Musculoskeletal changes in children prenatally exposed to polychlorinated biphenyls and related compounds (Yu-Cheng children)

Mixture of air pollution, brominated flame retardants, polychlorinated biphenyls, per- and polyfluoroalkyl substances, and organochlorine pesticides in relation to vitamin D concentrations in pregnancy

Over two-thirds of pregnant women in the U.S. have insufficient 25(OH)D (Vitamin D) concentrations, which can adversely impact fetal health. Several pollutants have been associated with 25(OH)D, but have not been considered in the context of chemical co-exposures. We aimed to determine associations between a broad mixture of prenatal environmental chemical exposures and 25(OH)D concentrations in mid-pregnancy. Stored mid-pregnancy serum samples were assayed from 421 women delivering live births in Southern California in 2000-2003. 25(OH)D, six BFRs, eleven polychlorinated biphenyls (PCBs), six per- and polyfluoroalkyl substances, and two organochlorine pesticides were detected in ≥60% of specimens. Gestational exposures to airborne particulate matter ≤ 10 μm (PM10) and ≤ 2.5 μm (PM2.5), nitrogen monoxide (NO), nitrogen dioxide (NO2), and ozone concentrations were derived from monitoring station data. Bayesian Hierarchical Modeling (BHM) and Bayesian Kernel Machine Regression (BKMR) analyses estimated overall mixture and individual chemical associations accounting for co-exposures and covariates with mean 25(OH)D levels, and BHM was used to estimate associations with insufficient (<75 nMol/L) 25(OH)D levels. Non-mixture associations for each chemical were estimated with linear and logistic models. PM10 [BHM estimate: -0.133 nmol/l 95% Credible Interval (-0.240, -0.026)] was associated with lower 25(OH)D in BHM and BKMR. Higher quantiles of combined exposures were associated with lower 25(OH)D, though with wide credible intervals. In non-mixture models, PM10, PM2.5, NO, and NO2 were associated with lower concentrations, while O3 and PBDE153 were associated with higher 25(OH)D and/or lower insufficiency. While some chemicals were associated with increased and others with decreased 25(OH)D concentrations, the overall mixture was associated with lower concentrations. Mixture analyses differed from non-mixture regressions, highlighting the importance of mixtures approaches for estimating real-world associations.

Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer's disease, Parkinson's disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood-brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population.

2,3',4,4',5-Pentachlorobiphenyl attenuated fast-twitch fibers and fiber size of skeletal muscle via disturbing thyroid hormone signaling and mitochondrial dynamics

Polychlorinated biphenyls (PCBs) affect multiple organs, and some of the effects are mediated by interfering with thyroid hormone (TH) signaling that regulates physiological processes in mammals. It remains unclear how PCBs affect skeletal muscle (SM). In our study, wistar rats were injected 2,3',4,4',5-Pentachlorobiphenyl (PCB118) intraperitoneally at 0, 10, 100, and 1,000 μg / kg / day for 13 weeks and C2C12 myoblasts were treated PCB118 (0, 0.25, 25, and 50 nM) for 24 hours or 48 hours. We found that myocyte cross sectional area (MCSA) was reduced, MyHC IIa and MyHC IIb mRNA levels significantly decreased, and muscle strength was weakened in PCB118-exposed rats. TH receptor α (TRα) and iodothyronine deiodinase type 2 (DIO2) were upregulated after PCB118 exposure both in vivo and vitro. Transmission electron microscopy showed significant mitochondrial abnormalities in PCB118-treated rats, and the expression of mitochondrial regulators such as PTEN-induced kinase 1 (PINK1) and GTPase dynamin-related protein 1 (DRP1) were altered after PCB118 exposure. These results suggest that PCB118 could weaken muscle strength and attenuate fast-twitch fibers and fiber size of SM in rats. TH signaling, mitochondrial dynamics and mitophagy were also disturbed by PCB118, which may contribute to the alternations of SM structure and function.

Environmental Factors That Affect Parathyroid Hormone and Calcitonin Levels

Calciotropic hormones, parathyroid hormone (PTH) and calcitonin are involved in the regulation of bone mineral metabolism and maintenance of calcium and phosphate homeostasis in the body. Therefore, an understanding of environmental and genetic factors influencing PTH and calcitonin levels is crucial. Genetic factors are estimated to account for 60% of variations in PTH levels, while the genetic background of interindividual calcitonin variations has not yet been studied. In this review, we analyzed the literature discussing the influence of environmental factors (lifestyle factors and pollutants) on PTH and calcitonin levels. Among lifestyle factors, smoking, body mass index (BMI), diet, alcohol, and exercise were analyzed; among pollutants, heavy metals and chemicals were analyzed. Lifestyle factors that showed the clearest association with PTH levels were smoking, BMI, exercise, and micronutrients taken from the diet (vitamin D and calcium). Smoking, vitamin D, and calcium intake led to a decrease in PTH levels, while higher BMI and exercise led to an increase in PTH levels. In terms of pollutants, exposure to cadmium led to a decrease in PTH levels, while exposure to lead increased PTH levels. Several studies have investigated the effect of chemicals on PTH levels in humans. Compared to PTH studies, a smaller number of studies analyzed the influence of environmental factors on calcitonin levels, which gives great variability in results. Only a few studies have analyzed the influence of pollutants on calcitonin levels in humans. The lifestyle factor with the clearest relationship with calcitonin was smoking (smokers had increased calcitonin levels). Given the importance of PTH and calcitonin in maintaining calcium and phosphate homeostasis and bone mineral metabolism, additional studies on the influence of environmental factors that could affect PTH and calcitonin levels are crucial.

A mechanism linking perinatal 2,3,7,8 tetrachlorodibenzo-p-dioxin exposure to lower urinary tract dysfunction in adulthood

Benign prostatic hyperplasia/lower urinary tract dysfunction (LUTD) affects nearly all men. Symptoms typically present in the fifth or sixth decade and progressively worsen over the remainder of life. Here, we identify a surprising origin of this disease that traces back to the intrauterine environment of the developing male, challenging paradigms about when this disease process begins. We delivered a single dose of a widespread environmental contaminant present in the serum of most Americans [2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), 1 µg/kg], and representative of a broader class of environmental contaminants, to pregnant mice and observed an increase in the abundance of a neurotrophic factor, artemin, in the developing mouse prostate. Artemin is required for noradrenergic axon recruitment across multiple tissues, and TCDD rapidly increases prostatic noradrenergic axon density in the male fetus. The hyperinnervation persists into adulthood, when it is coupled to autonomic hyperactivity of prostatic smooth muscle and abnormal urinary function, including increased urinary frequency. We offer new evidence that prostate neuroanatomical development is malleable and that intrauterine chemical exposures can permanently reprogram prostate neuromuscular function to cause male LUTD in adulthood.

