Developmental immunotoxicology of lead

Associations of multiple metals exposure with immunoglobulin levels in pregnant women: Hangzhou Birth Cohort Study

Metal may affect maternal immune function, but few epidemiological studies have reported the associations between multiple-metal exposure and maternal immunoglobulin (Ig) levels. Based on the Hangzhou Birth Cohort Study, 1059 participants were included, and eleven metals in whole blood samples and serum IgA, IgG, IgE and IgM levels were measured. Linear regression, quantile-based g-computation (QGC), and Bayesian kernel machine regression (BKMR) models were used to evaluate the associations. Compared with the first tertile of metal levels, arsenic (As) was negatively associated with IgE (β = -0.25, 95% confidence interval (CI) = -0.48 to -0.02). Moreover, significant associations of manganese (Mn) with IgA, IgG and IgM were demonstrated (β = 0.10, 95% CI = 0.04 to 0.18; β = 0.07, 95% CI = 0.03 to 0.12; β = 0.10, 95% CI = 0.03 to 0.18, respectively). Cadmium (Cd) were associated with higher levels of IgM. QGC models showed the positive association of the metal mixtures with IgA and IgG, with Mn playing a major role. Mn and Cd had positive contributions to IgM, while As had negative contributions to IgE. In the BKMR models, the latent continuous outcomes of IgA and IgG showed a significant increase when all the metals were at their 60th percentile or above compared to those at their 50th percentile. Therefore, exposure to metals was associated with maternal Igs, and mainly showed that Mn was associated with increased levels of IgA, IgG and IgM, and As was associated with low IgE levels.

Guardians under Siege: Exploring Pollution's Effects on Human Immunity

Chemical pollution poses a significant threat to human health, with detrimental effects on various physiological systems, including the respiratory, cardiovascular, mental, and perinatal domains. While the impact of pollution on these systems has been extensively studied, the intricate relationship between chemical pollution and immunity remains a critical area of investigation. The focus of this study is to elucidate the relationship between chemical pollution and human immunity. To accomplish this task, this study presents a comprehensive review that encompasses in vitro, ex vivo, and in vivo studies, shedding light on the ways in which chemical pollution can modulate human immunity. Our aim is to unveil the complex mechanisms by which environmental contaminants compromise the delicate balance of the body's defense systems going beyond the well-established associations with defense systems and delving into the less-explored link between chemical exposure and various immune disorders, adding urgency to our understanding of the underlying mechanisms and their implications for public health.

An insight on the plausible biological and non-biological detoxification of heavy metals in tannery waste: A comprehensive review

A key challenge for the tannery industries is the volume of tannery waste water (TWW) generated during the processing of leather, releasing various forms of toxic heavy metals resulting in uncontrolled discharge of tannery waste (TW) into the environment leading to pollution. The pollutants in TW includes heavy metals such as chromium (Cr), cadmium (Cd), lead (Pb) etc, when discharged above the permissible limit causes ill effects on humans. Therefore, several researchers have reported the application of biological and non-biological methods for the removal of pollutants in TW. This review provides insights on the global scenario of tannery industries and the harmful effects of heavy metal generated by tannery industry on micro and macroorganisms of the various ecological niches. It also provides information on the process, advantages and disadvantages of non-biological methods such as electrochemical oxidation, advanced oxidation processes, photon assisted catalytic remediation, adsorption and membrane technology. The various biological methods emphasised includes strategies such as constructed wetland, vermitechnology, phytoremediation, bioaugmentation, quorum sensing and biofilm in the remediation of heavy metals from tannery wastewater (TWW) with special emphasize on chromium.

Toxic metals and pediatric clinical immune dysfunction: A systematic review of the epidemiological evidence

BACKGROUND

Children are at high risk for exposure to toxic metals and are vulnerable to their effects. Significant research has been conducted evaluating the role of these metals on immune dysfunction, characterized by biologic and clinical outcomes. However, there are inconsistencies in these studies. The objective of the present review is to critically evaluate the existing literature on the association between toxic metals (lead, mercury, arsenic, and cadmium) and pediatric immune dysfunction.

METHODS

Seven databases (PubMed (NLM), Embase (Elsevier), CINAHL (Ebsco), Web of Science (Clarivate Analytics), ProQuest Public Health Database, and ProQuest Environmental Science Collection) were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in February 2024. Rayaan software identified duplicates and screened by title and abstract in a blinded and independent review process. The remaining full texts were reviewed for content and summarized. Exclusions during the title, abstract, and full-text reviews included: 1) not original research, 2) not epidemiology, 3) did not include toxic metals, 4) did not examine an immune health outcome, or 5) not pediatric (>18 years). This systematic review protocol followed the PRISMA guidelines. Rayaan was used to screen records using title and abstract by two blinded and independent reviewers. This process was repeated for full-text article screening selection.

RESULTS

The search criteria produced 7906 search results; 2456 duplicate articles were removed across search engines. In the final review, 79 studies were included which evaluated the association between toxic metals and outcomes indicative of pediatric immune dysregulation.

CONCLUSIONS

The existing literature suggests an association between toxic metals and pediatric immune dysregulation. Given the imminent threat of infectious diseases demonstrated by the recent COVID-19 epidemic in addition to increases in allergic disease, understanding how ubiquitous exposure to these metals in early life can impact immune response, infection risk, and vaccine response is imperative.

Involvement of Nrf2 Signaling in Lead-induced Toxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) is used as one of the main protective factors against various pathological processes, as it regulates cells resistant to oxidation. Several studies have extensively explored the relationship between environmental exposure to heavy metals, particularly lead (Pb), and the development of various human diseases. These metals have been reported to be able to, directly and indirectly, induce the production of reactive oxygen species (ROS) and cause oxidative stress in various organs. Since Nrf2 signaling is important in maintaining redox status, it has a dual role depending on the specific biological context. On the one hand, Nrf2 provides a protective mechanism against metal-induced toxicity; on the other hand, it can induce metalinduced carcinogenesis upon prolonged exposure and activation. Therefore, the aim of this review was to summarize the latest knowledge on the functional interrelation between toxic metals, such as Pb and Nrf2 signaling.

The concentrations of essential/toxic elements in serum of COVID-19 patients are not directly related to the severity of the disease

BACKGROUND

In recent months, the current COVID-19 pandemic has generated thousands of studies directly or indirectly related with this disease and/or the coronavirus SARS-CoV-2 causing the infection. On August 22, 2022, the database PUBMED included 287,639 publications containing the term COVID-19. However, in spite of the importance of trace elements in human health, including the immune system, data on the levels of metals/metalloids in COVID-19 patients is very limited.

METHODS

The concentrations of As, Cd, Cr, Cu, Hg, Fe, Mg, Mn, Pb, Se, V and Zn were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in 126 serum samples of individuals infected with SARS-CoV-2, as well as in 88 samples of non-infected individuals. Participants were divided into four groups: i) individuals COVID-19 positive (COVID-19 +) with an asymptomatic infection course; ii) individuals suffering mild COVID-19; iii) individuals suffering severe COVID-19, and iv) individuals COVID-19 negative (COVID-19-) (control group). The occurrence of the analyzed metals/metalloids was evaluated along with the biochemical profile, including blood cell counts, lipids, proteins and crucial enzymes.

