Grain mites. A small epidemic caused by Pyemotes species]

Pyemotes mites, of which the grain itch mite is the most important for human medicine, are ectoparasites of many insect species. Human infestation occurs only accidentally and temporally. The source materials are most often grain, straw and plant-based foods. Bites produce an intensely itching urticarial wheal capped by pin-point vesicles, which often are destroyed by scratching. Pyemotes dermatitis favours the back, the abdomen and the flexor side of the forearms. The mites are barely visible to the naked eye and reside only briefly on humans and thus are not found by physicians during clinical examination. When itching starts, the parasites have usually left their hosts. Therefore it is important to investigate the patient's environment and to identify the infested materials. We describe an outbreak of Pyemotes dermatitis in at least 16 persons, most of them warehouse workers in a hobby mail-order house. Infested decorative wheat was the source of the problem. Successful eradication was achieved by fumigation of the storage facilities with the insecticide methylbromide. Our cases demonstrate the importance of examination of environmental specimens for ectoparasites in cases of unexplained dermatoses. Biological agriculture avoiding insecticides may cause reappearance of this almost forgotten skin disease.     

Luminescence properties of ZnS:Mn nanocrystals embedded in SiO2 by ion implantation

Sequential multi-energy implantations of zinc and sulphur ions have been performed in a 250-nm thick SiO₂ layer thermally grown on 1 1 1 silicon. Energies and doses have been chosen to produce 10 at.% constant concentration profiles overlapping over about 100 nm. Manganese is subsequently introduced at various levels by the same way. Thermal treatments (from 700 to 1100 °C) lead to the formation of nanometric precipitates of the luminescent compound ZnS:Mn. A bimodal size distribution is observed, with a quasi-single layer of large particles (40 nm) in the end-of-range region and much smaller precipitates between this layer and the surface. The orange emission is maximal when the Mn concentration is close to 3%. Several hours at 900 °C is the best thermal budget for maximal luminescence intensity at room temperature. A shift of the excitation spectrum related to size variations, shows that the particles of smaller size are mainly responsible for the observed luminescence. In agreement with other authors, the luminescence lifetime is found in the ms range and increases with the nanocrystal diameter, tending to the lifetime of bulk ZnS. The luminescence of ZnS:Mn nanoparticles embedded in SiO₂ by ion implantation is also shown to be very stable during long UV light irradiation.     

Mineral oil contents in paper and board recycled to paperboard for food packaging

Types of paper and board fed into the recycling process to manufacture paperboard for food packaging were analysed for saturated and aromatic mineral oil hydrocarbons. The focus was on the hydrocarbons eluted from gas chromatography before n‐C₂₄, as these are relevant for migration into dry foods via the gas phase at ambient temperature. Newspapers and leaflets printed by similar techniques were identified as the predominant sources of mineral oil, whereas office paper, books and corrugated board were the starting materials of lowest mineral oil content. Paperboard produced from the latter sources would contain about five times less mineral oil than the average observed today, but the migration into food could still exceed the limit derived from the available acceptable daily intake by a factor of up to 20. On average, European newspapers produced by offset printing contained 4.1 g/kg <C₂₄ mineral oil with 21% aromatic hydrocarbons. One out of four Japanese newspapers only contained 430 mg/kg <C₂₄ saturated and less than 15 mg/kg aromatic hydrocarbons. However, the maximum migration from paperboard exclusively produced from such newspaper would still far exceed the limit. Copyright © 2010 John Wiley & Sons, Ltd.     

Taped Barrier Test for Internal Bags Used in Boxes of Recycled Paperboard: The Role of the Paperboard and Its Consequence for the Test

