Arthur D. Schwope

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.

High‐temperature migration of antioxidants from polyolefins

Migration rates of radiolabelled antioxidants, Irganox-1010 (I-1010) and Irganox-1076 (I-1076), were measured from low- and high-density polyethylenes (LDPE, HDPE) and polypropylene (PP) at temperatures up to 135 degrees C. Water, 8 and 95 per cent aqueous ethanol and corn oil were employed as food simulating liquids (FSL). The experiments were conducted in a high-pressure cell in a manner that allowed contact between the polyolefin plaque and the FSL only during the test period and not while being heated. The migrations of the antioxidants varied with the square root of time, and the Fickian diffusion coefficients could be correlated with temperature in an Arrhenius fashion. Under comparable test conditions, antioxidant migrations were largest from PP for aqueous simulants, but for non-aqueous simulants the highest losses were from LDPE. In both instances lowest losses were from HDPE. In most instances there was little difference between the migration behaviour of I-1010 and I-1076. A few tests were conducted to measure the antioxidant migrations to foods. The losses were usually larger than those to water but below those to corn oil.

Indirect Food Additive Migration from Polymeric Food Packaging Materials

Many foods contact polymeric packaging materials which contain residues of the polymerization process or additives employed to facilitate processing. The extent of migration of such materials from the packaging to foods is the focus of the present article. A major experimental program using eight polymer-migrant systems is described. Migration was measured to food-simulating liquids (FSL) and to foods. Accelerated tests were conducted with FSL under FDA guidelines conditions so as to develop correlations between such data and those found using foods under normal storage temperatures and shelf lives. In the majority of tests, the migration was found to be approximately proportional to the square root of time, to increase significantly with a rise in temperature, and to be proportional to the initial concentration of migrant in the polymer. Stirring in the FSL or food phase was generally not important except for the system involving dioctyl adipate migrating from polyvinyl chloride film. In some instances, after a period of time, migration rates became very low, and this effect was attributed to saturating the FSL or food phase with migrant. The foods comprised a variety of types, including liquid, semisolid, solid, and dry; both oily and aqueous foods were included. The physical steps involved in migration include the diffusion of the migrant from the interior of the film to the surface, where it can dissolve in the external FSL or food phase. The nature of the FSL or food is shown to be very important in that components can penetrate the polymer and dramatically increase migration rates. Consistent with the FDA guidelines in effect at the time of this study, testing was performed with five FSL (water, 3% acetic acid, 8% and 50% ethanol, and n-heptane) at 49 degrees C. Detailed comparisons were made between the migrations to foods and to FSL; following are the more relevant conclusions. (1) Three percent acetic acid showed no advantage over water as a food simulant even in those cases where the food could be considered acidic in nature. (2) Water, when used as an FSL at 49 degrees C for 5 days, overestimated migration in aqueous foods in about 75% of the cases. In some instances, however, the water phase became saturated with migrant. In other situations, this test protocol underpredicted migration--especially in those cases where there were components in the food that were able to penetrate into the polymer and enhance migration (such as orange juice).(ABSTRACT TRUNCATED AT 400 WORDS)

State-of-the-Art Review of Permeation Testing and the Interpretation of Its Results

Permeation testing is the most common means for assessing the effectiveness of clothing materials as barriers to chemicals, and standard procedures exist for conducting such tests. In recent years significant amounts of data have been generated. Unfortunately, much of the data has not been reported in sufficient detail to allow rigorous comparison, extrapolation, or generalization of the results. The purpose of this study is to summarize insights into the correct performance of the test and to present guidance that enables the comparison and interpretation of its results. Ficks laws are used to demonstrate the effects of analytical sensitivity; clothing material thickness and surface area; collection medium volume and flow rate; and test mode (i.e., open- versus closed-loop) on test results, particularly the measurement of breakthrough time. Strong evidence is presented that considerably more details of the experimental procedures are required if tests results are to be meaningful. At a minimum, the brea...

A Test Method for the Evaluation of Protective Glove Materials Used in Agricultural Pesticide Operations

The ASTM Standard Test Method for Resistance of Protective Clothing Materials to Permeation by Liquids and Gases (F 739-85) and the recommended permeation cell have been modified to permit the testing of protective clothing materials for permeation by the low volatility, low water solubility active ingredients present in many pesticide formulations. The modification makes use of solid collection medium, a thin (0.02-in. thick) sheet of silicone rubber, to collect permeants. Those compounds permeating the protective material can then be desorbed into an appropriate solvent and analyzed using conventional methods and instruments. A series of permeation tests have been conducted using samples of 10 common, commercially available protective glove materials and the modified cell. Permeation of the active ingredient as well as carrier solvent components of several concentrated pesticide formulations containing low volatility, low water solubility active ingredients and aromatic hydrocarbon carrier solvents has been monitored. The relative breakthrough and the total mass of material permeating the glove materials appears to be strongly related to the concentration of the aromatic carrier solvent present in the formulations studied to date. The collection method was found to be less useful for monitoring the permeation of active ingredients, which have reasonably high water solubilities. The results obtained by using this method with samples of protective glove materials challenged by several concentrated pesticide formulations are described. For these formulations containing xylene boiling range aromatic solvents, gloves made of nitrile rubber, butyl rubber, and Silver Shield were most resistant to permeation; natural rubber and polyethylene glove materials were least resistant.

PERMEATION RESISTANCE OF GLOVE MATERIALS TO AGRICULTURAL PESTICIDES

The toxicities of many agricultural pesticides require that hand protection be used by persons who mix, load, and apply these products, as specified on the label and material safety data sheet. Selection of gloves for formulations that contain organic solvents is particularly problematic because a solvent that permeates the glove can carry with it the active ingredient of the pesticide formulation. With a test method that measures the simultaneous permeation of the carrier solvent(s) and active ingredient(s), in particular those active ingredients that have low solubility in water and low volatility, over 100 permeation tests (in triplicate) with approximately 20 pesticide formulations were conducted with 13 different glove materials. These results are summarized and generalizations are presented within the perspective of the large base of permeation data for neat chemicals and another large permeation study with pesticides. Key among the findings is that the carrier solvent generally permeates first and at a much higher rate than the active ingredient. Furthermore, the permeation behavior of formulations containing solvents generally mirrored that of neat carrier solvents alone. Thus, insight into the selection of the most appropriate glove material for a given pesticide formulation can be gained from permeation data for neat chemicals. For the types of solvents that may be present in pesticide formulations, preferred materials include nitrile rubber, butyl rubber, and plastic film laminates. Natural rubber and polyvinyl chloride materials generally are not recommended.

Migration to dry foods

Plastic packaging is used for the containment of many dry foods. The United States Food and Drug Administration requires no migration testing of the packaging used for dry foods having no free oils on their surface. We illustrate with numerous examples that migration of additives from plastic packaging does, however, occur to such dry foods. Migration rates to these dry foods are lower than to food oils but are significantly higher than to water. It is suggested that activated carbon or alumina power could be used as a simulant for many dry foods.

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.