Determinants of polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), and dichlorodiphenyl trichloroethane (DDT) levels in the sera of young children

Application of a pharmacokinetic model in characterizing sources of polychlorinated biphenyl exposure and determining threshold daily intakes for adverse health effects in infants and toddlers

Characterization of PCB exposure sources for vulnerable population groups is essential to minimize the health effects of PCB exposure. At the same time, it is important to consolidate the knowledge on threshold intakes of PCBs for infants and toddlers to prevent health effects. We estimated total PCB concentrations from birth to 2 years of age in children from Slovak and Czech populations, which continue to have high PCB concentrations in breast milk. Using a pharmacokinetic (PK) model, we characterized dominant PCB exposure sources and estimated new threshold estimated daily intakes (TEDI) (above which adverse effects cannot be excluded) for postnatal PCB exposure in infants and toddlers. In the PK model, concentrations of seven indicator PCBs in breast milk and cord blood samples from 291 mother-child pairs from the Slovak birth cohort, and 396 breast milk samples from Czech mothers we used, together with their physiological characteristics and PCB concentrations from other exposure sources (food, dust, air). The estimated total PCB concentrations in children's blood at different ages were compared with threshold PCB concentrations of 500, 700 and 1000 ng·g_lipid^-1 in serum proposed by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) and the German Environment Agency (UBA), above which possible adverse health effects may be expected. We estimated that up to 20.6% of Slovak children and up to 45.7% of Czech children at two years of age exceeded the threshold value of 700 ng·g_lipid^-1 in blood. Mean TEDIs leading to values of 500 ng·g_lipid^-1 in blood for children up to two years ranged between 110 and 220 ng·kg^-1·bw·day^-1, varying according to breastfeeding duration. Breast milk and prenatal exposure contributed to 71%-85% of PCBs exposure at two years of age. In contrast, the contributions of PCBs from dust and indoor air were negligible.

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.

Embryonic PCB exposure alters phenotypic, genetic, and epigenetic profiles in turtle sex determination, a biomarker of environmental contamination

In species with temperature-dependent sex determination, embryonic gonadal differentiation can be modified by exposure to exogenous chemicals such as environmental contaminants. Although phenotypic outcomes of such events are well documented, the underlying molecular mechanisms are rarely described. Here we examine the genetic and epigenetic effect of the embryonic exposure to polychlorinated biphenyls (PCBs) on gonad differentiation in red-eared slider turtles (Trachemys scripta). Some PCB congeners are without effect whereas others synergize to alter sex determination in this species. Application of two potent PCB congeners alter the physiological processes of gonad development normally dictated by the male-producing temperature (MPT), resulting sex ratios significantly biased toward female hatchlings. Of these PCB-induced females, oviduct formation is prominently distorted regardless of ovary development. Further, gonadal expression of ovarian markers, aromatase, FoxL2, and Rspo1, is activated whereas testicular markers, Dmrt1 and Sox9, are suppressed compared with typical expression patterns observed at MPT. DNA methylation profiles of the aromatase promoter in PCB-treated gonads do not follow the typical methylation pattern observed in embryos incubating at female-producing temperature. Rather, the MPT-typical methylation profiles is retained despite the induced ovarian formation. Overall, our studies demonstrate that PCB exposure alters the transcriptional profiles of genes responsible for gonadal differentiation but does not re-establish the epigenetic marks of the aromatase promoter normally set by incubation temperatures in embryonic gonads.

Structure-activity relationship of selected meta- and para-hydroxylated non-dioxin like polychlorinated biphenyls: from single RyR1 channels to muscle dysfunction

Non-dioxin like polychlorinated biphenyls (NDL-PCBs) are legacy environmental contaminants with contemporary unintentional sources. NDL-PCBs interact with ryanodine receptors (RyRs), Ca(2+) channels of sarcoplasmic/endoplasmic reticulum (SR/ER) that regulate excitation-contraction coupling (ECC) and Ca(2+)-dependent cell signaling in muscle. Activities of 4 chiral congeners PCB91, 95, 132, and 149 and their respective 4- and 5-hydroxy (-OH) derivatives toward rabbit skeletal muscle ryanodine receptor (RyR1) are investigated using [(3)H]ryanodine binding and SR Ca(2+) flux analyses. Although 5-OH metabolites have comparable activity to their respective parent in both assays, 4-OH derivatives are unable to trigger Ca(2+) release from SR microsomes in the presence of Ca(2+)-ATPase activity. PCB95 and derivatives are investigated using single channel voltage-clamp and primary murine embryonic muscle cells (myotubes). Like PCB95, 5-OH-PCB95 quickly and persistently increases channel open probability (p o > .9) by stabilizing the full-open channel state, whereas 4-OH-PCB95 transiently enhances p o. Ca(2+) imaging of myotubes loaded with Fluo-4 show that acute exposure to PCB95 (5 µM) potentiates ECC and caffeine responses and partially depletes SR Ca(2+) stores. Exposure to 5-OH-PCB95 (5 µM) increases cytoplasmic Ca(2+), leading to rapid ECC failure in 50% of myotubes with the remainder retaining negligible responses. 4-OH-PCB95 neither increases baseline Ca(2+) nor causes ECC failure but depresses ECC and caffeine responses by 50%. With longer (3h) exposure to 300 nM PCB95, 5-OH-PCB95, or 4-OH-PCB95 decreases the number of ECC responsive myotubes by 22%, 81%, and 51% compared with control by depleting SR Ca(2+) and/or uncoupling ECC. NDL-PCBs and their 5-OH and 4-OH metabolites differentially influence RyR1 channel activity and ECC in embryonic skeletal muscle.

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.

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.

Neurophysiologic and neurobehavioral evidence of beneficial effects of prenatal omega-3 fatty acid intake on memory function at school age

BACKGROUND

The beneficial effects of prenatal and early postnatal intakes of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) on cognitive development during infancy are well recognized. However, few studies have examined the extent to which these benefits continue to be evident in childhood.

OBJECTIVE

The aim of this study was to examine the relation of n-3 PUFAs and seafood-contaminant intake with memory function in school-age children from a fish-eating community.

DESIGN

In a prospective, longitudinal study in Arctic Quebec, we assessed Inuit children (n = 154; mean age: 11.3 y) by using a continuous visual recognition task to measure 2 event-related potential components related to recognition memory processing: the FN400 and the late positive component (LPC). Children were also examined by using 2 well-established neurobehavioral assessments of memory: the Digit span forward from Wechsler Intelligence Scales for Children, 4th edition, and the California Verbal Learning Test-Children's Version.

RESULTS

Repeated-measures analyses of variance revealed that children with higher cord plasma concentrations of docosahexaenoic acid (DHA), which is an important n-3 PUFA, had a shorter FN400 latency and a larger LPC amplitude; and higher plasma DHA concentrations at the time of testing were associated with increased FN400 amplitude. Cord DHA-related effects were observed regardless of seafood-contaminant amounts. Multiple regression analyses also showed positive associations between cord DHA concentrations and performance on neurobehavioral assessments of memory.

