Plasma polychlorinated biphenyl levels in Dutch preschool children either breast-fed or formula-fed during infancy

Prenatal exposure to persistent organic pollutants and offspring allergic sensitization and lung function at 20 years of age

BACKGROUND

Prenatal exposures to persistent organic pollutants (POPs) have been associated with asthma medication use and self-reported symptoms, but associations with lung function and allergic sensitization have been minimally explored. The aim of the study was to examine the associations between prenatal exposures to POPs and allergic sensitization and lung function in 20-year-old offspring.

METHODS

In a Danish cohort of 965 pregnant women established in 1988-1989, six polychlorinated biphenyl (PCB) congeners, hexachlorobenzene (HCB), and dichlorodiphenyldichloroethylene (p,p'-DDE) were quantified in archived maternal serum drawn in gestational week 30 (n = 872). Among those with available maternal exposure information, at age 20, 421 offspring attended attended a clinical examination including measurements of allergic sensitization (serum-specific IgE ≥ 0.35 kUA /L) (n = 418) and lung function [forced expiratory volume in one second (FEV1 ) and forced vital capacity (FVC)] (n = 414).

RESULTS

There were no associations between maternal concentrations of POPs and offspring allergic sensitization at 20 years of age. Maternal concentrations of POPs were, however, positively associated with offspring airway obstruction (FEV1 /FVC < 75%). Compared to offspring in the first tertile of exposure, offspring in the third tertile of dioxin-like PCB exposure had an OR of 2.96 (95% CI: 1.14-7.70). Similar associations for non-dioxin-like PCBs, HCB, and p,p'-DDE were 2.68 (1.06-6.81), 2.63 (1.07, 6.46), and 2.87 (1.09, 7.57), respectively. No associations were observed with reduced lung function (FEV1 % of predicted value < 90%).

CONCLUSION AND CLINICAL RELEVANCE

Our data indicate that prenatal exposure to POPs appears to be associated with airway obstruction but not allergic sensitization at 20 years of age. The findings support that chronic obstructive lung diseases may have at least part of their origins in early life.

Measured Prenatal and Estimated Postnatal Levels of Polychlorinated Biphenyls (PCBs) and ADHD-Related Behaviors in 8-Year-Old Children

BACKGROUND

Epidemiologic studies of postnatal PCB exposure and behavior have not reported consistent evidence of adverse associations, possibly because of challenges in exposure estimation. We previously developed a pharmacokinetic model to improve estimation of children's PCB exposure.

OBJECTIVES

We aimed to assess whether estimated serum PCB levels in infancy are associated with attention deficit/hyperactivity disorder (ADHD)-related behaviors at 8 years of age among children whose cord serum PCB levels were previously shown to be associated with ADHD-related behaviors.

METHODS

We used a pharmacokinetic model to estimate monthly serum polychlorinated biphenyl (PCB)-153 levels in 441 infants (ages 1-12 months) based on parameters such as breastfeeding and cord serum PCB-153 levels. Behavior was evaluated at age 8 using the Conners' Rating Scale for Teachers (CRS-T). Associations between PCB-153 levels and ADHD-related CRS-T indices were assessed using multivariable quantile regression at the 50th and 75th percentiles of CRS-T scores, where higher percentiles reflect more adverse behaviors.

RESULTS

Cord serum PCB-153 levels (median, 38 ng/g lipids) were associated with ADHD-related behaviors, although statistical significance was observed with quantile regression models only at the 75th percentile. Associations with postnatal exposure estimates were attenuated. For example, hyperactive-impulsive behavior scores at age 8 years were 0.9 points (95% CI: 0.2, 2.5), 0.5 points (95% CI: 0.3, 2.3), and 0.3 points (95% CI: -0.2, 1.5) higher in association with interquartile range increases in serum PCB-153 at birth, 2 months, and 12 months of age, respectively.

CONCLUSIONS

Associations between estimated postnatal PCB-153 exposures and ADHD-related behaviors at 8 years of age were weaker than associations with PCB-153 concentrations measured in cord serum at birth.

CITATION

Verner MA, Hart JE, Sagiv SK, Bellinger DC, Altshul LM, Korrick SA. 2015. Measured prenatal and estimated postnatal levels of polychlorinated biphenyls (PCBs) and ADHD-related behaviors in 8-year-old children. Environ Health Perspect 123:888-894; http://dx.doi.org/10.1289/ehp.1408084.

Concentrations of Persistent Organic Pollutants in California Children's Whole Blood and Residential Dust

We evaluated relationships between persistent organic pollutant (POP) levels in the blood of children with leukemia and POP levels in dust from their household vacuum cleaners. Blood and dust were collected from participants of the California Childhood Leukemia Study at various intervals from 1999 to 2007 and analyzed for two polybrominated diphenyl ethers (PBDEs), two polychlorinated biphenyls (PCBs), and two organochlorine pesticides using gas chromatography-mass spectrometry. Due to small blood sample volumes (100 μL), dichlorodiphenyldichloroethylene (DDE) and BDE-153 were the only analytes with detection frequencies above 70%. For each analyte, depending on its detection frequency, a multivariable linear or logistic regression model was used to evaluate the relationship between POP levels in blood and dust, adjusting for child's age, ethnicity, and breastfeeding duration; mother's country of origin; household annual income; and blood sampling date. In linear regression, concentrations of BDE-153 in blood and dust were positively associated; whereas, DDE concentrations in blood were positively associated with breastfeeding, maternal birth outside the U.S., and Hispanic ethnicity, but not with corresponding dust-DDE concentrations. The probability of PCB-153 detection in a child's blood was marginally associated with dust-PCB-153 concentrations (p = 0.08) in logistic regression and significantly associated with breastfeeding. Our findings suggest that dust ingestion is a source of children's exposure to certain POPs.

Duration of breastfeeding and serum PCB 153 concentrations in children

Polychlorinated biphenyls (PCBs) are toxic, persistent, and bioaccumulative chemicals which, because of their lipophilic properties, are abundant in human breast milk. Breastfed infants are therefore at risk of being exposed to considerable amounts of PCBs. The commonly used exposure estimations, based solely on breast milk PCB levels and duration of breastfeeding, may lead to exposure misclassification. To improve assessments of exposure to PCBs, we determined PCB 153 serum concentration, as a model substance for PCBs, at the critical time of weaning for each child in 305 breastfed infants from 5 single time point concentration measurements spread over 7 years and data on duration of breastfeeding, using an earlier developed model of the system type. We approximated the dependence of PCB 153 serum concentration, Ctbf, adjusted to cord serum concentration, C0, on nursing period, by a polynomial function Ctbf/C0=0.596+0.278t-0.0047t(2) which reliably predicts exposure to PCB 153 of breastfed infants, important for assessment of dose-outcome relationships. Adjustment of current serum concentrations to cord serum concentration improved validity of exposure assessment.

Maternal concentrations of persistent organochlorine pollutants and the risk of asthma in offspring: results from a prospective cohort with 20 years of follow-up

BACKGROUND

Previous findings suggest that developmental exposures to persistent organochlorine pollutants (POPs) may be detrimental for the development of the immune system in the offspring. Whether these suspected immunoregulatory effects persist beyond early childhood remains unclear.

OBJECTIVES

The objective of this study was to evaluate the association between maternal serum concentrations of POPs and the risk of asthma in offspring after 20 years of follow-up.

