Approaches to detecting immunotoxic effects of environmental contaminants in humans

Perfluoroalkyl substances and immune cell counts in adults from the Mid-Ohio Valley (USA)

BACKGROUND

Although perfluoroalkyl substances (PFASs) may be immunotoxic, evidence for this in humans is scarce. We studied the association between 4 PFASs (perfluorohexane sulfonate [PFHxS], perfluorooctanoic acid [PFOA], perfluorooctane sulfonate [PFOS] and perfluorononanoic acid [PFNA]) and circulating levels of several types of immune cells.

METHODS

Serum PFASs and white blood cell types were measured in 42,782 (2005-2006) and 526 (2010) adults from an area with PFOA drinking water contamination in the Mid-Ohio Valley (USA). Additionally, the major lymphocyte subsets were measured in 2010. Ln(cell counts) and percentages of cell counts were regressed on serum PFAS concentrations (ln or percentiles). Adjusted results were expressed as the percentage difference (95% CI) per interquartile range (IQR) increment of each PFAS concentration.

RESULTS

Generally positive monotonic associations between total lymphocytes and PFHxS, PFOA, and PFOS were found in both surveys (difference range: 1.12-7.33% for count and 0.36-1.77 for percentage, per PFAS IQR increment), and were stronger for PFHxS. These associations were reflected in lymphocyte subset counts but not percentages, with PFHxS positively and monotonically associated with T, B, and natural killer (NK) cell counts (range: 5.51-8.62%), PFOA and PFOS with some T-cell phenotypes, and PFOS with NK cells (range: 3.12-12.21%), the associations being monotonic in some cases. Neutrophils, particularly percentage (range: -1.74 to -0.36), showed decreasing trends associated with PFASs. Findings were less consistent for monocytes and eosinophils.

CONCLUSION

These results suggest an association between PFHxS and, less consistently, for PFOA and PFOS, and total lymphocytes (although the magnitudes of the differences were small). The increase in absolute lymphocyte count appeared to be evenly distributed across lymphocyte subsets since associations with their percentages were not significant.

Perfluoroalkyl substances exposure and immunity, allergic response, infection, and asthma in children: review of epidemiologic studies

Background

Increased exposure to perfluoroalkyl substances (PFAS) potentially affects infant and childhood health through immunosuppression. Given rapidly evolving research on PFAS, it is important to comprehensively examine the impact of PFAS exposure among the pediatric population as new research becomes available due to potential fragility of the developing immune system.

Objectives

This review assessed the effects of PFAS fetal, infant and childhood exposures upon the development of immune function during early life stages.

Methods

Researchers completed a literature review, searching PubMed for human studies published since 2010 for PFAS and health outcomes among infants and children. Included articles incorporated key search terms in the title or abstract; non-research reports and non-English papers were excluded. The search identified 518 studies for possible inclusion. Following hands-on review, 34 were determined relevant. Subsequent analyses found 8 additional relevant articles, totaling 42 studies.

Results

Major immune-related sequelae from PFAS exposures on infant and child health outcomes documented in recent literature include:

• Strong indication of immunosuppression, with diminished childhood antibody response to vaccination, particularly with PFOA, PFOS and PFHxS exposures.

• Some indication of increased risks of childhood infectious diseases/infections, particularly from PFOS exposures.

• Limited indication of an effect of PFAS exposure on allergic reactions/allergen specific IgE antibodies.

• Limited indication of an effect of PFAS exposure on atopic dermatitis (AD).

• Limited indication of an effect of PFAS exposure on asthma and lung function.

Conclusion

This review summarizes recent findings of PFAS effects on infant and childhood immune health. Evidence of immunosuppression, diminished vaccine efficacy, and increased risk of infections, allergies, asthma and AD were described following in utero, infant, and early childhood PFAS exposures. Further investigation is warranted to characterize PFAS exposure pathways and potential modes of action in relation to PFAS effects on the developing immune system. Incontrovertible proof of PFAS immunotoxic effects could optimally be obtained by a large prospective study cohort of mothers and children from infancy through school-age. Regular assessments of circulating antibodies and response to infant and childhood vaccines during growth years could prove invaluable.

•

This review summarizes findings of PFAS effects on infant and child immune health.

•

In utero, infant, and early childhood PFAS exposures were examined.

•

Strong evidence of PFAS exposure on diminished childhood antibody vaccination response.

•

Moderate evidence of PFAS exposure on increased risk of childhood infectious diseases.

•

Limited evidence of PFAS exposure on allergic reactions, atopic dermatitis, asthma.