RESULTS

Serum levels of Mg, V, Cr, Cu, Cd, and Pb were higher in COVID-19 positive patients than those in the control group. Although no significant differences were observed between the different groups of patients, the concentrations of Cd, Pb, V and Zn showed a tendency to be higher in individuals with severe COVID-19 than in those showing mild symptoms or being asymptomatic. Arsenic and Hg were rarely detected, regardless if the subjects were infected by SARS-CoV-2, or not. The current results did not show significant differences in the levels of the rest of analyzed elements according to the severity of the disease (asymptomatic, mild and severe).

CONCLUSIONS

In spite of the results here obtained, we highlight the need to reduce the exposure to Cd, Pb and V to minimize the potential adverse health outcomes after COVID-19 infection. On the other hand, although a protective role of essential elements was not found, Mg and Cu concentrations were higher in severe COVID-19 patients than in non-infected individuals.

Prenatal exposure to multiple metallic and metalloid trace elements and the risk of bacterial sepsis in extremely low gestational age newborns: A prospective cohort study

BACKGROUND

Prenatal exposures to metallic and metalloid trace elements have been linked to altered immune function in animal studies, but few epidemiologic studies have investigated immunological effects in humans. We evaluated the risk of bacterial sepsis (an extreme immune response to bacterial infection) in relation to prenatal metal/metalloid exposures, individually and jointly, within a US-based cohort of infants born extremely preterm.

METHODS

We analyzed data from 269 participants in the US-based ELGAN cohort, which enrolled infants delivered at <28 weeks' gestation (2002-2004). Concentrations of 8 trace elements-including 4 non-essential and 4 essential-were measured using inductively coupled plasma tandem mass spectrometry in umbilical cord tissue, reflecting in utero fetal exposures. The infants were followed from birth to postnatal day 28 with bacterial blood culture results reported weekly to detect sepsis. Discrete-time hazard and quantile g-computation models were fit to estimate associations for individual trace elements and their mixtures with sepsis incidence.

RESULTS

Approximately 30% of the extremely preterm infants developed sepsis during the follow-up period (median follow-up: 2 weeks). After adjustment for potential confounders, no trace element was individually associated with sepsis risk. However, there was some evidence of a non-monotonic relationship for cadmium, with hazard ratios (HRs) for the second, third, and fourth (highest) quartiles being 1.13 (95% CI: 0.51-2.54), 1.94 (95% CI: 0.87-4.32), and 1.88 (95% CI: 0.90-3.93), respectively. The HRs for a quartile increase in concentrations of all 8 elements, all 4 non-essential elements, and all 4 essential elements were 0.92 (95% CI: 0.68-1.25), 1.19 (95% CI: 0.92-1.55), and 0.77 (95% CI: 0.57-1.06). Cadmium had the greatest positive contribution whereas arsenic, copper, and selenium had the greatest negative contributions to the mixture associations.

CONCLUSIONS

We found some evidence that greater prenatal exposure to cadmium was associated with an increased the risk of bacterial sepsis in extremely preterm infants. However, this risk was counteracted by a combination of arsenic, copper, and selenium. Future studies are needed to confirm these findings and to evaluate the potential for nutritional interventions to prevent sepsis in high-risk infants.

Association between occupational lead exposure and immunotoxicity markers: A systematic review and meta-analysis

Recent evidences suggest the role of chronic lead (Pb) exposure in altering immunological parameters. Present study aimed to systematically review existing literature and synthesize quantitative evidence on the association between chronic Pb exposure and changes in immunological markers. Observational studies reporting immunological markers such as leukocyte derivative counts (CD3⁺, CD4⁺, CD8⁺, CD45⁺, CD56⁺, lymphocyte, and total leukocyte), cytokine, Immunoglobulin (Igs), C-reactive protein (CRP) among Pb-exposed and unexposed controls were systematically searched from PubMed, Scopus and Embase digital databases from inception to January 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adhered during systematic review. Mean differences in the immunological markers between Pb-exposed and control groups were pooled using random-effects model. The heterogeneity was assessed using Cochran-Q test and I² statistic. The review included forty studies reporting immunological markers in Pb-exposed and unexposed control groups. The occupational Pb-exposed group exhibited significantly higher BLL, impaired immunological markers, characterized by a marginal lowering in lymphocyte count, lymphocyte subsets (CD3⁺, CD4⁺, CD4⁺/CD8⁺ ratio), IFN-γ and IgG levels, while CD8⁺, IgM, IgA, IgE, and cytokines (IL-4, IL-6, IL-10, and TNF-α) exhibited a trend of higher values in comparison to the control group. Further, inflammatory marker viz., total leukocyte count was significantly higher among Pb-exposed. The included studies exhibited high levels of heterogeneity. In conclusion, Occupational Pb exposure alters the immunological markers such as the circulating cytokines and leukocyte counts. However, high-quality, multicentered studies are required to strengthen present observations and further understand the Pb's role on the immune system. Prospero Registration ID: CRD42021228252.

Association between exposure to chemical mixtures in relation to serum total IgE among adults 19-86 years old

There is a scarcity of studies on the effects of mixed chemicals on total IgE. We aim to assess whether there is a link between chemical mixtures (blood and urine of 26 chemicals including lead, mercury, cadmium, t,t-muconic acid, benzylmercapturic acid , 1-hydroxypyrene, 2-naphthol, 2-hydroxyfluorene, 1-hydroxyphenanthrene, mono-(2-ethyl-5-hydroxyhexyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate, mono-n-butyl phthalate, mono-benzyl phthalate, mono-(2-ethyl-5-carboxypentyl) phthalate, mono-carboxyoctyl phthalate, mono-carboxy-isononly phthalate, mono (3-carboxypropyl) phthalate, bisphenol A, bisphenol F, bisphenol S, triclosan, methylparaben, ethylparaben, propylparaben, 3-phenoxybenzoic acid, and cotinine), and total IgE in 3,642 Korean adults aged ≥ 19. The effects of mixed chemical exposure on total IgE were identified using linear regression models, weighted quantile sum (WQS) regression, quantile g-computation (qgcomp), and Bayesian kernel machine regression (BKMR). The most relevant factors linked with IgE, according to the linear regression models, were blood or urine mercury and urine bisphenol A levels, with significant trends detected for these chemical tertiles (p < 0.01). The WQS index was significantly linked with ln2-transformed levels of serum total IgE (β = 0.30, 95 %CI 0.25-0.32). The qgcomp index also found a significant link between chemicals and ln2-transformed levels of serum total IgE (β = 0.52, 95 %CI 0.21-0.82), and elevated serum total IgE levels (OR = 2.55, 95 %CI 1.14-5.71). In BKMR analysis, the overall effect of the mixture was significantly associated with ln2-transformed levels of serum total IgE. The cutoff levels for exposure levels related to serum total IgE levels/elevated serum total IgE levels were reported. We discovered that whole-body exposure to 26 chemicals was associated with serum total IgE levels after assessing the findings of these four models. More research is needed in the future to gain a better understanding of the impact of mixed chemical exposure on allergic disorders and how to minimize chemical exposure, especially for people under the age of 18.