CONCLUSION

To our knowledge, this study provides the first neurophysiologic and neurobehavioral evidence of long-term beneficial effects of n-3 PUFA intake in utero on memory function in school-age children.

Determination and assessment of total mercury levels in local, frozen and canned fish in Lebanon

Fish is an important constituent of the Lebanese diet. However, very little attention in our area is given to bring awareness regarding the effect of the toxicity of mercury (Hg) mainly through fish consumption. This study aimed to report analytical data on total mercury levels in several fish species for the first time in thirty years and to also made individuals aware of the presence and danger from exposure to mercury through fish consumption. Fish samples were selected from local Lebanese markets and fisheries and included 94 samples of which were fresh, frozen, processed, and canned fish. All values were reported as microgram of mercury per gram of fish based on wet weight. The level of mercury ranged from 0.0190 to 0.5700 microg/g in fresh samples, 0.0059 to 0.0665 microg/g in frozen samples, and 0.0305 to 0.1190 microg/g in canned samples. The data clearly showed that higher levels of mercury were detected in local fresh fish as opposed to other types thus placing consumers at higher risk from mercury exposure. Moreover, the data revealed that Mallifa (yellowstripe barracuda/Sphyraena chrysotaenia), Sargous (white seabream/Diplodus sargus), Ghobbos (bogue/Boops boops), and shrimp (Penaeus sp.) were among the types containing the highest amounts of mercury. On the other hand, processed fish such as fish fillet, fish burger, small shrimp and crab are found to contain lower levels of mercury and are associated with lower exposure risks to mercury. Lebanese population should therefore, be aware to consume limited amounts of fresh local fish to minimize exposure to mercury.

Prenatal exposure to methylmercury and PCBs affects distinct stages of information processing: an event-related potential study with Inuit children

Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are seafood contaminants known for their adverse effects on neurodevelopment. This study examines the relation of developmental exposure to these contaminants to information processing assessed with event-related potentials (ERPs) in school-aged Inuit children from Nunavik (Arctic Québec). In a prospective longitudinal study on child development, exposure to contaminants was measured at birth and 11 years of age. An auditory oddball protocol was administered at 11 years to measure ERP components N1 and P3b. Multiple regression analyses were performed to examine the associations of levels of the contaminants to auditory oddball performance (mean reaction time, omission errors and false alarms) and ERP parameters (latency and amplitude) after control for potential confounding variables. A total of 118 children provided useable ERP data. Prenatal MeHg exposure was associated with slower reaction times and fewer false alarms during the oddball task. Analyses of the ERP parameters revealed that prenatal MeHg exposure was related to greater amplitude and delayed latency of the N1 wave in the target condition but not to the P3b component. MeHg effects on the N1 were stronger after control for seafood nutrients. Prenatal PCB exposure was not related to any endpoint for sample as a whole but was associated with a decrease in P3b amplitude in the subgroup of children who had been breast-fed for less than 3 months. Body burdens of MeHg and PCBs at 11 years were not related to any of the behavioural or ERP measures. These data suggest that prenatal MeHg exposure alters attentional mechanisms modulating early processing of sensory information. By contrast, prenatal PCB exposure appears to affect information processing at later stages, when the information is being consciously evaluated. These effects seem to be mitigated in children who are breast-fed for a more extended period.

An evaluation of the sexual differences in the accumulation of organochlorine compounds in children at birth and at the age of 4 years

This study of the body burden and serum concentrations of organochlorine compounds (OCs), represents a general population in a cohort from Menorca Island (birth 1997-1998) of children at birth and at 4 years of age; the study has shown that the concentrations of hexachlorobenzene (HCB), 4,4'-DDE, 4,4'-DDT, polychlorobiphenyl (PCB) congeners #153, #138 and #180 and total PCBs in sera collected at 4 years are much higher in breastfed children than in those fed with formula, e.g. HCB 0.48 vs 0.21 ng/ml, beta-HCH 0.32 vs 0.24 ng/ml, total DDTs 2.2 vs 0.57 ng/ml and total PCBs 1.4 vs 0.52 ng/ml. Comparison of gender differences in 4 years old children shows higher concentrations of all examined OCs in females than in males with the exception of HCB and PeCB in breastfed children, which are higher in males than in females, e.g. beta-HCH 0.34 vs 0.28 ng/ml, total DDTs 2.6 vs 1.7 ng/ml and total PCBs 1.6 vs 1.0 ng/ml for breastfed children and beta-HCH 0.23 vs 0.19 ng/ml, total DDTs 0.59 vs 0.48 ng/ml and total PCBs 0.58 vs 0.45 ng/ml for formula fed children. Gender comparison of the body burden between children fed with breastmilk or formula also shows higher concentrations in females than in males, e.g. beta-HCH 0.47 vs 0.35 microg, total DDTs 3.0 vs 1.8 microg and total PCBs 1.9 vs 1.2 microg for breastfed children, and beta-HCH 0.39 vs 0.17 microg, total DDTs 0.48 vs 0.27 microg and total PCBs 0.66 vs 0.55 microg for formula fed children. The results may suggest a higher capacity in female children for the retention of OCs incorporated through breastfeeding. However, these results should be taken with caution because the differences of the gender averages have low statistically significance when evaluated with the Student test.

Maternal serum preconception polychlorinated biphenyl concentrations and infant birth weight

BACKGROUND

Prenatal and postnatal polychlorinated biphenyl (PCBs) exposure has been associated with decrements in fetal and infant growth and development, although exposures during the preconception window have not been examined despite recent evidence suggesting that this window may correspond with the highest serum concentrations.

OBJECTIVES

We assessed maternal serum PCB concentrations at two sensitive developmental windows in relation to birth weight.

METHODS

Serum samples were collected from 99 women as they began trying to become pregnant (preconception) and after a positive pregnancy test (prenatal); 52 (53%) women gave birth and represent the study cohort. Using daily diaries, women recorded sexual intercourse, menstruation, and home pregnancy test results until pregnant or up to 12 menstrual cycles with intercourse during the estimated fertile window. With gas chromatography with electron capture, 76 PCB congeners were quantified (nanograms per gram serum) and subsequently categorized by purported biologic activity. Serum PCBs were log-transformed and entered both as continuous and categorized exposures along with birth weight (grams) and covariates [smoking (yes/no), height (inches), and infant sex (male/female)] into linear regression.

RESULTS

A substantial reduction in birth weight (grams) was observed for women in the highest versus the lowest tertile of preconception antiestrogenic PCB concentration (beta; = 429.3 g, p = 0.038) even after adjusting for covariates (beta; = 470.8, p = 0.04).

CONCLUSIONS

These data reflect the potential developmental toxicity of antiestrogenic PCBs, particularly during the sensitive preconception critical window among women with environmentally relevant chemical exposures, and underscore the importance of PCB congener-specific investigation.