Long-Term Immunological Alterations in Bottlenose Dolphin a Decade after the Deepwater Horizon Oil Spill in the Northern Gulf of Mexico: Potential for Multigenerational Effects

Health assessments were conducted on bottlenose dolphins in Barataria Bay, Louisiana, USA, during 2011 to 2018, to assess potential health effects following the Deepwater Horizon oil spill, compared to the unoiled Sarasota Bay, Florida, USA, reference dolphin population. We previously reported significant increases in T-lymphocyte proliferation, as well as lower T helper 1 (Th1) cytokines, higher Th2 cytokine IL-4, and lower T regulatory (Treg) cytokine IL-10 in Barataria Bay in 2011 compared to Sarasota Bay, consistent with Deepwater Horizon oil exposure. Although values between 2013 and 2016 were more similar to those observed in Sarasota Bay, T-cell proliferation was again elevated and cytokine balance tilted toward Th2 in Barataria Bay during 2017-2018. In 2018, Barataria Bay dolphins had significantly more circulating Treg cells than Sarasota Bay dolphins. Mice experimentally exposed to oil also had significantly increased T-lymphocyte proliferation and circulating Treg cell number, including effects in their unexposed progeny. In vitro stimulation resulted in greater Th2 responsiveness in Barataria Bay compared to Sarasota Bay dolphins, and in vitro oil exposure of Sarasota Bay dolphin cells also resulted in enhanced Th2 responsiveness. Evidence points to Treg cells as a potential target for the immunomodulatory effects of oil exposure. The immunological trends observed in Barataria Bay appeared exaggerated in dolphins born after the spill, suggesting the possibility of continued oil exposure or multigenerational health consequences of exposure to oil, as observed in mice. Environ Toxicol Chem 2021;40:1308-1321. © 2021 SETAC.

Effects of an environmentally relevant PCB-mixture on immune function, clinical chemistry, and thyroid hormone levels in adult female B6C3F1 mice

Polychlorinated biphenyls (PCBs) have been assessed for immunotoxicity; however, humans and wildlife are exposed to multiple PCBs environmentally. Therefore, the aim of this study was to examine the effects of a complex 37 PCB congener mixture identified in blubber specific to dolphins residing in the estuarine waters of Charleston, South Carolina. Immunotoxicity was determined in adult female B₆C₃F₁ mice by assessing lymphocyte proliferation, splenic and thymic immunophenotypes, and IgM production. Mice were exposed via oral gavage to the PCB-mixture (0, 1.8, 3.6, 7.1, or 14.3 mg/kg/day) for 28 days to yield a targeted total administered dose (TAD) 0, 50, 100, 200, or 400 mg/kg. Significant increased liver weight occurred at the highest treatment. IgM production was suppressed compared to control for all treatments. Numbers of thymic CD4+/CD8+, CD4-/CD8-, and CD4+/CD8- cells were not altered, but numbers of thymic CD4-/CD8+ cells were significantly increased in the highest treatment. Lymphocyte proliferation was not markedly affected by any treatment. The numbers of splenic CD4/CD8 T-cells or MHCII+ cells were not significantly changed. Humoral immunity using the plaque-forming cell assay for determining the specific IgM antibody-forming cell response appeared to be the most sensitive endpoint affected. As the lowest concentration tested resulted in decreased IgM production and total and free thyroxine (T₄) serum levels a NOAEL was not identified. The calculated ED₅₀ for suppression of IgM production was 2.4 mg/kg/day.

Pregabalin inhibits in vivo and in vitro cytokine secretion and attenuates spleen inflammation in Lipopolysaccharide/Concanavalin A -induced murine models of inflammation

Immune system alteration has been implicated in the pathogenesis of chronic pain conditions, epilepsy and generalized anxiety disorder. Targeting cytokines has recently been proposed for the management of such conditions. Pregabalin (PGB) is an antiepileptic agent used for the management of these conditions. However, little is known about its immunomodulatory effects on cytokine secretion in vivo and in vitro. Hence, a mitogen (Lipopolysaccharide [LPS] or Concanavalin A [ConA])-induced murine model of inflammation was used to investigate the effect of PGB on in vivo and in vitro IL-1β, IL-6, TNF-α and IL-2 cytokine secretion using ELISA. In addition, PGB effect on spleen histology, as a lymphoid organ, was examined. Our results revealed that PGB significantly inhibited the secretion of ConA-induced IL-6 secretion, basal and ConA-induced TNF-α and IL-2 secretion in splenocytes in vitro. In vivo, PGB inhibited basal and LPS/ConA-induced IL-6 and TNF-α secretion in addition to LPS-induced IL-1β and ConA-induced IL-2 secretion. Moreover, PGB attenuated mitogen-induced inflammatory changes in the spleen. These findings provide an evidence of the anti-inflammatory properties of PGB on cytokine secretion and lymphoid organ inflammation. This might give insights into the role of PGB in the management of the inflammatory state in PGB-indicated conditions.