Summary: We describe a new mechanism of benign prostate disease, initiated by fetal chemical exposure, which durably increases prostatic noradrenergic axon density and causes smooth muscle hyperactivity and urinary voiding dysfunction.

Exploring the associations of serum concentrations of PCBs, PCDDs, and PCDFs with walking speed in the U.S. general population: Beyond standard linear models

Studies have shown that persistent organic pollutants (POPs) can have various health effects. However, little is known about the effects of multiple chemicals with possible common sources of exposure on walking speed, a proxy index reflecting lower limb neuromuscular function and physical function. We simultaneously applied multiple linear and nonlinear statistical models to explore the complex exposure-response relationship between a mixture of 22 selected POPs and walking speed. A total of 14 polychlorinated biphenyls (PCBs), 3 polychlorinated dibenzo-p-dioxins (PCDDs), and 5 polychlorinated dibenzofurans (PCDFs) were measured in the serum of participants in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2002. Walking speed was measured during a physical examination. Linear regression (LR), least absolute shrinkage and selection operator (LASSO), and group LASSO were used to evaluate the linearity of mixtures, while restricted cubic spline (RCS) regression, random forest (RF), and Bayesian kernel machine regression (BKMR) models were used to evaluate the nonlinearity of mixtures. Potential confounders were adjusted in the above models. A total of 436 subjects were included in our final analysis. The results of the LR model did not identify any POP exposure that was significantly associated with walking speed. The LASSO results revealed an inverse association of one PCDD congener and two PCDF congeners with walking speed, while the group LASSO analysis identified PCDFs at the exposure level and at the group level. In the RCS analysis, two PCB congeners presented significant overall associations with walking speed. The PCB congener PCB194 showed statistically significant effects on the outcome (P = 0.01) when a permutation-based RF was used. The BKMR analysis suggested that PCBs and PCDFs (probabilities = 0.887 and 0.909, respectively) are potentially associated with walking speed. Complex statistical models, such as RCS regression, RF and BKMR models, can detect the nonlinear and nonadditive relationships between PCBs and walking speed, while LASSO and group LASSO can identify only the linear relationships between PCDFs and walking speed. Fully considering the influence of collinearity in each method during modelling can increase the comprehensiveness and reliability of conclusions in studies of multiple chemicals.

Associations of peri-pubertal serum dioxins and polychlorinated biphenyls with growth and body composition among Russian boys in a longitudinal cohort

BACKGROUND

Childhood exposure to organochlorines has been associated with alterations in somatic growth. We evaluated the associations of peri-pubertal serum levels of dioxin-like compounds (DLCs) and nondioxin-like polychlorinated biphenyls (NDL-PCBs), with adolescent growth, body composition, and near adult height (NAH) in a longitudinal cohort study of Russian boys.

METHODS

473 8-9 year-old boys had serum DLCs and associated toxic equivalents (TEQs) and NDL-PCBs concentrations measured. Physical examinations were performed at enrollment between 2003 and 2005, and annually over 11 years to 2016; annual bio-electric impedance analysis (BIA) of body composition began in 2006. We used mixed effects models to evaluate associations of quartiles of serum chemical concentrations with longitudinal measurements through age 19 of body mass index (BMI-Z) and height (HT-Z) z-scores, annual height velocity (HV), and BIA-derived height-adjusted fat (FMi) and fat-free mass (FFMi) indexes. Potential modification by age of the associations of chemical exposures with growth was evaluated. NAH (defined as HV < 1 cm/year) and age at NAH attainment were estimated using parametric survival models accounting for right censoring.

RESULTS

The medians of serum ∑TEQs, ∑DLCs, and ∑NDL-PCBs were 21.1 pg TEQ/g lipid, 362 pg/g lipid, and 250 ng/g lipid, respectively. In multivariable models, higher serum concentrations of peri-pubertal ∑TEQs, ∑DLCs, and ∑NDL-PCBs were associated with significantly lower BMI-Z, FMi, and FFMi over 11 years of follow-up. The differences in FFMi for boys with higher versus lower ΣTEQs and ΣNDL-PCBs increased with age. In multivariable models, higher ∑NDL-PCBs were associated with lower HT-Z, with attenuation of the association with age (interaction p < 0.001). The highest versus the lowest quartiles of ∑NDL-PCBs were not associated with differences in NAH, but were associated with an average of 6 months later attainment of NAH.

CONCLUSIONS

Our findings suggest that dioxin and NDL-PCB exposures during childhood are associated with alterations in body composition and subsequent somatic growth.

The association of peripubertal serum concentrations of organochlorine chemicals and blood lead with growth and pubertal development in a longitudinal cohort of boys: a review of published results from the Russian Children's Study

Organochlorine chemicals and lead are environmental exposures that have endocrine disrupting properties (EDCs) which interfere with many aspects of hormone action. Childhood and adolescence are windows of susceptibility for adverse health effects of EDCs. Our ongoing study, the Russian Children's Study (RCS), is one of the few longitudinal studies investigating the impact of EDCs on growth and puberty in boys. It is conducted in the historically contaminated city of Chapaevsk, in the Samara region. The study focuses on evaluating the associations of persistent organochlorine chemicals and lead with growth and pubertal timing. At enrollment in 2003-2005, we collected blood from 516 boys at ages 8-9 years to measure dioxins, furans, polychlorinated biphenyls (PCBs), chlorinated pesticides and lead. At enrollment and at annual visits through the ages of 18-19 years, a physician performed physical examinations that included pubertal staging and testicular volume measurements. We review the history of Chapaevsk as a research site and summarize published RCS data on the association of peripubertal serum concentrations of organochlorines and blood lead levels with growth, pubertal onset and sexual maturity. Overall, we found that persistent organochlorines and lead negatively affected growth during puberty. Our results also suggest that total toxic equivalents (TEQs), dioxin-like compounds, organochlorine pesticides and lead may delay, while nondioxin-like-PCBs may advance, the timing of male puberty. These findings promoted remediation programs in Chapaevsk, with improvement in health indicators, resulting in Chapaevsk being designated a member of the World Health Organization (WHO) network "Healthy Cities" in 2015.