Effect of occupational co-exposure to lead and cadmium on selected immunomodulatory cytokines

Occupational exposure to heavy metals like lead (Pb) and cadmium (Cd) is associated with the development of several diseases. The objective of this study was to determine the effect of occupational co-exposure to Pb and Cd on the blood levels of selected immune-modulatory cytokines related to T helper (Th), that is, Th1, interleukin-2 (IL-2), Th2, (IL-4 and IL-10), and Th17, (IL-17) cells. The study comprised 207 individuals divided into two groups: exposed (n = 110) and nonexposed (n = 97). Blood Pb and Cd were determined using Graphite Furnace Atomic Absorption Spectroscopy, and serum levels of cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The study revealed significantly higher blood Pb and Cd levels in the exposed group. A significant decrease in Th1 cytokine-IL-2 and Th2 cytokine-IL-10 was found, while IL-4 (Th2 cytokine) and IL-17 (Th17) levels were higher in the exposed group. In the mixed exposure analysis, among all the selected cytokines, IL-4 levels were significantly different between individuals having higher levels of both Pb and Cd versus lower levels of Pb and Cd. While IL-2 levels were highest among the low Pb and Cd group, the IL-17 levels were highest among individuals with higher Cd levels. The study demonstrated that co-exposure to low levels of Pb and Cd might have an immune-modulatory effect. The data suggested a metal-induced pro-inflammatory immune response.

Environmental Air Pollutants Inhaled during Pregnancy Are Associated with Altered Cord Blood Immune Cell Profiles

Air pollution exposure during pregnancy may be a risk factor for altered immune maturation in the offspring. We investigated the association between ambient air pollutants during pregnancy and cell populations in cord blood from babies born to mothers with asthma enrolled in the Breathing for Life Trial. For each patient (n = 91), daily mean ambient air pollutant levels were extracted during their entire pregnancy for sulfur dioxide (SO₂), nitric oxide, nitrogen dioxide, carbon monoxide, ozone, particulate matter <10 μm (PM₁₀) or <2.5 μm (PM_2.5), humidity, and temperature. Ninety-one cord blood samples were collected, stained, and assessed using fluorescence-activated cell sorting (FACS). Principal Component (PC) analyses of both air pollutants and cell types with linear regression were employed to define associations. Considering risk factors and correlations between PCs, only one PC from air pollutants and two from cell types were statistically significant. PCs from air pollutants were characterized by higher PM_2.5 and lower SO₂ levels. PCs from cell types were characterized by high numbers of CD8 T cells, low numbers of CD4 T cells, and by high numbers of plasmacytoid dendritic cells (pDC) and low numbers of myeloid DCs (mDCs). PM_2.5 levels during pregnancy were significantly associated with high numbers of pDCs (p = 0.006), and SO₂ with high numbers of CD8 T cells (p = 0.002) and low numbers of CD4 T cells (p = 0.011) and mDCs (p = 4.43 × 10⁻⁶) in cord blood. These data suggest that ambient SO₂ and PM_2.5 exposure are associated with shifts in cord blood cell types that are known to play significant roles in inflammatory respiratory disease in childhood.

Exposure of lead on intestinal structural integrity and the diversity of gut microbiota of common carp

Lead is an environmental toxicant that has toxicity effect to the health of aquatic organisms. Gut microbiota has been reported to be closely related to human health. The aim of this study was to investigate the effects of lead exposure on the composition of gut microbiota. The composition of gut microbiota alteration was detected by 16S rRNA gene sequencing, following a 42-day exposure of lead (1 mg/L). The results showed that compared with the normal control group, the carp of lead group showed severe intestinal tissues injury and decreased Zona Occludens 1 (ZO-1) and occludin expression. The production of LPS in serum was increased by the treatment of lead exposure. Our results showed gut bacterial diversity in lead-treated common carp was lower than the control group. At the phylum level, the abundance of Bacteroidetes (LPS producing bacteria) and Fusobacteria in lead-treated carp were much higher than the control carp. And the abundance of Actinobacteria decreased by lead exposure. At the genus level, we found the abundance of Bacteroides (LPS producing bacteria) and Plesiomonas (an important pathogenic bacteria), increased significantly by lead exposure. And the abundance of Akkermansia, a critical probiotics, was markedly inhibited by lead exposure. In conclusion, this study indicated exposure of carp to lead causes gut microbiota alterations and intestinal structural integrity destruction.

Early life blood lead levels and asthma diagnosis at age 4-6 years

The USA has a high burden of childhood asthma. Previous studies have observed associations between higher blood lead levels and greater hypersensitivity in children. The objective of the present study was to estimate the association between blood lead concentrations during early childhood and an asthma diagnosis between 48 and 72 months of age amongst a cohort with well-characterized blood lead concentrations. Blood lead concentrations were measured at 6, 12, 18, 24, 36, and 48 months of age in 222 children. The presence of an asthma diagnosis between 48 and 72 months was assessed using a questionnaire which asked parents or guardians whether they had been told by a physician, in the past 12 months, that their child had asthma. Crude and adjusted risk ratios (RR) of an asthma diagnosis were estimated for several parameterizations of blood lead exposure including lifetime average (6 to 48 months) and infancy average (6 to 24 months) concentrations. After adjustment for child sex, birthweight, daycare attendance, maternal race, education, parity, breastfeeding, income, and household smoking, age-specific or composite measures of blood lead were not associated with asthma diagnosis by 72 months of age in this cohort.

Changes in inflammatory cytokines, antioxidants and liver stiffness after chelation therapy in individuals with chronic lead poisoning

BACKGROUND

Chronic exposure to lead causes lead to accumulate mainly in the liver. In vivo studies have shown that lead toxicity is related to alterations in the inflammatory response. We aimed to evaluate the association between lead poisoning and liver fibrosis as well as the change in the degree of liver fibrosis, levels of inflammatory mediators and glutathione (GSH) after chelation therapy.

METHODS

Workers from a battery factory who were exposed to lead for > 12 months and had a blood lead level (BLL) > 70 μg/dL were enrolled (n = 86) in the study. Participants underwent chelation therapy with intravenous CaNa₂EDTA for 2 days followed by treatment with oral D-penicillamine for 90 days. The primary outcome was the change in the degree of liver fibrosis, which was presented as liver stiffness (LS) measured by FibroScan®. Secondary outcomes were the changes in the levels of serum GSH and inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) after chelation therapy.

RESULTS

Among the 86 participants, there was a positive correlation between the duration of lead exposure and LS (r = 0.249, p = 0.021). To avoid the confounding effect of obesity-related steatosis, only 70 individuals who had controlled attenuation parameters < 296 dB/m, BMI < 25 kg/m² and normal waist circumference were included in the interventional analysis. After chelation, the mean LS significantly decreased from 5.4 ± 0.9 to 4.8 ± 1.4 kPa (p = 0.001). Similarly, all of the inflammatory cytokines studied significantly decreased after chelation (p < 0.001); TNF-α decreased from 371.6 ± 211.3 to 215.8 ± 142.7; the levels of IL-1β decreased from 29.8 ± 1.7 to 25.9 ± 4.3; and the levels of IL-6 decreased from 46.8 ± 10.2 to 35.0 ± 11.9. On the other hand, the mean GSH level increased significantly from 3.3 ± 3.3 to 13.1 ± 3.7 (p < 0.001) after chelation therapy.

