Prenatal and postnatal serum PCB concentrations and cochlear function in children at 45 months of age.

BACKGROUND: Some experimental and human data suggest that exposure to polychlorinated biphenyls (PCBs) may induce ototoxicity, though results of previous epidemiologic studies are mixed and generally focus on either prenatal or postnatal PCB concentrations exclusively. OBJECTIVES: Our aim was to evaluate the association between pre- and postnatal PCB concentrations in relation to cochlear status, assessed by distortion product otoacoustic emissions (DPOAEs), and to further clarify the critical periods in development where cochlear status may be most susceptible to PCBs. METHODS: A total of 351 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 months of age. Maternal pregnancy, cord, and child 6-, 16-, and 45-month blood samples were collected and analyzed for PCB concentrations. At 45 months of age, DPOAEs were assessed at 11 frequencies in both ears. Multivariate, generalized linear models were used to estimate the associations between PCB concentrations at different ages and DPOAEs, adjusting for potential confounders. RESULTS: Maternal and cord PCB-153 concentrations were not associated with DPOAEs at 45 months. Higher postnatal PCB concentrations at 6-, 16-, and 45-months of age were associated with lower (poorer) DPOAE amplitudes. When all postnatal PCB exposures were considered as an area-under-the-curve metric, an increase in PCB-153 concentration from the 25th to the 75th percentile was associated with a 1.6-dB SPL (sound pressure level) decrease in DPOAE amplitude (95% CI: -2.6, -0.5; p = 0.003). CONCLUSIONS: In this study, postnatal rather than maternal or cord PCB concentrations were associated with poorer performance on otoacoustic tests at age 45 months.

Relative effect potency estimates of dioxin-like activity for dioxins, furans, and dioxin-like PCBs in adults based on two thyroid outcomes.

BACKGROUND: Toxic equivalency factors (TEFs) are an important component in the risk assessment of dioxin-like human exposures. At present, this concept is based mainly on in vivo animal experiments using oral dosage. Consequently, the current human TEFs derived from mammalian experiments are applicable only for exposure situations in which oral ingestion occurs. Nevertheless, these "intake" TEFs are commonly-but incorrectly-used by regulatory authorities to calculate "systemic" toxic equivalents (TEQs) based on human blood and tissue concentrations, which are used as biomarkers for either exposure or effect. OBJECTIVES: We sought to determine relative effect potencies (REPs) for systemic human concentrations of dioxin-like mixture components using thyroid volume or serum free thyroxine (FT4) concentration as the outcomes of interest. METHODS: We used a benchmark concentration and a regression-based approach to compare the strength of association between each dioxin-like compound and the thyroid end points in 320 adults residing in an organochlorine-polluted area of eastern Slovakia. RESULTS: REPs calculated from thyroid volume and FT4 were similar. The regression coefficient (ß)-derived REP data from thyroid volume and FT4 level were correlated with the World Health Organization (WHO) TEF values (Spearman r = 0.69, p = 0.01 and r = 0.62, p = 0.03, respectively). The calculated REPs were mostly within the minimum and maximum values for in vivo REPs derived by other investigators. CONCLUSIONS: Our REPs calculated from thyroid end points realistically reflect human exposure scenarios because they are based on chronic, low-dose human exposures and on biomarkers reflecting body burden. Compared with previous results, our REPs suggest higher sensitivity to the effects of dioxin-like compounds.

Anthropometric, socioeconomic, and maternal health determinants of placental transfer of organochlorine compounds.

The aim of this study was to relate placental transfer, quantified by the cord to maternal serum concentration ratio (C/M), of five organochlorine pesticides (OCP) hexachlorobenzene (HCB), ß-hexachlorocyclohexane (ß-HCH), γ-hexachlorocyclohexane (γ-HCH) , p,p'-DDT, p,p'-DDE and 15 polychlorinated biphenyl (PCB) congeners (28, 52, 101, 105, 114, 118, 123(+149), 138(+163), 153, 156(+171), 157, 167, 170, 180, and 189) to anthropometric, socioeconomic, and maternal health characteristics. We included into the study 1,134 births during the period 2002-2004 from two districts in eastern Slovakia with high organochlorine concentrations relative to other areas of the world. Only concentrations >LOD were taken into account. Variables as age, weight and height of mothers, parity, ethnicity, alcohol consumption, illness during pregnancy, smoking during pregnancy, hypertension, respiratory diseases, rheumatoid arthritis and diabetes mellitus, and birth weight were related to C/M. Results of regression analyses showed that C/M was predicted by several factors studied. Positive associations were observed for gestational alcohol consumption, fewer illnesses during pregnancy, maternal age, and maternal weight. Caucasians had a greater C/M compared to Romani for wet weight data of congeners 170 and 180 and in contrast C/M for HCB was greater in Romani. Our results show that drinking mothers compared to abstaining expose their fetuses not only to alcohol but to an increased level of several PCB congeners. A straightforward explanation of associations between C/M shifts and factors studied is very difficult, however, with regard to the high lipophilicity of OCPs and PCBs, changes in their kinetics probably reflect lipid kinetics.