Immunotoxicity testing using human primary leukocytes: An adjunct approach for the evaluation of human risk

Historically, immunotoxicity testing for chemicals, pesticides and pharmaceuticals has relied heavily on animal models to identify effects on the immune system followed by extrapolation to humans. Substantial progress has been made in the past decade on understanding human immune cell regulation, adaptive and innate immune responses and its modulation. The human immune system is complex and there exists diversity within composition, localization, and activation of different immune cell types between individuals. The inherent variation in human populations owing to genetics and environment can have a significant influence on the response of the immune system to infectious agents, drugs, chemicals and other environmental factors. Several recent reports have highlighted that mouse models of sepsis and inflammation are poorly predictive of human disease physiology and pathology. Rodent and human immune cells differ in the expression of cell surface proteins and phenotypes expressed in disease models, which may significantly influence the mechanism of action of xenobiotics and susceptibility yielding a different profile of activity across animal species. In the light of these differences and recent trends toward precision medicine, personalized therapies and the 3Rs (reduce, replace and refine animal use) approaches, the importance of using 'all human' model systems cannot be overstated. Hence, this opinion piece aims to discuss new models used to assess the effects of environmental contaminants and immune modulators on the immune response in human cells, the advantages and challenges of using human primary cells in immunotoxicology research and the implication for the future of immunotoxicity testing.

Investigative Immunotoxicology

Immunotoxicology is the study of immune system dysfunction that can result from occupational, inadvertent, or therapeutic exposure to a variety of chemical or biologic agents that alter the immune system and affect human health. Immunotoxicology can manifest in a variety of ways, with one of the most prominent effects being immunosuppression. Immunosuppression can be defined as a reduced ability of the immune system to respond to a challenge from a level considered normal, regardless of whether clinical disease results. Although immunosuppression can lead to an increased incidence and severity of infectious and neoplastic disease, interpreting data from experimental immunotoxicology studies, or even epidemiologic studies, for quantitative risk assessment has been a persistent challenge. Decades of research has resulted in the development of specific assays and the identification of sensitive endpoints that measure effects on the immune response, from which many regulatory agencies have developed specific immunotoxicity testing guidelines. However, establishing a direct link between exposure and disease manifestations for immunosuppression in humans is an ongoing challenge due to inherent limitations of epidemiological studies to draw causal conclusions. Efforts have been made to examine the relationships between laboratory measures of immune response and disease resistance in experimental animal models and also in human studies. The identification of sensitive endpoints and the development of experimental assays to identify suspect immunotoxicants are a primary focus of the field of immunotoxicology. This chapter is organized around sections discussing the impact and scientific basis of immunotoxicity testing, predictive immunotoxicity testing strategies, examples of immunotoxicity testing, and key considerations and recent developments related to effective testing strategies for health risk reduction.

Children's white blood cell counts in relation to developmental exposures to methylmercury and persistent organic pollutants

BACKGROUND

To explore possible markers of developmental immunotoxicity, we prospectively examined 56 children to determine associations between exposures to methylmercury and persistent organic pollutants since birth and the comprehensive differential counts of white blood cells (WBC) at age 5 years.

MATERIALS AND METHODS

Extended differential count included: neutrophils, eosinophils, basophils, lymphocytes (includingT cells, NK cells, and B cells), and monocytes. Organochlorine compounds (OCs) including polychlorinated biphenyls (PCBs) and pesticides, five perfluoroalkyl substances (PFASs), and total mercury (Hg) were measured in maternal (n=56) and children's blood at 18 months (n=42) and 5 years (n=54). We constructed latent functions for exposures at three different ages using factor analyses and applied structural equation models adjusted for covariates.

RESULTS

Prenatal mercury exposure was associated with depleted total WBC, especially for lymphocytes, where a one standard deviation (SD) increase in the exposure was associated with a decrease by 23% SD (95% CI: -43, -4) in the cell count. Prenatal exposure to OCs was marginally associated with decreases in neutrophil counts. In contrast, the 5-year PFASs concentrations were associated with higher basophil counts (B=46% SD, 95% CI: 13, 79). Significantly reduced subpopulations of lymphocytes such as B cells, CD4-positive T helper cells and CD4 positive recent thymic emigrants may suggest cellular immunity effects and dysregulation of T-cell mediated immunity.