Effects of dioxin-related compounds on bone mineral density in patients affected by the Yusho incident

Exposure to dioxin-related compounds results in many adverse health effects. Several studies have examined the effects of dioxin-related compounds on human bone metabolism with inconsistent results. In Japan in 1968, accidental human exposure to rice oil contaminated with dioxin-related compounds led to the development of Yusho oil disease. The aim of this study was to determine whether exposure to dioxin-related compounds was associated with bone mineral density in Yusho patients. In 2010, 262 women and 227 men underwent dual-energy X-ray absorptiometry bone scans as part of the nationwide Yusho health examination. Serum levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls were measured using high-resolution gas chromatography and high-resolution mass spectrometry. When adjusted for prefecture, 1,2,3,4,7,8-HxCDD and 2,3,7,8-TCDF were significantly positively associated with Z-scores in men. No congeners were positively associated with Z-scores in women. After adjustment for prefecture and body mass index, one congener, 1,2,3,4,6,7,8-HpCDD, was negatively associated with Z-scores in women. In contrast, no congeners remained significant in men after adjusting for body mass index. This may suggest that 1,2,3,4,6,7,8-HpCDD has a negative effect on bone mineral density in women; however, the findings should be interpreted carefully, because no increase in the serum level of this congener was observed in patients with Yusho disease.

Growth in Inuit children exposed to polychlorinated biphenyls and lead during fetal development and childhood

BACKGROUND

Because of their geographical location and traditional lifestyle, Canadian Inuit children are highly exposed to polychlorinated biphenyls (PCBs) and lead (Pb), environmental contaminants that are thought to affect fetal and child growth. We examined the associations of these exposures with the fetal and postnatal growth of Inuit children.

METHODS

We conducted a prospective cohort study among Inuit from Nunavik (Arctic Québec). Mothers were recruited at their first prenatal visit; children (n=290) were evaluated at birth and at 8-14 years of age. Concentrations of PCB 153 and Pb were determined in umbilical cord and child blood. Weight, height and head circumference were measured at birth and during childhood.

RESULTS

Cord blood PCB 153 concentrations were not associated with anthropometric measurements at birth or school age, but child blood PCB 153 concentrations were associated with reduced weight, height and head circumference during childhood. There was no association between cord Pb levels and anthropometric outcomes at birth, but cord blood Pb was related to smaller height and shows a tendency of a smaller head circumference during childhood.

INTERPRETATION

Our results suggest that chronic exposure to PCBs during childhood is negatively associated with skeletal growth and weight, while prenatal Pb exposure is related to reduced growth during childhood. This study is the first to link prenatal Pb exposure to poorer growth in school-age children.

Culture, Urbanism and Changing Human Biology

Anthropologists have long known that human activity driven by culture changes the environment. This is apparent in the archaeological record and through the study of the modern environment. Perhaps the largest change since the paleolithic era is the organization of human populations in cities. New environments can reshape human biology through evolution as shown by the evolution of the hominid lineage. Evolution is not the only process capable of reshaping our biology. Some changes in our human biology are adaptive and evolutionary while others are pathological. What changes in human biology may be wrought by the modern urban environment? One significant new change in the environment is the introduction of pollutants largely through urbanization. Pollutants can affect human biology in myriad ways. Evidence shows that human growth, reproduction, and cognitive functioning can be altered by some pollutants, and altered in different ways depending on the pollutant. Thus, pollutants have significance for human biologists and anthropologists generally. Further, they illustrate the bio-cultural interaction characterizing human change. Humans adapt by changing the environment, a cultural process, and then change biologically to adjust to that new environment. This ongoing, interactive process is a fundamental characteristic of human change over the millennia.

Serum dioxin concentrations and bone density and structure in the Seveso Women's Health Study

BACKGROUND

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a widespread environmental contaminant, is a known endocrine disruptor. In animal studies, TCDD exposure impairs bone metabolism and increases fragility. To our knowledge, no epidemiologic studies have examined this association.

OBJECTIVES

On 10 July 1976, a chemical explosion in Seveso, Italy, resulted in the highest known residential exposure to TCDD. In 1996, we initiated the Seveso Women's Health Study, a retrospective cohort study of the health of the women. In 2008, we followed up the cohort. Here, we evaluated the association between TCDD exposure and bone structure and geometry in adulthood, and considered whether timing of TCDD exposure before achievement of peak bone mass (assumed to occur 2 years after onset of menarche) modified the association.

METHODS

Individual TCDD concentration was measured in archived serum collected soon after the explosion. In 2008, 350 women who were <20 years old in 1976 underwent a dual-energy X-ray absorptiometry (DXA) bone scan. Bone mineral density was measured at the lumbar spine and hip, and hip geometry was extracted from hip DXA scans using the hip structural analysis method.

RESULTS

Among premenopausal women, TCDD serum levels were associated with some indexes indicating better bone structure in women exposed before peak bone mass (n=219), with stronger associations in those exposed before 5 years of age (n=46). In contrast, among postmenopausal women, TCDD levels were associated with evidence of better bone structure in women exposed after peak bone mass (n=48) than in other women (n=18).

CONCLUSIONS

Our current results do not support the hypothesis that postnatal TCDD exposure adversely affects adult bone health. Continued follow-up of women who were youngest at exposure is warranted. Future studies should also focus on those exposed in utero.

Mortality after exposure to polychlorinated biphenyls and dibenzofurans: 30 years after the "Yucheng accident"

BACKGROUND

In 1979, approximately 2,000 people in central Taiwan were accidentally exposed to polychlorinated biphenyls and dibenzofurans due to ingestion of contaminated cooking oil. This event was called Yucheng, "oil-syndrome" in Chinese. We followed the exposed persons and compared their cause-specific mortality with that of neighborhood referents 30 years after the accident.

METHODS

We obtained age- and gender-matched referents from the 1979 neighborhoods of the exposed people. Cause-specific mortality was compared between exposed subjects (N=1803) and their neighborhood referents (N=5170) using standardized mortality ratios (SMR). Total person-years for the Yucheng subjects and neighborhood referents were 48,751 and 141,774, respectively.

RESULTS

The SMR for all causes (SMR=1.2, 95% CI: 1.1-1.3), diseases of the circulatory system (SMR=1.3, 95% CI: 1.0-1.6), and diseases of the musculoskeletal system and connective tissue (SMR=6.4, 95% CI: 2.8-12.7) were elevated in Yucheng subjects. Among Yucheng males, the SMRs for diseases of the digestive system (SMR=1.9, 95% CI: 1.2-2.8), malignant neoplasm of stomach (SMR=3.5, 95% CI: 1.5-7.0), and malignant neoplasm of lymphatic and hematopoietic tissue (SMR=3.0, 95% CI: 1.1-6.6) were increased. The SMR for total neoplasms was increased (SMR=1.3, 95% CI: 0.9-1.7).

CONCLUSION

We conclude that exposure to PCBs/PCDFs at levels that produced symptoms in many affects mortality patterns 3 decades after exposure.

Serum concentrations of organochlorine pesticides and growth among Russian boys

BACKGROUND

Limited human data suggest an association of organochlorine pesticides (OCPs) with adverse effects on children's growth.

OBJECTIVE

We evaluated the associations of OCPs with longitudinally assessed growth among peripubertal boys from a Russian cohort with high environmental OCP levels.