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

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

Dynamics of lymphocyte subsets in children living in an area polluted by polychlorinated biphenyls.

Immune system development, particularly in the pre-natal and early post-natal periods, has far-reaching health consequences during childhood, as well as throughout life. Exposure to poly-chlorinated biphenyls (PCBs) during pre-natal and early life has been previously associated with changes in the incidence of infectious and allergic diseases in children, and humoral immunity alterations. Lymphocyte immunophenotyping is an important tool in the diagnosis of immunologic and hematologic disorders. This study used a lysed whole blood method for analysis of lymphocyte sub-populations in samples from children born and living in two districts: a highly-contaminated area (Michalovce) and one (Svidnik/Stropkov) with ≈ 2-fold lower environmental PCB levels. The percentages of B-lymphocytes (CD19(+)), activated HLADR(+)CD19(+) cells, and CD8(+) T-lymphocytes significantly increased at 6- and 16-months-of-age in both selected regions as compared to in cord blood values (p < 0.001). Levels of CD3(+) cells increased significantly (from 61 to 65%) in samples from Michalovce (p < 0.01). Levels of CD4(+) T-lymphocytes declined 10% among 16-month-olds in both regions (Michalovce at p < 0.001 and Svidnik/Stropkov at p < 0.01). Natural killer (NK) cell levels decreased 50% in Michalovce 6- and 16-month-old children and 42% among 6-month-olds in Svidnik/Stropkov (p < 0.001). Compared with the less-contaminated region, Michalovce samples showed significantly higher expression of CD3(+) T-lymphocytes, B-lymphocytes, and activated B-lymphocytes, whereas NK cells were less expressed. Even after adjustment for selected covariates, e.g., maternal cigarette smoking, age, parity, ethnicity, birth weight, and gender of infant, the levels of CD19(+), HLADR(+)CD19(+), and CD3(-)CD(16 + 56)(+) cells were seen to remain significantly different between the districts. These results showed that early-life environmental PCB exposure was associated with fluctuations in major lymphocyte subsets in children, suggesting that there is a post-natal immune system response to PCB exposures.

Serum PCB concentrations and cochlear function in 12-year-old children.

Experimental evidence from animals indicates that exposure to polychlorinated biphenyls (PCBs) causes deterioration of the outer hair cells (OHCs) of the cochlea. To test this hypothesis in humans, we measured serum PCB concentrations in 574 12-year-old children residing in three districts in the Slovak Republic using high-resolution gas chromatography with microelectron capture detection. As a marker of cochlear status, we measured transient evoked (TE) and distortion product (DP) otoacoustic emissions (OAEs), and assessed the cross-sectional association between serum PCBs and OAEs. Median total PCB concentrations were 352.8, 150.5, and 134.9 ng/g lipid in Michalovce, Svidnik, and Bratislava, respectively. In multivariate regression models where otoacoustic measures were modeled as a function of log (base 10) PCB concentrations with adjustment for gender, age, and site of examination, dioxin-like PCBs, nondioxin-like PCBs and a PCB grouping targeting upregulation of hepatic uridine 5'-diphospho-glucuronosyltransferase were significantly associated with lower TEOAE powers at 1000 and 1500 Hz. At 1500 Hz, we observed a strong association with sum of PCBs and DL-PCBs, in the left ear only. The DPOAEs at 1000 Hz were associated with all four PCB groupings. The results of this study show that PCBs may affect the OHCs of the cochlea, a result consistent with findings from animal studies published to date.

Availability and comparability of human biomonitoring data across Europe: a case-study on blood-lead levels.