CONCLUSION

Developmental exposure to environmental immunotoxicants appears to have different impacts on WBC counts in childhood.

Immunotoxicity of commercial-mixed glyphosate in broad snouted caiman (Caiman latirostris)

The expansion and intensification of agriculture during the past 50 years is unprecedented, and thus environmental problems have been triggered at different scales. These transformations have caused the loss of habitat and biodiversity, and disruption of the structure and functioning of ecosystems. As a result of the expansion of the agricultural frontier in the recent past, many areas of the natural geographic distribution of the local wildlife, among them crocodilians and particularly the broad snouted caiman (Caiman latirostris), are being exposed to contaminants. The present study was designed to evaluate the effect of commercially-mixed glyphosate (RU) on some parameters of the immune system of C. latirostris. Two groups of caimans were exposed for two months to different concentrations of RU recommended for its application in the field, while one group was maintained as an unexposed control. The RU concentration was progressively decreased through the exposure period to simulate glyphosate degradation in water. After exposure, total and differential white blood cell (WBC), and complement system activity (CS) were determined. In addition, the animals were injected with a solution of lipopolysaccharide (LPS) from Escherichia coli to trigger an immune response and evaluate the parameters associated with it. The results showed that an effect of the herbicide on CS was observed, as animals exposed to RU showed a lower CS activity than animals from the negative control (NC) but not in total WBC. In the case of leukocyte population counts, differences were only found for heterophils and lymphocytes.

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.

Potential effects of polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) on immune cells and blood biochemistry measures: a cross-sectional assessment of the NHANES 2003-2004 data

BACKGROUND

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are widely distributed in the environment and may have adverse effects on the immune system.

METHODS

Lipid adjusted serum levels of 19 Dioxin Like (DL), 17 Non Dioxin Like (NDL) PCBs, 5 OCPs, and measures of complete blood count and routine biochemistry profile were obtained from the NHANES 2003-2004 cycle. For each of the PCB/OCP variables, individuals were put into four exposure groups and blood markers were compared across these groups.

RESULTS

Serum levels of PCBs and OCPs increased with age. Total white blood cell (WBC) count, red blood cells (RBC), hemoglobin, and hematocrit measures were lowest in the group with the highest serum PCBs. Results for the OCPs varied. For Mirex, WBC declined in the highest exposure; no significant differences were observed for p-p'-DDT or p-p'-DDE; and higher levels of WBC were observed at the highest exposure groups of serum trans-nonachlor and oxychlordane. Liver enzymes (AST, ALT, and GGT) were significantly higher in the highest exposure groups of PCBs/OCPs.

CONCLUSIONS

We observed significant associations between PCB/OCP levels and blood markers in the general population. All of the levels were within normal ranges but the consistency of results is remarkable and may reflect subclinical effects. Largest differences were observed for NDL PCBs. Thus, routine application of toxic equivalency factors, which assume dioxin like mechanisms and aryl hydrocarbon receptor involvement, may not adequately reflect the effects of NDL PCBs in the mixture.

Prenatal exposure to bisphenol A and phthalates and childhood respiratory tract infections and allergy

BACKGROUND

There is growing concern that prenatal exposure to bisphenol A (BPA) and phthalates, which are widely used in consumer products, might affect susceptibility to infections and the development of allergy and asthma in children, but there are currently very few prospective studies.

OBJECTIVE

We sought to evaluate whether prenatal exposure to BPA and phthalates increases the risk of respiratory and allergic outcomes in children at various ages from birth to 7 years.

METHODS

We measured BPA and metabolites of high-molecular-weight phthalates, 4 di-(2-ethylhexyl) phthalate (DEHP) metabolites (Σ4DEHP) and mono-benzyl phthalate (MBzP), and 3 low-molecular-weight phthalate (LMWP) metabolites (Σ3LMWP) in urine samples collected during the first and third trimesters in pregnant women participating in the Infancia y Medio Ambiente-Sabadell birth cohort study. The occurrence of chest infections, bronchitis, wheeze, and eczema in children was assessed at ages 6 and 14 months and 4 and 7 years through questionnaires given to the mothers. Atopy (specific IgE measurement) and asthma (questionnaire) were assessed at ages 4 and 7 years, respectively.