METHODS

A cohort of 499 boys enrolled in the Russian Children's Study between 2003 and 2005 at 8-9 years of age were followed prospectively for 4 years. At study entry, 350 boys had serum OCPs measured. Physical examinations were conducted at entry and annually. The longitudinal associations of serum OCPs with annual measurements of body mass index (BMI), height, and height velocity were examined by multivariate mixed-effects regression models for repeated measures, controlling for potential confounders.

RESULTS

Among the 350 boys with OCP measurements, median serum hexachlorobenzene (HCB), β-hexachlorocyclohexane (βHCH), and p,p´-dichlorodiphenyldichloroethylene (p,p´-DDE) concentrations were 159 ng/g lipid, 168 ng/g lipid, and 287 ng/g lipid, respectively. Age-adjusted BMI and height z-scores generally fell within the normal range per World Health Organization standards at entry and during follow-up. However, in adjusted models, boys with higher serum HCB, βHCH, and p,p´-DDE had significantly lower mean [95% confidence interval (CI)] BMI z-scores, by -0.84 (-1.23, -0.46), -1.32 (-1.70, -0.95), and -1.37 (-1.75, -0.98), respectively, for the highest versus lowest quintile. In addition, the highest quintile of p,p´-DDE was associated with a significantly lower mean (95% CI) height z-score, by -0.69 (-1.00, -0.39) than that of the lowest quintile.

CONCLUSIONS

Serum OCP concentrations measured at 8-9 years of age were associated with reduced growth, particularly reduced BMI, during the peripubertal period, which may affect attainment of optimal adult body mass and height.

Serum dioxins and polychlorinated biphenyls are associated with growth among Russian boys

OBJECTIVE

We evaluated the associations of serum dioxins and polychlorinated biphenyls (PCBs) with longitudinally assessed growth measurements among peripubertal Russian boys.

METHODS

A total of 499 boys from Chapaevsk, Russia, aged 8 to 9 years were enrolled in the study from 2003 to 2005 and were followed prospectively for 3 years. Blood samples were collected and physical examinations were conducted at entry and repeated at annual study visits. Multivariate mixed-effects regression models for repeated measures were used to examine the associations of serum dioxins and PCBs with longitudinal measurements of BMI, height, and height velocity.

RESULTS

Serum dioxin (total 2005 toxic equivalency [TEQ] median: 21.1 pg/g lipid) and PCBs (median sum of PCBs: 250 ng/g lipid) were measured in 468 boys. At study entry and during 3 years of follow-up, >50% of the boys had age-adjusted BMI and height z scores within 1 SD of World Health Organization-standardized mean values for age. Boys in the highest exposure quintile of the sum of dioxin and PCB concentrations and total TEQs had a significant decrease in mean BMI z scores of 0.67 for dioxins and TEQs and 1.04 for PCBs, compared with boys in the lowest exposure quintile. Comparison of the highest versus the lowest quintile revealed that higher serum PCB concentrations were associated with significantly lower height z scores (mean z-score decrease: 0.41) and height velocity (mean decrease: 0.19 cm/year) after 3 years of follow-up.

CONCLUSIONS

Our findings suggest that exposures to dioxins and PCBs are associated with reduced growth during the peripubertal period and may compromise adult body mass, stature, and health.

Prenatal and postnatal exposure to polychlorinated biphenyls and child size at 24 months of age

Research suggests that exposure to polychlorinated biphenyls (PCBs) may result in decreased child growth, though the critical window(s) are unclear. We investigated the association between PCBs and child size at age 24 months (n=44). PCBs were measured in first trimester serum, breast milk, and child serum at age 24 months, and dichotomized at the median. Age- and gender-specific z-scores were calculated for anthropometric measures. Using linear regression, we observed no significant changes in z-scores with prenatal or postnatal serum PCB concentrations. PCB-77 in breast milk was associated with a significant decrease in z-score for length. To our knowledge, this study is the first to examine child size in relation to PCBs measured early in pregnancy, as well as quantifying a far greater number of congeners. Further research is needed to clarify critical windows, congener-specific effects, and effect modification by sex in relation to PCBs and child anthropometric measures.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

Exposure to a mixture of polychlorinated biphenyls and polychlorinated dibenzofurans resulted in a prolonged time to pregnancy in women

BACKGROUND

Polychlorinated biphenyls (PCBs), dibenzofurans (PCDFs), and dibenzodioxins (PCDDs) may affect the female reproductive system in animals and humans. In 1978-1979, a mass poisoning occurred in central Taiwan due to PCB/PCDF-contaminated cooking oil; this incident was called Yucheng ("oil disease" in Chinese).

OBJECTIVE

The purpose of our study was to determine whether PCB/PCDF exposure affected fertility in exposed women.

METHODS

After the event, we followed the exposed individuals and a reference group who were sex-, age-, and community-matched. In 2003, we obtained fertility histories from Yucheng and reference women by telephone interview. We used Kaplan-Meier survival curves and multivariable Cox regression to compare time to pregnancy (TTP) between Yucheng and reference women, and we performed multiple logistic regression to determine whether PCB/PCDF exposure caused infertility.

RESULTS

In total, 412 women responded, with a median TTP of 4 months in Yucheng women and 3 months in reference women (p = 0.019). After adjusting for confounders by Cox regression, we found a fecundability ratio of 0.90 [95% confidence interval (CI), 0.80-1.00] for Yucheng women. Among the 408 women who had non-contraceptive sexual activity for > 12 months, 19.7% of Yucheng women and 9.7% of reference women did not become pregnant (i.e., they were infertile). After we adjusted for confounders by logistic regression, the infertility odds ratio was 2.34 (95% CI, 1.23-4.59) for Yucheng women compared with the reference group.

CONCLUSIONS

We found prolonged TTP and reduced fertility among women previously exposed to PCBs/PCDFs. Because of the limited sample size and the relatively small decrease in the fertility rate, these effects require cautious interpretation and further investigation for confirmation.

Polychlorinated biphenyls, organochlorine pesticides and neurodevelopment

PURPOSE OF REVIEW

Although environmental levels of polychlorinated biphenyls and certain organochlorine pesticides--hexachlorobenzene, dichlorodiphenyl trichloroethane and its primary metabolite, dichlorodiphenyl dichloroethene--are generally on the decline, early-life exposures to these prevalent contaminants continue. The review will describe current understanding of the potential neurodevelopmental consequences of low-level exposures to these contaminants.

RECENT FINDINGS

Animal models suggest that early-life exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene or hexachlorobenzene are associated with decreased cognitive or behavioral function in later development. Despite almost 30 years of research, however, results of human studies are inconsistent regarding the nature of the observed effects and their persistence over time. Overall, epidemiologic studies support modest associations of primarily prenatal polychlorinated biphenyl exposures with differences in neuromotor development, decrements in cognition and behavioral deficits, particularly regarding attention and impulse control. There are limited published human data regarding potential neurodevelopmental toxicities of early-life exposures to dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene.