Assessing inter-generational transfer of a brominated flame retardant

Studies have shown that the lipophilic nature of polybrominated biphenyl (PBB) causes it to preferentially accumulate in breast milk posing a potential hazard for suckling infants. The purpose of this study was to examine the inter-generational transfer of PBB from mother to child and whether this association was modified by maternal breast-feeding patterns. One hundred and forty-five mother-child pairs that were participants of the Michigan Long-Term PBB Study were included in this analysis. Mothers were exposed to PBB via contaminated food between 1973 and 1974 and children were exposed in utero and for some, through breast-feeding. Seventy-three percent of children had a non-detectable serum PBB concentration (limit of detection (LOD) = 1 microg L(-1)). Mothers' serum PBB concentration at enrollment ranged from <LOD to 933 microg L(-1). The following variables were associated with the child having a detectable serum PBB concentration: maternal serum PBB > or =8 microg L(-1), breast-feeding > or =5.5 months, maternal age at child's birth > or =28 years, and being born during the PBB exposure period. Among mothers with a detectable serum PBB concentration, those who breast-fed > or =5.5 months were 6 times more likely to have a child with a detectable serum PBB concentration, compared to a non-breast-fed child (95% C.I., 2.0-19.6).

Effects of birth order and maternal age on breast cancer risk: modification by whether women had been breast-fed

BACKGROUND

Early life risk factors for breast cancer have been investigated in relation to hormonal, nutritional, infectious, and genetic hypotheses. Recent studies have also considered potential health effects associated with exposure to environmental contaminants in breastmilk.

METHODS

We analyzed data from a population-based case-control study of women living in Wisconsin. Cases (n = 2016) had an incident diagnosis of invasive breast cancer in 2002-2006 reported to the statewide tumor registry. Controls (n = 1960) of similar ages were randomly selected from driver's license lists. Risk-factor information was collected during structured telephone interviews. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from multivariable logistic regression.

RESULTS

In multivariable models, maternal age and birth order were not associated with breast cancer risk in the full study population. The odds ratio for breast cancer risk associated with having been breast-fed in infancy was 0.83 (95% CI = 0.72-0.96). In analyses restricted to breast-fed women, maternal age associations with breast cancer were null (P = 0.2). Increasing maternal age was negatively associated with breast cancer risk among women who were not breast-fed; the odds ratio for breast cancer associated with each 5-year increase in maternal age was 0.90 (0.82-1.00). Higher birth order was inversely associated with breast cancer risk among breast-fed women (for women with 3 or more older siblings compared with first-born women, OR = 0.58 [CI = 0.39-0.86]) but not among nonbreast-fed women (1.13 [0.81-1.57]).

CONCLUSION

These findings suggest that early life risk factor associations for breast cancer may differ according to breast-feeding status in infancy.

A decay model for assessing polybrominated biphenyl exposure among women in the Michigan Long-Term PBB Study

The Michigan Long-Term PBB Study was established following exposure to polybrominated biphenyls (PBBs) in the early 1970s. Serum samples from cohort members were analyzed for PBB during 1976-1993. More than 20 years following this industrial incident, some participants still had measurable serum PBB concentration levels. Thus, there is continuing interest in understanding the elimination of PBB from the body. In the present study, we estimated serum PBB decay and investigated the effects of covariates on serum PBB decay rates among 406 female cohort members. We developed a decay model using a general linear mixed model, which attributes unique intercept and slope estimates for each individual while borrowing information across individuals for predicting these quantities. Age at exposure and body mass index (BMI) at the initial measurement were time-independent covariates. Time since exposure, smoking history, pregnancy status, and breast-feeding status were time-dependent covariates. Higher BMI was associated with a slower decay rate; smokers had a faster decay rate than nonsmokers; and increasing age at exposure was marginally associated with a slower decay rate. Our results suggest a faster serum PBB decay rate for women who breast-fed during the interval between serum PBB measurements. To evaluate the predictive performance of our modeling approach, we compared the results from this model with those from a previously developed ordinary least squares (OLS) two-stage decay model. The mixed-effects decay model predicted the observed serum PBB concentration levels significantly better than the OLS two-stage decay model (mixed-effects model, r=0.93; OLS two-stage model, r=0.86; P<0.0001).

PBDEs and PBBs in the adipose tissue of women from Spain

Polybromodiphenyl ethers (PBDEs) and polybromobiphenyls (PBBs) were investigated in adipose tissue of women living in Southeastern Spain. Mean Sigma PBDE (BDE 28, 75, 71, 47, 66, 77, 100, 119, 99, 85, 154, 153, 138, and 183) and Sigma PBB (PBB 18, 29, 31, 22, 38, 37, 53, 52, 49, 75, 80, 56, 77, 103, 101, 155, 154, 153, and 169) levels were 3.85 and 0.36 ng/g of lipid, respectively. Among PBDEs, congeners 153, 47, 183, 99, and 100 were the most frequent and abundant and together constituted 96% of the total amount of PBDEs in adipose tissue. Concentrations of PBDEs in this population were similar to those reported in other parts of Spain and in Swedish and Belgium populations but lower than those found in other Western countries. Among PBB congeners studied, PBB 153 presented the highest concentrations and contributed 79% of all PBBs. There are no published data on PBB congeners in adipose tissues of the Spanish population for comparison, but the levels found were similar to those described in other European countries. Further research is needed to determine trends in human exposure to PBDEs and PBBs and to explore putative effects on human health.

In utero and post-natal accumulation of organochlorine compounds in children under different environmental conditions

A study of intake of organochlorine compounds (OCs) in children both in utero and at the age of four years has been performed in two cohorts. One encompasses children born in Menorca Island between 1997 and 1998, and the other those born between 1997-1999 in Ribera d'Ebre, an in-land industrial-agricultural area of Catalonia. Comparison of the OC concentrations in serum samples from both populations, including those obtained from cord blood and blood collected at four years, provides information on the influence of local pollution sources in the accumulation of these compounds. Statistically significant differences (p < 0.01) have been found for hexachlorobenzene, indicating that chronic airborne contamination to this compound in Ribera d'Ebre involved higher in utero exposure, which increased in the first four years of growth. Similarly, in the cohort of Menorca, higher in utero exposure to PCBs was observed and this increased subsequently in the first four years of growth. Other compounds encompassing temporal contamination episodes such as gamma-HCH involved higher in utero exposure but strongly diminished in the first four years of growth. Overall, it can be concluded that local chronic pollution by OCs has a direct effect in children living in the surrounding areas. This influence is reflected in higher exposure, both in utero and in the first years of growth, that significantly stands out over the background contamination due to the ubiquity of these compounds.

Potential for phytoremediation of polychlorinated biphenyl-(PCB-)contaminated soil

Weathered soils contaminated with commercial-grade Aroclor 1260 from three sites in Canada were used to investigate the polychlorinated biphenyl (PCB) phytoextraction potential of nine plant species (Festuca arundinacea, Glycine max, Medicago sativa, Phalaris arundinacea, Lolium multiflorum, Carex normalis, and three varieties of Cucurbita pepo ssp. pepo) under controlled greenhouse conditions. The soils used varied in PCB concentration (90-4200 microg/g) and total organic content (0.06-2.02%). Greenhouse experiments controlled for PCB volatilization through the use of a vented enclosure and by isolating the contaminated soils with parafilm. After 8 wks, PCB concentrations of 47-6700 microg/g were observed in root tissues. Although PCB concentrations in shoot tissues were lower (< 1-470 microg/g), the absolute amounts of PCBs observed in shoot tissue were significant (1.7-290 microg) once shoot biomass was accounted for. Congener signatures indicated that tetra- to hexa-chlorobiphenyls contributed the largest proportions to shoot tissues, but hepta-to nona-chorobiphenyls were also present in measurable amounts. Overall, the results indicate that varieties of C. pepo were more effective at extracting PCBs from soil than other plants screened The evidence suggests that this was mainly due to root uptake of PCBs and tranlocation to the shoots, rather than volatilization of PCBs from soil. All plants screened showed signs of stress in the most highly contaminated soil (4200 microg/g), but not in the two lower PCB contaminated soils (250 and 90 microg/g, respectively). No detectable decreases in soil PCB concentrations were observed in these short-term greenhouse experiments, but the results suggest that this may be achievable through multiple plantings.

