Evaluating substances used in food contact plastic materials: Importance of the chemical information

In Europe, the substances used for the manufacture of plastic materials intended to come in contact with food have to belong to a positive list. The data requested for assessing these substances are specified by the Scientific Committee for Food (SCF) in the Practical Guide of the European Commission (EC). This review shows how this document contributes to preserving consumer health on the basis of chemical information. Some practical examples are treated to illustrate the approach of the SCF to protect consumer safety.     

Prediction of worst case migration from packaging to food using mathematical models

Prediction of migration from packaging to food is often made using equations which are not always designed specifically for the problem. At least, these equations should overestimate migration, in order to be on the safe side. Integration of Fick's equation under the assumption of 'infinite packaging' provides an equation which is very practical since it requires only a few experimental data. It is shown here that, unfortunately, the use of this equation leads to a systematic underestimation of the diffusivity, by the square of the percentage of migration at steady state. In contrast to widely accepted opinion, this model is not conservative. A conservative approach requires that the diffusivity is determined under 'finite packaging' assumptions, associated with very large volumes of food and with long term experiments. These equations are applied to the migration of a phenolic antioxidant from polypropylene.     

The criminalization of the mentally ill.

Comments on the contribution of L. A. Teplin (see record 1985-12217-001) who discussed issues relating to the incarceration of the mentally ill. Although the present author agrees with Teplin's conclusions and recommendations, he asserts that the logic of the argument presented was not convincing. Teplin does not include the role of the magistrate in discussing the process through which mentally ill people end up in jail, and she thus lacks a comprehensive viewpoint. No direct data were presented to support the conclusion that the criminalization of the mentally ill is a result of inadequate funding for the mental health system. (1 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of goal-subgoal conflict on planning ability after frontal- and temporal-lobe lesions in humans

Twenty-one patients with unilateral prefrontal cortical neurosurgical lesions (11 left and 10 right) and 38 patients with unilateral temporal lobectomy (19 left and 19 right) were compared to 44 matched control subjects on their performance on the 3-D Computerized Tower of Hanoi (3-D CTOH) test. The problems were split into those with or without a significant goal-subgoal conflict determined by whether the correct first move in each problem took the subject apparently away or towards the final goal state. The left frontal lesion and right temporal lobectomy groups were significantly impaired on problems with goal-subgoal conflicts. In the left frontal group, this deficit was confined to earlier four-move problems, whereas the right temporal group showed a more general deficit on later five-move problems. The left frontal lesion deficit is explained in terms of an inability to inhibit the response compatible with achieving a final goal, whereas the impairment in the right lesion group was related to a specific impairment in spatial memory.     

Molecular mobility in starchy materials studied by electron spin resonance

Phase transitions in hydrated starch–sorbitol system were investigated both by molecular (electron spin resonance, ESR) and macroscopic (differential scanning calorimetry, DSC) methods. In rapid‐tumbling region, one did not observe the same phenomena by DSC and by ESR. The transitions observed by ESR, which seemed to reflect more the interactions probe–matrix than plasticization, probably corresponded to the interactions probe–sorbitol. For system concentrated in plasticizer, it was conceivable to admit that a demixion of sorbitol occurred. In slow‐tumbling region, a correspondence in temperature mobility changes measured by mechanical spectroscopy and ESR was observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 990–997, 2003     

Functional barriers in PET recycled bottles. Part I. Determination of diffusion coefficients in bioriented PET with and without contact with food simulants

