The onset of directed reaching demarks the emergence of a qualitatively new skill. In this study we asked how intentional reaching arises from infants' ongoing, intrinsic movement dynamics, and how first reaches become successively adapted to the task. We observed 4 infants weekly in a standard reaching task and identified the week of first arm-extended reach, and the 2 weeks before and after onset. The infants first reached at ages ranging from 12 to 22 weeks, and they used different strategies to get the toy. 2 infants, whose spontaneous movements were large and vigorous, damped down their fast, forceful movements. The 2 quieter infants generated faster and more energetic movements to lift their arms. The infants modulated reaches in task-appropriate ways in the weeks following onset. Reaching emerges when infants can intentionally adjust the force and compliance of the arm, often using muscle coactivation. These results suggest that the infant central nervous system does not contain programs that detail hand trajectory, joint coordination, and muscle activation patterns. Rather, these patterns are the consequences of the natural dynamics of the system and the active exploration of the match between those dynamics and the task.

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. These chemicals commonly enter the human body through inhalation of cigarette smoke or consumption of contaminated food. Of these two pathways, dietary intake of PAHs constitutes a major source of exposure in humans. Although many reviews and books on PAHs have been published, factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received much less attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. The utilitarian value of structure and metabolism in predicting PAH toxicity and carcinogenesis is also emphasized. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet, and contaminated soil is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs from a multimedia exposure perspective.

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The onset of directed reaching demarks the emergence of a qualitatively new skill. In this study we asked how intentional reaching arises from infants' ongoing, intrinsic movement dynamics, and how first reaches become successively adapted to the task. We observed 4 infants weekly in a standard reaching task and identified the week of first arm-extended reach, and the 2 weeks before and after onset. The infants first reached at ages ranging from 12 to 22 weeks, and they used different strategies to get the toy. 2 infants, whose spontaneous movements were large and vigorous, damped down their fast, forceful movements. The 2 quieter infants generated faster and more energetic movements to lift their arms. The infants modulated reaches in task-appropriate ways in the weeks following onset. Reaching emerges when infants can intentionally adjust the force and compliance of the arm, often using muscle coactivation. These results suggest that the infant central nervous system does not contain programs that detail hand trajectory, joint coordination, and muscle activation patterns. Rather, these patterns are the consequences of the natural dynamics of the system and the active exploration of the match between those dynamics and the task.

The objective of this study was to develop and test a procedure for the identification of chemicals registered under the REACH Regulation that are of potential health concern and are likely to occur in the food chain. For this purpose, 100 data-rich substances registered under REACH together with four positive controls were evaluated. The evaluation of the 104 substances took into account parameters related to exposure (tonnage, release, biodegradation and potential bioaccumulation) and toxicity (repeated dose toxicity, genotoxicity and reproductive toxicity) organised in six blocks. All substances were scored for each block. ACC-HUMANsteady software was used to evaluate the potential for bioaccumulation in eleven different food items using input data derived from QSAR predictions. The extraction of the relevant experimental data generated under REACH was successful, but encountered several problems in relation to the data extraction process and subsequent evaluation steps. Several weighting scenarios were tested to aggregate scores for the six blocks into a total score to enable a ranking of the 104 substances. Scenarios that assigned high total scores to chemicals that combined high scores in the exposure blocks with high scores in the toxicity blocks identified a set of substances of potential concern (including the positive controls). In addition, a Pivot table selection was implemented that can be used without weighting. Further analyses compared the scores derived from experimental data with those derived from predicted data. These analyses found a good agreement of scores for biodegradability, but considerable disagreement of scores for toxicity endpoints. In conclusion, a scoring and ranking procedure was developed for the identification of chemicals of potential concern in the food chain (potential emerging risks) that showed a good level of differentiation. The focus on (semi-)automated processes ensures that this procedure can be applied to all chemicals registered under the REACH Regulation. © European Food Safety Authority

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