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Several chemical compounds are resistant to degradation and end up in the food chain. One group of these chemicals is poly-chlorinated biphenyls (PCBs) which are used as flame retardants and plasticizers. Although PCBs were banned several decades ago, PCBs are still found in environmental media, including in the body of humans. PCBs are transferred from mother to fetus via the placenta during pregnancy. Considering that the prenatal period is a sensitive period during which essential developmental processes take place, exposure to environmental chemicals might have considerable and permanent consequences for outcomes in later life.The aim of this review is to provide an update on the latest insights on the effects of prenatal exposure to PCBs on neurological, sexual and pubertal development in children. We give an overview of recent literature, and discuss it in the light of the findings in a unique Dutch birth cohort, with data on both neurological and pubertal development into adolescence.The findings in the studies included in this review, together with the findings in the Dutch cohort, demonstrate that prenatal exposure to PCBs can interfere with normal child development, not only during the perinatal period, but up to and including adolescence. Higher prenatal exposure to PCBs was found to be both negatively and positively associated with neurodevelopmental outcomes. Regarding pubertal development, higher prenatal PCB exposure was found to be associated with more advanced pubertal development, also in the Dutch cohort, whereas other studies also found delayed pubertal development. These findings raise concern regarding the effects of man-made chemical compounds on child development. They further contribute to the awareness of how environmental chemical compounds can interfere with child development and negatively influence healthy ageing.

BACKGROUND: Evolving evidence suggests that vegetation surrounding schools is beneficial to children's academic performance, however vehicle emissions are adversely related. Little is known about concurrent impacts of vegetation and vehicle emissions on academic performance. This study examined associations of vegetation and vehicle emissions near urban Australian primary schools with children's academic performance.METHODS: Vegetation within schoolyards and Euclidean buffers (100, 300 and 1000m) was assessed using the Normalised Difference Vegetation Index (NDVI). Weighted road density (WRD) was computed for each buffer as a vehicle emissions proxy. Cross-sectional associations and mediating pathways between vegetation and vehicle emissions and standardised average academic scores in Literacy (Reading, Writing, Language Conventions) and Mathematics for Grades 3 and 5 attending 3745 primary schools in urban areas (population ≥10,000) of Australia in 2018 were assessed using generalised linear models adjusted for school socio-educational status.RESULTS: Significant positive associations were found between vegetation and Reading in Grades 3 and 5, Mathematics in Grade 3 (all buffers), Writing in Grade 3 (100 and 300m), and Language Conventions in Grades 3 and 5 (most buffers). Increased vehicle emissions were negatively associated with Reading and Mathematics in Grades 3 and 5 (most buffers), and Language Conventions in Grade 3 (300 and 1000m) and Grade 5 (100-1000m). Within 300m, vehicle emissions partially mediated associations between vegetation with Mathematics in Grade 3 (proportion mediated, 21%), Reading and Language Conventions in Grade 5 (15%, 37% respectively).CONCLUSIONS: Our findings contribute to growing evidence that vegetation around primary schools is associated with higher achievement in Literacy and Mathematics, with partial mediation by vehicle emissions. Future studies should conduct on-site measurement of vehicle emissions and audit vegetation around schools to confirm findings and inform urban/school planners and school leaders on designing and modifying school environments to support learning.

Christoph Völter was supported by a scholarship of the German National Academic Foundation. Planning defined as the predetermination of a sequence of actions towards some goal is crucial for complex problem solving. To shed light on the evolution of executive functions, we investigated the ontogenetic and phylogenetic origins of planning. Therefore, we presented all four great apes species (N = 12) as well as 4- and 5-year-old human preschoolers (N = 24) with a vertical maze task. To gain a reward placed on the uppermost level of the maze, subjects had to move the reward to the bottom through open gaps situated at each level of the maze. In total, there were ten gaps located over three of the maze's levels, and free passage through these gaps could be flexibly blocked using multiple traps. Due to the decision tree design of the maze, the subjects had to plan their actions depending on the trap configuration up to two steps ahead to successfully retrieve the reward. We found that (1) our measure of planning was negatively correlated with age in nonhuman apes, (2) younger apes as well as 5-year-old children planned their moves up to two steps ahead whereas 4-year-olds were limited to plan one step ahead, and (3) similar performance but different underlying limitations between apes and children. Namely, while all species of nonhuman apes were limited by a lack of motor control, human children exhibited a shortage in shifting their attention across a sequence of subgoals. (C) 2013 Elsevier B.V. All rights reserved. Postprint

In accordance with dynamic systems theory, we assume that variability is an important developmental phenomenon. However, the standard methodological toolkit of the developmental psychologist offers few instruments for the study of variability. In this article we will present several new methods that are especially useful for visualizing and describing intra-individual variability in individual time-serial data of repeated observations. In order to illustrate these methods, we apply them to data of early language development. After reviewing the common techniques and measures, we present new methods that show variability in developmental time-series data: the moving min-max graph, and the progmax-regmin graph. In addition, we demonstrate a technique that is able to detect sudden increases of variability: the critical frequency method. Also, we propose a technique that is based on a central assumption of the measurement-error-hypothesis: namely the symmetric distribution of error. Finally, as traditional statistical techniques have little to offer in testing variability hypotheses, we examine the possibilities that are provided by random sampling techniques. Our aim with the present discussion of variability and the demonstration of some simple yet illustrative techniques is to help researchers focus on rich additional sources of information that will lead to more interesting hypotheses and more powerful testing procedures, adapted to the unique nature of developmental data. (C) 2002 Elsevier Science Inc. All rights reserved.

We investigated the influence of early nutrition with and without long-chain polyunsaturated fatty acids (LCP) on later development of less than or equal to 2500 g newborns receiving preterm formula without LCP (n=75), preterm formula with 18:3 omega 6 and LCP omega 3 (at two doses; n=26) or their mother's own milk (n=27). All diets were given from birth to day 42. Erythrocytes (RBC) fatty-acid compositions were determined on day 42. Bayley's mental development (MDI) and psychomotor development (PDI) indices were assessed at 19 months. Multivariate regression analysis revealed that PDI was most strongly related to RBC 22:6 omega 3 in the cohort of 101 infants who received formula. The most consistent correlations were between development and early LCP omega 3 intake, and between development and parameters of RBC LCP omega 3 status day 42, in infants who received formula with 18:3 omega 6 and LCP omega 3. Development of formula-fed low-birthweight infants seems positively influenced by early dietary LCP omega 3. (C) 1999 Harcourt Publishers Ltd.