The impact of an interaction-based classroom program on executive function development in low-SES preschoolers: first support for effectiveness

Studies have shown that children from a low socioeconomic status (SES) family are likely to have lower academic scores, indicating an SES-achievement gap. This inequality already starts in preschool and persists throughout children’s lives. Since executive functions (EFs) have been put forward as contributing factors in this SES-achievement gap, it is crucial to target early EF development to remediate the adverse effects of poverty. In this quasi-experimental study, a classroom program delivered by teachers (i.e., “Put your EF glasses on”) was implemented to strengthen preschoolers’ EFs, consistent with the idea that well-developed EFs can foster school readiness and prevent school failure. The program aimed to boost children’s EFs through high-quality teacher-child interactions, EF-supporting activities (e.g., games), and a supportive classroom structure. Teachers (n = 24) and children (n = 224, Mage = 52.61 months) from 8 Belgian schools participated in this quasi-experimental pilot study and were divided into experimental and control groups. Teachers in the experimental group carried out the program (receiving materials and coaching to support implementation), whereas teachers in the control group practiced teaching as usual. Before and after the program, all teachers filled out the BRIEF-P, a questionnaire about daily executive problems in preschool children. We compared the effect of the classroom program in low-SES versus middle-to-high-SES children on EF problem scores. Results revealed that all low-SES children started with significantly higher EF problems (total problem score, working memory, inhibition, and planning and organizing) scores than middle-to-high-SES children. A positive effect of the program was found among low-SES children. More specifically, EF problems (total problem score, working memory, shifting, and planning and organizing) remained stable over time in the low-SES group in the experimental group, but there was no program effect on emotional control and inhibition. In the control group, these EF problems increased for low-SES children, expanding the gap between low and middle-to-high-SES children. There were no program effects for middle-to-high-SES children. These results show that a teacher-mediated classroom program can support EF development, especially in preschoolers at sociodemographic risk

The Belgian PCB and dioxin incident of January-June 1999: exposure data and potential impact on health.

In January 1999, 500 tons of feed contaminated with approximately 50 kg of polychlorinated biphenyls (PCBs) and 1 g of dioxins were distributed to animal farms in Belgium, and to a lesser extent in the Netherlands, France, and Germany. This study was based on 20,491 samples collected in the database of the Belgian federal ministries from animal feed, cattle, pork, poultry, eggs, milk, and various fat-containing food items analyzed for their PCB and/or dioxin content. Dioxin measurements showed a clear predominance of polychlorinated dibenzofuran over polychlorinated dibenzodioxin congeners, a dioxin/PCB ratio of approximately 1:50,000 and a PCB fingerprint resembling that of an Aroclor mixture, thus confirming contamination by transformer oil rather than by other environmental sources. In this case the PCBs contribute significantly more to toxic equivalents (TEQ) than dioxins. The respective means +/- SDs and the maximum concentrations of dioxin (expressed in TEQ) and PCB observed per gram of fat in contaminated food were 170.3 +/- 487.7 pg, 2613.4 pg, 240.7 +/- 2036.9 ng, and 51059.0 ng in chicken; 1.9 +/- 0.8 pg, 4.3 pg, 34.2 +/- 30.5 ng, and 314.0 ng in milk; and 32.0 +/- 104.4 pg, 713.3 pg, 392.7 +/- 2883.5 ng, and 46000.0 ng in eggs. Assuming that as a consequence of this incident between 10 and 15 kg PCBs and from 200 to 300 mg dioxins were ingested by 10 million Belgians, the mean intake per kilogram of body weight is calculated to maximally 25,000 ng PCBs and 500 pg international TEQ dioxins. Estimates of the total number of cancers resulting from this incident range between 40 and 8,000. Neurotoxic and behavioral effects in neonates are also to be expected but cannot be quantified. Because food items differed widely (more than 50-fold) in the ratio of PCBs to dioxins, other significant sources of contamination and a high background contamination are likely to contribute substantially to the exposure of the Belgian population