Human health effects of airborne lower-chlorinated polychlorinated biphenyls (LC-PCBs) are largely unexplored. Since PCBs may cross the placenta, maternal exposure could potentially have negative consequences for fetal development. We aimed to determine if exposure to airborne PCB during pregnancy was associated with adverse birth outcomes. In this cohort study, exposed women had lived in PCB contaminated apartments at least one year during the 3.6 years before conception or the entire first trimester of pregnancy. The women and their children were followed for birth outcomes in Danish health registers. Logistic regression was performed to estimate odds ratios (OR) for changes in secondary sex ratio, preterm birth, major congenital malformations, cryptorchidism, and being born small for gestational age. We performed linear regression to estimate difference in birth weight among children of exposed and unexposed mothers. All models were adjusted for maternal age, educational level, ethnicity, and calendar time. We identified 885 exposed pregnancies and 3327 unexposed pregnancies. Relative to unexposed women, exposed women had OR 0.97 (95% CI 0.82, 1.15) for secondary sex ratio, OR 1.13 (95% CI 0.76, 1.67) for preterm birth, OR 1.28 (95% CI 0.81, 2.01) for having a child with major malformations, OR 1.73 (95% CI 1.01, 2.95) for cryptorchidism and OR 1.23 (95% CI 0.88, 1.72) for giving birth to a child born small for gestational age. The difference in birth weight for children of exposed compared to unexposed women was - 32 g (95% CI-79, 14). We observed an increased risk of cryptorchidism among boys after maternal airborne LC-PCB exposure, but due to the proxy measure of exposure, inability to perform dose-response analyses, and the lack of comparable literature, larger cohort studies with direct measures of exposure are needed to investigate the safety of airborne LC-PCB exposure during pregnancy.

Background: Since the number of persons diagnosed with multi-morbidity is increasing, there is a need for generic instruments to be able to assess, measure and compare ADL ability across diagnoses. Accordingly, the ADL-Interview (ADL-I) was developed to be used in rehabilitation research and clinical practice. The aim of this study was to investigate if the ADL-I can be used to provide valid and reliable ADL ability measures across gender and diagnostic groups. Methods: ADL-I data were extracted from an existing research database on persons with chronic conditions including medical, rheumatological, oncological, neurological, geriatric and psychiatric diagnoses. Data were analysed based on Rasch Measurement methods to examine: the psychometric properties of the rating scale; ADL item and person fit to the Rasch model; if the difficulty of the ADL tasks differs across gender and diagnostic groups, and if the ADL-I provides precise and reliable measures of ADL ability. Results: Data on n = 2098 persons were included in the final analysis. Initial evaluation of the 0–3 rating scale revealed threshold disordering between categories 1 and 2. After removal of 16 underfitting items, the variance explained by the Rasch dimension increased from 54.3 to 58.0%, thresholds were ordered, but the proportion of persons with misfitting ADL-I measures increased slightly from 8.7 to 9.1%. The person separation index improved slightly from 2.75 to 2.99 (reliability = 0.90). Differential test function analysis, however, supported that the 16 underfitting items did not represent a threat to the measurement system. Similarly, ADL items displaying differential item functioning across gender and diagnoses did not represent a threat to the measurement system. The ADL items and participants were well distributed along the scale, with item and person measures well targeted to each other, indicating a small ceiling effect and no floor effect. Conclusions: The study results overall suggest that the ADL-I is producing valid and reliable measures across gender and diagnostic groups among persons within a broad range of ADL ability, providing evidence to support generic use of the ADL-I. Trial registration: N/A.

Objectives Evidence on the association between night work and Parkinson's disease (PD) is sparse and conflicting, calling for more definitive studies. Methods We included 20 138 female nurses from the Danish Nurse Cohort without PD who at baseline in 1993 and/or 1999 reported their most common current work schedule (day, evening, night, and rotating (a combination of at least two of these)), including information on lifetime cumulative duration (years) of each shift in a 2009 follow-up survey. We obtained information on PD hospital contacts and PD medication until November 2018 via linkage to the Danish National Patient (inpatient from 1977 and outpatient contacts from 1995 onwards) and Prescription Registers starting in 1995. We defined the incidence of PD as the first-ever hospital contact due to PD, or the first-ever redeemed levodopa prescription, whichever came first. We used Cox regression models to calculate HRs and 95% CIs, adjusting for age, smoking status, coffee consumption and use of hormone replacement therapy. Results We found no significant difference in PD risk among nurses who reported working evening (HR=0.86; 95% CI=0.55 to 1.34), night (HR=1.26; 95% CI=0.79 to 2.02) or rotating shifts (HR=0.83; 95% CI=0.56 to 1.21) at cohort baseline in 1993 or 1999, when compared with permanent day workers. Similarly, persistency of shift work (working the same work schedule for 6+ years) or duration of shift work was not associated with PD risk. Conclusions Overall, there was little evidence for an association between various shift work schedules including night work and PD in this cohort of middle-aged female nurses.