Assessment of TiO2 (nano)particles migration from food packaging materials to food simulants by single particle ICP-MS/MS using a high efficiency sample introduction system.

TiO2 is the most widely used white pigment in plastics and food packaging industry, thus the question of its migration towards food and hence the impact on consumers is raised. Since recent research indicate its potential toxicity, it is necessary to study TiO2 contamination as a consequence of food storage. For this purpose, plastic containers from commercially-available dairy products and custom-made TiO2-spiked polypropylene materials were put in contact with 50% (v/v) ethanol and 3% (w/v) acetic acid, which were used here as food simulants. The migration assays were carried out under standard contact conditions of packaging use (as recommended by Commission Regulation (EU) N° 10/2011 for food contact migration testing), and under conditions of extreme mechanical degradation of the packaging. The TiO2 (nano)particles released in the food simulants were analysed by single particle inductively coupled plasma-tandem mass spectrometry in mass-shift mode and using a high efficiency sample introduction system (APEX™ Ω) to avoid matrix effects from food simulants. For the dairy product containers and for the spiked polypropylene, results showed release of TiO2 particles of rather large sizes (average size: 164 and 175 nm, respectively) under mechanical degradation conditions, i.e. when the polymeric structure is damaged. The highest amounts of TiO2 were observed in 50% ethanol after 10 days of storage at 50 °C (0.62 ng cm-2) for the dairy product containers and after 1 day of storage at 50 °C (0.68 ng cm-2) for the spiked polypropylene. However, the level of Ti released in particle form was very small compared to the total Ti content in the packaging and far below the acceptable migration limits set by European legislation. Release under standard contact conditions of use of the container was not measurable, thus the migration of TiO2 particles from this packaging to dairy products among storage is expected to be negligible.

The food additive titanium dioxide hinders intestinal production of TGF-ß and IL-10 in mice, and long-term exposure in adults or from perinatal life blocks oral tolerance to ovalbumin.

Food hypersensitivities are increasing in industrialized countries, and foodborne nanoparticles (NPs) are suspected as co-factors in their aetiology. Food-grade titanium dioxide (fg-TiO2), a food colouring agent, is composed of NPs with immunomodulatory properties. We investigated whether fg-TiO2 may compromise the establishment of oral tolerance (OT) to food proteins using a model of OT induction to ovalbumin (OVA) in mice, and whether a perinatal exposure could trigger this effect. In pregnant mice fed a TiO2-enriched diet, ICP-MS and TEM-EDX analyses showed passage of TiO2 NPs into the foetus. When their weaned offspring were fed the same diet, a breakdown in OT to OVA was observed at adulthood, characterized by a high anti-OVA IgG production compared to controls. However, adult mice directly exposed to fg-TiO2 did not induce OT to OVA either, ruling out a developmental origin for these effects. When these mice were orally challenged with OVA, intestinal inflammation demonstrated hypersensitivity to OVA. In OVA-naïve mice, fg-TiO2 exposure impaired intestinal TGF-ß and IL-10 production, of key role in OT induction and maintenance. These findings showed that long-term exposure to TiO2 as food additive alters anti-inflammatory cytokine profile, and leads to OT failure regardless of the timing of TiO2 exposure throughout life.

Certification of a reference material of metal content in atmospheric particles deposited on filters.

Air quality is one of the areas in Europe where a series of EU Directives have been published with the aim of achieving improved long-term and harmonised air quality objectives across the European Union. This paper describes the production of a certified reference material, aiming to support QA/QC programmes of analytical laboratories in the framework of the air quality monitoring activities. The certified values are the As, Cd, Ni and Pb masses in PM10 particles deposited on quartz filters (CRM SL-MR-2-PSF-01). All the steps of the certification, i.e. the material characterisation, homogeneity and stability evaluation and uncertainty calculation, were performed according to the ISO guide 35 guidelines. The certification was conducted using the characterisation by a single method approach based on isotope dilution for cadmium, nickel, and lead and gravimetric standard addition calibration for arsenic associated with inductively coupled mass spectrometry (ICP-MS). The amounts of the four elements are in the range of the target values regulated by EU Directives.

Method development for genomic Legionella pneumophila DNA quantification by inductively coupled plasma mass spectrometry.

The development of a method for the quantification of Legionella pneumophila genomic deoxyribonucleic acid is considered. The method is based on the quantification by inductively coupled plasma mass spectrometry (ICP-MS) of the mass fraction of phosphorus, stoichiometrically presented in the DNA molecules. Through the DNA sequencing data, it was possible to convert the ICP-MS analysis results into DNA genome units. L. pneumophila DNA samples were analyzed using ICP-sector field MS and ICP-quadrupole MS with a collision/reaction cell. Spectrophotometric measurements of the absorbance at 260nm and real-time PCR techniques were used to independently confirm the ICP-MS results. The comparison of the methods showed that the ICP-MS method provides better accuracy with respect to currently applied analytical techniques such as UV spectrophotometry, fluorescent dye methods, and real-time PCR. Moreover, with the use of calibration standards whose values are traceable to the International System of Units and the possibility of evaluating the contribution to the overall uncertainty of each step of the measurement procedure, the method enables long-term comparability of the measurement results. These advantages make the ICP-MS method suitable for nucleic acid investigation, from nucleotides to genomic DNA, as well as for the certification of the reference materials containing nucleic acids.