Effect of socioeconomic status on exposures to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) among pregnant African-American women

In this study, the authors investigated the associations between socioeconomic status and exposures to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) in a cohort of inner-city African-American pregnant women. Data for this study were derived from the Columbia Presbyterian Medical Center subcohort of the National Collaborative Perinatal Project. African-American women from whom venous blood had been collected during their third trimester of pregnancy during the time period between 1960 and 1965 were included in the current study (n = 152). Prenatal samples were assayed for PCB and DDE concentrations. The authors used linear-regression analysis to explore the association between socioeconomic indicators and PCB and DDE concentrations. Mean concentrations of the 4 most abundant congeners (i.e., PCB4) and total DDE were 3.9 microg/l and 37.2 microg/l, respectively. In adjusted analyses, income was associated significantly with an increase in serum concentrations of PCBs, whereas education was not. Neither income nor education was associated with concentrations of DDE. The authors concluded that maternal socioeconomic indicators may influence the effects of exposure to PCBs among African-American pregnant women.

In utero exposure to background levels of polychlorinated biphenyls and cognitive functioning among school-age children

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. In utero exposure to background levels of PCBs has been associated with intellectual impairment among children in most, but not all, studies. The authors evaluated prenatal PCB exposure in relation to cognitive test (intelligence quotient (IQ)) scores on the Wechsler Intelligence Scale for Children at age 7 years. Pregnant women were recruited from 12 US study centers from 1959 to 1965, and their children were followed until age 7 years (the Collaborative Perinatal Project). Third trimester serum was analyzed for PCBs in 1997-1999 for 732 women selected at random and for an additional 162 women whose children had either a low or a high IQ score. The PCB-IQ association was examined in multivariate models. Among those in the lowest exposure category (<1.25 microg of PCB/liter of serum), the fully adjusted mean IQ score was 93.6 (standard error: 1.8); among those in the highest category (> or =5 microg of PCB/liter), the mean IQ was 97.6 (standard error: 1.2); and overall the increase in IQ per unit increase in PCB level (microg/liter) was 0.22 (95% confidence interval: -0.28, 0.71). In these data, in utero exposure to background levels of PCBs was not associated with lower IQ at age 7 years.

Prenatal DDT exposure in relation to anthropometric and pubertal measures in adolescent males

DDT (dichlorodiphenyltrichloroethane), a pesticide once used widely in agriculture and now limited to public health use, remains a controversial chemical because of a combination of benefits and risks. DDT or its breakdown products are ubiquitous in the environment and in humans. Compounds in the DDT family have endocrine actions and have been associated with reproductive toxicity. A previous study reported associations between prenatal exposure to p,p -DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene] and increased height and weight in adolescent boys. We examined a group with higher exposures to see whether similar associations would occur. Our study group was 304 males born in Philadelphia in the early 1960s who had participated in a previous study. Anthropometric and pubertal measures from one to six visits during their adolescent years were available, as were stored maternal serum samples from pregnancy. We measured p,p -DDE, p,p -DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane], and o,p -DDT [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)-ethane] in the maternal serum. Outcomes examined in the boys were height, ratio of sitting height to height, body mass index, triceps skinfold thickness, ratio of subscapular to the sum of triceps and subscapular skinfold thicknesses, skeletal age, serum testosterone, and serum dehydroepiandrosterone sulfate. No associations between prenatal exposure to any of the DDT compounds and any outcome measure were seen.

Mercury in canned tuna: white versus light and temporal variation

There are abundant data and advisories for mercury levels in wild fish, but far fewer for commercial fish that compose a large majority of the fish most people eat. Until recently, relatively little attention has been devoted to examining mercury in canned tuna, despite its great importance in human diets. There is substantial media coverage of the benefits and risk from fish consumption, but few peer-reviewed data on canned tuna, the most commonly consumed fish in the United States. In this paper, we examine the levels of total mercury in canned tuna obtained from a New Jersey grocery store from 1998 to 2003, looking for temporal consistency within this data set and particularly for comparison with the Food and Drug Administration's 1991 study. We analyzed 168 cans individually for total mercury. All values are reported as parts per million (= microg/g) on a wet weight basis. In a subset of samples analyzed for total and inorganic mercury, the inorganic mercury was below detection levels; hence at least 89% of the mercury can be considered methylmercury. We found that white-style tuna had significantly more total mercury (mean 0.407 ppm) than light-style tuna (mean 0.118 ppm), presumably reflecting that "white" tuna is albacore, a species relatively larger than the skipjack tuna, which is commonly available as "light" or "chunk light." The maximum mercury in a can was 0.997 ppm, but 25% of white tuna samples exceeded 0.5 ppm. Data suggest a slight increase in levels since 1991, and mercury levels were significantly higher in 2001 than in other years. The mean level of mercury in white tuna (mean 0.407 ppm) was significantly higher than the mean value of 0.17 ppm currently used by the U.S. Food and Drug Administration (FDA) in its risk assessment and public information. There were no significant differences in mercury levels in tuna packed in oil compared to water. Draining contents had no effect on mercury levels, and the fluid, both oil and water, contained little mercury. These data indicate that people who eat canned tuna frequently can choose light tuna and reduce their mercury intake. Canned mackerel had much lower levels of mercury than tuna. Since cans of white tuna frequently exceed the FDA's original action level of 0.5 ppm, it would be prudent to continue some systematic monitoring of the nation's canned fish supply, particularly as the targets of commercial fisheries inevitably change as certain stocks become depleted.