METHODS

A birth cohort with 965 women was formed in 1988-1989 in Aarhus, Denmark. Concentrations of six polychlorinated biphenyls (PCBs) (congeners 118, 138, 153, 156, 170, 180), hexachlorobenzene (HCB), and dichlorodiphenyldichloroethylene (p,p´-DDE) were quantified in maternal serum (n=872) collected in gestation week 30. Information about offspring use of asthma medications was obtained from the Danish Registry of Medicinal Product Statistics.

RESULTS

Maternal serum concentrations of HCB and dioxin-like PCB-118 were positively associated with offspring asthma medication use after 20 years of follow-up (p for trend<0.05). Compared with subjects in the first tertile of maternal concentration, those in the third tertile of PCB-118 had an adjusted hazard ratio (HR) of 1.90 (95% CI: 1.12, 3.23). For HCB the HR for the third versus the first tertile of maternal concentration was 1.92 (95% CI: 1.15, 3.21). Weak positive associations were also estimated for PCB-156 and the non-dioxin-like PCBs (PCBs 138, 153, 170, 180). No associations were found for p,p´-DDE.

CONCLUSIONS

Maternal concentrations of PCB-118 and HCB were associated with increased risk of asthma in offspring followed through 20 years of age.

Maternal concentrations of persistent organochlorine pollutants and the risk of asthma in offspring: results from a prospective cohort with 20 years of follow-up

BACKGROUND

Previous findings suggest that developmental exposures to persistent organochlorine pollutants (POPs) may be detrimental for the development of the immune system in the offspring. Whether these suspected immunoregulatory effects persist beyond early childhood remains unclear.

OBJECTIVES

The objective of this study was to evaluate the association between maternal serum concentrations of POPs and the risk of asthma in offspring after 20 years of follow-up.

METHODS

A birth cohort with 965 women was formed in 1988-1989 in Aarhus, Denmark. Concentrations of six polychlorinated biphenyls (PCBs) (congeners 118, 138, 153, 156, 170, 180), hexachlorobenzene (HCB), and dichlorodiphenyldichloroethylene (p,p´-DDE) were quantified in maternal serum (n=872) collected in gestation week 30. Information about offspring use of asthma medications was obtained from the Danish Registry of Medicinal Product Statistics.

RESULTS

Maternal serum concentrations of HCB and dioxin-like PCB-118 were positively associated with offspring asthma medication use after 20 years of follow-up (p for trend<0.05). Compared with subjects in the first tertile of maternal concentration, those in the third tertile of PCB-118 had an adjusted hazard ratio (HR) of 1.90 (95% CI: 1.12, 3.23). For HCB the HR for the third versus the first tertile of maternal concentration was 1.92 (95% CI: 1.15, 3.21). Weak positive associations were also estimated for PCB-156 and the non-dioxin-like PCBs (PCBs 138, 153, 170, 180). No associations were found for p,p´-DDE.

CONCLUSIONS

Maternal concentrations of PCB-118 and HCB were associated with increased risk of asthma in offspring followed through 20 years of age.

Breastfeeding and risk of atopic dermatitis up to the age 42 months: a birth cohort study in Japan

PURPOSE

The purpose of this study was to investigate the association between breastfeeding and atopic dermatitis (AD) up to the age 42 months.

METHODS

Data from a nationally representative population-based birth cohort study in Japan were used (N = 38,757). Feeding pattern and breastfeeding duration were investigated via questionnaires when infants were aged 6 months. Physician-diagnosed AD during the previous 1 year was ascertained via questionnaires when the children were aged 18, 30, and 42 months. The associations between feeding patterns or breastfeeding duration and physician-diagnosed AD from the age 6 to 42 months, categorized by AD status (no history of AD, episodic AD, and persistent AD), were analyzed using ordered logistic regression adjusted for covariates.

RESULTS

Breastfeeding was positively associated with AD, with dose-response association (P for trend < .001). Exclusively breastfed infants were 1.26 times more likely to have AD (95% confidence interval, 1.12-1.41) than infants fed formula alone. Furthermore, children with a longer breastfeeding duration were also significantly more likely to have AD (P for trend < .001).

CONCLUSIONS

Breastfeeding is associated with an increased risk of AD up to the age 42 months. Further study is needed to elucidate the mechanism underlying the association between breastfeeding and AD.

Toxicokinetic modeling of persistent organic pollutant levels in blood from birth to 45 months of age in longitudinal birth cohort studies

BACKGROUND

Despite experimental evidence that lactational exposure to persistent organic pollutants (POPs) can impact health, results from epidemiologic studies are inconclusive. Inconsistency across studies may reflect the inability of current methods to estimate children's blood levels during specific periods of susceptibility.

OBJECTIVES

We developed a toxicokinetic model to simulate blood POP levels in children from two longitudinal birth cohorts and aimed to validate it against blood levels measured at 6, 16, and 45 months of age.

METHODS

The model consisted of a maternal and a child lipid compartment connected through placental diffusion and breastfeeding. Simulations were carried out based on individual physiologic parameters; duration of breastfeeding; and levels of POPs measured in maternal blood at delivery, cord blood, or breast milk. Model validity was assessed through regression analyses of simulated against measured blood levels.

RESULTS

Simulated levels explained between 10% and 83% of measured blood levels depending on the cohort, the compound, the sample used to simulate children's blood levels, and child's age when blood levels were measured. Model accuracy was highest for estimated blood POP levels at 6 months based on maternal or cord blood levels. However, loss in model precision between the 6th and the 45th month was small for most compounds.

CONCLUSIONS

Our validated toxicokinetic model can be used to estimate children's blood POP levels in early to mid-childhood. Estimates can be used in epidemiologic studies to evaluate the impact of exposure during hypothesized postnatal periods of susceptibility on health.

Prenatal exposure to organochlorine compounds and neuropsychological development up to two years of life

Polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), and dichlorodiphenyl dichloroethylene (pp'DDE) are persistent, bioaccumulative, and toxic environmental pollutants with potential neurotoxic effects. Despite a growing body of studies investigating the health effects associated with these compounds, their specific effects on early neuropsychological development remain unclear. We investigated such neuropsychological effects in a population-based birth cohort based in three regions in Spain (Sabadell, Gipuzkoa, and Valencia) derived from the INMA [Environment and Childhood] Project. The main analyses in this report were based on 1391 mother-child pairs with complete information on maternal levels of organochlorine compounds and child neuropsychological assessment (Bayley Scales of Infant Development) at age 14 months. We found that prenatal PCB exposure, particularly to congeners 138 and 153, resulted in impairment of psychomotor development (coefficient=-1.24, 95% confidence interval=-2.41, -0.07), but found no evidence for effects on cognitive development. Prenatal exposure to pp'DDE or HCB was not associated with early neuropsychological development. The negative effects of exposure to PCBs on early psychomotor development suggest that the potential neurotoxic effects of these compounds may be evident even at low doses.

Prenatal exposure to polychlorinated biphenyls and child neuropsychological development in 4-year-olds: an analysis per congener and specific cognitive domain

Polychlorinated biphenyls (PCB) are synthetic organochlorine compounds with potential neurotoxic effects. Although negative effects on neuropsychological development have been observed in previous studies on PCB exposure, there are inconsistencies in these effects at current exposure levels of these compounds which are much lower than for previous generations. This study aimed to disentangle the effects of prenatal and postnatal PCB exposure on neuropsychological development at 4 years of age. This study is based on a population-based birth cohort design established in Menorca (Spain) as part of the INMA [Environment and Childhood] Project. We assessed general neuropsychological development using the McCarthy Scales of Children's Abilities (MCSA). A total of 422 4-year old children were assessed with the MCSA. Levels of PCBs were measured in cord blood (n=405) and in blood samples taken at 4 years (n=285). We found no statistically significant effects of the sum of prenatal PCBs on MCSA scores. Nevertheless, individual congener analyses yielded significant detrimental effects of prenatal PCB153 on the majority of MCSA scores, while no effects were reported for other congeners. The levels of PCBs at 4 years of age were not associated with neuropsychological development. Thus, prenatal exposure to low-level concentrations of PCBs, particularly PCB153, was associated with an overall deleterious effect on neuropsychological development at 4 years of age, including negative effects on executive function, verbal functions and visuospatial abilities, but not on motor development.