CONCLUSION

The duration of lead exposure was significantly correlated with the degree of liver fibrosis. Chelation treatment was associated with increased levels of GSH and decreased levels of proinflammatory cytokines and could potentially reduce the degree of LS.

TRIAL REGISTRATION

This study was retrospectively registered and approved by the Thai Clinical Trial Registry (TCTR) on 2019-11-07. The TCTR identification number is TCTR20191108001 .

COVID-19, an opportunity to reevaluate the correlation between long-term effects of anthropogenic pollutants on viral epidemic/pandemic events and prevalence

Occupational, residential, dietary and environmental exposures to mixtures of synthetic anthropogenic chemicals after World War II have a strong relationship with the increase of chronic diseases, health cost and environmental pollution. The link between environment and immunity is particularly intriguing as it is known that chemicals and drugs can cause immunotoxicity (e.g., allergies and autoimmune diseases). In this review, we emphasize the relationship between long-term exposure to xenobiotic mixtures and immune deficiency inherent to chronic diseases and epidemics/pandemics. We also address the immunotoxicologic risk of vulnerable groups, taking into account biochemical and biophysical properties of SARS-CoV-2 and its immunopathological implications. We particularly underline the common mechanisms by which xenobiotics and SARS-CoV-2 act at the cellular and molecular level. We discuss how long-term exposure to thousand chemicals in mixtures, mostly fossil fuel derivatives, exposure toparticle matters, metals, ultraviolet (UV)–B radiation, ionizing radiation and lifestyle contribute to immunodeficiency observed in the contemporary pandemic, such as COVID-19, and thus threaten global public health, human prosperity and achievements, and global economy. Finally, we propose metrics which are needed to address the diverse health effects of anthropogenic COVID-19 crisis at present and those required to prevent similar future pandemics.

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Developmental exposure to environmental factors can disrupt the immune system.

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Long-term low-dose exposure to chemical mixtures is linked to imunodeficiency

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Immunodeficiency contributes to chronic diseases and the current Covid-19 pandemics.

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Environmental chemicals and microorganisms share similar molecular pathomechanisms (AhR pathway).

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Understanding the underlying pathomechanisms helps to improve public health.

Evaluating the effects between metal mixtures and serum vaccine antibody concentrations in children: a prospective birth cohort study

BACKGROUND

Many populations are exposed to arsenic, lead, and manganese. These metals influence immune function. We evaluated the association between exposure to single and multiple metals, including arsenic, lead, and manganese, to humoral immunity as measured by antibody concentrations to diphtheria and tetanus toxoid among vaccinated Bangladeshi children. Additionally, we examined if this association was potentially mediated by nutritional status.

METHODS

Antibody concentrations to diphtheria and tetanus were measured in children's serum at age 5 (n = 502). Household drinking water was sampled to quantify arsenic (W-As) and manganese (W-Mn), whereas lead was measured in blood (B-Pb). Exposure samples were taken during pregnancy, toddlerhood, and early childhood. Multiple linear regression models (MLRs) with single or combined metal predictors were used to determine the association with antibody outcomes. MLR results were transformed to units of percent change in outcome per doubling of exposure to improve interpretability. Structural equation models (SEMs) were used to further assess exposure to metal mixtures. SEMs regressed a latent exposure variable (Metals), informed by all measured metal variables (W-As, W-Mn, and B-Pb), on a latent outcome variable (Antibody), informed by measured antibody variables (diphtheria and tetanus). Weight-for-age z-score (WFA) at age 5 was evaluated as a mediator.

RESULTS

Diphtheria antibody was negatively associated with W-As during pregnancy in MLR, but associations were attenuated after adjusting for W-Mn and B-Pb (- 2.9% change in diphtheria antibody per doubling in W-As, 95% confidence interval [CI]: - 7%, 1.5%). Conversely, pregnancy levels of B-Pb were positively associated with tetanus antibody, even after adjusting for W-As and W-Mn (13.3%, 95% CI: 1.7%, 26.3%). Overall, null associations were observed between W-Mn and antibody outcomes. Analysis by SEMs showed that the latent Metals mixture was significantly associated with the latent Antibody outcome (β = - 0.16, 95% CI: - 0.26, - 0.05), but the Metals variable was characterized by positive and negative loadings of W-As and B-Pb, respectively. Sex-stratified MLR and SEM analyses showed W-As and B-Pb associations were exclusive to females. Mediation by WFA was null, indicating Metals only had direct effects on Antibody.

CONCLUSIONS

We observed significant modulation of vaccine antibody concentrations among children with pregnancy and early life exposures to drinking water arsenic and blood lead. We found distinct differences by child sex, as only females were susceptible to metal-related modulations in antibody levels. Weight-for-age, a nutritional status proxy, did not mediate the association between the metal mixture and vaccine antibody.

Leukocyte apoptosis, TNF-α concentration and oxidative damage in lead-exposed workers

Lead intoxication can generate pro-inflammatory conditions that have been proposed to be associated with cell injuries and oxidative stress. The pro-inflammatory state can participate in the pathophysiology of this toxicity to generate immune response dysfunctions, which could condition the presence of clinical manifestations and susceptibility to infections already described in lead-exposed patients. In the present work, we study workers of a battery recycler factory (n = 24) who are chronically exposed to lead and compared them with non-lead exposed workers (n = 17). Lead-exposed workers had high lead concentrations in blood (med 69.8 vs. 1.7 μg/dL), low δ-ALAD activity (med 149 vs. 1100 nmol PBG/h/mL), high lipid peroxidation (med 0.86 vs. 0.69 nmol/mL) and high erythrocytes apoptosis (med 0.81 vs. 0.50% PS externalization) in relation to non-lead exposed workers. Also, lead-exposed workers had a high incidence of signs and symptoms related to lead intoxication and a higher frequency of infections. The higher leukocyte apoptosis (med 18.3 vs. 8.2% PS externalization) and lower basal TNF-α concentration (med 0.38 vs. 0.94 pg/mL) in lead-exposed workers imply an immune response dysfunction; however, there was no difference in the TNF-α concentration when leukocytes were stimulated with lipopolysaccharide in whole blood (med 44 vs. 70 pg/mL), suggesting that lead-exposed workers might develop adaptation mechanisms to reduce basal TNF-α release through downregulation processes proposed for this cytokine.

Associations Between Metal Levels in Whole Blood and IgE Concentrations in Pregnant Women Based on Data From the Japan Environment and Children's Study

Background

Metal exposures could possibly affect allergic responses in pregnant women, although no studies have yet shown a clear relationship between the two, and such exposures might also affect the development of allergic diseases in children.