RESULTS

The relative risks (RRs) of wheeze (RR, 1.20; 95% CI, 1.03-1.40; P = .02), chest infections (RR, 1.15; 95% CI, 1.00-1.32; P = .05), and bronchitis (RR, 1.18; 95% CI, 1.01-1.37; P = .04) at any age increased for each doubling in concentration of maternal urinary BPA. Σ4DEHP metabolites were associated with the same outcomes (wheeze: RR, 1.25; 95% CI, 1.04-1.50, P = .02; chest infections: RR, 1.15; 95% CI, 0.97-1.35; P = .11; bronchitis: RR, 1.20; 95% CI, 1.01-1.43; P = .04). MBzP was associated with higher risk of wheeze (RR, 1.15; 95% CI, 1.00-1.33; P = .05). The risk of asthma at age 7 years was also increased with increasing prenatal BPA, Σ4DEHP, and MBzP exposure. There were no other exposure-outcome associations.

CONCLUSIONS

Prenatal exposure to BPA and high-molecular-weight phthalates might increase the risk of asthma symptoms and respiratory tract infections throughout childhood.

Persistent organic pollutants and children's respiratory health: the role of cytokines and inflammatory biomarkers

Evidence of adverse effects of persistent organic pollutants (POPs) on the developmental respiratory and immune systems in children is still limited, and the biological mechanisms behind such effects are not fully understood. The aim of the present study is to evaluate the effects of prenatal DDE, HCB and ΣPCB exposure on children's respiratory health from birth to 14 years and to evaluate the role of immune biomarkers in these associations. We measured prenatal DDE, HCB and ΣPCB levels in 405 participants of the INMA-Menorca birth cohort (Spain) and collected information on wheeze, chest infections, atopy and asthma from birth until the age of 14 years. At age 4 years, 275 children provided serum samples and IL6, IL8, IL10, TNFα and C-reactive protein were measured. We applied linear and logistic regression models and generalized estimating equations. Prenatal DDE was associated with wheeze at age 4 years [RR (95% CI) per doubling of concentration=1.35 (1.07, 1.71)], but not thereafter. Prenatal HCB was associated with wheeze [1.58 (1.04, 2.41)] and chest infections [1.89 (1.10, 3.25)] at age 10years. No associations were found with ΣPCBs. IL10 levels increased with increasing POP concentration, with HCB showing the strongest association [β (95% CI)=0.22 (0.02, 0.41)]. IL8, IL10 and TNFα were associated with wheeze and/or chest infections and IL10 was associated with asthma. Prenatal DDE and HCB exposure was associated with respiratory health of children at different ages. This study further suggests a possible role of IL10, but not of the other immune biomarkers examined, as an early marker of chronic immune-related health effects of POPs.

Effects of β-glucan on some environmental toxins: An overview

BACKGROUND

Beta-glucans are naturally occurring polysaccharides and constituents of the cell wall of certain pathogenic bacteria and fungi. They have proven healing and immunostimulating properties, linked to enhanced macrophage and natural killer cell function which likely involves specific interaction with several cell surface receptors, such as lactosylceramide, selected scavenger receptors, and dectin-1 (betaGR). In particular, glucan reduces the immunosuppressive effects of a number of agents including chemo therapy and radiation. More recent studies suggest a positive function for glucan in the immunosuppression caused by toxic agents in the environment.

AIM

An overview of the effects of glucan on the mycotoxin, aflotoxin and other environmental toxins (mercury-thimerosal, depleted uranium).

CONCLUSION

Glucan is effective as a natural immunomodulator and could be used as an inexpensive solution to reducing the adverse effects of some environmental toxins.

Glucan–resveratrol–vitamin C combination offers protection against toxic agents

Biological immunomodulators are routinely evaluated as a natural source of molecules with profound effects on the immune system. They belong to a group of physiologically active compounds, collectively termed biological response modifiers. Most of the studies were focused on immune system stimulation. Recently, they have become the focus of studies seeking molecules that are able to overcome negative effects of various immunotoxins. This paper concentrates on the effects of a glucan/resveratrol/vitamin C combination on immunosuppressive effects of mercury and perfluorinated hydrocarbons. Effects described in this review have strong clinical potential, as environmental contaminants have adverse effects on all aspects of the immune system and represent a serious threat to the health of both humans and animals.