A major outcome for recycled plastics consists of making food packaging materials. However, any contamination of collected plastics with chemicals may then be of concern for public health. A solution to mind migration is to use a layer of virgin polymer, named functional barrier, intercalated between the recycled layer and the food. This article aims to provide experimental values of diffusion coefficients (D) of model pollutants (surrogates) in poly(ethylene terephthalate) (PET) to be used for modeling migration through functional barriers. Diffusion coefficients of a large set of surrogates at low concentrations in PET were measured in various conditions. A solid‐to‐solid diffusion test was designed to avoid the use of a solvent that may induce plasticizing of the material and partitioning effects at the interface. Using [Log D = f(molecular weight)] correlations, the values of diffusion coefficients and activation energies of the surrogates measured by this method were shown to be consistent with the literature data obtained for gases, in permeation experiments, where no plasticization occurred. Migration from PET into food simulants was then studied. Migration into an aqueous medium is largely influenced by the solubility of the surrogates, the less soluble ones being not detected, despite high D values. With ethanol solvent, there were no partitioning effects, and the high plasticization effect of PET by ethanol considerably increases the apparent diffusion coefficients. The effects of temperature and plasticization on the relationship between diffusion coefficients and molecular weight are discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2845–2858, 2004     

Incentive-compatible interdomain routing

The routing of traffic between Internet domains, or Autonomous Systems (ASes), a task known as interdomain routing, is currently handled by the Border Gateway Protocol (BGP, Rekhter and Li in RFC 4271 of the Internet Engineering Task Force, 2006). Using BGP, ASes can apply semantically rich routing policies to choose interdomain routes in a distributed fashion. This expressiveness in routing-policy choice supports domains?? autonomy in network operations and in business decisions, but it comes at a price: The interaction of locally defined routing policies can lead to unexpected global anomalies, including route oscillations or overall protocol divergence (see, e.g., Varadhan et?al. in Comput Networks 32(1):1?C16, 2000). Networking researchers have addressed this problem by devising constraints on policies that guarantee BGP convergence without unduly limiting expressiveness and autonomy (see, e.g., Gao and Rexford in IEEE/ACM Trans Network 9(6):681?C692, 2001; Griffin et?al. in Proceedings of 9th ACM Conference on Applications, Technologies, Architectures, and Protocols for Computer Communication (SIGCOMM??03), pp. 61?C72. ACM Press, New York, 2003). In addition to taking this engineering or ??protocol- design?? approach, researchers have approached interdomain routing from an economic or ??mechanism-design?? point of view. It is known that lowest-cost-path (LCP) routing can be implemented in an incentive-compatible, BGP-compatible manner (Feigenbaum et?al. in Distribut. Comput 18(1):61?C72, 2005; Shneidman and Parkes in Proceedings of 23rd ACM Symposium on Principles of Distributed Computing (PODC??04), pp. 88?C97. ACM Press, New York, 2004) but that several other natural classes of policies cannot (Feigenbaum et?al. in Theor Comput Sci 378(2):175?C189, 2007; Feigenbaum et?al. in Distribut Comput 18(4):293?C305, 2006). In this paper, we present the first example of a class of interdomain-routing policies that is more general than LCP routing and for which BGP itself is both incentive-compatible and guaranteed to converge. We also present several steps toward a general theory of incentive-compatible, BGP-compatible interdomain routing.     

Diffusion coefficients of additives in polymers. I. Correlation with geometric parameters

Diffusion coefficients of a broad range of molecules with molecular weight ranging from 100 to 800 g/mol have been measured in polypropylene, by solid/solid contact methods (without liquid contact), at 40°C. The behaviors of the different molecules are compared to those of linear alkanes. The diffusion coefficients are correlated to parameters describing size, shape, and flexibility of the molecules. The concept of weighted fractionated volume is introduced using molecular modeling. It enables the classification of the molecules according to modes of molecule displacement (crawling, jumps, or dual mode). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2422–2433, 2001     

Additive diffusion coefficients in polyolefins. II. Effect of swelling and temperature on the D = f(M) correlation

Diffusion coefficients of a large panel of molecules were experimentally measured in virgin polypropylene at 40 and 70°C and in swollen polypropylene at 40°C. The influence of mobility increase brought out by temperature or swelling are compared. The effects are more important for high molecular weight compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2434–2443, 2001