SUMMARY

Exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene are likely detrimental to neurodevelopment. Effective control of exposure is complicated by variable exposure sources and variable contaminant levels in food, particularly fish, for which it is important to balance the risk of contaminants with nutritional benefits.

Modulatory effects of Aroclors 1221 and 1254 on bone turnover and vertebral histology in intact and ovariectomized rats

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants. Two PCB mixtures, Aroclors 1221 and 1254 have been suggested to have estrogenic and anti-estrogenic properties, respectively. We have examined whether these PCB mixtures modulate bone turnover and vertebral histology in intact and ovariectomized (ovx) rat models. Thirty-two adult female rats were divided into four groups subcutaneously receiving 4% DMSO (control), A1221 (10 mg/kg), A1254 (10 mg/kg) oestradiol (E2, 30 microg/kg). These compounds were injected to the animals for a period of 6 weeks at two daily intervals. In the second model, rats (n=32) were ovx and allowed to recover for a period of 3 weeks. Control group received vehicle (4% DMSO) alone. Remaining rats were divided into three groups and injected (s.c.) with A1221, A1254 and E2 for 5 weeks. Urine samples were collected prior to end of the experiments. Then, all animals were decapitated. Serum parathyroid hormone (PTH), calcitonin and osteocalcin levels were determined by immunoradiometric method. Serum concentrations of alkaline phosphatase (ALP), calcium and inorganic phosphate were determined by enzymatic-colorimetric method. Urinary deoxypyridinoline (DPD) was measured by ELISA. Lumbar vertebrae (L2) of all animals were dissected out and processed for light microscopy. Levels of urinary DPD were significantly lowered in E2 -treated intact rats (p<0.001). Ovx significantly increased urinary DPD excretion (p<0.01) compared to intact control values. Administration of A1221 and A1254 had no significant effects in intact rats, however, they significantly reduced (p<0.05) and increased (p<0.001) urinary DPD levels in ovx rats, respectively. Neither of the PCB mixtures significantly changed serum osteocalcin and ALP levels in intact or ovx rats (except A1221 increased ALP in intact model, p<0.01). Both PCB mixtures had differential effects on serum PTH, calcitonin, calcium and inorganic phosphate concentrations. Treatment with A1221 reversed the adverse effects of ovariectomy on L2 histology. However, A1254 produced necrotic areas in vertebral bone, and this effect was expanded in ovx animals. Our findings suggest that both Aroclor compounds interfere with bone turnover mechanisms, particularly in ovx rats.

Prenatal exposure to polychlorinated biphenyls and postnatal growth: a structural analysis

Normal endocrine function in utero and early in childhood influences later height and weight attainment. Polychlorinated biphenyls (PCBs) are persistent environmental contaminants with suspected endocrine-disrupting properties. PCBs may mimic or inhibit hormone and endocrine processes based in part on their structural configuration, with non-ortho-substituted PCBs having a coplanar orientation and ortho-substituted PCBs becoming increasingly noncoplanar. Coplanar and noncoplanar PCBs have known differences in biologic effect. Animal studies link prenatal PCB exposure to adverse birth and early-life growth outcomes, but epidemiologic studies are conflicting. We examined whether prenatal exposure to PCBs, categorized by their degree of ortho-substitution, affected childhood height and weight attainment in 150 children (109 boys and 41 girls) with African-American mothers born at the Columbia-Presbyterian Hospital from 1959 through 1962. Stratifying by sex, we used regression models for repeated measures to investigate associations between maternal levels of PCBs and height and weight through 17 years of age. Maternal levels of ortho-substituted PCBs were associated with reduced weight through 17 years of age among girls but not among boys. Tri-ortho-substituted PCBs were marginally associated with increased height in boys. Although limited by sample size, our results suggest that prenatal exposure to PCBs may affect growth, especially in girls, and that ortho-substitution is an important determinant of its effect on growth.

Effects of Pollution on Human Growth and Development: An Introduction

Pollution is a worldwide problem and its potential to influence the physiology of human populations is great. Studies of human growth and development in relation to pollution have increased in number and quality since the mid-twentieth century. Many studies have found that some pollutants have detrimental effects on human growth, particularly prenatal growth. The heavy metal, lead, is commonly found in human populations and is related to smaller size at birth and studies have reported decrements that range up to about 200 grams. Noise stress from transportation sources also is related to reduced prenatal growth with somewhat smaller decrements reported. Studies of humans exposed to polychlorinated biphenyls, one of the persistent organic pollutants, have reduced size at birth, advanced sexual maturation and altered hormone levels related to thyroid regulation. Thus different pollutants exert effects through different physiological pathways. However, some studies have not observed these effects, which indicates that the situation is complex and requires further study with better study designs. Determining the effects of pollutants on human physiology and growth is difficult as it requires fairly large numbers of subjects who are not purposely exposed but for whom exposure can be measured. These effects of pollutants and the mechanisms of effect require further study to understand and, it is hoped, to blunt or block any detrimental effects on human health and well-being.

In utero polychlorinated biphenyl exposures in relation to fetal and early childhood growth

BACKGROUND

Polychlorinated biphenyls (PCBs) are industrial chemicals that were used widely for approximately 50 years. Now banned, they are still ubiquitous because of their persistence in the environment, the food chain, and human fatty tissue. High in utero exposures cause developmental deficits accompanied by growth retardation. Studies examining intrauterine growth at lower exposures have been inconsistent, with most such investigations having relied on surrogate exposure indicators such as consumption of fish from contaminated bodies of water.

METHODS

In the 1960s, serum specimens were collected from pregnant women participating in the Child Health and Development Study in the San Francisco Bay Area. The women were interviewed and their serum samples stored at -20 degrees C. At 5 years of age, detailed anthropometric measurements were made on children born in the years 1964-1967. We measured PCBs in specimens from 399 mothers using gas chromatography/electron capture detection. We conducted multiple linear regression to examine the relationship between these organochlorine concentrations and both intrauterine and 5-year growth, with adjustment for medical, lifestyle, sociodemographic, and specimen characteristics.

RESULTS

In male infants, higher total in utero PCB exposure was associated with reduced birth weight, head circumference, and weight-for-gestational age. An increase from the 10th to 90th percentile in total PCBs was related to 290 g lower birth weight, a 0.7-cm decrease in head circumference, and for weight for gestational age, a reduction in z-score of 0.6. In girls, smaller head circumference and shorter gestations were observed. In contrast, prenatal PCBs were associated with greater growth in 5-year-old girls, with no apparent effect in 5-year-old boys.