Assessment of exposure to PCB 153 from breast feeding and normal food intake in individual children using a system approach model

Investigators have typically relied on a single or few discrete time points as measures of polychlorinated biphenyl (PCB) body burden, however health effects are more likely to be the result of integrative exposure in time, optionally expressed as an area under the time curve (AUC) of PCB serum concentration. Using data from a subgroup of 93 infants from a birth cohort in eastern Slovakia-a region highly polluted by PCBs-we fit a system type model, customized to our longitudinal measures of serum PCB concentrations in cord, 6, 16, and 45 month blood specimens. The most abundant congener, PCB 153, was chosen for modeling purposes. In addition to currently used methods of exposure assessment, our approach estimates a concentration time profile for each subject, taking into account mean residence time of PCB 153 molecules in the body, duration of breast feeding, hypothetical PCB 153 concentration in steady-state without breast feeding and alternately without normal food intake. Hypothetical PCB 153 concentration in steady-state without normal food intake correlates with AUC (r=0.84, p<0.001) as well as with duration of breast feeding (r=0.64, p<0.001). It makes possible to determine each subject's exposure profile expressed as AUC of PCBs serum concentration with a minimum model parameters. PCB body burden in most infants was strongly associated with duration of breast feeding in most, but not all children, was apparent from model output.

Transcriptome-wide gene expression in a rat model of attention deficit hyperactivity disorder symptoms: rats developmentally exposed to polychlorinated biphenyls

Polychlorinated biphenyls (PCB) exposure in rodents provides a useful model for the symptoms of Attention deficit hyperactivity disorder (ADHD). The goal of this study is to identify genes whose expression levels are altered in response to PCB exposure. The brains from 48 rats separated into two age groups of 24 animals each (4 males and 4 females for each PCB exposure level (control, PCB utero, and PCB lactational)) were harvested at postnatal days 23 and 35, respectively. The RNA was isolated from three brain regions of interest and was analyzed for differences in expression of a set of 27,342 transcripts. Two hundred seventy-nine transcripts showed significant differential expression due to PCB exposure mostly due to the difference between PCB lactational and control groups. The cluster analysis applied to these transcripts revealed that significant changes in gene expression levels in PFC area due to PCB lactational exposure. Our pathway analyses implicated 27 significant canonical pathways and 38 significant functional pathways. Our transcriptome-wide analysis of the effects of PCB exposure shows that the expression of many genes is dysregulated by lactational PCB exposure, but not gestational exposure and has highlighted biological pathways that might mediate the effects of PCB exposure on ADHD-like behaviors seen in exposed animals. Our work should further motivate studies of fatty acids in ADHD, and further suggests that another potentially druggable pathway, oxidative stress, may play a role in PCB induced ADHD behaviors.

Non-cancer effects of chemical agents on children's health

This paper provides an overview about the non-cancer health effects for children from relevant chemical agents in our environment. In addition, a meta-analysis was conducted on the association between sudden infant death syndrome (SIDS) and maternal smoking during pregnancy as well as postnatal exposure to environmental tobacco smoke (ETS). In children, birth deformities, neurodevelopment, reproductive outcomes and respiratory system are mainly affected by chemical exposures. According to recent systematic reviews, evidence is sufficient for cognitive impairments caused by low lead exposure levels. Evidence for neurotoxicity from prenatal methylmercury exposure is sufficient for high exposure levels and limited for low levels. Prenatal exposure to polychlorinated biphenyls (PCB) and related toxicants results in cognitive and motor deficits. Maternal smoking during pregnancy is a risk factor for preterm birth, foetal growth deficit and SIDS. The meta-analytic pooled risk estimate for SIDS based on 15 studies is 2.94 (95% confidence interval: 2.43-3.57). Postnatal exposure to ETS was found to increase the SIDS risk by a factor of 1.72 (95% CI: 1.28-2.30) based on six studies which took into account maternal smoking during pregnancy. Additionally, postnatal ETS exposure causes acute respiratory infections, ear problems, respiratory symptoms, more severe asthma, and it slows lung growth. These health effects are also of concern for postnatal exposure to ambient and indoor air pollution. Children differ from adults with respect to several aspects which are relevant for assessing their health risk. Thus, independent evaluation of toxicity in childhood populations is essential.

Allergy and sensitization during childhood associated with prenatal and lactational exposure to marine pollutants

BACKGROUND

Breast-feeding may affect the risk of developing allergy during childhood and may also cause exposure to immunotoxicants, such as polychlorinated biphenyls (PCBs), which are of concern as marine pollutants in the Faroe Islands and the Arctic region.

OBJECTIVES

The objective was to assess whether sensitization and development of allergic disease is associated with duration of breast-feeding and prenatal or postnatal exposures to PCBs and methylmercury.

METHODS

A cohort of 656 singleton births was formed in the Faroe Islands during 1999-2001. Duration of breast-feeding and history of asthma and atopic dermatitis were recorded at clinical examinations at 5 and 7 years of age. PCB and mercury concentrations were determined in blood samples obtained at parturition and at follow-up. Serum from 464 children (71%) at 7 years of age was analyzed for total immunoglobulin E (IgE) and grass-specific IgE.

RESULTS

The total IgE concentration in serum at 7 years of age was positively associated both with the concomitant serum PCB concentration and with the duration of breast-feeding. However, the effect only of the latter was substantially attenuated in a multivariate analysis. A raised grass-specific IgE concentration compatible with sensitization was positively associated with the duration of breast-feeding and inversely associated with prenatal methylmercury exposure. However, a history of asthma or atopic dermatitis was not associated with the duration of breast-feeding, although children with atopic dermatitis had lower prenatal PCB exposures than did nonallergic children.

CONCLUSIONS

These findings suggest that developmental exposure to immunotoxicants may both increase and decrease the risk of allergic disease and that associations between breast-feeding and subsequent allergic disease in children may, at least in part, reflect lactational exposure to immunotoxic food contaminants.

Polychlorinated dioxins, furans, and biphenyls in blood of children and adults living in a dioxin-contaminated area in Tokyo

The soil of a residential area in Tokyo was found to contain dioxins, namely polychlorinated dioxins, furans, and dioxin-like biphenyls, the levels of which exceeded the environmental guideline [1,000 pg toxic equivalent (TEQ)/g] by up to 6.8 times. To assess the exposure levels of people living in this area and to study the possible relationship of blood dioxin concentrations of children with breast milk and/or formula feeding, a health survey was carried out in 2006, involving a total of 138 people, including 66 children aged 3-15 years, and blood dioxin concentrations and the characteristics and lifestyles of these people were analyzed. Mean ± standard error of the mean (SEM) of blood dioxin concentrations (pg/g-lipid) of group 1 (3-6 years old), group 2 (7-15 years old), and group 3 (≥16 years old) were 13 ± 1.9, 6.6 ± 0.65, and 10 ± 0.54, respectively. The congener/isomer profile of dioxins in blood samples differed markedly from that of the contaminated soil samples. According to the feeding mode of children, blood dioxin concentrations (pg/g-lipid) were 17 ± 2.9 for breast milk only, 7.4 ± 0.82 for both breast milk and formula, and 4.7 ± 1.1 for formula only, with a significant difference from one another. We conclude that people living in the dioxin-contaminated area are less likely to be exposed to excessive amounts of dioxins, and that blood dioxin concentrations of children aged 3-15 years seem to be strongly affected by breast feeding duration.