Methods

We investigated the relationship between metal concentrations in whole blood and immunoglobulin E (IgE; total and specific) in 14,408 pregnant women who participated in the Japan Environment and Children’s Study. The subjects submitted self-administered questionnaires, and blood samples were collected from them twice, specifically, during the first trimester and again during the second/third trimester. Concentrations of the metals Cd, Pb, Hg, Se, and Mn, as well as serum total and allergen-specific IgEs for egg white, house dust-mites (HDM), Japanese cedar pollen (JCP), animal dander, and moth, were measured. Allergen-specific IgE(s) were divided based on concentrations <0.35 or ≥0.35 UA/mL, and the metal levels were divided into quartiles.

Results

Multivariable logistic regression analysis showed that there was a significant negative correlation between HDM- and animal dander-specific IgEs and Hg and Mn concentrations. Conversely, there was a significant positive relationship between JCP-specific IgE and Hg and Se concentrations.

Conclusions

Metal exposures may be related to both increases and decreases in allergen-specific IgEs in pregnant women.

Immunotoxic effects of lead on birds

The ingestion of lead (Pb) shot pellets is a well-known cause of avian mortality, but exposure of birds to Pb may have other sublethal effects that can affect population sustainability. One of these effects is the alteration of the immunological status. Pb can affect most components of the avian immune system and imbalance the relationship among them. Pb exposure typically alters the ratio between T_h1- and T_h2-type responses mounted by different classes of T-lymphocytes, causing the depression of the T_h1 responses that are associated with cell-mediated immunity. Immunodepressing effects of Pb on birds are observed at blood levels above 50 μg dL^-1, but developing birds show immunodepressing effects at much lower concentrations (> 10 μg dL^-1). Impacts of Pb on the avian immune system also relate to reduced resistance to infection. We review immunotoxic effects of Pb on birds affected by shot ingestion as well as by other sources of exposure to this element.

Ecogenetics of lead toxicity and its influence on risk assessment

Lead (Pb) toxicity is a public health problem affecting millions worldwide. Advances in 'omic' technology have paved the way to toxico-genomics which is currently revolutionizing the understanding of interindividual variations in susceptibility to Pb toxicity and its functional consequences to exposure. Our objective was to identify, comprehensively analyze, and curate all the potential genetic and epigenetic biomarkers studied to date in relation to Pb toxicity and its association with diseases. We screened a volume of research articles that focused on Pb toxicity and its association with genetic and epigenetic signatures in the perspective of occupational and environmental Pb exposure. Due to wide variations in population size, ethnicity, age-groups, and source of exposure in different studies, researchers continue to be skeptical on the topic of the influence of genetic variations in Pb toxicity. However, surface knowledge of the underlying genetic factors will aid in elucidating the mechanism of action of Pb. Moreover, in recent years, the application of epigenetics in Pb toxicity has become a promising area in toxicology to understand the influence of epigenetic mechanisms such as DNA methylation, chromatin remodeling, and small RNAs for the regulation of genes in response to Pb exposure during early life. Growing evidences of ecogenetic understanding (both genetic and epigenetic processes) in a dose-dependent manner may help uncover the mechanism of action of Pb and in the identification of susceptible groups. Such studies will further help in refining uncertainty factors and in addressing risk assessment of Pb poisoning.

Blood Lead Concentrations and Antibody Levels to Measles, Mumps, and Rubella among U.S. Children

Child blood lead concentrations have been associated with measures of immune dysregulation in nationally representative study samples. However, response to vaccination-often considered the gold standard in immunotoxicity testing-has not been examined in relation to typical background lead concentrations common among U.S. children. The present study estimated the association between blood lead concentrations and antigen-specific antibody levels to measles, mumps, and rubella in a nationally representative sample of 7005 U.S. children aged 6-17 years. Data from the 1999-2004 cycles of the National Health and Nutrition Examination Survey (NHANES) were used. In the adjusted models, children with blood lead concentrations between 1 and 5 µg/dL had an 11% lower anti-measles (95% CI: -16, -5) and a 6% lower anti-mumps antibody level (95% CI: -11, -2) compared to children with blood lead concentrations <1 µg/dL. The odds of a seronegative anti-measles antibody level was approximately two-fold greater for children with blood lead concentrations between 1 and 5 µg/dL compared to children with blood lead concentrations <1 µg/dL (OR = 2.0, 95% CI: 1.4, 3.1). The adverse associations observed in the present study provide further evidence of potential immunosuppression at blood lead concentrations <5 µg/dL, the present Centers for Disease Control and Prevention action level.

Trace element profile in pemphigus foliaceus and in pemphigus vulgaris patients from Southeastern Brazil

Pemphigus foliaceus (PF) and pemphigus vulgaris (PV) are autoimmune bullous diseases; they are endemic in the northeastern region of the state of São Paulo, Southeastern Brazil. Patients' copper (Cu), zinc (Zn), and selenium (Se) metabolic deficiencies have already been associated with PV pathogenesis in the Middle East but not in Brazil. Lead (Pb), Cu, Zn, and Se concentrations were determined in whole blood or serum samples obtained from 56 PV patients, 62 PF patients, and 135 healthy controls from the endemic region and compared. The PV patients had higher (above the reference values) Pb and lower Zn levels as compared to controls. Both the PV and the PF patients presented decreased Se levels as compared to controls. The PV, PF, and control groups did not differ in terms of Cu concentration. These results indicate that high Pb blood levels are related with environmental contamination and consequently with PV pathogenesis. Moreover, Zn and Se depletion, observed in the PV patients and in the PV and the PF patients, respectively, may result from metabolic consumption verified in chronic diseases.

Antagonistic effects of selenium on lead-induced autophagy by influencing mitochondrial dynamics in the spleen of chickens

Lead (Pb) may damage the immune function in human and animal. Selenium (Se) has antagonistic effects on Pb. In our study, brown layer chickens were randomly allocated to control group, Se group (1 mg/kg Se), Se+Pb group (1 mg/kg Se and 350 mg/kg Pb), and Pb group (350 mg/kg Pb). The chickens were sacrificed on the 90^th day; spleen tissues were subjected to observation of ultrastructure and detection of spleen-related indexes. The results revealed that in the Pb group, expression levels of the cytokines IL-1 and TNF-α significantly increased, and expression levels of IL-2 and INF-γ significantly decreased; activities of antioxidant enzyme GPX, SOD and CAT significantly decreased, and expression level of malondialdehyde (MDA) significantly increased; expression levels of mitochondrial fission-related genes (Mff and Drp1) significantly increased, and expression levels of mitochondrial fusion-related genes (Opa1, Mfn1 and Mfn2) significantly decreased; expression of autophagy-related genes (Beclin 1, Dynein, Atg 5, LC3-I and LC-II) was upregulated, while expression of mammalian target of rapamycin (mTOR) was downregulated. The results of transmission electron microscopy indicated that Pb induced mitochondrial fragmentation, and triggered autophagy in the spleen of chickens. The Se and Pb co-treatment remarkably alleviated these injuries induced by Pb in the spleen of chickens. In conclusion, Pb can induce the oxidative stress to influence the mitochondrial dynamics balance and lead to autophagy, which triggers the immune dysfunction in the spleen of chickens; the Se exhibits the antagonistic effects on lead-induced autophagy by influencing mitochondrial dynamics in the spleen of chickens.