CONCLUSIONS

Maternally mediated exposure to PCBs may be detrimental to fetal growth, particularly in boys. These effects apparently are not persistent. Interpretation of greater childhood growth of girls is unclear.

Serum concentrations and profiles of polychlorinated biphenyls in Taiwan Yu-cheng victims twenty years after the incident

In 1979, about 2000 people in central Taiwan were intoxicated via rice oil consumption that was contaminated with polychlorinated biphenyls (PCBs). This "Yu-cheng" incident was one of the two known major human PCB intoxication episodes. Twenty years after the intoxication, serum samples of 435 Yu-cheng victims, 414 adults and 21 children, were collected. Sixteen PCB congeners were analyzed with a gas chromatograph-electron capture detector. We found the median concentration of total PCBs in the adult serum was 1500 ng/g lipid, still substantially higher than that of the general population in Taiwan (3.7-fold) and most seafood consumers in the world. Most of analyzed PCB congeners in children were below or around the detection limits. Congener #138, however, had the highest concentrations, approximately accounting for 55% and 29% in the child and adult groups, respectively. Given that PCBs are persistent organic pollutants and endocrine disruptors, the concentrations and congener-specific profiles regarding the Yu-cheng victims provide valuable information for the investigation of such chemicals in humans.

Transforming growth factor-beta3 restores fusion in palatal shelves exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

The pollutant, 2,3,7,8-tetrachlorodibenzo-p-dioxin ("dioxin"), has been implicated in the etiology of a wide variety of human birth defects. In an effort to identify pharmacological blockers of dioxin-induced terata, we performed a histological and microscopic analysis of the developing murine palate that had been exposed to dioxin. In both in vivo and in vitro model systems, we observed that dioxin exposure leads to a reduction in the number of filopodial extensions at the medial epithelial edge of the developing palate. Given that this filopodial aberration is similar to the phenotype observed in Tgfbeta3 null mice, a mutant known to display a 100% incidence of cleft palate, we examined the interaction between TGFbeta3 and dioxin in palatal fusion. We found that that the addition of TGFbeta3 to an in vitro palate culture model prevented the dioxin-induced reduction in filopodial density. Moreover, TGFbeta3 exposure completely prevented the dioxin-induced block of palatal fusion in this system. Although these data do not point to a direct cellular or molecular mechanism for TGFbeta3 dioxin antagonism, these results do suggest that TGFbeta3 or stimulators of this signaling pathway hold potential as antidotes for dioxin-induced terata and that this opposing pharmacology may extend to additional toxicological endpoints.

Is bone mineral composition disrupted by organochlorines in east Greenland polar bears (Ursus maritimus)?

We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane (DDT) and its metabolites, chlordanes (CHLs), dieldrin, hexacyclohexanes, hexachlorobenzene] and polybrominated diphenyl ether (PBDE) compounds. To ensure that the BMD value in skull represented the mineral status of the skeletal system in general, we compared BMD values in femur and three lumbar vertebrae with skull in a subsample. We detected highly significant correlations between BMD in skull and femur (r = 0.99; p < 0.001; n = 13) and skull and vertebrae (r = 0.97; p < 0.001; n = 8). BMD in skulls sampled in the supposed pre-organochlorine/PBDE period (1892-1932) was significantly higher than that in skulls sampled in the supposed pollution period (1966-2002) for subadult females, subadult males, and adult males (all, p < 0.05) but not adult females (p = 0.94). We found a negative correlation between organochlorines and skull BMD for the sum of PCBs (SigmaPCB; p < 0.04) and SigmaCHL (p < 0.03) in subadults and for dieldrin (p < 0.002) and SigmaDDT (p < 0.02) in adult males; indications for SigmaPBDE in subadults were also found (p = 0.06). In conclusion, the strong correlative relationships suggest that disruption of the bone mineral composition in East Greenland polar bears may have been caused by organochlorine exposure.

Epidemiological evidence on reproductive effects of persistent organochlorines in humans

Organochlorines are widespread pollutants in humans. Concern about adverse reproductive effects of these compounds arises from accidental exposure of humans and experimental studies. Recently, this issue has been addressed by a number of studies of exposed populations and hospital-based case-referent studies. These studies indicate that high concentrations of persistent organochlorines may adversely affect semen quality and cause testicular cancer in males, induce menstrual cycle abnormalities and spontaneous abortions in females, and cause prolonged waiting time pregnancy, reduced birth weight, skewed sex ratio, and altered age of sexual development. However, most effects have been demonstrated at exposure levels above the present day exposure level in European and North American populations. Due to inherent methodological problems in several of the available studies, additional research is needed to fully elucidate the possible adverse effects of organochlorines on human reproductive health.

Neonatal and childhood teeth in relation to perinatal exposure to polychlorinated biphenyls and dibenzofurans: observations of the Yucheng children in Taiwan

In order to determine the effect of perinatal polychlorinated biphenyls and dibenzofurans (PCBs/PCDFs) exposure on neonatal and childhood teeth in Yucheng children, we carried out complete dental examinations on 73 Yucheng children born to mothers who ingested high levels of PCBs/PCDFs and 75 matched controls, aged 7-11 years, in 1992. Ten of 73 (10%) exposed children were reported to have borne teeth during the neonatal period, while none of the controls did. The exposed group also had a significantly higher percentage of teeth with congenitally missing tooth germ compared to the controls (29 vs 2.7%) or rotation (19 vs 2.7%). The percentages of developmental defects increased significantly with increasing maternal serum PCB levels, childhood PCB and PCDF levels, and the duration of breast feeding. The maternal PCB level clearly played a more important role in an increased risk of neonatal teeth and developmental defects. The defects were apparent from the lowest tertile, with a total PCB level of <10 ppb in maternal serum measured nearest to childbirth. The number of permanent teeth tended to be less in exposed children than in the control group from the age of 11 years onwards. Our present study has demonstrated for the first time a dose-response relationship between perinatal PCBs/PCDFs exposure and dental defects.

Childhood growth and exposure to dichlorodiphenyl dichloroethene and polychlorinated biphenyls

OBJECTIVES

Dichlorodiphenyl dichloroethene (DDE) and polychlorinated biphenyls (PCB), toxic contaminants known to be persistent in the environment, may affect growth. We investigated whether growth from birth to 10 years of age is associated with blood concentrations of DDE and PCB taken at 8 years of age.

STUDY DESIGN

We ambispectively followed up a cohort of 343 German children. DDE and PCB blood concentrations were determined in 1995. Height measurements were conducted prospectively between 1994 and 1997 and obtained retrospectively from each Child's Health Card. Linear regression models for repeated measurements, controlling for confounding factors, were applied.

