Potential Hazards of Skin Exposure to Nanoparticles

Safety Assessment of Nanomaterials to Eyes: An Important but Neglected Issue

The production and application of nanomaterials have grown tremendously during last few decades. The widespread exposure of nanoparticles to the public is provoking great concerns regarding their toxicity to the human body. However, in comparison with the extensive studies carried out to examine nanoparticle toxicity to the human body/organs, one especially vulnerable organ, the eye, is always neglected. Although it is a small part of the body, 90% of outside information is obtained via the ocular system. In addition, eyes usually directly interact with the surrounding environment, which may get severer damage from toxic nanoparticles compared to inner organs. Therefore, the study of assessing the potential nanoparticle toxicity to the eyes is of great importance. Here, the recent advance of some representative manufactured nanomaterials on ocular toxicity is summarized. First, a brief introduction of ocular anatomy and disorders related to particulate matter exposure is presented. Following, the factors that may influence toxicity of nanoparticles to the eye are emphasized. Next, the studies of representative manufactured nanoparticles on eye toxicity are summarized and classified. Finally, the limitations that are associated with current nanoparticle-eye toxicity research are proposed.

An improved experimental methodology to evaluate the effectiveness of protective gloves against nanoparticles in suspension

Recent studies underline the potential health risks associated to the "nano" revolution, particularly for the workers who handle engineered nanoparticles (ENPs) that can be found in the formulation of several commercial products. Although many Health & Safety agencies recommend the use of protective gloves against chemicals, few studies have investigated the effectiveness of these gloves towards nanoparticle suspensions. Moreover, the data that are available are often contradictory. This study was designed to evaluate the effectiveness of protective gloves against nanoparticles in suspension. For this purpose, a new methodology was developed in order to take into account parameters encountered in the workplace such as mechanical deformations (MD) that simulate hand flexion and sweat. The effects of the precise experimental protocol on the concentrations of nanoparticles that were detected in the sampling suspension were assessed. Several samples of nitrile rubber gloves (73 µm thick), taken from different boxes, were brought into contact with gold nanoparticles (5 nm) in water. During their exposure to ENPs, the glove samples submitted systematic mechanical deformations and were placed in contact with a physiological solution simulating human sweat. Under these conditions, results obtained by inductively coupled plasma mass spectrometry (ICPMS) showed that the 5 nm gold nanoparticles passed through the protective gloves. This result was acquired, in spite of the observation of significant losses during the sampling phase that will be important for future experiments evaluating the effectiveness of these materials.

Identifying a size-specific hazard of silica nanoparticles after intravenous administration and its relationship to the other hazards that have negative correlations with the particle size in mice

Many of the beneficial and toxic biological effects of nanoparticles have been shown to have a negative correlation with particle size. However, few studies have demonstrated biological effects that only occur at specific nanoparticle sizes. Further elucidation of the size-specific biological effects of nanoparticles may reveal not only unknown toxicities, but also novel benefits of nanoparticles. We used surface-unmodified silica particles with a wide range of diameters and narrow size intervals between the diameters (10, 30, 50, 70, 100, 300, and 1000 nm) to investigate the relationship between particle size and acute toxicity after intravenous administration in mice. Negative correlations between particle size and thrombocytopenia, liver damage, and lethal toxicity were observed. However, a specific size-effect was observed for the severity of hypothermia, where silica nanoparticles with a diameter of 50 nm induced the most severe hypothermia. Further investigation revealed that this hypothermia was mediated not by histamine, but by platelet-activating factor, and it was independent of the thrombocytopenia and the liver damage. In addition, macrophages/Kupffer cells and platelets, but not neutrophils, play a critical role in the hypothermia. The present results reveal that silica nanoparticles have particle size-specific toxicity in mice, suggesting that other types of nanoparticles may also have biological effects that only manifest at specific particle sizes. Further study of the size-specific effects of nanoparticles is essential for safer and more effective nanomedicines.