Organochlorine contaminants in flounder (Platichthys flesus) and mullet (Mugil cephalus) from Douro estuary, and their use as sentinel species for environmental monitoring

In order to monitor the presence of organic pollutants in Douro estuary (NW Portugal), two sentinel fish species, grey mullet (Mugil cephalus) and flounder (Platichthys flesus), were periodically sampled from May 2001 to April 2002. At all sampling periods, several specimens of both species were allowed to depurate in clean sea water. Levels of PCBs and DDTs were quantified in liver and muscle of both species. The accumulation of PCBs was higher in muscle of mullet, with a maximum of 345 ng/g dw, than in flounder, with a maximum 52ng/g dw. In the liver, flounder showed the highest levels (811 ng/g dw). Of the 18 congeners analysed, CBs 180 (hepta), 153 and 138 (hexachlorobiphenyls) were predominant in the tissue of both species. The maximum concentration of tDDT was measured in flounder liver (301ng/g dw). In contrast, a 10-fold higher tDDT was recorded in mullet muscle (63-69 ng/g dw and 8-16 ng/g dw for mullet and flounder, respectively). The hepatic ethoxyresorufin O-deethylase (EROD) activity was periodically determined. Consistently, a 10-fold higher enzymatic activity was present in mullet in comparison with flounder (1536 pmol/min/mg protein in mullet and 156 pmol/min/mg protein in flounder). In mullet, no correlation could be found between EROD activity and gonado-somatic index (GSI) or hepato-somatic index (HSI). On the contrary, during the reproductive season, female flounder showed a negative correlation between EROD activity and GSI. Despite being in clean sea water for 1 month period, no significant decrease in the tissue content of PCBs and tDDT was found. However, mullet's EROD activity followed a clear pattern, with a decrease enzymatic activity after being in captivity. Female flounder displayed a similar trend during the resting season. Yet, during the reproductive season, an increased EROD activity was recorded after being in captivity for 1 month, which may be associated with a modulation effect of steroids on CYP 1A1. Histological analyses of gonad revealed that 21% of male mullet displayed testis-ova, while no male flounder was found to show gonadal abnormalities. Overall, the study reports the accumulation of significant levels of PCBs and DDTs in the tissues of the studied species. It also provides important evidences supporting the use of grey mullet as a sentinel species for monitoring the presence of organic contaminants and xeno-estrogenic pollution in southern European estuaries.

Epidemiologic studies of PCB congener profiles in North American fish consuming populations

Long range atmospheric and stream transport and oceanic currents drive the ecologic process of PCB deposition in the abiotic environment. In contrast short range transport via bioaccumulation-biomagnification up the food chain determines PCB congener profiles and concentrations and their adverse effects in biological organisms. Two research approaches to congeners, with potential to associate specific adverse human health effects with PCB concentrations in indigenous small populations, are summarized in this study. The field epidemiological approach includes giving questionnaires to target population groups in conjunction with sampling for PCBs (and selected persistent organic pollutants and metals), in foods purchased or hunted and collected by Inuit peoples. Direct determination of contaminant levels in food sources and among individuals in selected comparative subpopulations is also presented.

Prenatal exposure to polychlorinated biphenyls and attention at school age

OBJECTIVE

To examine the relation of prenatal polychlorinated biphenyl (PCB) exposure to child performance on neuropsychological tests of attention and information processing. Study design In this prospective, longitudinal study, assessment of prenatal PCB exposure was based on umbilical cord serum and maternal serum and milk concentrations. The children were tested in their homes at age 11 years. Multiple regression was used to examine the relation of this exposure to performance on 15 neuropsychological tests after controlling for a broad range of potential confounding variables.

RESULTS

Adverse effects were seen primarily in children who had not been breast fed. Among these children, prenatal PCB exposure was associated with greater impulsivity, poorer concentration, and poorer verbal, pictorial, and auditory working memory. There was no evidence of visual-spatial deficit or increased hyperactivity.

CONCLUSIONS

These findings are consistent with earlier reports of greater vulnerability to prenatal PCB exposure in children who were not breast fed. It is not clear whether the protection offered by breast-feeding is caused by nutrients in breast milk or better quality of intellectual stimulation often provided by breast-feeding mothers.

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.

Fish, shellfish, and meat meals of the public in Singapore

Understanding different patterns of fish consumption is an important component of the assessment of risk from contaminants in fish. While there have been extensive studies of fish consumption in Western cultures, less attention has been devoted to the role of fish and meat in the diets of people in other cultures. A survey of 212 people living in Singapore was conducted to examine the relative importance of fish, shellfish, and other meat in their diets and to ascertain whether there were differences as a function of age, income, education or gender. As expected, fish and shellfish played an important role in their daily diets. On average, people ate fish in about 10 meals a week, chicken for eight meals, and shrimp and pork for about six meals each. While nearly 8% never ate fish, 18% ate fish at all 21 meals a week and over 20% ate shellfish for all 21 meals. Income explained about 14% of the variation in the number of fish meals consumed, and age explained about 8% of the variation in number of chicken meals per week. There were no gender differences in the number of meals of each type. People less than 26 years old ate significantly more pork, chicken, and other meat meals and fewer shellfish meals than older people. People with higher incomes ate significantly more fish meals than those with lower incomes. Chinese individuals ate significantly more meals of pork, chicken, and other meat than other ethnic groups, and they ate only 26% of their meals at home, while others ate 33% of their meals at home. The data indicate a great deal of variation in the number of meals of fish, shellfish, and other meats eaten by the people interviewed, making dietary and risk assessments challenging.

Hormonally active agents in the environment and children's behavior: assessing effects on children's gender-dimorphic outcomes

BACKGROUND

Early sex hormone exposure contributes to gender-dimorphic behavioral development in mammals, including humans. Environmental toxicants concentrated in contaminated sport fish can interfere with the actions of sex steroids.

METHODS

This study developed an outcome variable by combining gender-dimorphic behaviors that differentiates boys and girls. Offspring of participants in the New York State Angler Cohort Study (NYSACS) were targeted in a parent-report postal survey. Instruments were selected based on findings of gender differences in the general population.

RESULTS

A linear discriminant function model incorporating three gender behavior scales correctly classified the sex of 97.7% of children (252 boys and 234 girls) from a random NYSACS sample. The discriminant function was cross-validated by correctly classifying the sex of 98.4% of children (457 boys and 425 girls) from the remaining NYSACS cases and 97.6% of children (154 boys and 142 girls) from an independent school sample. Within-sex stepwise multiple regression analyses revealed that masculine behavior increased among boys with age and with the number of years of maternal sport fish consumption. In girls, older age and previous live-born siblings were associated with more masculine behavior, whereas feminine behavior increased with the duration of breast feeding. These associations were replicated in an independent sample.

CONCLUSIONS

A linear discriminant function effectively transformed the binary classification of sex (male-female) to a bipolar continuum of gender (masculinity-femininity). Findings from this study are consistent with the hypothesis that environmental contaminants contribute to shifts in gender-role behavior. Future investigations will need to account for competing explanations of this effect.