RESULTS

Growth was significantly reduced by an average of 1.8 cm (P <.0275) for girls in the highest DDE concentration quartile (>.44 microg/L in whole blood) compared with girls in the lowest quartile (0.08-0.2 microg/L). There was no observed growth effect of DDE in boys. PCB blood concentrations were not related to growth reduction in either girls or boys.

CONCLUSIONS

Background level concentrations to DDE, but not PCB, during childhood are associated with a small reduction in growth for girls evident through the age of 8 years. The observed differences narrow at the year 9 examination and disappear at the year 10 examination. No effects on boys' heights were observed.

Polychlorobiphenyls inhibit skeletal muscle differentiation in culture

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent pollutants whose role in developmental toxicity is of great concern. The observation that the offspring of PCB-exposed mothers (both in humans and rodents) display reduced body mass prompted us to investigate the effects of commercial mixtures of PCB congeners (Aroclor 1232, 1254, and 1262) on differentiation of both a myogenic cell line and primary myogenic cell cultures. The fusion of L6 myoblasts into multinucleated myotubes and the increase of creatine kinase (CK) activity were dose-dependently inhibited by Aroclor 1254 at concentrations (0.1-4 microg/ml) that caused no effect on cell density. Ultrastructural analysis demonstrated that Aroclor 1254 also prevented the accumulation of contractile filaments while inducing hypertrophy of the smooth endoplasmic reticulum and appearance of membrane-filled autophagosomes. Half-maximal inhibition (IC50) of CK activity accumulation occurred at 0.01 microg/ml for Aroclor 1262, 2 microg/ml for Aroclor 1254, and 8 microg/ml for Aroclor 1232. Aroclor-dependent inhibition of myogenic differentiation was also shown by the reduced expression and nuclear accumulation of beta-galactosidase in primary cultures of fetal myoblasts from transgenic mice expressing this reporter gene under the control of the myosin light chain promoter. These data show that skeletal muscle differentiation is specifically impaired by PCBs and may explain the reported depression of body mass growth in PCB-exposed offspring at birth. Furthermore, myogenic cell cultures are highly sensitive to PCBs and allow the detection of biological effects of environmental levels of these pollutants.

Effect of prenatal exposure to polychlorinated biphenyls on cognitive development in children: a longitudinal study in Taiwan

BACKGROUND

From 1978 to 1979, a group of people in Taiwan were exposed to high levels of heat-degraded polychlorinated biphenyls (PCBs) owing to accidental ingestion of contaminated rice oil. Children born to mothers following the exposure ('Yucheng' children) were known to have hyperpigmented skin and other dysmorphology after birth.

AIMS

To determine the effect of prenatal exposure to PCBs on cognitive development in Yucheng children.

METHOD

One hundred and eighteen Yucheng children prenatally exposed to PCBs and degradation products, and community-matched control children who were exposed to background levels only, were followed from 1985 to 1998. The Bayley Scale for Infant Development, Chinese version of the Stanford-Binet IQ Test, Raven's Coloured Progressive Matrices and Raven's Standardised Progressive Matrices were used to assess the cognitive development of these children.

RESULTS

The Yucheng children scored lower than control children on each of these methods of measurement between the ages of 2 and 12 years.

CONCLUSIONS

Prenatal exposure to PCBs and their derivatives has long-term adverse effects on cognitive development in humans.

Behavioral assessments of learning and attention in rats exposed perinatally to 3,3',4,4',5-pentachlorobiphenyl (PCB 126)

Evidence from humans suggests that cognitive dysfunction may result from perinatal exposure to polychlorinated biphenyls (PCBs), and the results of some animal research with PCBs have been interpreted in terms of possible impairment of attention. Long-Evans rats were fed 3,3',4,4',5-pentachlorobiphenyl (PCB 126), a coplanar congener, at doses of 0.25 or 1 microgram/kg/day [corrected] throughout gestation and nursing. Male offspring of these rats were trained as adults to perform 2 tests of attention for food reward. First, a cued target-detection task, modeled after Posner's covert orienting method for humans, was used to assess visuospatial attention. In this task, a visual target stimulus was presented in 1 visual hemifield on each trial, preceded either by a valid cue, an invalid cue, or no cue. A valid cue appeared in the same hemifield as the target, and an invalid cue appeared in the opposite hemifield. As expected, valid cues increased accuracy and speed of target detection and invalid cues decreased accuracy and speed; moreover, these effects were systematically related to changes in cue intensity and target duration. However, perinatal exposure to PCB 126 did not affect acquisition or performance of this task. The second task assessed sustained attention by means of a signal detection method in which a brief, spatially-constant but temporally unpredictable, visual signal indicated which of 2 responses would yield food. Varying the intensity of the signal greatly affected the probability of correctly reporting the signal. Perinatal exposure to PCB 126 did not affect acquisition of the response rule or performance of the task. Finally, all rats were challenged with chlordiazepoxide (CDP) at doses of 0, 3, 5, 8, or 12 mg/kg SC, 20 min before testing in the sustained attention task. In control rats, low doses (3, 5, and 8 mg/kg) of CDP reduced accuracy at low signal intensities only, suggesting an increase in visual threshold. The high dose of CDP reduced accuracy at all signal intensities and increased the false-alarm rate as well, suggesting an impairment of attention. The rats exposed perinatally to PCB 126 at 0.25 micrograms/kg [corrected] were unaffected by CDP, and those exposed to PCB 126 at 1 microgram/kg [corrected] showed a smaller decrement in performance after CDP than did the controls. Taken together, these data provide little support for the possibility that perinatal exposure to PCB 126 causes deficits in attention, but suggest that PCB 126 may alter GABA-mediated pathways in the CNS during development.

Polychlorinated dibenzo-p-dioxins and related compounds: the blood levels of young Japanese women

We investigated PCDDs and related compounds in the blood of young Japanese women, approximately 20 years of age, who had not yet had children, and discussed how the TEQ level of PCDDs and related compounds in their blood may affect the next generation. Means of total TEQ levels were 0.063 pg/g for whole blood basis and 21 pg/g for lipid basis. TEQ of PCDDs, PCDFs and coplanar PCBs accounted for about 43, 34 and 23% of the total TEQ in the whole blood basis, respectively. In the lipid basis, their values were about 44, 34 and 22%, respectively. Previously, we investigated PCDDs and related compounds levels in mother's breast milk, lymphocyte subpopulation and thyroid function of their children, and found negative correlations between the TEQ level of PCDDs and related compounds and CD4+/CD8+, and/or the TEQ level of PCDDs and related compounds and the T4 level in 36 mothers and children. Of these cases, the average age was approximately 28 years. PCDDs and related compounds may be related to immunopathy, such as atopic dermatitis. The effects of PCDDs and related compounds on babies of young Japanese women are important and must be further evaluated.

