Prenatal Environmental Exposure to Persistent Organic Pollutants and Reproductive Hormone Profile and Pubertal Development in Dutch Adolescents.

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), may interfere with hormonal processes. Knowledge about the effects of prenatal exposure to PCBs and their hydroxylated metabolites (OH-PCBs) on pubertal development is limited. Therefore, the aim of the current study was to determine whether prenatal environmental PCB and OH-PCB exposure are associated with reproductive hormone levels and pubertal characteristics in 13- to 15-year-old children. In this Dutch observational cohort study, 194 mother-infant pairs were included (1998-2002). Maternal pregnancy serum levels of PCBs, OH-PCBs, and other POPs were measured. At follow-up (2014-2016), we measured serum or plasma levels of reproductive hormones in their children. We assessed Tanner stages and testicular volume (by clinician or standardized self-assessment), and participants completed questionnaires on pubertal onset. In total, 101 adolescents (14.4 ± 0.8 years; 53.7% of invited) participated, and 55 were boys. In boys, higher prenatal PCB levels were associated with higher testosterone levels, higher pubic hair stage, larger testicular volume, and younger age at onset of growth spurt and voice break. In girls, higher prenatal PCB levels were associated with higher stages for breast development. In conclusion, higher prenatal PCB exposure could be associated with more advanced pubertal development in 13- to 15-year-old children.

Impact of Preanalytical Factors on Calprotectin Concentration in Stool: A Multiassay Comparison.

BACKGROUND: Measuring calprotectin concentration in stool is increasingly important in monitoring disease activity and treatment response in inflammatory bowel disease. This study evaluates the impact of preanalytical storage conditions on reliability of calprotectin testing using 5 different calprotectin immunoassays. METHODS: Aliquots of homogenized fresh fecal samples in untreated or extracted form were stored at room temperature or 4°C. Calprotectin concentration was measured day 0 to 4 and 8. Five different immunoassays and accompanying extraction buffers were used (CALiaGold, Phadia EliA, Bühlmann fCal turbo, ELISA Bühlmann, Inova Quanta Flash). Repeated measurements of change from baseline calprotectin levels over time were analyzed using a mixed model analysis. RESULTS: Calprotectin concentrations declined over time under all preanalytical conditions with all assays, except for extracted feces stored at 4°C. The rate of decline was greatest in untreated stool kept at room temperature, reaching significant difference from baseline already after 1 day (P < 0.001). In extracted feces kept at room temperature, significant difference from baseline was reached after 2 days, and in untreated feces at 4°C, after 4 days. However, the results differed significantly between assays. After 4 days of storage at room temperature, the mean calprotectin decline from baseline differed between 30% and 60%, dependent on the assay used. CONCLUSIONS: Fecal calprotectin concentration in stool samples declines over time, and the rate of decline is greater at higher temperatures. In extracted feces stored at 4°C, calprotectin is most stable. It is assay-dependent how long extracted feces stored at 4°C give reliable test results.