Recently, it has become clear that the complexity of environmental health issues requires an approach that takes into account the complexities, interdependencies and uncertainties of the real world. An urgent issue that has surfaced is the need for accurate tools to better describe exposure characterization to environmental chemicals. By including human biomonitoring (HBM) data, a greater precision in exposure and associated risk estimates and more accurate dose-response relationships may be achieved. A restricting issue still is the availability of reliable and comparable HBM data. The aim of the current study was twofold: (1) to find out whether it is practically feasible to collect raw, individual HBM data across Europe; and (2) to evaluate the comparability and use of these HBM data for environmental health impact assessment at a European scale. Blood-lead (B-Pb) was selected as the chemical of choice because of its long history as an environmental pollutant in HBM programs and its known public health relevance. Through literature search and identification of HBM experts across Europe, HBM programs that measured B-Pb were identified and asked to share individual data on age, gender and B-Pb levels. Following this request, more than 20,000 individual data points from 8 European countries were collected. Analysing these data made clear that it is difficult to use disparate data collections because of the inherent variability with respect to the gender and age of participants and calendar-years sampled. When these confounders were taken however, there was no additional variability in B-Pb distributions among different countries. It was concluded that while it is possible to collect HBM data from different sources across Europe, the need to get data from comparable (sub-)populations is essential for appropriate use and interpretation of HBM data for environmental health impact assessment.

Exposure to polychlorinated biphenyls and hearing impairment in children.

The objective of this cross-sectional epidemiological study was to assess if long-term exposure to polychlorinated biphenyls (PCBs) is associated with hearing impairment. Four hundred and thirty-three children aged 8-9 years residing in an area polluted by PCBs in Eastern Slovakia were examined otoscopically, tympanometrically and by pure tone audiometry. PCB levels in their serum were determined by gas chromatography. Transient otoacoustic emissions (TEOAE) were measured in a subgroup of 161 children. The mean of the sum of PCB concentrations in serum was 528.2ng/g serum lipids (median 321ng/g serum lipids). Serum PCB concentrations were associated with an increase of hearing threshold at low frequencies and a negative correlation between serum PCBs and the amplitude of TEOAE response was observed in the uppermost tertile of children grouped with regard to serum PCBs, not related to thyroid hormone levels. It was concluded that long-term environmental exposure to PCBs is associated with subclinical but diagnosable hearing deficits.

Cord serum immunoglobulin E related to the environmental contamination of human placentas with organochlorine compounds.

Allergic diseases are on the rise in both prevalence and severity, especially in industrialized countries. The process of allergic sensitization needs an understanding of the role environmental factors play in its development. In addition to traditionally considered air pollutants, various persistent organochlorine pollutants, which accumulate in the human body over a lifetime via food intake, are toxic in humans. Placental contamination by chemicals may act as a biologic marker for the exposure of the mother or for the fetus via transplacental transfer. Placentas were collected from term deliveries in two Slovak regions. The samples were then analyzed for 21 selected organochlorine compounds. Specimens of cord blood from 2,050 neonates were gathered for the determination of levels of total immunoglobulin E (IgE). The regions were chosen according to their environmental characteristics: a city polluted with organic chemical industry versus a rural region devoid of industrial sources of pollution. In addition, data regarding the incidence rate of atopic eczema cases in the regions were considered. Comparisons between regions revealed that both the placental contamination with 16 of 21 organochlorine compounds and the cord serum IgE levels were significantly higher in the industrial region. The findings pointed to an association between organochlorine compounds and the higher levels of total IgE in newborns, signaling a higher allergic sensitization in the industrial region. This association was supported by the higher incidence rate of atopic eczema cases in the population registered in the industrial region.

Sites of lead and nickel accumulation in the placental tissue.

1. There is a variety of quantitative analytical data regarding the total concentrations of heavy metals in human placentae. However, little is known about sites of metal accumulation in the placental tissue structural zones in relation to the environment. In this study, the lead and the nickel particulate deposits in the placental chorionic plate, the chorionic villous tree and the basal plate, using tissue histochemical reactions for lead and nickel, have been estimated. The degree of metal contamination of placentae was assessed according to an arbitrary scale. Both metals have shown a common mode of accumulation in the placental tissue structural zones. Among the observed contaminated structures in the placental tissue, the syncytiotrophoblast was the most frequent site for lead and nickel particulate deposits. 2. The frequency distribution of both metals within the mentioned placental zones, using four metal contamination degrees, was determined. A heavily contaminated zone was found to be the chorionic villous tree, especially in samples from the industrial region. 3. A comparison between two Slovak regions (an industrial and a rural one) using statistical tests was performed. The frequency of samples without any lead occurrence in the chorionic villous tree was found to be 10% in the industrial region, and 16% in the rural region. Regarding the nickel deposits, the frequency of non-contaminated samples in the industrial region was 2%, whereas in the rural region 6%. A relationship between traffic related pollution and human placenta contamination was found in both investigated regions.