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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.

Background: Previously, we reported an association between higher maternal polychlorinated biphenyl (PCB) concentrations and smaller thymus volume in newborns in a birth cohort residing in eastern Slovakia., Objective: In the present report we address whether thymus volume at later ages is influenced by prenatal and early postnatal PCB exposure., Methods: At the time of delivery, 1,134 mother-infant pairs were enrolled. Maternal and 6- and 16-month infant blood samples were collected and analyzed for 15 PCB congeners. Thymus volume was measured in infants shortly after birth and at ages 6 and 16 months using ultrasonography., Results: Higher maternal PCB concentration was associated with reduced thymus volume at birth [a 0.21 SD reduction in thymus volume for an increase in total maternal PCB concentration from the 10th to the 90th percentile; 95% confidence interval (CI): -0.37, -0.05], whereas maternal PCB concentration was not predictive of 6- and 16-month thymus volume. Six-month infant PCB concentration was associated with a 0.40 SD decrease in 6-month thymus volume (95% CI: -0.76, -0.04). There was also some suggestion that thymus volume at 16 months was positively associated with concurrent infant PCB concentration., Conclusions: The potential adverse effects of in utero PCB exposure on thymic development may extend beyond the neonatal period. Results from this highly exposed cohort provide suggestive evidence that postnatal PCB concentrations may be influential, but a smaller set of 6-month PCB measurements limited statistical power at that time point. Implications regarding impaired immunologic maturation or long-term clinical implications remain to be determined.

Ingestion has been a primary route of PCB exposure for people, especially those not working directly in industrial settings. During 2002-2004, women were recruited at delivery from two districts in eastern Slovakia: Michalovce with high PCB contamination from a chemical manufacturing plant, and Svidnik located 70 km to the northwest, having lower environmental levels of PCBs. Concentrations of 15 PCB congeners were measured in maternal serum using high-resolution gas chromatography with electron capture detection. A food frequency questionnaire was developed and validated at the Research Institute of Nutrition and School of Medicine in Bratislava, Slovakia. The questionnaire was comprised of 88 food items representative of the national dietary habits and designed to ascertain (1) the source of food items as reported by the women (locally produced or purchased from a retail outlet) and (2) quantities consumed of high-fat food categories representative of the national dietary habits. Our primary goal was to identify specific food sources, either locally produced or purchased from retail stores, that might predict serum concentrations of PCBs. We used multiple linear regression to examine the relationship of dietary fats to lipid-adjusted serum PCB levels in 948 adult women (Michalovce N=662, Svidnik N=284) who had recently given birth. We adjusted for residential district, age, body mass index, education and duration of previous lactation. Consumption of fat from locally produced foods was significantly associated with higher levels of lipid-adjusted serum PCB (beta=0.06, P=0.007). Fat from foods purchased in retail outlets showed no significant association (beta=-0.02, P=0.36). There was no interaction between district and diet in predicting serum PCB levels. Comparing women in Michalovce consuming 20 g of fat per day from local sources with those consuming 1 g of fat per day from local sources, lipid-adjusted serum concentrations were predicted to be higher by 81 ng/g lipid or 14.8% 630 ng/g lipid versus 549 ng/g lipid.

Polychlorinated biphenyls (PCB) were widely used for industrial purposes and consumer products, but because of their toxicity, production was banned by most industrialised countries in the late 1970s. In eastern Slovakia, they were produced until 1985. During 2002-04, a birth cohort of mothers (n = 1057) residing in two Slovak districts was enrolled at delivery, and their specimens and information were collected after birth. Congeners of PCBs were measured in maternal serum by high-resolution gas chromatography with electron capture detection. In this study, we used multiple linear regression to examine the effects of prenatal PCB exposure on birthweight adjusted for gestational age, controlling for inter-pregnancy interval, and maternal smoking, age, education, ethnicity, pre-pregnancy body mass index and height. The association between total maternal serum PCB levels and birthweight was not statistically significant. However, an interaction model indicated that maternal PCB concentrations were associated with lower birthweight in Romani boys. Based on the fitted regression model, the predicted birthweight of Romani boys at the 90th percentile of maternal PCBs (12.8 ng/mL) was 133 g lower than the predicted birthweight at the 10th percentile of maternal PCBs (1.6 ng/mL). This is a similar magnitude of effect to that observed for maternal smoking and birthweight. These results suggest that higher levels of PCBs in maternal blood sera may inhibit growth in boys, particularly in those already affected by social factors related to ethnicity. This study is consistent with previous findings that boys are more susceptible than girls to growth restriction induced by in utero organochlorine exposures, and further indicates that high PCBs may magnify the influence of social disadvantage in this vulnerable group of boys.