Relationships of putative endocrine disruptors to human sexual maturation and thyroid activity in youth

Endocrine disruption has become a significant human health concern, but is difficult to study outside of the laboratory for several reasons including the multiplicity of exposures, the difficulty in assessing each exposure, and the variety of possible outcomes among human populations. This review summarizes our studies of the relationships of measured persistent organic pollutants (PCBs, p,p'-DDE, HCB and mirex), and heavy metals (lead and mercury), to outcomes directly related to thyroid function and sexual maturation. These studies were conducted in a sample of Native American youth from the Akwesasne Mohawk community. The participants were first studied during puberty (10-16.9 years of age) and then at approximately 18 years of age. Results from these studies show that PCB levels are positively related to TSH and negatively to free T4. Further, these effects are conditioned by breastfeeding history. Anti-thyroid peroxidase antibody levels also are related to PCB levels suggesting elevated risk of autoimmune disease among the exposed. Earlier age at menarche is associated with higher PCB levels while risk of delay is associated with higher lead levels. Some evidence that the timing of exposure produces different effects is presented, and the level of exposure in the participants suggests that effects observed may be relevant to a considerable proportion of the US population. Further investigations are warranted to determine effect thresholds and mechanisms.

Allergy in day care children: prevalence and environmental risk factors

AIM

To investigate the prevalence of atopic disease among Finnish day care children and the relationship between atopy and environmental factors.

METHODS

A cross-sectional study of 594 day care children aged 1-6 years from Helsinki, Finland. Each child's history of atopic diseases and environmental exposure was collected in a questionnaire completed by the parents.

RESULTS

The prevalence of diagnosed asthma was 0.9% for the 1-3-year olds and 5.5% for the 4-6-year olds, atopic eczema/dermatis was 16% in both groups, and allergic rhinitis 5% in the younger group, 9% in the older group. According to multivariable logistic regression models, breastfeeding (exclusive > or =4 months or partial > or =6 months) reduced the risk of atopic diseases (OR = 0.60; CI(95) 0.39-0.93, p = 0.021). Atopic diseases were more common in the oldest age group, 5-6-year olds, compared to the youngest, 1-2-year olds (OR = 2.18; CI(95) 1.14-4.15, p = 0.018). One parent with atopic disease increased the child's risk (OR = 1.89; CI(95) 1.20-2.97, p = 0.006), more so if both parents had a history (OR = 3.17; CI(95) 1.48-6.78, p = 0.003).

CONCLUSION

Our results support the hypothesis that breastfeeding for at least six months may protect against atopic diseases. The child's greater age (5-6 years) and parental history of atopic diseases increased the risk of atopy.

Breastfeeding and atopic eczema in Japanese infants: The Osaka Maternal and Child Health Study

Epidemiological studies associated with breastfeeding have provided conflicting results about whether it is preventive or a risk factor for atopic eczema in children. The current prospective study investigated the relationship between breastfeeding and the risk of atopic eczema in Japan. A birth cohort of 763 infants was followed. The first survey during pregnancy and the second survey between 2 and 9 months postpartum collected information on potential confounding factors and atopic eczema status. Data on breastfeeding and symptoms of atopic eczema were obtained from questionnaires in the third survey from 16 to 24 months postpartum. The following variables were a priori selected as potential confounders: maternal age, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, indoor domestic pets (cats, dogs, birds, or hamsters), family income, maternal and paternal education, maternal smoking during pregnancy, baby's sex, baby's birth weight, baby's older siblings, household smoking in the same room as the infant, and time of delivery before the third survey. In the third survey, 142 infants (18.6%) were revealed to have developed atopic eczema based on criteria of the International Study of Asthma and Allergies in Childhood. In an overall analysis, neither exclusive nor partial breastfeeding was significantly related to the risk of atopic eczema. After excluding 64 infants identified with suspected atopic eczema in the second survey, both exclusive breastfeeding for 4 months or more and partial breastfeeding for 6 months or more were independently associated with an increased risk of atopic eczema only among infants with no parental history of allergic disorders [multivariate odds ratios were 2.41 (95% confidence interval, 1.10-5.55) and 3.39 (95% confidence interval, 1.20-12.36), respectively]. The authors found that, overall, neither exclusive nor partial breastfeeding had a strong impact on the risk of atopic eczema. However, a parental allergic history may affect the risk.

Prenatal exposure to polychlorinated biphenyls: a neuropsychologic analysis

OBJECTIVES

A large body of literature documents the effects of prenatal exposure to polychlorinated biphenyls (PCBs) on cognitive development of children. Despite this fact, no integrative synthesis has been published yet to identify the cognitive functions that are particularly affected. Our aim is to review this literature in an attempt to identify the cognitive profile associated with prenatal PCB exposure.

DATA SOURCES

Studies were identified by searching the PubMed database for articles published before June 2008. We reviewed data from nine prospective longitudinal birth cohorts for different aspects of cognition.

DATA EXTRACTION

Associations between indicators of prenatal PCB exposure and performance on cognitive tasks reported in the selected studies are summarized and classified as general cognitive abilities, verbal or visual-spatial skills, memory, attention, and executive functions.

DATA SYNTHESIS

The most consistent effects observed across studies are impaired executive functioning related to increased prenatal PCB exposure. Negative effects on processing speed, verbal abilities, and visual recognition memory are also reported by most studies. Converging results from different cohort studies in which exposure arises from different sources make it unlikely that co-exposure with another associated contaminant is responsible for the observed effects.

CONCLUSION

Prenatal PCB exposure appears to be related to a relatively specific cognitive profile of impairments. Failure to assess functions that are specifically impaired may explain the absence of effects found in some studies. Our findings have implications in the selection of cognitive assessment methods in future studies.

Breastfeeding and the risk of wheeze and asthma in Japanese infants: the Osaka Maternal and Child Health Study

Epidemiological evidence for an effect of breastfeeding on asthma continues to be inconclusive. The present prospective study examined the relationship between breastfeeding and the risk of wheeze and asthma in Japanese infants. A birth cohort of 763 infants was followed. The first survey during pregnancy and the second survey between 2 and 9 months postpartum collected information on potential confounding factors. Data on breastfeeding, wheeze, and asthma were obtained from questionnaires in the third survey from 16 to 24 months postpartum. Adjustment was made for maternal age, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, indoor domestic pets (cats, dogs, birds, or hamsters), family income, maternal and paternal education, maternal smoking during pregnancy, baby's sex, baby's older siblings, household smoking in the same room as the infant, and time of delivery before the third survey. By the third survey, the cumulative incidence of wheeze and asthma was 22.1% and 4.3%, respectively. Neither exclusive breastfeeding for 4 months or more nor partial breastfeeding for 6 months or more were materially related to the risk of wheeze. No measurable association was observed between exclusive breastfeeding for 4 months or more and the risk of asthma. Partial breastfeeding for 6 months or more was inversely related to the risk of asthma although the adjusted odds ratio (OR) was not statistically significant. When infants were stratified according to whether there was a negative or positive allergic history in at least 1 parent, a nearly 40% and 60% decrease, respectively, in the ORs were found for exclusive and partial breastfeeding only in infants without a parental allergic history, although the ORs were not statistically significant. The present prospective study showed no statistically significant relationship between breastfeeding duration and the risk of wheeze or asthma in Japanese infants.

