Exposure to gallium arsenide nanoparticles in a research facility: a case study using molecular beam epitaxy

We evaluated GaAs nanoparticle-concentrations in the air and on skin and surfaces in a research facility that produces thin films, and to monitored As in the urine of exposed worker. The survey was over a working week using a multi-level approach. Airborne personal monitoring was implemented using a miniature diffusion size classifier (DiSCMini) and IOM sampler. Environmental monitoring was conducted using the SKC Sioutas Cascade Impactor to evaluate dimensions and nature of particles collected. Surfaces contamination were assessed analyzing As and Ga in ghost wipes. Skin contamination was monitored using tape strips. As and Ga were analyzed in urines collected every day at the beginning and end of the shift. The greatest airborne exposure occurred during the cutting operations of the GaAs Sample (88883 np/cm3). The highest levels of contamination were found inside the hood (As max = 1418 ng/cm2) and on the laboratory floor (As max = 251 ng/cm2). The average concentration on the worker's skin at the end of the work shift (3.36 ng/cm2) was more than 14 times higher than before the start of the shift. In weekly urinary biomonitoring an average As concentration of 19.5 µg/L, which was above the Società Italiana Valori di Riferimento (SIVR) reference limit for the non-occupational population (2.0 - 15 µg/L), but below the ACGIH limit (30 µg/L). Overall, airborne monitoring, surface sampling, skin sampling, and biomonitoring of worker confirmed the exposure to As of workers. Systematic cleaning operations, hood implementation and correct PPE management are needed to improve worker protection.

TLR7 Gln11Leu single nucleotide polymorphism in patients with sarcoidosis

Sarcoidosis is a multi-factorial systemic disease with increased activity of the cellular immune components which is responsible of the formation of non-caseating granulomas in involved organs. Recent views on the etiology indicate interactions between inherited susceptibility and environmental or lifestyle factors. Concerning genes that may influence susceptibility to sarcoidosis Toll-like receptors (TLRs) may represent plausible candidates. In this present study, we investigated the X-linked TLR7 rs179008/Gln11Leu polymorphism situated on exon 3. SNP genotyping of the TLR7 exon polymorphism was performed by TaqMan allelic discrimination using the StepOnePlus™ Real-Time PCR System (Applied Biosystems). In females, the incidence of the AT genotypes of the polymorphism was significantly lower in sarcoidosis patients compared to control subjects  (P=0.0001). We could observe in control subjects a significant preponderance of the T allele of the TLR7 rs179008/Gln11Leu polymorphism compared to sarcoidosis female patients (P=0.008). In males, no significant differences between patients and controls emerged in allele frequencies of the TLR7 rs179008/Gln11Leu polymorphism. The presence of the TLR7 rs179008/Gln11Leu polymorphism in sarcoidosis may determine an alteration of TLR7 function hampering the signaling pathway involved in the onset of both cellular and humoral autoimmunity. This is consistent with the view that in some circumstances genetic mutations affecting components of the immune system can prevent systemic autoimmunity.

[Definition and validation of a comfort index calculation method for office seats]

BACKGROUND

Among its other required features, a highly comfortable chair should adapt its contact surfaces, namely the seat and the back rest, to the shape of the body of the person sitting on it. However, "comfort" is not usually perceived as an absolute value, but is derived from a subjective comparison between two or more chairs.

OBJECTIVES

The purpose of this research was the definition of an objective comfort index (IC), i.e., derived from instrumental measurements, and which would also represent an absolute comfort value.

METHODS

Analytical evaluation of the distribution of body weight, by means of a barometric matrix, shows that a comfortable chair tends to minimize peak and average values of pressure at the level of the contact areas located between the body and the seat and the back of the chair. To define a comparison parameter for determining an absolute comfort value, a reference chair (SDR) was developed. The seat and the back of this chair are rigid, with poor compliance. A comfort value of zero was, by definition, assigned to this chair. Therefore, the Comfort index (IC) was obtained by the mathematical calculation of the ratios of averages, peaks and gradients of pressure, appropriately weighted, and the corresponding values measured on the tested chair and on the SDR.

RESULTS

It is shown that the anthropometric characteristics of each subject are irrelevant to the assessment of the IC, which depends only on the compliance characteristics of the seat and back surfaces of the tested chair

CONCLUSIONS

IC can be improved through analysis of a larger number of seats, which would thus constitute the basis for the use of an objective evaluation of seating comfort.