Effects of PCB exposure on neuropsychological function in children

In the last decade advances in the analytic methods for quantification of polychlorinated biphenyls (PCBs) have resulted in widespread availability of congener-specific analysis procedures, and large amounts of data on PCB congener profiles in soil, air, water, sediments, foodstuffs, and human tissues have become available. These data have revealed that the PCB residues in environmental media and human tissues may not closely resemble any of the commercial PCB mixtures, depending on source of exposure, bioaccumulation through the food chain, and weathering of PCBs in the environment. At the same time, toxicological research has led to a growing awareness that different classes of PCB congeners have different profiles of toxicity. These advances in analytic techniques and toxicological knowledge are beginning to influence the risk assessment process. As the data from ongoing PCB studies assessing the mediators of neurobehavioral outcomes in children are published, the weight of evidence for PCB effects on neurodevelopment is growing. Studies in Taiwan, Michigan (USA), New York (USA), Holland, Germany, and the Faroe Islands have all reported negative associations between prenatal PCB exposure and measures of cognitive functioning in infancy or childhood. The German study also reported a negative association between postnatal PCB exposure and cognitive function in early childhood--a result that had not been found in previous studies. Only one published study in North Carolina (USA) has failed to find an association between PCB exposure and cognitive outcomes. Despite the fact that several more recent studies have used congener-specific analytic techniques, there have been only limited attempts to assess the role of specific PCB congeners or classes of congeners in mediating neurodevelopmental outcomes. From a statistical standpoint, attempts to determine the role of individual congeners in mediating outcomes are hampered by the fact that concentrations of most individual congeners are highly correlated with each other and with total PCBs. From a toxicological standpoint, these efforts are hampered by the fact that many of the PCB congeners present in human tissues have never been studied in the laboratory, and their relative potency to produce nervous system effects is unknown. More complete information on the health effects of various congeners or congener classes would allow more informed scientific and risk assessment decisions.

Comparison of polychlorinated biphenyl levels across studies of human neurodevelopment

Polychlorinated biphenyls (PCBs) are persistent pollutants that are ubiquitous in the food chain, and detectable amounts are in the blood of almost every person in most populations that have been examined. Extensive evidence from animal studies shows that PCBs are neurotoxins, even at low doses. Interpretation of human data regarding low-level, early-life PCB exposure and subsequent neurodevelopment is problematic because levels of exposure were not similarly quantified across studies. We expressed the exposure levels from 10 studies of PCB and neurodevelopment in a uniform manner using a combination of data from original investigators, laboratory reanalyses, calculations based on published data, and expert opinion. The mainstay of our comparison was the median level of PCB 153 in maternal pregnancy serum. The median concentration of PCB 153 in the 10 studies ranged from 30 to 450 ng/g serum lipid, and the median of the 10 medians was 110 ng/g. We found that (a)) the distribution of PCB 153 exposure in most studies overlapped substantially, (b)) exposure levels in the Faroe Islands study were about 3-4-fold higher than in most other studies, and (c)) the exposure levels in the two recent U.S. studies were about one-third of those in the four earlier U.S. studies or recent Dutch, German, and northern Québec studies. Our results will facilitate a direct comparison of the findings on PCBs and neurodevelopment when they are published for all 10 studies.

Comparison of polychlorinated biphenyl levels across studies of human neurodevelopment

Polychlorinated biphenyls (PCBs) are persistent pollutants that are ubiquitous in the food chain, and detectable amounts are in the blood of almost every person in most populations that have been examined. Extensive evidence from animal studies shows that PCBs are neurotoxins, even at low doses. Interpretation of human data regarding low-level, early-life PCB exposure and subsequent neurodevelopment is problematic because levels of exposure were not similarly quantified across studies. We expressed the exposure levels from 10 studies of PCB and neurodevelopment in a uniform manner using a combination of data from original investigators, laboratory reanalyses, calculations based on published data, and expert opinion. The mainstay of our comparison was the median level of PCB 153 in maternal pregnancy serum. The median concentration of PCB 153 in the 10 studies ranged from 30 to 450 ng/g serum lipid, and the median of the 10 medians was 110 ng/g. We found that (a)) the distribution of PCB 153 exposure in most studies overlapped substantially, (b)) exposure levels in the Faroe Islands study were about 3-4-fold higher than in most other studies, and (c)) the exposure levels in the two recent U.S. studies were about one-third of those in the four earlier U.S. studies or recent Dutch, German, and northern Québec studies. Our results will facilitate a direct comparison of the findings on PCBs and neurodevelopment when they are published for all 10 studies.

Effects of perinatal exposure to PCBs and dioxins on play behavior in Dutch children at school age

Polychlorinated biphenyls (PCBs) and dioxins are known as neurotoxic compounds that may modulate sex steroid hormones. Steroid hormones play a mediating role in brain development and may influence behaviors that show sex differences, such as childhood play behavior. In this study we evaluated the effects of perinatal exposure to environmental levels of PCBs and dioxins on childhood play behavior and whether the effects showed sex differences. As part of the follow-up to the Dutch PCB/dioxin study at school age, we used the Pre-School Activity Inventory (PSAI) to assess play behavior in the Rotterdam cohort (n = 207). The PSAI assesses masculine or feminine play behavior scored on three subscales: masculine, feminine, and composite. Prenatal exposure to PCBs was defined as the sum of PCB 118, 138, 153, and 180 in maternal and cord plasma and breast milk. For breast milk we measured additional PCBs as well as 17 dioxins. Respondents returned 160 questionnaires (age 7.5 years +/- 0.4). Effects of prenatal exposure to PCBs, measured in maternal and cord plasma, on the masculine and composite scales were different for boys and girls (p <.05). In boys, higher prenatal PCB levels were related with less masculinized play, assessed by the masculine scale (p(maternal) =.042; p(cord) =.001) and composite scale (p(cord) =.011), whereas in girls higher PCB levels were associated with more masculinized play, assessed by the composite scale (p(PCBmilk) =.028). Higher prenatal dioxin levels were associated with more feminized play in boys as well as girls, assessed by the feminine scale (p =.048). These effects suggest prenatal steroid hormone imbalances caused by prenatal exposure to environmental levels of PCBs, dioxins, and other related organochlorine compounds.

Polychlorinated biphenyls in the blood plasma: current exposure of the population in Germany

Until the 1970s, polychlorinated biphenyls (PCB) were used as industrial chemicals for diverse commercial applications, leading to a ubiquitous contamination of nature and man. In the 1980s, PCBs were prohibited by law in many industrialized countries. Hence, in recent years a steady decline in PCB levels has been seen. Here we report on PCB plasma levels in children and adults in Germany in 1998.

PARTICIPANTS AND METHODS

130 children/youth (0 to <18 y) and 494 adults (18 to 65 y) living in an urban environment participated in this study. Occupational exposure to PCBs was excluded by questionnaire. Gas chromatography/electron capture detection was used to analyze blood plasma samples.

RESULTS

In all blood specimens, PCB congeners 28, 52, and 101 were below the limit of quantification (<0.1 microg/L) and only the congeners 138, 153, and 180 were detected. The 95th percentiles in the age groups 0 to <6 y, 6 to <12 y, 12 to <18 y, 18 to 25 y, 26 to 35 y, 36 to 45 y, 46 to 55 y, and >55 y were as follows: PCB 138: 1.02; 1.05; 0.61; 1.01; 1.22; 1.44; 2.23; 2.94 microg/L plasma; PCB 153: 1.47; 1.23; 0.59; 1.26; 1.53; 2.11; 3.27; 3.98 microg/l plasma; PCB 180: 0.88; 1.23; 0.39; 0.88; 1.16; 1.71; 2.16; 3.31 microg/L.

DISCUSSION

In adults, plasma levels of PCBs increased with age. In comparison with published reference values on internal PCB exposure in the population in Germany, based on data obtained in 1991/4 and 1994/5, the steady decline in PCB levels reflects the falling external and internal PCB exposure after the ban on PCB. For the first time, current PCB exposure during childhood and adolescence in Germany is provided here. In childhood, internal PCB exposure declined with age, especially in children who had been breastfed. An impact of breastfeeding on internal PCB exposure was found in age groups up to 12 years old.