Fish consumption and PCB-associated health risks in recreational fishermen on the James River, Virginia

Consumption of sport-caught fish contaminated with high levels of polychlorinated biphenyls (PCBs) may pose human health risks. To obtain estimates of fish consumption and fishing behaviors in recreational fishermen in Virginia, on-site interviews (n=143; 134 men and 9 women) were conducted at seven public boat landings along the James River. Using existing PCB concentration data from James River fish tissue samples collected from 1997, and 1999 to 2001, default and point estimates were calculated and Monte Carlo analyses conducted to estimate potential risks under different consumption scenarios. A mean of 55 fish meals/yr and 14 James River sport-caught fish (JRSCF) meals/yr were reported. Caucasians fished less often (mean of 58 d), consumed less fish (mean of 43 meals/yr) and had smaller portion sizes (mean of 11.7 oz) compared to other races combined (130 d; 82 meals/yr; and 15.6 oz). On average, respondents reported consuming 10 meals of James River catfish a year (5 kg/yr). Risk estimates produced from Monte Carlo analysis were consistently lower than the default and point estimates. Several individuals exceeded acceptable risk levels and the mean cancer and non-cancer risks among catfish consumers exceeded acceptable levels. Eighteen percent of individuals had no knowledge of fish advisories in Virginia and 4% of the subjects indicated they would consume fish under advisory. Based on reported consumption, a significant risk to recreational fishermen, as a result of consuming PCB-contaminated catfish, was found. Risks associated with consuming other species were within acceptable limits.

Cross-sectional study of allergic disorders associated with breastfeeding in Japan: the Ryukyus Child Health Study

Uncertainties remain as to whether breastfeeding is protective against childhood allergic disorders. Positive relationships of breastfeeding with asthma and atopic eczema were observed in two previous Japanese studies. This cross-sectional study investigated the association between the feeding pattern after birth and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 24,077 children aged 6-15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Allowance was made for age, sex, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Breastfeeding, regardless of exclusivity, for 13 months or longer and exclusive breastfeeding for 4-11 months were independently associated with a higher prevalence of atopic eczema, particularly among children without a parental allergic history. A clear positive dose-response relationship was observed between prolonged duration of breastfeeding, regardless of exclusivity, but not exclusive breastfeeding, and the prevalence of atopic eczema. We found a significant positive trend for atopic eczema across the three categories (formula milk, partial and exclusive breastfeeding) in the first 4 months of life although the odds ratio for exclusive breastfeeding was not statistically significant. No material association was found between the feeding pattern after birth and the prevalence of wheeze or allergic rhinoconjunctivitis. Prolonged breastfeeding may be associated with a higher prevalence of atopic eczema in Japanese children.

Neuro-genetic multioptimization of the determination of polychlorinated biphenyl congeners in human milk by headspace solid phase microextraction coupled to gas chromatography with electron capture detection

Polychlorinated biphenyls (PCB) can eventually contaminate breast milk, which is a serious issue to the newborn due to their high vulnerability. Solid phase microextraction (SPME) can be a very convenient technique for their isolation and pre-concentration prior chromatographic analysis. Here, a simultaneous multioptimization strategy based on a neuro-genetic approach was applied to a headspace SPME method for determination of 12 PCB in human milk. Gas chromatography with electron capture detection (ECD) was adopted for the separation and detection of the analytes. Experiments according to a Doehlert design were carried out with varied extraction time and temperature, media ionic strength and concentration of the methanol (co-solvent). To find the best model that simultaneously correlate all PCB peak areas and SPME extraction conditions, a multivariate calibration method based on a Bayesian Neural Network (BNN) was applied. The net output from the neural network was used as input in a genetic algorithm (GA) optimization operation (neuro-genetic approach). The GA pointed out that the best values of the overall SPME operational conditions were the saturation of the media with NaCl, extraction temperature of 95 degrees C, extraction time of 60 min and addition of 5% (v/v) methanol to the media. These optimized parameters resulted in the decrease of the detection limits and increase on the sensitivity for all tested analytes, showing that the use of neuro-genetic approach can be a promising way for optimization of SPME methods.

Reducing exposure to dioxins and related compounds through foods in the next generation

Dioxins and related compounds are undesirable and unintended contaminants in the food supply, and dietary intake is the major route of exposure. Reducing dietary exposure to dioxins among the most vulnerable segments of the population (i.e., pregnant women, infants, and young girls) is an effective strategy for reducing body burdens in future generations. Exposure to dioxins through foods can be minimized by selecting lower-fat versions of meats, poultry, and dairy products. Consuming all foods, including fatty fish, in recommended amounts is congruent with the goal of reducing dioxin intake exposure and maintaining good health.

Serum polychlorinated biphenyl and organochlorine insecticide concentrations in a Faroese birth cohort

A prospective birth cohort of 1022 participants was established in the Faroe Islands over a 21-month period during 1986-1987. We collected questionnaire data on potential persistent organic pollutant (POP) concentration predictors, such as duration of breastfeeding and blubber consumption. To assess the participants' exposure from in utero to 14 years of age to polychlorinated biphenyls (PCBs) and the insecticide p,p'-DDT and its primary degradate p,p'-DDE, we measured 37 PCB congeners and pesticides in 316 umbilical cord samples taken from participants at birth, in 124 serum samples collected from participants at approximately 7 years of age, and in 795 serum samples collected from participants at 14 years of age. Measurements of higher chlorination PCB congeners made on individuals' serum samples collected at 7 years and 14 years were highly correlated (typically r > 0.5, p > 0.01), although their concentrations at 7 years were generally two to three times higher than at 14 years. Similarly, umbilical cord PCB concentrations were correlated with PCB concentrations in both 7- and 14-year serum samples. Sex-specific differences in higher chlorination PCB and p,p'-DDE concentrations were found at 14 years but not at 7 years, although a sex interaction with blubber consumption and nursing duration was observed at both ages. Both duration of breastfeeding and consumption of blubber were significant predictors of serum summationPCB concentrations at 7 and 14 years. Multivariate analyses showed that breastfeeding duration was the primary contributor to serum summationPCB concentrations at 7 years, and blubber consumption was the primary contributor at 14 years. These data suggest that infant exposures from breastfeeding were sufficiently large so that continued exposures to PCBs, p,p'-DDT, and p,p'-DDE through the diet have not fully diluted their contribution to the summationPCB and p,p'-DDE body burden of the children.

Predictors of serum dioxin levels among adolescent boys in Chapaevsk, Russia: a cross-sectional pilot study

BACKGROUND

Toxicological studies and limited human studies have demonstrated associations between exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) and adverse developmental and reproductive health effects. Given that children may be particularly susceptible to reproductive and developmental effects of organochlorines, and the paucity of information available regarding childhood exposures to dioxins in particular, we undertook a pilot study to describe the distribution of, and identify potential predictors of exposure to, dioxin-like compounds and dioxins among adolescent boys in Chapaevsk, Russia. The pilot study was also designed to guide the development of a large prospective cohort study on the relationship of exposure to PCDDs, PCDFs, and PCBs with growth and pubertal development in peri-pubertal Chapaevsk boys.