The kinetics of cell surface receptor expression in children perinatally exposed to polychlorinated biphenyls

Exposure to polychlorinated biphenyls (PCBs) during pre-natal and early life can alter normal immune system development. Blood specimens from newborns, 6-, and 16-month-old infants were collected in the Michalovce and Svidnik/Stropkov districts, areas with, respectively, high and low environmental PCB contamination, and lymphocyte receptor expression was evaluated by multi-color flow cytometry. The results indicate that the percentage of lymphoid dendritic cells (DC) and naïve/resting T-lymphocytes were significantly increased at 6-months in Michalovce as compared to the same cell types in cord blood samples (p < 0.001), whereas natural regulatory T-lymphocytes and suppressor inducer T-lymphocytes were reduced (p < 0.001). Overall, a positive linear correlation of terminally differentiated effector memory (TEM) T-lymphocyte population with age, but a negative linear correlation for myeloid DC from birth to 6-months in both regions were found. Michalovce samples indicated significantly higher expression of memory T-lymphocytes (birth, 6(th), and 16(th) month), TEM T-lymphocytes (birth and 6(th) month), and lymphoid DC (6(th) month) compared to the Svidnik/Stropkov regions. After adjustment for relevant covariates, such as maternal age, parity, season of birth, breastfeeding, birth weight, and gender, the myeloid DC, suppressor inducer T-lymphocytes, truly naïve helper/inducer T-lymphocytes, and TEM T-lymphocytes remained significantly different between districts in cord blood samples. The multivariate analysis models for 6- and 16-month samples showed district differences in all cellular determinants, except for lymphoid DC and macrophage-like cells. This study provides the first evidence that pre-natal and early post-natal exposure to PCBs affects the dynamics of cell surface receptor expression on lymphoid DC and DC-like cells, suggesting impaired immunologic development following pre-natal and early post-natal PCB exposure.

Analysis of the toxicogenomic effects of exposure to persistent organic pollutants (POPs) in Slovakian girls: correlations between gene expression and disease risk

The chemical composition of persistent organic pollutants (POPs) in the environment is not uniform throughout the world, and these contaminants contain many structurally different lipophilic compounds. In a well-defined study cohort in the Slovak Republic, the POP chemicals present in the peripheral blood of exposed children were chemically analyzed. The chemical analysis data revealed that the relative concentration and profile of structurally different organic pollutants, including polychlorinated biphenyls (PCBs), 2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), 2,2'-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (p,p'-DDT), hexachlorobenzene (HCB) and β-hexachlorocyclohexane (β-HCH), may vary from individual to individual, even within the same exposure area. These chemicals can be broadly classified into two groups. The first group, the PCB congeners, primarily originated from industrial compounds and their byproducts. The second group of compounds originated from or was commonly used in the agricultural sector (e.g., DDT, HCB). The objective of this study was to examine the effects of the two POP exposure profiles on gene expression. For the study population, we selected pre-pubertal girls (mean age of 46.2±1.4 months) with high POP concentrations in their blood (>75% tile of total POP) and classified them in the high 'PCB' group when the total PCB concentration was significantly higher than the total concentration of other POP components and in the 'Other Than PCB' (OTP) group, when the total PCB concentration was significantly lower than the concentration of the other major POP constituents. A matched control group of girls (<25% tile of total POP) was selected for comparison purpose (n=5 per group). Our aims were to determine whether there were any common effects of high POP exposure at a toxicogenomic level and to investigate how exposure may affect physiological functions of the children in two different exposure scenarios. Global gene expression analysis using a microarray (Affymetrix Gene Chip Human genome U133 Plus 2.0 Array) platform was conducted on the total RNA of peripheral blood mononuclear cells from the girls. The results were analyzed by Partek GS, Louis, MI, which identified twelve genes (ATAD2B, BIVM, CD96, CXorf39, CYTH1 ETNK1, FAM13A, HIRA, INO80B, ODG1, RAD23B, and TSGA14) and two unidentified probe sets, as regulated differentially in both the PCB and OTP groups against the control group. The qRT-PCR method was used to validate the microarray results. The Ingenuity Pathway Analysis (IPA) software package identified the possible molecular impairments and disease risks associated with each gene set. Connective tissue disorders, genetic disorders, skeletal muscular disorders and neurological diseases were associated with the 12 common genes. The data therefore identified the potential molecular effects of POP exposure on a genomic level. This report underscores the importance of further study to validate the results in a random population and to evaluate the use of the identified genes as biomarkers for POP exposure.

