Exposure to polychlorinated biphenyls and the thyroid gland - examining and discussing possible longitudinal health effects in humans.

BACKGROUND: Many previous studies have dealt with the effect of polychlorinated biphenyls (PCBs) on the thyroid gland, but their findings are inconsistent. One problem of these studies has been their use of cross-sectional designs. OBJECTIVES: The aim of the current study is to investigate longitudinal effects of PCBs on the thyroid gland, focusing on: morphological changes in thyroid tissue (i.e. thyroid volume), changes in thyroid hormones and in thyroid antibodies. METHODS: A total of 122 individuals (Mage=44.7) were examined over a period of four years (t(1) until t(4)). Medical history was collected via interviews, an ultrasound examination was performed and blood samples were taken to determine plasma PCB levels, thyroid stimulating hormone (TSH), free triiodthyronine (fT3), free thyroxine (fT4), thyroid peroxidase antibodies (TPOab), thyreoglobulin antibodies (TGab) and thyroid-stimulating hormone receptor antibodies (TSHRab). Rank correlation coefficients and mixed effect models were performed controlling for age and total lipids. RESULTS: There were negative correlations between higher chlorinated biphenyls and fT3, cross-sectionally as well as longitudinally. We also found an interaction effect of higher-chlorinated PCBs over time for fT4 as well as TSHRab. In case of high exposure, a decrease in fT4 and an increase in TSHRab level were found over time. In regards to the other variables, our findings yielded no clear results in the examined time period. CONCLUSION: This is the first study to shows a PCB-related effect on fT3, fT4 and TSHRab over a four year period. The data also suggest that morphological and antibody findings remain inconsistent and do not allow for unambiguous interpretation.

Predicting Hair Cortisol and Cortisone Concentration in Postpartum Women through Repeated Measurements of Perceived Stress.

To investigate whether hair cortisol (HCC) and hair cortisone (HCNC) can be predicted by repeated stress reports from postpartum women in different mental health conditions (non-depressed, ND, adjustment disorder, AD, postpartum depression, PPD), 240 mothers (mean age 31.8 years; SD = 4.7) were monitored from within 1 to 6 days of childbirth over a period of three months. HCC and HCNC in 3 cm hair samples were assessed via triple mass spectrometry after liquid chromatographic separation. Every second day, participants reported their stress levels online. The summed perceived stress scores were not found to be predictive of HCC. However, perceived stress predicted a decrease in HCNC (rSpearman = -0.153, p = 0.035) and an increase in the HCC/HCNC ratio (rSpearman = 0.304, p < 0.001) in the ND group. With AD in the first few weeks after childbirth, an inverse effect appeared for HCNC (rSpearman = 0.318, p = 0.011), suggesting an overall downregulation of the HPA axis owing to the stressful experience of adjusting to the new situation. No effects were found for mothers developing PPD. The indirect results of HPA-axis activity are better indicators of the experience of psychological stress in postpartum women than the absolute HCC value.

Prevalence and incidence rates of mental syndromes after occupational exposure to polychlorinated biphenyls.

Mental disorders were often reported following hazardous substance exposure. The present study analyses this association in relation to a work-related exposure to PCBs (polychlorinated biphenyls). Specifically, the aim was to investigate (a) the relationship of inner PCB burden and the severity of mental symptoms and (b) the prevalence and incidence of mental syndromes. This study was initiated as part of the occupational medical surveillance program HELPcB (Health Effects in high level exposure to PCB). A total of 136 individuals were included in the analysis. The plasma PCBs were collected via biomonitoring and the psychological syndromes (i.e., somatoform, depressive, anxiety, panic) with a standardized screening instrument. The relationship of PCB and the severity of mental syndromes were analyzed via linear regression. Prevalence rates, the respective odds ratios (OR) and the incidence rates were calculated with logistic regressions. We thereby compared the higher-PCB burdened individuals with those individuals showing PCB levels comparable to the general population. We found especially a significant relationship between PCB burden and depressivity. Within the higher-PCB-exposed group prevalence rates were descriptively higher than for normal-exposed participants, except for anxiety syndrome. Similarly, the higher exposed group had a higher risk for developing a depressive syndrome. The incidence rates were always descriptively higher in higher-exposed group. To summarize, this study supports a relationship between PCB exposure and mental illness.