Search

Plenty of new approach methodologies (NAMs) for risk assessment have been developed but only some are included in OECD Test Guidelines (TGs) for regulatory implementation. Nevertheless, NAMs are increasingly applied, e.g. for nanomaterial (NM) risk assessments. The EFSA Guidance on NM risk assessment suggests that NAM‐derived data concerning degradation/dissolution (in relevant biofluids), intestinal uptake/crossing, genotoxicity, cytotoxicity, oxidative stress, (pro‐)inflammatory potential and barrier integrity, for many of which no OECD TGs exist, have to be evaluated first. Consequently, NM risk assessments involve data from non‐guideline studies, requiring time‐consuming and challenging case‐by‐case evaluations. Establishing an OECD TG is a formal process aiming for international use according to the Mutual Acceptance of Data (MAD). However, not every promising NAM can be prioritised for OECD TGs. A qualification, based on an expert opinion, may enable an efficient use of adequate NAMs for a specific context‐of‐use. Furthermore, it supports the optimisation of promising NAMs for regulatory applications. Existing qualification systems operate in the context of e.g., drug development tools (FDA) and research and development into pharmaceuticals (EMA). The NAMS4NANO consortium was tasked to propose a generic framework for a qualification system for chemical risk assessment in the food and feed sector to speed up the regulatory use of NAMs. Here we describe our proposal including the process and evaluation criteria. A detailed test method description, preferably as standard operating procedures (SOPs), describing the set‐up of the NAM including its application and evaluation phase is crucial. Furthermore, the scientific validity, i.e. its reliability and relevance for the context‐of‐use, needs to be demonstrated, for which we suggest a less rigorous process compared to OECD TGs. We propose to initially establish a qualification system for NM risk assessment, aligned with the EFSA framework. This document is an interim version to stipulate a broader discussion among experts and stakeholders. [ABSTRACT FROM AUTHOR]

Metal sub-microparticles (SMPs) and nanoparticles (NPs) presence in food is attributable to increasing pollution from the environment in raw materials and finished products. In the present study, a multifaceted analytical strategy based on Environmental Scanning Electron Microscopy and High-Angle Annular Dark-Field—Scanning Transmission Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (ESEM-EDX, HAADF-STEM-EDX) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was proposed for the detection and characterization of metal and metal-containing SMPs and NPs in durum wheat samples, covering a size measurement range from 1 nm to multiple µm. ESEM-EDX and ICP-MS techniques were applied for the assessment of SMP and NP contamination on the surface of wheat grains collected from seven geographical areas characterized by different natural and anthropic conditions, namely Italy, the USA, Australia, Slovakia, Mexico, Austria, and Russia. ICP-MS showed significant differences among the mean concentration levels of metals, with the USA and Italy having the highest level. ESEM-EDX analysis confirmed ICP-MS concentration measurements and measured the highest presence of particles < 0.8 µm in size in samples from Italy, followed by the USA. Less marked differences were observed when particles < 0.15 µm were considered. HAADF-STEM-EDX was applied to a selected number of samples for a preliminary assessment of internal contamination by metal SMPs and NPs, and to expand the measurable particle size range. The multifaceted approach provided similar results for Fe-containing SMPs and NPs. ICP-MS and ESEM-EDX also highlighted the presence of a significant abundance of Ti- and Al-containing particles, while for STEM-EDX, sample preparation artifacts complicated the interpretation. Finally, HAADF-STEM-EDX results provided relevant information about particles in the low nm range, since, by applying this technique, no particles smaller than 50 nm were observed in accordance with ESEM-EDX. [ABSTRACT FROM AUTHOR]

Whipped cream canisters, also known as nitrous oxide whippets, are traditionally used in the culinary arts to prepare food foams. In recent years, however, these gas canisters have been cracked open and inhaled to produce a "legal" high. Users of these whippets have reported the presence of an oily residue containing metallic particles. This contamination was investigated using liquid chromatography‐, gas chromatography‐ and inductively coupled plasma‐mass spectrometry (ICP‐MS) and optical emission spectrometry (ICP‐OES). The particulate matter was also analyzed by scanning transmission electron microscopy (STEM) combined with energy‐dispersive X‐ray spectroscopy (EDX). The presence of cyclohexyl isothiocyanate was confirmed at a maximum concentration of 67 μg per whippet. ICP‐MS and ICP‐OES analysis revealed the presence of mainly iron and zinc, but also, traces of aluminum, chromium, cobalt, nickel, and lead were found. STEM‐EDX analysis confirmed the presence of nano‐sized particles containing iron and zinc. When simulating inhalation, using the multiple path particle dosimetry model, it was confirmed that these nano‐sized particles can reach the deeper parts of the lungs. Most users assume that inhaling a food‐grade nitrous oxide whippet for a "legal" high poses no risks. However, this research shows that users are exposed to cyclohexyl isothiocyanate, a substance classified as a respiratory sensitizer. The presence of zinc in the particulate matter could potentially be linked to lung lesions. [ABSTRACT FROM AUTHOR]

Abstract Background The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM. Results Bright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose. Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM. Conclusion The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor.

Transmission electron microscopy (TEM) in combination with a systematic selection procedure for unbiased random image collection, semi-automatic image analysis, and data processing has been validated for size, shape, and surface topology measurements of silica nanoparticles. The validation study, assessing the precision and accuracy of the TEM method, consists of series of measurements on two colloidal silica-certified reference materials, with number-based modal area-equivalent circular diameters (ECD) of 19.4 nm (ERM-FD100) and 27.8 nm (ERM-FD304). The measurement uncertainties are estimated for the modal and median particle size, shape, and surface topology parameters of single primary particles. The single primary particles are distinguished from agglomerates using a linear discriminant analysis approach. After optimization of the binning process, the mode associated with the number-based particle size distribution is obtained by lognormal fitting. The methodology described in this paper relies on a high level of automation of calibration, image acquisition, image analysis, and data analysis and gives robust results for the modal ECD. The expanded uncertainty of the modal ECD is estimated to be about 3 %. The largest contribution to the expanded uncertainty stems from the uncertainty associated with the trueness of the TEM method. [ABSTRACT FROM AUTHOR]

Background: The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM. Results: Bright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose. Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM. Conclusion: The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor. [ABSTRACT FROM AUTHOR]