Sociodemographic, reproductive and dietary predictors of organochlorine compounds levels in pregnant women in Spain

Organochlorine pesticides and polychlorinated biphenyls (PCBs) are consistently found in human tissues. Serum levels of organochlorine compounds (OC) in pregnant women in particular have raised concern about possible harm to humans in the early phases of physical and behavioural development. The objective of the present study was to evaluate the association between concentration of OCs in serum of two cohorts of pregnant women from Gipuzkoa and Sabadell in Spain and socioeconomic, reproductive and dietary variables. Concentration of polychlorinated biphenyls (PCBs: 28, 52, 101, 118, 138, 153 and 180), hexachlorobenzene (HCB), beta and gamma-hexachlorocyclohexane (β-HCH and γ-HCH), heptachlor epoxide, dichlorodiphenyl dichloroethylene (p,p'-DDE) and dichlorodiphenyl trichloroethane (p,p'-DDT) were measured in the serum of 1259 pregnant women. Associations between OCs and potential predictor variables were assessed using linear regression models adjusted for potential confounders. The compounds most commonly found in the serum were p,p'-DDE (99% of the samples) and PCB-153 (95% of the samples). Geometric means of serum concentrations (ng g⁻¹ lipid) of organochlorine pesticides were 110.0, 19.1, and 33.5 for p,p'-DDE, β-HCH, and HCB respectively, while the geometric means of PCBs were 21.8, 38.9 and 26.9 for PCB 138, 153, and 180 respectively. The levels of all OCs increased with age. BMI was positively associated with the concentration of organochlorine pesticides but inversely related to PCB concentrations. The serum levels of OCs fell only after a cumulative period of breastfeeding of over a year. Levels of PCBs were related to fish intake, but in general dietary factors did not improve the explained variability of the concentrations of OCs. Overall, the levels of OCs found in the study are at the lower end of the range reported in Spain and other countries.

Asthma and infectious respiratory disease in children--correlation to residence near hazardous waste sites

Rates of hospitalization for asthma and respiratory infectious disease in children were modeled as a function of residence: (1) in a zip code containing a hazardous waste site with persistent organic pollutants ('POPs'); (2) in a zip code with a waste site that did not contain POPs ('other'); or (3) in a zip code without any identified waste site ('clean'), as well as other demographic covariates. After adjustment, living in a zip code containing a POPs waste site significantly increased the frequency of hospitalization for asthma and infectious respiratory disease. Living in a zip code with an 'other' waste site also increased hospitalization frequencies for both diseases. The association was strongest for zip codes whose residents were in the lowest quartile of medium family income. This evidence supports the hypothesis that living near a hazardous waste site increases risk of respiratory disease in children.

Alterations of human immune system functions in relation to environmental contamination, gender and alcohol consumption intensity

Environmental contamination and use of alcohol may be a cause of immune system disturbances and various diseases. The aim of this study was to evaluate changes of different alcohol consumption intensity on the immune condition of women and men living in a district contaminated with industrial siftings (Trakai) and in a relatively clean district (Sirvintos). The immune system parameters were investigated in 282 Trakai district inhabitants (127 males and 155 females) and in 282 Sirvintos district inhabitants (129 males and 153 females). Due to gender and alcohol consumption intensity the immune system functions were evaluated in the following groups: abstainers, light alcohol users, moderate alcohol users and alcohol abusers. Absolute number of CD5+, CD4+, concentration of IgA in blood serum and some other investigated indices of light alcohol users were significantly increased in the male group of Trakai district in comparison with females of this district. However, in the same group of light alcohol drinkers of Sirvintos district, males had lower indices (CD5+, CD4+, CD4+/CD8+, IgM) than females. Immune system parameters of males who were light and moderate alcohol users in Trakai district were stimulated in comparison with the same alcohol consumption groups of males in Sirvintos district. Our investigations showed that combination of environmental pollution and different intensity of alcohol consumption cause various alterations of immune system functions in males and females.

Determinants of serum concentrations of organochlorine compounds in Swedish pregnant women: a cross-sectional study

BACKGROUND

We performed a cross-sectional study of associations between personal characteristics and lipid-adjusted serum concentrations of certain PCB congeners and chlorinated pesticides/metabolites among 323 pregnant primiparous women from Uppsala County (age 18-41 years) sampled 1996-1999.

METHODS

Extensive personal interviews and questionnaires about personal characteristics were performed both during and after pregnancy. Concentrations of organochlorine compounds in serum lipids in late pregnancy were analysed by gas chromatography. Associations between personal characteristics and serum levels of organochlorine compounds were analysed by multiple linear regression.

