Food-contact materials, including paper, have to comply with a basic set of criteria concerning safety. This means that paper for food contact should not give rise to migration of components, which can endanger human health. The objectives of this pilot study were, first, to compare paper of different qualities as food-contact materials and to perform a preliminary evaluation of their suitability, from a safety point of view, and, second, to evaluate the use of different in vitro toxicity tests for screening of paper and board. Paper produced from three different categories of recycled fibres (B-D) and a raw material produced from virgin fibres (A) were obtained from industry, and extracts were examined by chemical analyses and diverse in vitro toxicity test systems. The products tested were either based on different raw materials or different treatments were applied. Paper category B was made from 40% virgin fibres, 40% unprinted cuttings from newspapers, and 20% de-inked newspapers and magazines. Paper categories C and D were based on newspapers and magazines. However, paper D was de-inked, whereas C was not. To identify constituents of the papers with a potential to migrate into foodstuff, samples of the paper products were extracted with either 99% ethanol or water. Potential migrants in the extracts were identified and semiquantified by GC-IR-MS or GC-HRMS. In parallel to the chemical analyses, a battery of four different in vitro toxicity tests with different endpoints were applied to the same extracts. (1) a cytotoxicity test using normal human skin fibroblasts. The test was based on measurements of the reduction of resazurin to resorufin by cellular redox processes and used as a screening test for acute or general toxicity; (2) a Salmonella/microsome assay (Ames test) as a screening test for mutagenic and potentially carcinogenic compounds; (3) a recombinant yeast cell bioassay as a screening test for compounds with oestrogenic activity; (4) an aryl hydrocarbon (Ah)-receptor assay (CALUX assay) as a screening test for compounds with dioxin-like activity. In addition, the papers were testedfor microbial content and, in general, the microbiological load was quite low. The following microorganisms were counted and identified on both surface and homogenized pulp samples: the total number of aerobic bacteria, the number of aerobic and anaerobic spore formers, the number of Bacillus cereus/thuringiensis, and the number of yeast and moulds. The chemical analyses showed a significantly higher amount and different composition pattern of chemicals extracted with ethanol compared with water. Analyses of the ethanol extracts showed a distinctly smaller number and lower concentrations of chemicals in extracts prepared from sample A compared with extracts of samples B-D. The compounds identified in B-D were similar, but the amounts were lower in B compared with C and D. In accordance with the chemical analyses, the water extracts were less cytotoxic than the ethanol extracts. The extract prepared from virgin fibres was...
Hepatic microsomes from rats pretreated with PCB were found to metabolize the food mutagen 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) to two major metabolites, one of which was identified as the N-hydroxy derivative, 2-hydroxy-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (N-OH-PhIP). This identification was based on mass spectral (MS), UV and HPLC data by comparison with N-OH-PhIP prepared by chemical synthesis, as well as the specific activity of the compound in the Ames Salmonella test. Synthetic N-OH-PhIP was prepared by catalytic reduction of the nitro derivative of PhIP, which was synthesized from PhIP by diazotization and reaction with sodium nitrite. N-OH-PhIP was mutagenic to Salmonella typhimurium TA98 without metabolic activation and had a specific mutagenic activity of 2700 revertants/nmol. N-OH-PhIP thus seems to be a proximate mutagenic metabolite of PhIP. Other direct acting mutagens were not detected in the microsomal incubation mixture after HPLC separation. N-OH-PhIP also induced sister chromatid exchange (SCE) in Chinese hamster ovary cells (CHO cells) without metabolic activation. The specific activity of N-OH-PhIP in this assay was approximately 3 times higher than the activity of PhIP with microsomal activation.
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