Exposure of South Carolinians to commercial meats and fish within their meat and fish diet

There has been considerable interest in the public's exposure to a variety of contaminants through the consumption of wild fish and game, yet there is little information on consumption of commercial meats and fish, or the relationship between commercial and self-caught fish. We conducted a dietary survey in 1999 to estimate exposure levels of 464 individuals from people attending the Palmetto Sportsmen's Classic. Mean consumption was similar for beef, chicken/turkey, and wild-caught fish, and much lower for pork and store-bought fish, and still lower for restaurant fish. There were no ethnic differences in the consumption of most commercial fish and meats, although the differences for chicken approached significance. There were significant ethnic differences in consumption of wild-caught fish. Women ate significantly less of all meat types, except store-bought fish. People over 45 ate less beef than younger people, and people younger than 32 ate significantly more chicken than others. There were no significant differences in consumption patterns as a function of income, except for chicken and wild-caught fish; people with higher incomes ate more chicken than others, and people with lower incomes ate more wild-caught fish than others. When all wild-caught and commercial fish and meats are considered, there are significant differences only for ethnicity and gender. Blacks consume significantly more fish than Whites, and men consume significantly more than women.

Man-made chemicals found in remote areas of the world: the experimental definition for POPs

Members of the United Nations Economic Commission for Europe (UN-ECE) signed a legally binding protocol on persistent organic pollutants (POPs) in February 1998 under the Convention on Long-Range Transboundary Air Pollution. A treaty that intends to control the production, import, export, disposal and use of toxic chemicals that persist for decades in the environment has been formally signed at a conference in May 2001 in Stockholm. The 2001 POP treaty, like the 1998 LRTAP POP protocol, contains a provision on adding further chemicals to the initial group of twelve or fifteen. The occurrence of a compound or a group of compounds in so called remote and pristine areas, e.g. in the Artic or in the Southern Hemisphere, proves its stability under the chemical and biological conditions of the environment. Compounds identified in this way, in samples taken primarily in very remote regions of the planet, are classified by their environmental fate and global distribution as persistent organic pollutants (POPs), regardless of any political assessments.

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.

Effects of neonatal polychlorinated biphenyl exposure on female sexual behavior

The effects of polychlorinated biphenyls (PCBs) on development and reproduction are well documented. However, very little is known about the effects of PCBs on sexual behavior. In this study, we examined the effects of two commercial PCB mixtures, Aroclor 1221 (A1221) and Aroclor 1254 (A1254), on the development of female sexual behavior and of the incertohypothalamic dopaminergic cells (A11 and A13) in Long-Evans rats. Neonatal exposure to A1254 significantly reduced sexual receptivity and reduced the female's latency to approach a male after an intromission. Neonatal treatment with A1221 did not affect female sexual behavior nor did treatment of adult females with A1221 or A1254. Since sexual behavior is affected by dopamine and since PCBs have been reported to alter dopamine content in the brain, we examined the effects of A1221 or A1254 on dopaminergic cells in the incertohypothalamic region of neonatally exposed rats. None of the treatments significantly affected the number of A11 or A13 neurons that were immunoreactive for tyrosine hydroxylase (TH) or the expression of Fos (i.e., the product of the immediate early gene c-fos) in these dopaminergic neurons. Therefore, the disruption of behavior induced by neonatal treatment with A1254 does not appear to be mediated by toxic effects of the mixture on incertohypothalamic dopaminergic systems.

Are we reaching the target audience? Evaluation of a fish fact sheet

According to the US Environmental Protection Agency, over 16% of freshwater lakes and 7% of the rivers are under some sort of fish consumption advisory because of the presence of toxic chemicals. There is considerable interest in the issuing of information, advisories, and fact sheets concerning the consumption of wild-caught fish from contaminated waters, and in the actual consumption patterns of subsistence and recreational anglers. Despite the large number of consumption advisories issued by state agencies, there is little information on how these advisories, or other forms of risk communication, are perceived by target audiences, notably fishermen and women of child-bearing age. The states of South Carolina and Georgia issue consumption advisories for fish from the Savannah River, among other sites. To gain a greater insight into the perception of anglers about a supplemental fish fact sheet jointly developed by South Carolina, Georgia, federal agencies, and the Consortium for Risk Evaluation with Stakeholder Participation, we interviewed fisherman along the Savannah River. The objectives were to determine: (1) whether they had previously read the Fish Fact Sheet or had heard about the consumption advisories; (2) what major message they obtained from the sheet; (3) who they felt the fact sheet was aimed at, and who should get the Fish Fact Sheet; (4) who should be concerned about health risks from consuming the fish; and (5) the best method of disseminating such information. We interviewed 92 fishermen (37% black, 62% white) during the fishing season of 1999. Half had heard some information about consumption advisories, mainly from the media (64%). The study concluded that there were no ethnic differences in whether they had heard about the advisories, understood the major message of the fact sheet, felt they could reduce their risk from consuming the fish, or felt that it made a difference which agency issued the fact sheet. There were significant ethnic differences in the ways people thought the risk from eating fish could be reduced, sources of information about the risks from consuming fish, and what other information they would like about the risks associated with contaminated fish.

Polychlorinated biphenyls (PCBs) and neurological development in children: a systematic review

BACKGROUND

Polychlorinated biphenyls (PCBs) are complex mixtures of persistent contaminants that are widespread in the environment. Newborns are exposed across the placenta and through breast feeding. Experimental animal studies have indicated that PCBs are neurotoxic. The neurological effects of these compounds on children are not clear.

METHODS

A systematic review of literature on the relation between neurological development in children and exposure to polychlorinated biphenyls.

RESULTS

Seven follow up studies evaluated the effect of prenatal exposure to PCBs. Two of these studies evaluated highly exposed children. In newborns, an increase of the abnormal reflexes was observed in all four studies evaluating it. During the first months of life, a decrease in motor skills was observed in four of the five studies that investigated psychomotor development; deficits in the acquisition of cognitive skills were observed only in one study assessing non-highly exposed populations. At 4 years of age, an effect on the cognitive areas was observed in four of the five studies that evaluated it. Postnatal exposure to PCBs through breast feeding was not clearly related to any effect on neurological development.

CONCLUSIONS

These studies suggest a subtle adverse effect of prenatal PCBs exposure on child neurodevelopment. Differences in study design, inconsistency in some of the results, and the lack of adequate quantitative exposure data, do not allow the derivation of the degree of risk associated with neurodevelopmental effects at current levels of exposure.