Maternal Glucocorticoid Elevation and Associated Fetal Thymocyte Apoptosis are Involved in Immune Disorders of Prenatal Caffeine Exposed Offspring Mice

Our previous study showed that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) and glucocorticoid elevation in the fetus. Researchers suggested that IUGR is a risk factor for T helper cell (Th)1/Th2 deviation. However, whether PCE can induce these immune disorders and the underlying mechanisms of that induction remain unknown. This study aimed to observe the effects of PCE on the Th1/Th2 balance in offspring and further explore the developmental origin mechanisms from the perspective of glucocorticoid overexposure-induced thymocyte apoptosis. An IUGR model was established by caffeine administration from gestational day (GD) 9 to GD 18, and the offspring were immunized on postnatal day (PND) 42. The results show that maternal glucocorticoid overexposure increased fetal thymocyte apoptosis by activating both the Fas-mediated and the Bim-regulated apoptotic pathways. After birth, accelerated thymocyte apoptosis and Th1 suppression were also found in the PCE offspring at PND 14 and PND 49. Moreover, the PCE offspring showed immune disorders after immunization, manifesting as increased IgG1/IgG2a ratio and IL-4 production in the serum. In conclusion, PCE could induce fetal overexposure to maternal glucocorticoids and increase thymocyte apoptosis, which could persist into postnatal life and be implicated in Th1 inhibition and further immune disorders.

Perinatal lead (Pb) exposure results in sex and tissue-dependent adult DNA methylation alterations in murine IAP transposons

Epidemiological and animal data suggest that adult chronic disease is influenced by early-life exposure-induced changes to the epigenome. Previously, we observed that perinatal lead (Pb) exposure results in persistent murine metabolic- and activity-related effects. Using phylogenetic and DNA methylation analysis, we have also identified novel intracisternal A particle (IAP) retrotransposons exhibiting regions of variable methylation as candidate loci for environmental effects on the epigenome. Here, we now evaluate brain and kidney DNA methylation profiles of four representative IAPs in adult mice exposed to human physiologically relevant levels of Pb two weeks prior to mating through lactation. When IAPs across the genome were evaluated globally, average (sd) methylation levels were 92.84% (3.74) differing by tissue (P < 0.001), but not sex or dose. By contrast, the four individual IAPs displayed tissue-specific Pb and sex effects. Medium Pb-exposed mice had 3.86% less brain methylation at IAP 110 (P < 0.01), while high Pb-exposed mice had 2.83% less brain methylation at IAP 236 (P = 0.01) and 1.77% less at IAP 506 (P = 0.05). Individual IAP DNA methylation differed by sex for IAP 110 in the brain and kidney, IAP 236 in the kidney, and IAP 1259 in the kidney. Using Tomtom, we identified three binding motifs that matched to each of our novel IAPs impacted by Pb, one of which (HMGA2) has been linked to metabolic-related conditions in both mice and humans. Thus, these recently identified IAPs display tissue-specific environmental lability as well as sex-specific differences supporting an epigenetic link between early exposure to Pb and later-in-life health outcomes. Environ. Mol. Mutagen. 58:540-550, 2017. © 2017 Wiley Periodicals, Inc.

Immunological effects of occupational exposure to lead (Review)

It is well-known that occupational and environmental exposure to several factors, including benzene, heavy metals, chemicals and mineral fibers, is associated with the risk of developing a great number of diseases. Numerous studies have been carried out in order to investigate the mechanisms of toxicity of these substances, with particular regard to the possible toxic effects on the immune system. However, little is known about the influence of heavy metals, such as lead, on the immune system in human populations. Lead is a heavy metal still used in many industrial activities. Human exposure to lead can induce various biological effects depending upon the level and duration of exposure, such as toxic effects on haematological, cardiovascular, nervous and reproductive systems. Several studies demonstrated that exposure to lead is associated to toxic effects also on the immune system, thus increasing the incidence of allergy, infectious disease, autoimmunity or cancer. However, the effects of lead exposure on the human immune system are not conclusive, mostly in occupationally exposed subjects; nevertheless some immunotoxic abnormalities induced by lead have been suggested. In particular, in vivo, in vitro and ex vivo lead is able to improve T helper 2 (Th2) cell development affecting Th1 cell proliferation. Further studies are required to better understand the mechanisms of lead immunotoxicity and the ability of lead to affect preferentially one type of immune response.

Alleviation of lead-induced oxidative stress and immune damage by selenium in chicken bursa of Fabricius

We investigated lead (Pb)-induced oxidative stress and immune damage in the chicken bursa of Fabricius (BF) and the ameliorative effect of selenium (Se). Seven-day-old male chickens were randomly divided into four groups and were provided standard diet and drinking water, Na₂SeO₃ added to the standard diet and drinking water, standard diet and (CH₃COO)₂Pb added to drinking water, and Na₂SeO₃ added to the standard diet and (CH₃COO)₂Pb added to drinking water for 30, 60, and 90 days. The presence of Pb inhibited total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities; decreased glutathione (GSH) content; increased malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents; inhibited interleukin (IL)-2 and interferon-γ (IFN-γ) messenger RNA (mRNA) expression; and increased IL-4, IL-6, IL-10, IL-12β, and IL-17 mRNA expression. The presence of Se relieved all of the above Pb-induced changes. There were close correlations among GSH, CAT, T-AOC, SOD, GPx, MDA, and H₂O₂ and among IL-2, IL-4, IL-6, IL-12β, IL-17, and IFN-γ. Our data showed that Pb caused oxidative stress and immune damage in the chicken BF. Se alleviated Pb-induced oxidative stress and immune damage in the chicken BF.

The association between serum lead and total immunoglobulin E levels according to allergic sensitization

BACKGROUND

Results of several studies showed that blood lead concentration is positively associated with total immunoglobulin E (IgE) value. However, no study has investigated whether allergic sensitization could be responsible for the association between lead exposure and total IgE value.

OBJECTIVE

We investigated whether there was difference in the association between lead exposure and the total IgE value, depending on the presence or absence of Dermatophagoides farinae sensitization.

METHODS

We used data obtained from the Korea National Health and Nutrition Examination Survey. Serum levels of heavy metals, such as mercury, cadmium, and lead, were measured. Total and D. farinae specific IgE levels were measured, and the urinary cotinine level was investigated. Information about sex, age, body mass index, and household income were also obtained. We analyzed the association between serum lead and total IgE levels, after adjusting other variables.

RESULTS

In an multivariate linear regression analysis, only the serum concentration of lead among the three heavy metals was positively associated with logarithmic transformed total IgE (coefficient [B], 0.026 [95% confidence interval {CI}], 0.008-0.044). When we performed the same analysis on groups divided by allergic D. farinae sensitization status, we found a significant positive association between serum lead and logarithmic transformed total IgE values in subjects with D. farinae sensitization (B, 0.043 [95% CI, 0.014-0.071]) but not in subjects without D. farinae sensitization (B, 0.015 [95% CI, -0.008 to 0.039]).

CONCLUSIONS

A positive association between the serum lead and total IgE levels was statistically significant in subjects with D. farinae sensitization, which indicated that the immunologic effects of lead exposure may be greater in people with allergic sensitization.