METHODS

221 boys age 14 to 17 participated in the pilot study. Each of the boys, with his mother, was asked to complete a nurse-administered detailed questionnaire on medical history, diet, and lifestyle. The diet questions were used to measure the current and lifetime consumption of locally grown or raised foods. Blood samples from 30 of these boys were sent to the Centers for Disease Control and Prevention (CDC) for analysis of dioxins, furans and PCBs.

RESULTS

The median (25th, 75th percentile) concentrations for total PCDDs, PCDFs and coplanar PCBs were 95.8 pg/g lipids (40.9, 144), 33.9 pg/g lipids (20.4, 61.8), and 120 pg/g lipids (77.6, 157), respectively. For WHO-TEQs, the median (25th, 75th percentile) for total PCDDs, PCDFs, and coplanar PCBs were 0.29 (0.1, 9.14), 7.98 (5.27, 12.3), and 7.39 (4.51, 11.9), respectively. Although TCDD was largely non-detectable, two boys had high TCDD levels (17.9 and 21.7 pg/g lipid). Higher serum levels of sum of dioxin-like compounds and sum of dioxin TEQs were positively associated with increased age, consumption of fish, local meats other than chicken, PCB 118, and inversely with weeks of gestation.

CONCLUSION

The total TEQs among Chapaevsk adolescents were higher than most values previously reported in non-occupationally exposed populations of comparable or even older ages. Dietary consumption of local foods, as well as age and weeks of gestation, predicted dioxin exposure in this population.

Prenatal exposure to polychlorinated biphenyls and breastfeeding: opposing effects on auditory P300 latencies in 9-year-old Dutch children

Effects of perinatal exposure to polychlorinated biphenyls (PCBs) on auditory P300 latencies and amplitudes were evaluated in children from a Rotterdam cohort. From this cohort of healthy, term babies, the 26 lowest and 26 highest prenatally PCB-exposed children from the breastfed and the formula-fed groups (n=104) were invited for P300 assessment when they were 9 years of age. For P300 assessment an auditory simple odd-ball paradigm was used. In the 83 participating children, 60 assessments (32 males, 28 females) satisfied the measurement criteria and were included in the data analyses. After adjusting for confounding variables, children with high prenatal exposure were found to have longer P300 latencies than children with low prenatal exposure. Lactational exposure to PCBs through breastfeeding milk was not related to P300 latencies. P300 latencies were shorter in children breast-fed for at least 16 weeks than in children breastfed for 6 to 16 weeks and formula-fed children. P300 amplitudes were not related to perinatal PCB exposure nor breastfeeding. Results of this exploratory study suggest that prenatal exposure to environmental levels of PCBs and related compounds delays mechanisms in the central nervous system that evaluate and process relevant stimuli, whereas breastfeeding accelerates these mechanisms.

Persistent hematologic and immunologic disturbances in 8-year-old Dutch children associated with perinatal dioxin exposure

Perinatal exposure to Dutch "background" dioxin levels in 1990 was high, but comparable with that of other industrialized Western European countries. Exposure during the sensitive perinatal period may cause permanent disturbances. Therefore, we assessed the health status and various hematologic and immunologic parameters among our longitudinal cohort. A medical history was taken and venipuncture performed in a longitudinal cohort of 27 healthy 8-year-old children who had documented perinatal dioxin exposure. Linear regression revealed a decrease in allergy in relation to prenatal (p = 0.02) and postnatal (p = 0.03) dioxin exposure. Increases in CD4+ T-helper cells (p = 0.006) and in CD45RA+ cells (p = 0.02) were seen in relation to postnatal exposure. A persistently decreased platelet count (p = 0.04) and increased thrombopoietin concentration (p = 0.03) were seen in relation to postnatal exposure. This follow-up has shown a decrease in allergy, persistently decreased thrombocytes, increased thrombopoietin, and increased CD4+ T-helper and increased CD45RA+ cell counts. This study provides indications of effects at the stem cell level of perinatal dioxin exposure, persisting until minimally 8 years after birth.

Assessment of pre- and postnatal exposure to polychlorinated biphenyls: lessons from the Inuit Cohort Study

Polychlorinated biphenyls (PCBs) are food-chain contaminants that have been shown to induce adverse developmental effects in humans. In the course of an epidemiologic study established to investigate neurodevelopmental deficits induced by environmental PCB exposure in the Inuit population of northern Québec (Nunavik, Canada), we compared three biomarkers of prenatal exposure and models to predict PCB plasma concentration at 6 months postpartum. Concentrations of 14 PCB congeners were measured by high-resolution gas chromatography with electron capture detection in lipids extracted from maternal plasma, cord plasma, breast milk (collected at approximately 1 month postpartum), and 6-month-old infant plasma samples. Similar congener profiles were observed in all biologic samples, and PCB-153, the most abundant and persistent PCB congener, was strongly correlated with other frequently detected PCB congeners in all biologic media. When expressed on a lipid basis, maternal plasma, cord plasma, and milk concentrations of this congener were strongly intercorrelated, indicating that PCB concentration in any of these biologic media is a good indicator of prenatal exposure to PCBs. A multivariate model that included maternal PCB-153 plasma lipid concentration, breast-feeding duration, and the sum of two skin-fold thicknesses (an index of infant body fat mass) explained 72% of PCB-153 plasma concentration variance at 6 months postpartum (p < 0.001). By contrast, based on the product of breast-feeding duration times the concentration of PCBs in plasma lipids, which was used as an index of postnatal PCB exposure in several studies, only 36% of infant plasma concentration was explained.

Comparison of dioxin and PCB concentrations in human breast milk samples from Hong Kong and the Netherlands

The adverse effects of dioxins and polychlorinated biphenyls (PCBs) on human health are of increasing concern. These lipophilic compounds are concentrated through the food chain and are present in human milk. This study compares PCB levels in human milk samples from Hong Kong and Dutch mothers. Ten breast milk samples from Hong Kong and 10 from the Netherlands were collected during home visits between 2 and 6 weeks postpartum. Total toxic equivalence (TEQ) of dioxin and PCBs were determined using the DR-CALUX(R) bioassay. The total dioxin and PCB levels in breast milk samples for Hong Kong ranged from 3.1 to 29.9 pg TEQ g(-1) lipid and for the Netherlands from 8.9 to 89.5 pg TEQ g(-1) lipid. Despite Hong Kong's high degree of industrialization, the levels of dioxin and PCBs were fourfold lower in the Hong Kong than in the Dutch samples. This may be due to a lower dietary intake of dioxins and PCBs in Hong Kong because of lower background levels of these contaminants or to different food habits.

Infant exposure to dioxin-like compounds in breast milk

We used a one-compartment, first-order pharmacokinetic model to predict the infant body burden of dioxin-like compounds that results from breast-feeding. Validation testing of the model showed a good match between predictions and measurements of dioxin toxic equivalents (TEQs) in breast-fed infants, and the exercise highlighted the importance of the assumption of the rate of dissipation of TEQs in the infant. We evaluated five nursing scenarios: no nursing (i.e., formula only), and nursing for 6 weeks, 6 months, 1 year, and 2 years. We assumed that an infant weighs 3.3 kg at birth and is exposed to a total of 800 pg TEQ/day by consumption of breast milk, leading to an estimated body weight-based dose of 242 pg TEQ/kg-day, which drops to 18 pg TEQ/kg-day after 1 year. This decline is due to declines in dioxin concentration in mother's milk and infant body weight increases. This range is significantly higher, on a body-weight basis, than adult TEQ exposure, which has been estimated to average about 1 pg TEQ/kg-day. For the nursing scenarios of >or= 6 months, we predict that body burdens (expressed as a body lipid concentration) peak at around 9 weeks at 44 ppt TEQ lipid. We predict that the body burden of the formula-fed infants will remain below 10 ppt TEQ lipid during the first year. These results compare to the current adult average body burden of 25 ppt TEQ lipid. We also found that an infant who had been breast-fed for 1 year had an accumulated dose 6 times higher than a 1-year-old infant who had not been breast-fed. For a 70-year lifetime, individuals who had been breast-fed had an accumulated dose 3-18% higher than individuals who had not been breast-fed.

