Kenneth R. Sidman

Migration of BHT and Irganox 1010 from low-density polyethylene (LDPE) to foods and food-simulating liquids.

The most widely used food-wrapping material is low-density polyethylene (LDPE). Food-wrap grades contain antioxidants to minimize degradation during processing and, in the final films, such additives are normally present at levels of several hundred ppm. During use, the antioxidants may migrate into food stored in LDPE wraps. Two typical antioxidants, BHT and Irganox 1010, were radiolabelled to allow accurate analytical measurement of the extent of their migration into foods and food-simulating liquids (FSL). The results show that BHT, a much smaller and more volatile molecule than Irganox 1010, migrates more rapidly into foods, but the differences are less for FSL. In most instances, migration appears to be controlled by diffusion of the antioxidant in the polymer, and the quantity lost can be correlated in a linear fashion with the square root of time. With aqueous FSL, and, presumably aqueous-type foods, however, anomalies result; the migration is often erratic, but is more closely related to time than to the square root of time. A tentative model developed to explain these facts assumes that the antioxidants decompose in aqueous media and the net migration rate is controlled largely by the rate of chemical decomposition. It is also shown that dry foods can be surprisingly effective sinks for antioxidants under typical storage conditions.

Biodegradable, implantable sustained release systems based on glutamic acid copolymers☆

Abstract Polymer pellets that contain drugs and may be implanted under the skin offer effective means for providing sustained, controlled drug therapy to humans and animals. Among the most useful drug delivery systems are those based on biodegradable polymers that ultimately are absorbed by the body — eliminating the need for their surgical removal. Copolymers of L-glutamic acid and γ-ethyl L-glutamate biodegrade to L-glutamic acid and ethanol, at rates that are determined by the initial copolymer composition. The materials are permeable to a wide range of drugs, including steroids, narcotic antagonists, peptide hormones, antimalarials, and anticancer agents. When fabricated into matrix rods or capsules, the copolymers have been used to release drugs in animals at constant rates for prolonged periods of time. p]In this study, rods composed of a blend of drug and copolymer were found to be useful for the long-term release (i.e., 6 to 24 months) of drugs having low aqueous solubility, such as progesterone and levonorgestrel. Capsules, composed of a copolymer sheath surrounding the drug, were better suited for shorter durations of release (i.e., up to 6 months) of drugs having higher aqueous solubility, such as luteinizing hormone-releasing hormone and naltrexone. The physical dimensions and copolymer compositions of either dosage form were readily varied to meet specific delivery rate and duration objectives while satisfying equally important degradation requirements.

Plasticizer migration from polyvinyl chloride film to solvents and foods

Polyvinyl chloride (PVC) films used for food wraps contain significant concentrations of plasticizers, along with other additives. The rate of migration of these plasticizers to foods and food-simulating solvents is the principal concern of this paper, which reviews prior experimental studies and presents new data for radiolabelled dioctyl adipate. Analytical models are described to correlate many of the data, criteria are presented for identifying the controlling step in the mechanism of transfer of plasticizer from PVC films into foods and food-simulating solvents, and tentative recommendations are offered for the selection of food simulants and for the type of experiment necessary to allow an unambiguous interpretation of the data.

Migration of Irganox 1010 from ethylene-vinyl acetate films to foods and food-simulating liquids

In a series of experiments on the migration of the antioxidant Irganox 1010 from ethylene-vinyl acetate (EVA) films into food-simulating liquids and foods, the antioxidant was found to migrate rapidly from EVA film into n-heptane, 100% ethanol and corn oil. The rate of migration into these media was greater from EVA than from low-density polyethylene (LDPE) under comparable conditions. In contrast, little migration of Irganox 1010 was recorded on exposure of the EVA film to aqueous media, whereas migration from LDPE into such media was relatively high.

Sorption—desorption phenomena of chemicals from polymer (paint) films

Abstract The sorption and later desorption of a toxic chemical from polymers and, more specifically, paint films represent a potential hazard to personnel in proximity to these contaminated surfaces. Such hazards may be due to resultant vapor concentrations or to direct transfer of the chemical to the skin upon touching the surface. Desorption rates are dependent on the properties of the chemical/polymer pair, boundary conditions, partition coefficient, and the initial concentration profile in the material. The initial concentration profile is dependent on the diffusion coefficient and solubility of the chemical in the polymer as well as the duration of the contamination period. An analytical model is developed to predict desorption fluxes on the basis of the contamination scenario, the conditions external to the contaminated material and physical properties as determined by independent tests. The model predicted well the desorption of diethyl malonate, a toxic chemical simulant, from alkyd paint films.