Primary aromatic amines (PAAs) in black nylon and other food-contact materials, 2004–2009
Primary aromatic amines (PAAs) were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in migrates from 234 samples of food-contact materials, including black nylon (polyamide) kitchen utensils (n = 136), coloured plastics (28), and clear/printed multilayer film/laminates (41), from retailers, importers, and food producers. A further 29 utensils in use were obtained from colleagues. Very high PAA migration was found from black nylon kitchen utensils to the food simulant 3% acetic acid: the ‘non-detectable’ limit (20 µg aniline equivalents kg−1 food) was exceeded by up to 2100 times. All the other materials were compliant. The majority of the non-compliant utensils came from China. The predominant PAAs were aniline and 4,4′-methylenedianiline (4,4′-MDA). The frequency of violations decreased from the year 2004 (55%) to the autumn of 2005 (13%), possibly due to increased demands for in-house documentation, but they remained almost constant from 2005 to 2009. The validity of the results was shown by recovery studies, participation in proficiency testing, and comparative testing of utensils by two laboratories. Migration modelling was used to compare how various compliance migration test conditions influenced the final test results. Long-term release of PAAs was fitted by diffusion modelling experiments and long-term release was also seen as expected from used utensils. Toxicologists consider these migration levels of the suspected carcinogenic PAAs as a problem of major concern.