Air Pollution During Pregnancy and Cord Blood Immune System Biomarkers

OBJECTIVES

We aimed to determine whether average and trimester-specific exposures to ambient measures of nitrogen dioxide (NO2) and particular matter (PM2.5) were associated with elevated cord blood concentrations of immunoglobulin E (IgE) and two epithelial cell produced cytokines: interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP).

METHODS

This study utilized data and biospecimens from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. There were 2001 pregnant women recruited between 2008 and 2011 from 10 Canadian cities. Maternal exposure to NO2 and PM2.5 was estimated using land use regression and satellite-derived models.

RESULTS

We observed statistically significant associations between maternal NO2 exposure and elevated cord blood concentrations of both IL-33 and TSLP among girls but not boys.

CONCLUSIONS

Maternal NO2 exposure may impact the development of the newborn immune system as measured by cord blood concentrations of two cytokines.

Effects of Regular Treadmill Exercise on a DNA Oxidative-Damage Marker and Total Antioxidant Capacity in Rat Hippocampal Tissue

Background and Purpose

Regular exercise can result in changes in the levels of oxidative stress in the hippocampus; however, little attention has been paid to physical-activity-induced neuronal protection to exposure to lead compounds. This study investigated the effects of regular treadmill exercise on a DNA oxidative-damage marker [8-hydroxy-2'-deoxyguanosine (8-OHdG)] and the total antioxidant capacity (TAC) of hippocampal tissue in lead-acetate exposed rats.

Methods

This study investigated the effects of 8 weeks of regular treadmill exercise on 8-OHdG and the TAC of hippocampal tissue in lead-acetate-exposed rats. Wistar rats were randomly divided into four groups: baseline, sham (control), lead, and exercise+lead. The exercise program involved running on a treadmill with increasing intensity five times a week for 8 weeks. Animals in the lead and exercise+lead groups received lead acetate at 20 mg/kg body weight intraperitoneally three times weekly for 8 weeks. Animals in the sham group received solvent (ethyl oleate) at 30 mg/kg body weight three times weekly for 8 weeks. TAC and 8-OHdG were measured by spectrophotometric and ELISA techniques, respectively. Data were analyzed by ANOVA and Tukey's post-hoc test with a significance cutoff of p≤0.05.

Results

The level of 8-OHdG and the TAC were significantly higher and lower, respectively, in the lead group than in the baseline and sham groups (p<0.01). However, the 8-OHdG level and TAC value in hippocampal tissue were significantly decreased and increased, respectively, in the exercise+lead group relative to the lead group (p<0.05).

Conclusions

The TAC of hippocampal tissue may be directly associated with neural protection mechanisms of exercise following lead acetate injection, and the beneficial effects of regular exercise in preventing hippocampal neuronal damage could be due to decreased hippocampal oxidative stress such as reflected by a lower 8-OHdG level and increased TAC.

Inhaled lead affects lung pathology and inflammation in sensitized and control guinea pigs

The association between lead exposure and respiratory diseases including asthma is controversial. Some studies indicate that exposure to environmental lead pollution may cause asthma; however, there is not sufficient data in this regard. The effect of lead on lung pathological findings and serum inflammatory mediators in sensitized and non-sensitized guinea pigs exposed to inhaled lead was examined. Eleven animal groups including control, sensitized, three groups of non sensitized animals, three groups during sensitization, and three groups after sensitization exposed to aerosol of three lead concentrations (n = 6 for each group) were studied. Serum inflammatory mediators levels and lung pathological changes were evaluated. All pathological changes and serum ET-1, EPO, NO levels were significantly higher in the sensitized and non sensitized animals exposed to lead than control group (p < 0.05 to p < 0.001). There was no significant difference between non sensitized groups exposed to high lead concentration and sensitized group. Serum inflammatory mediators levels and pathological findings in sensitized groups exposed to lead both during and after sensitization were significantly higher than sensitized non exposed group (p < 0.05 to p < 0.001). The data of exposed animals to high lead concentration were significantly higher than those of medium and low concentrations; those of medium concentration were also higher than low concentration (p < 0.05 to p < 0.001). In summary, the present study indicates that exposure to inhaled lead is able to induce respiratory changes similar to asthma. In addition, the results indicated that exposure to environmental lead is able to aggravate asthma severity both during development of asthma or after its manifestation.

Decreased blood hepatitis B surface antibody levels linked to e-waste lead exposure in preschool children

Lead (Pb) is a widespread environmental contaminant that can profoundly affect the immune system in vaccinated children. To explore the association between blood Pb and HBsAb levels in children chronically exposed to Pb, we measured hepatitis B surface antibody (HBsAb) titers, to reflect the immune response in the children of Guiyu, an electronic and electrical waste (e-waste) recycling area well known for environmental Pb contamination. We performed secondary exploratory analyses of blood Pb levels and plasma HBsAb titers in samples, taken in two phases between 2011 and 2012, from 590 children from Guiyu (exposed group) and Haojiang (reference group). Children living in the exposed area had higher blood Pb levels and lower HBsAb titers compared with children from the reference area. At each phase, generalized linear mixed models (GLMMs) showed that HBsAb titers were significantly negatively associated with child blood Pb levels. This work shows that a decreased immune response to hepatitis B vaccine and immune system might have potential harm to children with chronic Pb exposure. Importantly, nearly 50% of chronically exposed children failed to develop sufficient immunity to hepatitis in response to vaccination. Thus different vaccination strategies are needed for children living under conditions of chronic Pb exposure.

Altered immune response in mallard ducklings exposed to lead through maternal transfer in the wild

Lead (Pb) poisoning has caused significant mortality in waterfowl populations worldwide. In spite of having been banned since 2003, prevalence of Pb shot ingestion in mallards (Anas platyrhynchos) from the Ebro delta was still 15.5% in 2011-12. We collected mallard eggs from this area to study the effects of maternally transferred Pb on eggshell properties and on immune response and oxidative balance of ducklings. Eggshell Pb levels were positively correlated with Pb levels in the blood of ducklings. Ducklings with blood Pb levels above 180 ng mL(-1) showed reduced body mass and died during the first week post hatching. Blood Pb levels positively correlated with humoral immune response, endogenous antioxidants and oxidative stress biomarkers, and negatively correlated with cellular immune response. Pb shot ingestion in birds can result in maternal transfer to the offspring that can affect their developing immune system and reduce their survival in early life stages.

Maternal exposure to metals and persistent pollutants and cord blood immune system biomarkers

BACKGROUND

The fetal time period is a critical window of immune system development and resulting heightened susceptibility to the adverse effects of environmental exposures. Epidemiologists and toxicologists have hypothesized that persistent organic pollutants, pesticides and metals have immunotoxic properties. Immunotoxic effects may manifest as an altered immune system profile at birth. Immunoglobulin E, thymic stromal lymphopoietin (TSLP), and interleukin-33 (IL-33) may be implicated in the etiology of childhood allergy and are detectable at birth. The objective of this study was to examine the potential relationship between maternal concentrations of metals, persistent organic pollutants, and pesticides and elevated umbilical cord blood concentrations of IgE, TSLP, and IL-33 in a Canadian birth cohort.

METHODS

This study utilized data collected in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada cohort study of 2,001 pregnant women. Of these women, 1258 had a singleton, term birth and cord blood sample. Logistic regression was used to determine associations between log-transformed continuous variables and immune system biomarkers.