Effects of prenatal PCB and dioxin background exposure on cognitive and motor abilities in Dutch children at school age

OBJECTIVE

Our purpose was to evaluate whether effects of exposure to environmental levels of PCBs and dioxins on development in the Dutch cohort persist until school age.

STUDY DESIGN

In the Dutch PCB/dioxin study, cognitive and motor abilities were assessed with the McCarthy Scales of Children's Abilities in children at school age. During infancy, half of this population was fully breast-fed for at least > or = 6 weeks and the other half formula fed. Prenatal exposure to PCBs was defined as the sum of PCB118, 138, 153, and 180 in maternal and cord plasma. In breast milk, additional measurements of 17 dioxins, 6 dioxin-like PCBs, and 20 nondioxin-like PCBs were done.

RESULTS

Negative effects of prenatal PCB and dioxin exposure on cognitive and motor abilities were seen when parental and home characteristics were less optimal. These effects were not measurable in children raised in more optimal environments.

CONCLUSIONS

Neurotoxic effects of prenatal PCB and dioxin exposure may persist into school age, resulting in subtle cognitive and motor developmental delays. More optimal intellectual stimulation provided by a more advantageous parental and home environment may counteract these effects of prenatal exposure to PCBs and dioxins on cognitive and motor abilities.

Diet and organochlorine contaminants in women of reproductive age under 40 years old

The diet of the breast-feeding mother impacts on the quality and quantity of the milk that she feeds her child. Milk can be a vehicle for toxins, such as drugs and their metabolites, viruses, nicotine, caffeine, alcohol, and organochlorine molecules such as PCBs, DDT, HCB, HCH and dioxins, which can harm the health of the breast-feeding child. The 24-h recall diet was considered appropriate to adequately study the diet of breast-feeding mothers and was used in the present preliminary study to establish the possible relationship between the food items consumed and the presence of pesticides in her milk. Two groups of randomly selected healthy breast-feeding volunteers aged between 17 and 35 years from two different areas were recruited: 34 from intensive agriculture zone, El Ejido (Almeria), from the "Hospital de Poniente" and 21 urban zone, the city of Granada, from the "Clinico" University Hospital. Application of the Spearman Correlation Test to the results from Almeria showed a certain positive correlation between the total intake of fats and both the p,p'DDD (rho=0.53, p< or =0.05) and methoxychlor (rho=0.48, p< or =0.05) in mature milk, and between the energy supplied by vegetables and the endosulfan-lactone in mature milk (rho=0.50, p< or =0.05). Among the group of breast-feeding women from Granada, there was a strong correlation between the intake of fats and both the p,p'DDT in transition milk (rho=0.90, p< or =0.05) and the p,p'DDD in mature milk (rho=0.90, p< or =0.05). In conclusion, there is a statistically significant relationship between the consumption of fatty foods and some organochlorine molecules and between the consumption of vegetables and pesticides, and the latter relationship occurs in Almeria but not in Granada.

Immunologic effects of background exposure to polychlorinated biphenyls and dioxins in Dutch preschool children

Prenatal exposure to polychlorinated biphenyls (PCBs) and dioxins is associated with changes in the T-cell lymphocyte population in healthy Dutch infants. We investigated whether these changes persist into later childhood and whether background exposure to PCBs and dioxins is associated with the prevalence of infectious or allergic diseases and humoral immunity at preschool age. The total study group consisted of 207 healthy mother-infant pairs. We estimated prenatal exposure to PCBs and dioxins by the sum of PCBs 118, 138, 153, and 180 (sigmaPCB) in maternal and cord plasma and in breast-fed infants by the dioxin, planar, and mono-ortho PCB toxic equivalent (TEQ) levels in human milk. At 42 months of age, current body burden was estimated by the PCB in plasma. We assessed the prevalence of infectious and allergic diseases by parent questionnaire, and measured humoral immunity by antibody levels for mumps, measles, and rubella after primary vaccination. We performed immunologic marker analyses of lymphocytes in a subgroup of 85 children. Prenatal PCB exposure was associated with an increased number of lymphocytes, T-cells, and CD3CD8(+) (cytotoxic), CD4(+)CD45RO(+) (memory), T-cell receptor (TcR) [alpha]ss(+), and CD3(+)HLA-DR(+) (activated) T cells and lower antibody levels to mumps and measles at preschool age. Adjusted for confounders, prenatal PCB exposure was associated with less shortness of breath with wheeze, and current PCB body burden was associated with a higher prevalence of recurrent middle-ear infections and of chicken pox and a lower prevalence of allergic reactions. A higher dioxin TEQ was associated with a higher prevalence of coughing, chest congestion, and phlegm. We conclude that in Dutch preschool children the effects of perinatal background exposure to PCBs and dioxins persist into childhood and might be associated with a greater susceptibility to infectious diseases. Common infections acquired early in life may prevent the development of allergy, so PCB exposure might be associated with a lower prevalence of allergic diseases.

Immunologic effects of background exposure to polychlorinated biphenyls and dioxins in Dutch preschool children

Prenatal exposure to polychlorinated biphenyls (PCBs) and dioxins is associated with changes in the T-cell lymphocyte population in healthy Dutch infants. We investigated whether these changes persist into later childhood and whether background exposure to PCBs and dioxins is associated with the prevalence of infectious or allergic diseases and humoral immunity at preschool age. The total study group consisted of 207 healthy mother-infant pairs. We estimated prenatal exposure to PCBs and dioxins by the sum of PCBs 118, 138, 153, and 180 (sigmaPCB) in maternal and cord plasma and in breast-fed infants by the dioxin, planar, and mono-ortho PCB toxic equivalent (TEQ) levels in human milk. At 42 months of age, current body burden was estimated by the PCB in plasma. We assessed the prevalence of infectious and allergic diseases by parent questionnaire, and measured humoral immunity by antibody levels for mumps, measles, and rubella after primary vaccination. We performed immunologic marker analyses of lymphocytes in a subgroup of 85 children. Prenatal PCB exposure was associated with an increased number of lymphocytes, T-cells, and CD3CD8(+) (cytotoxic), CD4(+)CD45RO(+) (memory), T-cell receptor (TcR) [alpha]ss(+), and CD3(+)HLA-DR(+) (activated) T cells and lower antibody levels to mumps and measles at preschool age. Adjusted for confounders, prenatal PCB exposure was associated with less shortness of breath with wheeze, and current PCB body burden was associated with a higher prevalence of recurrent middle-ear infections and of chicken pox and a lower prevalence of allergic reactions. A higher dioxin TEQ was associated with a higher prevalence of coughing, chest congestion, and phlegm. We conclude that in Dutch preschool children the effects of perinatal background exposure to PCBs and dioxins persist into childhood and might be associated with a greater susceptibility to infectious diseases. Common infections acquired early in life may prevent the development of allergy, so PCB exposure might be associated with a lower prevalence of allergic diseases.

