Preparation and analysis of styrene oligomers containing migrates from various polystyrenes used in food packaging

An oligostyrene-like product (F2L5250) was reported to have estrogen-like a ctivity (statistically significant increases in means for absolute uterine weight and the ratios of the uterine weight to terminal body weight) in juv enile female rats provided a dietary concentration of 100 ppm FL5250 for fo ur consecutive days. The highest no-effect-level (NOEL)for estrogenic activ ity was 80 ppm in the diet, corresponding to a daily intake of 13.3 mg F2L5 250/kg. Although it is unlikely that such estrogenic tetramers would occur br comme rcial polystyrene, the Styrene Steering Committee (SSC) of the European Che mical Industry Council (CEFIC) sponsored the current extensive project to a ddress any concern that human consumption of styrene oligomers migrating fr om polystyrene containers into food, e.g.,from packaged yoghurt, or from th e use of EPS coffee cups and related products, might affect human health. T o ensure confidentiality and compliance with the highest scientific and reg ulatory standards, the entire project was conducted without knowledge of th e oligomer migrates tested, and all activities were managed and audited und er a contract between the SSC and a third party, Argus International. This paper describes the preparation and analyses of the 23 representative polystyrenes [9 general purpose polystyrenes (GPPS) 8 high impact polystyre nes (HIPS) and 6 expandable polystyrenes (EPS)] evaluated for es;estrogenic ity in an in vivo uterotrophic assay in immature female rats. The polystyre ne samples were chosen to represent food packaging applications, They were obtained from participating European Polystyrene Manufacturers, coded at th e TNO Nutrition and Food Research Institute, Utrecht, The Netherlands (TNO) and sent to BASF, Ludwigshafen, Germany for preparation of test bars (GPPS and HIPS) or test foam parts (EPS). The prepared polystyrene test bars or test foam parts were submitted to elu tion with 50% aqueous (v/v) ethanol for 10 days at 40 degrees C, a procedur e which simulates lan exposure at ambient temperature for several weeks and represents an exaggeration in comparison with yoghurt, for which directive 85/572/EEC1 defines 3% aqueous acetic acid as the official food simulant. To further exaggerate the potential concentration of the possible migrates, the surface/volume ratio selected for elution was the maximum experimental ly possible, ie., approximately 56 dm(2)/kg food for the GPPS and HIPS bars and approximately 38 dm(2)/kg food for the EPS foam, representing a multip le of approximately 9 (GPPS and HIPS) and 6 (EPS), times the conventional s urface/volume ratio of 6 dm(2)/kg. These obtained styrene oligomer migrates were then diluted to 25% aqueous (v/v) ethanol, a concentration that could be tolerated by the test animals. After dilution, the low and high concent rations represented multiples of 0.5 and 4.6 (GPPS and HIPS) and 0.5 and 3. 2 (EPS) the conventional surface/volume ratio, respectively. These levels s imulated daily human consumption of 500 or 5,000 g of food for the GPPS and NIPS samples and of 500 or 3,150 g of food for the EPS samples, respective ly The results of the homogeneity, stability and concentration analyses of the styrene dimers and trimers in the migrates indicated that the concentra tions of migrants were highest as the result of 50% aqueous ethanol extract ion of HIPS test bars followed by GPPS test bars and EPS test foam parts.