Internal bags with a functional barrier are a promising solution to render recycled paperboard acceptable for food packaging. Producers and users of such bags as well as control authorities need a tool to evaluate whether a bag satisfies the requirements of safety. In the previously proposed methods, the criterion focused on the permeability of the barrier layer. This neglected the influence of absorption or adsorption of the substances in the paperboard and the plastic of the bag. To take these contributions into account, it was proposed to change the criterion and use the percentage of the amount of (surrogate) substances in the recycled paperboard that passes into the food. This paper explains this, in particular how the method better reflects the reality in a pack of food. Firstly, donors should be prepared from recycled paperboard, as the behaviour differs from that of paper. Secondly, absorption into the paperboard seems to be a slow process. It was noted that freshly added surrogate substances were easily extracted by methyl tert‐butyl ether, but the extraction yield decreased during storage over some weeks. To catch this reality of the substances in the paperboard, donors need to be conditioned before use. Finally, absorption in the paperboard may depend on the concentration, which prompted a further reduction of the amounts of the surrogate substances used for testing. It turned out that usually the hydrocarbon (C17) determines the barrier efficiency; triethyl citrate is no longer used, as it was never a relevant surrogate. Copyright © 2016 John Wiley & Sons, Ltd.     

The Detection of Adulteration with Desterolized Oils

Edible oils are desterolized in order to render them “undetectable” when admixed to other oils. Such frauds remain, however, detectable by the olefinic degradation products of the sterols: the degradation products approximately have the composition of the sterols they originate from. Presence of campestatriene (degraded brassicasterol) reveals the presence of desterolized rapeseed oil. The ratio of the degradation products of sitosterol and campesterol is a sensitive indicator for desterolized sunflower, soybean, palm, or grapeseed oil in oils of low campesterol content, such as olive and walnut oil. Analyses were performed by on-line coupled LC-GC.     

Mineral oil hydrocarbons in food: a review

Work on mineral oil hydrocarbons (MOH) contaminating food is reviewed up to about 2010, when the subject received broad publicity. It covers the period of the main discoveries and elimination or reduction of the dominant sources: release agents used in industrial bakeries, spraying of rice, additions to animal feed, contamination of edible oils from various sources and migration from paperboard packaging. In most cases, highly refined (‘white’) oils were involved, but also technical oils, e.g. from the environment, and more or less crude oil fractions from jute and sisal bags. There were numerous unexpected sources, and there might still be more of those. The exposure of the consumers to MOH must have been markedly reduced in the meantime. Environmental influx may have become dominant, particularly when taking into account that these MOH go through several degradation processes which might enrich the species resisting metabolic elimination. Major gaps are in the systematic investigation of sources and the largely unavoidable levels from environmental contamination, but also in the toxicological evaluation of the various types of hydrocarbons. A regulation is overdue that avoids the present discrepancy between the low tolerance to MOH perceived as contaminants and the very high legal limits for some applications – the MOH are largely the same.     

Is recycled newspaper suitable for food contact materials? Technical grade mineral oils from printing inks

Recycled paper and board used in food packaging materials (boxes, paper bags) often cause migration of mineral oil into food at levels which are unacceptable according to present toxicological assessments. When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C₂₀ may migrate into the packed food within a few weeks, those up to n-C₂₈ at a decreasing rate. Unprinted recycled board contained 300–1,000 mg/kg mineral oil <n-C₂₈. The main sources are the inks used for printing newspapers: newspapers contained roughly 3,000 mg/kg mineral oil <n-C₂₈. These mineral oils fall into classes for which JECFA established a tolerable daily intake of 0.01 mg/kg body weight. Using standard assumptions for calculating specific migration limits, a maximum tolerable concentration in food of 0.6 mg/kg is derived. This evaluation assumes highly refined white oils, whereas the oils found in recycled board are of technical quality and contain 15–25% aromatic compounds, predominantly with 1–3 aromatic rings, as shown by comprehensive GC × GC. This finding precipitates authorities into a dilemma: recycling is supported for the sustainable use of materials, but on the basis of present toxicological assessments the migration is often far beyond acceptable.     

Chlorination of alumina in kaolinitic clay

The chlorination of alumina in kaolinitic clay with Cl₂ and CO gas mixtures was studied gravimetrically. The effects of the calcination method and of NaCl addition on the reactivity of the clay were examined. Fast reaction rates were achieved only with samples previously exposed to a sulfating treatment. Optimum conditions, with maximum yield and selectivity to A1C1₃ and minimum SiO₂ conversion, were found between 770 and 970 K. At higher temperatures the SiCl₄ formed poisons the reactive alumina surface by selective chemisorption with a marked decrease of the reaction rate.