Effects of polychlorinated biphenyls on the nervous system

The neurological effects of polychlorinated biphenyls (PCBs) have been extensively investigated in humans and in animals. The main focus in human studies has been on the effects in neonates and young children, although studies of adults have also been conducted. A great deal of concern exists that even low levels of PCBs transferred to the fetus across the placenta may induce long-lasting neurological damage. Because PCBs are lipophilic substances, there is also concem that significant amounts might be transferred to nursing infants via breast milk. Studies in humans who consumed large amounts of Great Lakes fish contaminated with environmentally persistent chemicals, including PCBs. have provided evidence that PCBs are important contributors to subtle neurobehavioral alterations observed in newborn children and that some of these alterations persist during childhood. Some consistent observations at birth have been motor immaturity and hyporeflexia and lower psychomotor scores between 6 months and 2 years old. There is preliminary evidence that highly chlorinated PCB congeners, which accumulate in certain fish, are associated with neurobehavioral alterations seen in some newbom children. Subtle neurobehavioral alterations have also been observed in children bom to mothers in the general population with the highest PCB body burdens. Because of the limitations of epidemiological studies, these effects cannot be attributed entirely to PCB exposure. In one general population study, there was strong evidence that dioxins, as well as PCBs, were contributors to the neurobehavioral effects seen in exposed children. Children born to women who accidentally consumed rice oil contaminated with relatively high amounts of PCBs and chlorinated dibenzofurans (CDFs) during pregnancy also had neurodevelopmental changes. Studies in animals support the human data. Neurobehavioral alterations have been also observed in rats and monkeys following prenatal and/or postnatal exposure to commercial Aroclor mixtures, defined experimental congener mixtures, single PCB congeners, and Great Lakes contaminated fish. In addition, monkeys exposed postnatally to PCB mixtures of congeneric composition and concentration similar to that found in human breast milk showed learning deficits long after exposure had ceased. A few other generalizations can be made from the data in animals. It appears that ortho-substituted PCB congeners are more active than coplanar PCBs in modifying cognitive processes. In addition, one effect observed in both rats and monkeys--deficits on delayed spatial alternation--has been known to be induced by exposure to ortho-substituted PCBs, defined experimental mixtures, and commercial Aroclors. Both dioxin-like and non-dioxin-like PCB congeners have been shown to induce neurobehavioral alterations in animals. Changes in levels of neurotransmitters in various brain areas have also been observed in monkeys, rats, and mice. Of all the observed changes, the most consistent has been a decrease in dopamine content in basal ganglia and prefrontal cortex, but further research is needed before specific neurobehavioral deficits can be correlated with PCB-induced changes in specific neurotransmitters in specific brain areas.

Health risks to infants from exposure to PCBs, PCDDs and PCDFs

Global contamination by a variety of anthropogenic persistent organic chemicals, such as dioxins and PCBs, has resulted in human exposure throughout all phases of development. Detectable concentrations of PCBs and dioxins have been found in amniotic fluid, placenta and foetal tissue samples while infants who are breast-fed can obtain blood levels greater than those of their mother's. In two separate food poisoning episodes where infants were exposed in utero to elevated levels of heat-degraded PCBs (PCBs, PCQs, PCDFs), a variety of adverse mental and physical developmental abnormalities have been observed. In additional human cohorts where exposure could be considered as environmental or background, more subtle effects, including lower birth weights, alterations in thyroid hormones and lymphocyte subpopulations and detriments in neurological development, have been consistently seen. In most instances, negative associations were made between in utero exposure to contaminants compared with lactational. Although the observed neurodevelopmental deficits have been described as subtle, there could be unknown consequences related to future intellectual functionality. Current regulatory efforts should focus on identification and control of environment and food chain contamination as in utero exposure is a direct consequence of the accumulated maternal body burdens.

Effects of environmental exposure to polychlorinated biphenyls and dioxins on cognitive abilities in Dutch children at 42 months of age

OBJECTIVE

To study possible adverse effects of environmental exposure to polychlorinated biphenyls (PCB) and dioxins on cognitive functioning in young children.

METHODS

In a follow-up of the Dutch PCB/Dioxin study, cognitive abilities were assessed with the Kaufman Assessment Battery for Children in 42-month-old children (n = 395). In a subgroup (n = 193) verbal comprehension was assessed with the Reynell Language Developmental Scales. Prenatal PCB exposure was estimated from the sum of PCBs 118, 138, 153, and 180 (SigmaPCB) in maternal plasma. Lactational exposure was assessed from breast milk PCB and dioxin concentrations, multiplied by the number of weeks of breast-feeding. Current PCB body burden was estimated from SigmaPCB in 42-month-old plasma samples.

RESULTS

After adjustment was done for covariables, maternal SigmaPCB was associated with lower scores on the overall cognitive and sequential and simultaneous processing scales of the Kaufman Assessment Battery for Children (all P <.05). The highest exposed group (SigmaPCB >/= 3 microg/L) scored 4 points lower on all 3 scales of the K-ABC when compared with the lowest exposed group (SigmaPCB < 1.5 microg/L). Both lactational exposure and current exposure to PCBs and dioxins were not related to 42-month cognitive performance.

CONCLUSIONS

In utero exposure to "background" PCB concentrations is associated with poorer cognitive functioning in preschool children. Children of mothers at the upper end of exposure are especially at risk. Therefore maternal PCB body burden should be reduced, and breast-feeding should not be discouraged.

Dietary exposure to polychlorinated biphenyls and dioxins from infancy until adulthood: A comparison between breast-feeding, toddler, and long-term exposure

Food is the major source for polychlorinated biphenyl (PCB) and dioxin accumulation in the human body. Therefore, investigating food habits from early ages until reproductive age (25 years) is important in order to assess exposure risk for the next generation. The objective of this study was to assess the PCB/dioxin exposure and the relative contribution of different foods to total exposure during preschool age. Particularly, the importance of lactational PCB/dioxin exposure vs. dietary exposure until adulthood was investigated. A cohort of 207 children was studied from birth until preschool age. Based on 3 planar PCBs and 17 2,3,7,8-substituted dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) measured in breast milk, a model was developed to calculate the cumulative toxic equivalent (TEQ) intake during breast-feeding (0-1 year). In 3. 5-year-old children, daily dietary intake of planar PCB-TEQ and dioxin-TEQ was measured with a validated food questionnaire. Cumulative TEQ intake from 1 to 5 years was estimated using the PCB- and dioxin-TEQ intake measured with the food questionnaire. Cumulative TEQ intake from 6 to 25 years was estimated using national food consumption and contamination data of PCB- and dioxin-TEQ intake. In toddlers, dairy products contributed 43% to PCB-TEQ and 50% to dioxin-TEQ intake. Meat and meat products contributed 14% and 19%, respectively, and processed foods 23% and 15%, respectively. Breast-feeding for 6 months contributed to the cumulative PCB/dioxin TEQ intake until 25 years of age, 12% in boys and 14% in girls. The daily TEQ intake per kilogram body weight is 50 times higher in breast-fed infants and three times higher in toddlers than in adults. Long-term dietary exposure to PCBs and dioxins in men and women is partly due to breast-feeding (12 and 14%, respectively). After weaning, dairy products, processed foods, and meat are major contributors of PCB and dioxin accumulation until reproductive age. Instead of discouraging breast-feeding, maternal transfer of PCBs and dioxins to the next generation must be avoided by enforcement of strict regulations for PCB and dioxin discharge and by reducing consumption of animal products and processed foods in all ages.