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.

Effects of environmental exposure to polychlorinated biphenyls and dioxins on birth size and growth in Dutch children

Lower birth weight and growth retardation has been found in studies with laboratory animals, in children born of mothers exposed to accidental high levels of polychlorinated biphenyls (PCBs) and related compounds, and in children born of mothers who consumed PCB-contaminated fish. The effect of background exposure to PCBs and dioxins on birth size and growth in human newborns, however, is still unknown. This study examined birth size and postnatal growth of term newborns in relation to their background PCB and dioxin exposure. Birth weight and weight, length, and head circumference were measured at 10 d and 3, 7, 18, and 42 mo of age in 207 children, of whom 105 were breast-fed and 102 were formula-fed during infancy. The effect of in utero exposure to PCBs on birth size, assessed by cord and maternal plasma PCB levels, was investigated in the whole group. The effect of prenatal PCB exposure on postnatal growth was studied in the formula-fed group, whereas the effect of prenatal as well as lactational exposure to PCBs and dioxins on postnatal growth was studied in the breast-fed group. After adjustment for covariates, cord and maternal plasma PCB levels where both negatively associated with birth weight. Infants with high cord plasma PCB levels (P90 = 0.80 microL) weighed 165 g less compared with infants with low cord plasma PCB levels (P10 = 0.20 microg/L). Cord and maternal plasma PCB levels where both significantly associated with lower growth rate, defined as change in SD score (SDS) of weight, length, and head circumference from birth to 3 mo in the formula-fed group (all p values <0.05). No negative effects of prenatal PCB exposure on growth rate were found from 3 to 42 months of age. Postnatal PCB and dioxin exposure was not negatively associated with growth rate in the breast-fed group. In utero exposure to environmental levels of PCBs is negatively associated with birth weight and postnatal growth until 3 mo of age. Although this growth delay was described in healthy term born infants, intrauterine and postnatal growth retardation are potentially harmful to the developing human and should be avoided by reducing maternal PCB and dioxin body burden, and consequently fetal exposure to these pollutants.

Middle-ear disease in children exposed prenatally to polychlorinated biphenyls and polychlorinated dibenzofurans

During 1978 and 1979, an episode of poisoning from ingestion of rice oil contaminated with polychlorinated biphenyls and polychlorinated dibenzofurans occurred in central Taiwan. We followed-up children who had been born between June 1978 and March 1985, as well as matched unexposed children. The mothers of exposed children had consumed contaminated oils before the children were born. In 1993, otolaryngologists examined the middle ear of each child with a pneumatic otoscope, and they measured the middle-ear pressure by tympanometry with a Rion RS20 impedance audiometer. The exposed children had a significantly higher prevalence of middle-ear diseases than their matched controls. The exposed children who had ear diseases had higher serum levels of 2,3,4,7,8-pentachloro- and 1,2,3,4,7,8-hexachloro-dibenzofurans than the children who did not have similar diseases. Therefore, in this study, children exposed to polychlorinated biphenyls and polychlorinated dibenzofurans had a higher incidence of middle-ear diseases than their controls.

Reassessment of PCDD/DFs and Co-PCBs toxicity in contaminated rice-bran oil responsible for the disease "Yu-Cheng"

Reassessment of dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co-PCBs) in toxic Yu-Cheng rice-bran oil was carried out. The contaminating source appears to be a mixture of KC-400 and KC-500. The oil contains 176 micrograms/g PCBs and 37.194 ng/g 2,3,7,8,-TCDD toxicity equivalency (TEQ). The TEQ contributions from the PCDDs (4.472 ng/g), PCDFs (19.568 ng/g), and Co-PCBs (13.154 ng/g) are 12% 53% and 35%, respectively. Complete identification and quantitation suggests that 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 2,3,7,8,-TCDF. 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD and PCB# 77 are candidates for the primary causal agents of Yu-Cheng disease.

Follow-up of skin manifestations in Yu-Cheng children

We report an 11-year follow-up study on the dermatological manifestations of Yu-Cheng children born to mothers who were poisoned by polychlorinated biphenyl (PCB)-contaminated cooking oil between 1977 and 1979. Eighty-eight children born to these mothers, and 86 matched controls, were examined by one dermatologist. Chloracne scars were found in one patient, and there were nail abnormalities in about one-third of the exposed patients. Transverse grooves, irregular depressions, and koilonychia/nail flattening were significantly more frequent than in the control group, based on Fischer's exact test. This study indicates that in Yu-Cheng children the nail changes are the most persistent abnormality after PCB intoxication, and their occurrence may indicate developmental retardation of the fetal nail matrix. Such a finding might also suggest that PCBs remaining in the mother could exert an effect on nail growth in children born several years after the intoxication event.

Early development of Yu-Cheng children born seven to twelve years after the Taiwan PCB outbreak

In Taiwanese children born seven to twelve years after their mothers' or fathers' intoxication of heat-degraded polychlorinated biphenyls (PCBs) (Yu-Cheng mothers or fathers), we measured the development and behavioral problems in 1991-2. The development was assessed with the Chinese Child Developmental Inventory (CCDI), and the behavioral problems with Rutter's Child Behavior Scale A. Children of Yu-Cheng mothers had delayed development on several subscales of CCDI and on the combined general development score. Girls were more affected than boys in their development. Children of Yu-Cheng fathers did not score differently from unexposed controls on this measurement. In Rutter's scale, the scores in Yu-Cheng mothers' children and Yu-Cheng fathers' children were not different from those of their unexposed controls. We conclude that children born seven to twelve years after mothers' exposure to degraded PCBs had delayed development, but they did not show more behavior problems when compared with unexposed controls.

Blood serum levels of PCDFs and PCBs in Yu-Cheng children peri-natally exposed to a toxic rice oil

Children secondarily exposed through their mothers to a toxic rice oil containing PCDFs and PCBs in the Yu-cheng incident have shown developmental delay even a decade after the incident. Forty-five serum samples were collected from these children in February 1991 ad small amounts analyzed for their contaminant content using sample enrichment and isotope dilution mass spectrometry. In about one-half the samples, detectable levels of PCDFs and PCBs could still be determined with average values for 2, 3, 4, 7, 8-PnCDF and 1, 2, 3, 4, 7, 8-HxCDF of 300 and 620 ng/kg serum lipid, respectively. The mean of the total PCBs on a whole weight basis was 7.5 micrograms/kg. These concentrations of PCDFs and PCBs are still 10 to 25 times higher than those from a matched control population. Although the serum levels did not correlate with developmental delays, those for the two PCDFs but not the total PCBs correlated with duration of breast feeding indicative of postnatal exposure. The results of this study suggest that estimation of past prenatal exposure of children to PCDFs is best carried out using current mother and not current child blood concentrations.