RESULTS

Participation rate was 82% (325 of 395 women). Serum concentrations of PCB congeners IUPAC no. 28, 52, 101, 105 and 167, and o, p'-DDT and -DDE, p, p'-DDT and -DDD, oxychlordane, and gamma- and alpha-HCH were in many cases below the limit of quantification (LOQ). No statistical analysis of associations with personal characteristics could be performed for these substances. Concentrations of PCB congeners IUPAC no. 118, 138, 153, 156 and 180, HCB, beta-HCH, trans-nonachlor and p, p'-DDE increased with increased age and were highest in women sampled early during the 4 year study period. This shows that older women and women sampled early in the study had experienced the highest life-time exposure levels, probably mainly during childhood and adolescence. The importance of early exposures was supported by lower PCB concentrations and higher beta-HCH and p, p'-DDE concentrations among women born in non-Nordic countries. Moreover, serum concentrations of certain PCBs and pesticide/metabolites were positively associated with consumption of fatty fish during adolescence, and concentrations of CB 156, CB 180 and p, p'-DDE increased significantly with number of months women had been breast-fed during infancy. Short-term changes in bodily constitution may, however, also influence serum concentrations, as suggested by negative associations between concentrations of organochlorine compounds and BMI before pregnancy and weight change during pregnancy.

CONCLUSION

Although some of the associations could be caused by unknown personal characteristics confounding the results, our findings suggest that exposures to organochlorine compounds during childhood and adolescence influence the body burdens of the compounds during pregnancy.

Lead and immune function

The heavy metal lead is a widely deposited environmental toxicant known to impact numerous physiological systems, including the reproductive, neurological, hepatic, renal, and immune systems. Studies illustrating the capacity of lead to impair immune function and/or host resistance to disease date back to at least the 1960s. However, it has only been in recent years that lead has been recognized among a new category of immunotoxicants-those that dramatically shift immune functional capacity while producing only modest changes to immune cell populations and lymphoid organs. These relatively noncytotoxic immunomodulating chemicals and drugs represent the immunotoxic hazards most difficult to identify and problematic for risk assessment using historic approaches. As a result, such environmental factors are also among the most likely to contribute to chronic immune-related disease at relevant exposure levels. This review considers the animal and human evidence that lead exposure can produce a stark shift in immune functional capacity with a skewing predicted to elevate the risk of atopic and certain autoimmune diseases. At the same time, host defenses against infectious agents and cancer may be reduced. Age-based exposure studies also suggest that levels of blood lead previously thought to be safe, that is, below 10 microg/dl, may be associated with later life immune alterations.

Evaluation of serum immunoglobulins among individuals living near six Superfund sites

Residents living in communities near Superfund sites have expressed concern that releases from these facilities affect their health, including adverse effects on their immune systems. We used data from six cross-sectional studies to evaluate whether people who live near several Superfund sites are more likely to have individual immunoglobulin test results (IgA, IgG, and IgM) below or above the reference range than those who live in comparison areas with no Superfund site. Study participants consisted of target-area residents who lived close to a Superfund site and comparison-area residents who were not located near any Superfund or hazardous waste sites. A consistent modeling strategy was used across studies to assess the magnitude of the relationship between area of residence and immunoglobulin test results, adjusting for potential confounders and effect modifiers. In all study areas, the results suggest that people who live near a Superfund site may have been more likely to have IgA test results above the reference range than comparison areas residents regardless of modeling strategy employed. The effect measures were larger for residents who lived in communities near military bases with groundwater contamination. For all analyses the wide confidence intervals reflect uncertainty in the magnitude of these effects. To adequately address the question of whether the immune system is affected by low-level exposures to hazardous substances, we recommend that more functional immunotoxicity tests be conducted in human populations where individual exposure information is available or when it can be reasonably estimated from environmental exposure measurements.

Associating changes in the immune system with clinical diseases for interpretation in risk assessment

This overview unit discusses the relationship between immunosuppression, a potential consequence of immunotoxicity, and disease progression. It also discusses other factors, such as stress and age, that affect disease susceptibility. These factors play an important role in risk assessment for exposures to environmental factors.

Discovery in toxicology: mediation by gene expression array technology

Toxicogenomics is a term that represents the merging of toxicology with novel genomics techniques. Data generated in the new-age era of toxicology is relatively complex, requires new bioinformatics tools for adequate interpretation, and allows for the rapid generation of testable hypotheses. Hazard identification and risk assessment processes will advance from the use of genomics techniques, which will lead to greater understanding of mechanism(s) of action of toxicants, development of novel biomarkers of exposure and effect, and better identification of sensitive subpopulations.