Bioaccumulation study of food contaminant isopropylthioxanthone (ITX) in fish using solid phase extraction (SPE) and HPLC/MS/MS and GC-MS.

Abstract: The alert for food contamination by Isopropylthioxanthone (ITX), a highly lipophilic molecule used as photoinitiator in UV-cured inks for printing the surface of food packagings, arose in Europe in November 2005, when the Italian authorities withdraw from the market thirty million liters of infants milk, because of contamination with ITX [1]. Some weeks later, a report published by the European Food Safety Agency (EFSA) stated that the observed level of ITX in some milk products (27–440 μg l−1) and fruit juices (5–249 μg l−1) did not constitute a real risk for the consumers’ health [2]. However, no fully convincing data on ITX genotoxicity have been published to date. In fact, whereas contradictory results were displayed in a limited in vitro study [3], the negative results obtained in two in vivo studies [4] and [5] did not confirm the ITX mutagenic effects in experimental animals. Noteworthy, in a recent article Momo et al. [6] reported that ITX can effect the mobility/rigidity status of biological membranes by strong interactions with the cellular lipid bilayer. In the present study, the bioaccumulation level of ITX in fish was studied after exposed them for three weeks. Samples were extracted from homogenized fish tissue using n-hexane, purified with solid-phase extraction (SPE) silica gel cartridge, and then analyzed in and HPLC-MS/MS and GC/MS. good recovery at final fortified concentration 20.0 µg/L obtained was 68% with RSD of 3.5%. The contaminant ITX was found in all five treated fish samples in a concentration range of 34.45–115.48 μg l−1, which indicated that ITX could be potentially accumulated in fish. Further study on its toxicity and mechanism of bioaccumulation is deserved effort. Moreover, this efficient extraction method has shown to be suitable for detecting low level of ITX in fish matrixes with good recovery at low µg/kg level. Reference: [1] 2005 Chronology of Withdrawal of Nestlè and Other Liquid Milks, document available at www.ibfan.org/site2005/abm/paginas/articles/arch_art/416-1.doc. [2] Opinion of the Scientific Panel of Food Additives, Flavourings, Processing Aids and Materials in contact with Food on a request from the commission related to 2-isopropyl thioxanthone (ITX) and 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB) in food contact materials, EFSA J. 293 (2005) 1 (available at http://www.efsa.eu.int/science/afc/afc_opinions/catindex_en.html). [3] D. Kirkland, M. Aardema, L. Henderson and L. Muller, Mutat. Res. 584 (2005), p. 1. [4] B.V. Notox, Notox Project 411885, 5 October 2004. [5] B.V. Notox, Notox Project 411874, 23 November 2004. [6] F. Momo, S. Fabris and R. Stevanato, Biophys. Chem. 127 (2007), p. 36.