of juvenile chickens after in ovo exposure to PCB 126 or an environmentally relevant OC mixture extracted from eggs of double crested cormorants (Phalacrocorax auritus) from Green Bay, Lake Michigan, USA. Fertile white leghorn chicken (Gallus domesticus) eggs were injected before incubation with 0.55-1.79 ng TCDD equivalents (TEQ)/egg PCB 126 and 1.2-4.9 ng TEQs/egg of cormorant egg extract into the air cell in two separate experiments. After hatching, the immune function was tested using in vivo phytohemagglutinin (PHA) skin response in 11-day-old chicks, antibody titers to immunization with sheep red blood cells (SRBC) in 28-day-old chicks, and, at necropsy, thymus and bursal mass and cellularity. PCB 126 decreased antibody titers at all doses and decreased the thymus and bursa index but not cellularity at 1.79 ng TEQ/egg. The cormorant egg extract caused no significant alterations in immune function even though it has been demonstrated as immunotoxic in chicken embryos. However, twofold to threefold increases in total anti-SRBC titers in 28-day-old chicks exposed to 1.2 or 2.4 ng TEQ/egg of cormorant extract were similar to elevations in anti-SRBC titer observed in Caspian tern (Sterna caspia) chicks from a highly OC-contaminated site in Saginaw Bay, Lake Huron. Posthatch exposure to OC through fish consumption in addition to in ovo OC exposure might be associated with the immune modulation reported in wild birds. Chicks in this study might have begun to compensate for embryonic immunotoxicity by the ages at which we studied them.