PCBs and neurodevelopmental effects in Michigan children: an evaluation of exposure and dose characterization

Despite the fact that PCB levels in the general environment have continued to decline over the past decade, concern for potential neurodevelopmental deficits from in utero exposure to these compounds remains unabated. In fact, some regulatory and scientific bodies have concluded that the evidence suggesting that prenatal exposure to PCBs may lead to neurodevelopmental deficits is one of the greatest public health concerns surrounding PCBs. The primary basis for the concern that low-level in utero exposure to PCBs causes neurodevelopmental deficits in children is a series of reports on a cohort of Michigan children presumably exposed to PCBs as a result of their mother's consumption of Great Lakes fish. These children, known collectively as the Jacobson cohort, have been followed from birth to 11 years of age. The investigators following these children concluded that they have demonstrated persistent neurodevelopmental effects in this cohort attributable solely to PCBs. However, a detailed analysis of the cohort's exposure characterization, particularly in the initial reports, reveals considerable uncertainty as to the actual exposure status of mothers characterized as "fish eaters" and their offspring. Failure to adequately characterize the PCB exposure of these mothers, or their children, precludes any causal association between in utero exposure to PCBs and neurodevelopmental deficits.

Concentrations and frequencies of polychlorinated biphenyl congeners in a Native American population that consumes Great Lakes fish

OBJECTIVE

Polychlorinated biphenyl congener profiles were examined in serum samples from 61 Native American (Ojibwa) volunteers who regularly consumed fish harvested from the Great Lakes region. A total of 93 peaks are reported which represent 126 individual chlorobiphenyls.

RESULTS

When ranked by frequency, 13 peaks comprising single or co-eluting chlorobiphenyls occurred in all 61 samples (a frequency of 100%). These included chlorobiphenyls 138 + 158 + 163, 105 + 132 + 153, 180, 118, 196 + 203, 74, 182 + 187, 199, 183, 114 + 134, 195 + 208, 206, and 194. These 13 peaks also occurred at concentrations higher than those of all other measured chlorobiphenyls, except for the addition of the peak containing chlorobiphenyls 170 and 190, which was below detection in 15% of the samples and ranked fifth in average concentration. The highly chlorinated chlorobiphenyls resembled human serum profiles previously reported in the literature.

METHODS

Individual chlorobiphenyls were identified using a gas chromatograph equipped with a 60-meter DB-5 capillary column and electron capture detection.

CONCLUSION

When compared to other human residue analyses for fish-eating populations, the Ojibwa samples contained higher proportions of lightly chlorinated and labile chlorobiphenyls such as 8, 16 + 32, 17, 18, 25, 41 + 64 + 71, 33, 52, 110, and 129. These proportions were similar to those found in carp, whitefish, or whitefish livers harvested from the Great Lakes region. These data indicate that regular meals of lower trophic level fish, such as whitefish from the Great Lakes, may distort steady-state human chlorobiphenyl profiles with respect to certain lightly chlorinated or labile chlorobiphenyls.

Gender differences in meal patterns: role of self-caught fish and wild game in meat and fish diets

The hypothesis that there are gender differences in consumption patterns of self-caught fish and wild game in the meat and fish diet was examined for 415 people attending the Palmetto Sportsmen's Classic in Columbia, South Carolina. Women were less likely to eat most types of wild fish and game than were men, although there were no gender differences in the percentage eating beef, chicken, pork, and restaurant and store-bought fish. Similarly, women consumed significantly fewer meals of wild-caught fish and game than did men, although the number of meals of most store-bought foods did not differ. Both men and women who ate more meals of fish ate a higher percentage of wild-caught fish than either store-bought or restaurant fish. People with low number of fish and meat meals ate mainly fish; people eating over 30 meals of meat and fish a month ate mainly meat. Only about 9% of those interviewed said that they changed their fish consumption patterns when they, or their spouse, were pregnant. These gender-specific data on protein consumption can be used for exposure assessment and risk management decisions regarding consumption advisories for wild-caught fish and game.

Neonatology for the generalist: human milk banks and evidence-based medicine

Human milk (HM) banks provide pasteurised milk from screened donors for infants in many countries but not in Australia. There are potential benefits and risks from feeding donor milk with the benefits most likely for preterm infants. A randomized clinical trial is required to provide conclusive evidence. Promotion of breast-feeding with the establishment of HM banks may prove to be an important primary health care activities for infants in Australia.

PCB congener profile in the serum of humans consuming Great Lakes fish

The State of Michigan has a long history of research into human exposure to environmental contaminants through consumption of recreationally caught fish. A large cohort of Lake Michigan residents who eat fish (fish-eaters) and those who do not eat fish (nonfish-eaters) established in 1980 served as the basis for the congener-specific polychlorinated biphenyl (PCB) exposure evaluation reported here. In this paper we present the serum PCB congener profile for a subset of this cohort who were over 50 years of age. Serum samples were collected in 1993-1995 and were evaluated by a dual column capillary column gas chromatography procedure capable of detecting over 90 PCB congeners. This evaluation demonstrated significant PCB exposure in the fish-eaters (mean serum PCB of 14.26 ppb; n = 101). This elevated exposure allowed the establishment of a detailed profile of the PCB congeners found in humans exposed by this route. Twenty-two congeners of varying concentrations were the most prevalent and constituted over 95% of the total PCB present in most subjects. Four congeners, 138/163 (2,2',3,4,4',5-PCB/2,3,3',4', 5,6-PCB), 180 (2,2',3,4,4',5,5'-PCB), and 153 (2,2',4,4',5,5'-PCB), accounted for 55-64% of the total PCB load. Other congeners, some of toxicologic significance, were also detected by this analytical protocol. Nonfish-eaters had lower total serum PCB levels (mean = 4. 56; n = 78), but the same general pattern of PCB congeners was present. It was demonstrated that careful selection of a subset of prevalent PCB congeners could provide a cost-effective assessment of exposure without losing critical scientific information.

Prenatal exposure to endocrine disrupting chemicals: effects on behavioral development

Numerous chemicals released into the environment by man are able to disrupt the functioning of the endocrine system by binding to hormonal receptors. Exposure to estrogenic endocrine disruptors during critical periods in fetal life can alter the development of reproductive organs, the neuroendocrine system and subsequent behavior. We present a series of studies on the effects of exposure during fetal life to low, environmentally relevant doses of two pesticides, o,p'DDT and methoxychlor, and of low doses of the synthetic estrogen, diethylstilbestrol on subsequent neuro-behavioral development in house mice. The main findings can be summarized as follows: (1) Mice prenatally exposed to methoxychlor showed changes in reflex development. Exposure to a very low dose of methoxychlor appeared to produce an increased reactivity during early postnatal life. (2) Methoxychlor exposed periadolescent mice showed a decreased reaction time exploring both a novel environment and a novel object. (3) The onset of male intrasex aggression appeared to be delayed in males prenatally exposed to low doses of methoxychlor, since exposed males showed low levels of aggressive interactions during early adolescence but not after they reached adulthood. (4) The rate of depositing urine marks in a novel environment was increased in males prenatally exposed to DES, and also to o,p'DDT and methoxychlor. (5) The proportion of both males and females attacking a same-sex conspecific was increased in mice prenatally exposed to low doses of DES and, marginally, to o,p'DDT. This effect appeared to be related to a decreased latency to attack. However, males prenatally exposed to o,p'DDT displayed a decreased intensity of aggression. The possible implications of perturbing the hormonal milieu during fetal development on the modulation of developmental turnpoints and future behavioral responses are discussed.