Validation of methods for the detection and quantification of engineered nanoparticles in food.

The potential impact of nanomaterials on the environment and on human health has already triggered legislation requiring labelling of products containing nanoparticles. However, so far, no validated analytical methods for the implementation of this legislation exist. This paper outlines a generic approach for the validation of methods for detection and quantification of nanoparticles in food samples. It proposes validation of identity, selectivity, precision, working range, limit of detection and robustness, bearing in mind that each "result" must include information about the chemical identity, particle size and mass or particle number concentration. This has an impact on testing for selectivity and trueness, which also must take these aspects into consideration. Selectivity must not only be tested against matrix constituents and other nanoparticles, but it shall also be tested whether the methods apply equally well to particles of different suppliers. In trueness testing, information whether the particle size distribution has changed during analysis is required. Results are largely expected to follow normal distributions due to the expected high number of particles. An approach of estimating measurement uncertainties from the validation data is given.

Tattoo inks in general usage contain nanoparticles.

BACKGROUND: To our knowledge tattooing has never been thought of as a method of introducing nanoparticles (NPs) into the human body by the intradermal route, and as such it has never been a topic of research in nanotoxicology. The content of NPs in tattoo inks is unknown. OBJECTIVES: To classify the particle sizes in tattoo inks in general usage. METHODS: The particle size was measured by laser diffraction, electron microscopy and X-ray diffraction. RESULTS: The size of the pigments could be divided into three main classes. The black pigments were the smallest, the white pigments the largest and the coloured pigments had a size in between the two. The vast majority of the tested tattoo inks contained significant amounts of NPs except for the white pigments. The black pigments were almost pure NPs, i.e. particles with at least one dimension <100 nm. CONCLUSIONS: The finding of NPs in tattoo inks in general usage is new and may contribute to the understanding of tattoo ink kinetics. How the body responds to NP tattoo pigments should be examined further.