RESULTS

Inverse relationships were observed between lead, DDE, PCB-118, and a summary index of organophosphorous metabolites and jointly elevated concentrations of IL-33 and TSLP. None of the environmental contaminants were associated with increased odds of a high cord blood immune system biomarker concentration.

CONCLUSIONS

In this primarily urban Canadian population of pregnant women and their newborns, maternal blood or urine concentrations of persistent organic pollutants, pesticides, and metals were not associated with immunotoxic effects that manifest as increased odds of elevated concentrations of IgE, TSLP or IL-33.

Function of respiratory system evaluated using selected spirometry parameters in persons occupationally exposed to lead without evident health problems

This study aimed at evaluation of selected spirometric parameters in persons occupationally exposed to lead without evident health problems. The studies were conducted on 69 men occupationally exposed to lead. Occupational exposure to lead was characterized by estimation of blood lead concentration (Pb-B) and blood zinc protoporphyrin concentration (ZnPP). Function of respiratory system was examined using spirometric analysis with evaluation of its basic parameters: forced vital capacity (FVC), forced expiratory volume (in 1s) (FEV1), Tiffeneau index (FEV1%VC) and peak expiratory flow (PEF). In the study group negative linear correlations were documented between Pb-B and FVC, FEV 1 and FEV1%VC. A more pronounced age, higher values of BMI and higher blood lead concentration constituted independent risk factors for reduced FEV1%VC.

CONCLUSION

Persons occupationally exposed to lead with elevated blood lead concentration and blood zinc protoporphyrin concentration manifested the impaired function of respiratory system, evaluated using parameters of spirometry.

Genome-wide association study of blood lead shows multiple associations near ALAD

Exposure to high levels of environmental lead, or biomarker evidence of high body lead content, is associated with anaemia, developmental and neurological deficits in children, and increased mortality in adults. Adverse effects of lead still occur despite substantial reduction in environmental exposure. There is genetic variation between individuals in blood lead concentration but the polymorphisms contributing to this have not been defined. We measured blood or erythrocyte lead content, and carried out genome-wide association analysis, on population-based cohorts of adult volunteers from Australia and UK (N = 5433). Samples from Australia were collected in two studies, in 1993-1996 and 2002-2005 and from UK in 1991-1992. One locus, at ALAD on chromosome 9, showed consistent association with blood lead across countries and evidence for multiple independent allelic effects. The most significant single nucleotide polymorphism (SNP), rs1805313 (P = 3.91 × 10(-14) for lead concentration in a meta-analysis of all data), is known to have effects on ALAD expression in blood cells but other SNPs affecting ALAD expression did not affect blood lead. Variants at 12 other loci, including ABO, showed suggestive associations (5 × 10(-6) > P > 5 × 10(-8)). Identification of genetic polymorphisms affecting blood lead reinforces the view that genetic factors, as well as environmental ones, are important in determining blood lead levels. The ways in which ALAD variation affects lead uptake or distribution are still to be determined.

Quantile regression in environmental health: Early life lead exposure and end-of-grade exams

Conditional means regression, including ordinary least squares (OLS), provides an incomplete picture of exposure-response relationships particularly if the primary interest resides in the tail ends of the distribution of the outcome. Quantile regression (QR) offers an alternative methodological approach in which the influence of independent covariates on the outcome can be specified at any location along the distribution of the outcome. We implemented QR to examine heterogeneity in the influence of early childhood lead exposure on reading and math standardized fourth grade tests. In children from two urban school districts (n=1,076), lead exposure was associated with an 18.00 point decrease (95% CI: -48.72, -3.32) at the 10th quantile of reading scores, and a 7.50 point decrease (95% CI: -15.58, 2.07) at the 90th quantile. Wald tests indicated significant heterogeneity of the coefficients across the distribution of quantiles. Math scores did not show heterogeneity of coefficients, but there was a significant difference in the lead effect at the 10th (β=-17.00, 95% CI: -32.13, -3.27) versus 90th (β=-4.50, 95% CI: -10.55, 4.50) quantiles. Our results indicate that lead exposure has a greater effect for children in the lower tail of exam scores, a result that is masked by conditional means approaches.

Lead exposure and increased food allergic sensitization in U.S. children and adults

BACKGROUND

Whether blood lead levels are associated with sensitization to food allergens in adults and children is unclear. Prior studies have shown that exposure to lead is associated with atopic sensitization and modulation of several cytokines (eg, interleukin [IL]-12, IL-10, interferon [IFN]-γ, and IL-4 production) and with T-cell dysregulation and bias toward T helper 2 (Th2) activity. The objective of this work was to assess whether exposure to lead is independently associated with allergic symptoms and sensitizations in a large nationally representative sample of children and adults.

METHODS

We studied 2712 children and 4333 adults enrolled in the 2005-2006 cycle of the National Health and Nutritional Examination Surveys (NHANES). Participants were tested for serum-specific immunoglobulin E (IgE) levels to food allergens as well as blood lead levels. Food allergens tested included shrimp, egg, peanut, and milk. Logistic regression models adjusted for demographic factors, body mass index, history of asthma, smoking, housing characteristics, and current exposure to animals in the home, to assess the association of blood lead levels with sensitization to food allergens.

RESULTS

Median (interquartile range [IQR]) for serum blood was 0.87 μg/L (0.61 to 1.31) in children and 1.48 μg/L (0.92 to 2.34) in adults. At baseline, 672 (24.7%) of children participants and 719 (16.6%) of adult participants tested positive for increased sensitization to food allergens. A 2-fold increase in blood lead levels in adult participants was associated with increased sensitization to food allergens (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.02 to 1.22). Blood lead was not associated with sensitization to food allergens among pediatric participants (OR, 0.95; 95% CI, 0.82 to 1.10).

CONCLUSION

Exposure to lead was associated with increased odds of sensitization to food allergens in adult but not children participants.

Fluorescent nanohybrid of gold nanoclusters and quantum dots for visual determination of lead ions

Highly green emissive gold nanoclusters (Au NCs) are synthesized using glutathione as a stabilizing agent and mercaptopropionic acid as a ligand, and the intensity of fluorescence is specifically sensitive to lead ions. We then fabricated a ratiometric fluorescence nanohybrid by covalently linking the green Au NCs to the surface of silica nanoparticles embedded with red quantum dots (QDs) for on-site visual determination of lead ions. The green fluorescence can be selectively quenched by lead ions, whereas the red fluorescence is inert to lead ions as internal reference. The different response of the two emissions results in a continuous fluorescence color change from green to yellow that can be clearly observed by the naked eyes. The nanohybrid sensor exhibits high sensitivity to lead ions with a detection limit of 3.5 nM and has been demonstrated for determination of lead ions in real water samples including tap water, mineral water, groundwater, and seawater. For practical application, we dope the Au NCs in poly(vinyl alcohol) (PVA) film and fabricate fluorescence test strips to directly detect lead ions in water. The PVA-film method has a visual detection limit of 0.1 μM, showing its promising application for on-site identification of lead ions without the need for elaborate equipment.

Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique

Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.