R. Wrobel

Cytotoxicity and genotoxicity of nanosized and microsized titanium dioxide and iron oxide particles in Syrian hamster embryo cells.

Potential differences in the toxicological properties of nanosized and non-nanosized particles have been notably pointed out for titanium dioxide (TiO(2)) particles, which are currently widely produced and used in many industrial areas. Nanoparticles of the iron oxides magnetite (Fe(3)O(4)) and hematite (Fe(2)O(3)) also have many industrial applications but their toxicological properties are less documented than those of TiO(2). In the present study, the in vitro cytotoxicity and genotoxicity of commercially available nanosized and microsized anatase TiO(2), rutile TiO(2), Fe(3)O(4), and Fe(2)O(3) particles were compared in Syrian hamster embryo (SHE) cells. Samples were characterized for chemical composition, primary particle size, crystal phase, shape, and specific surface area. In acellular assays, TiO(2) and iron oxide particles were able to generate reactive oxygen species (ROS). At the same mass dose, all nanoparticles produced higher levels of ROS than their microsized counterparts. Measurement of particle size in the SHE culture medium showed that primary nanoparticles and microparticles are present in the form of micrometric agglomerates of highly poly-dispersed size. Uptake of primary particles and agglomerates by SHE exposed for 24 h was observed for all samples. TiO(2) samples were found to be more cytotoxic than iron oxide samples. Concerning primary size effects, anatase TiO(2), rutile TiO(2), and Fe(2)O(3) nanoparticles induced higher cytotoxicity than their microsized counterparts after 72 h of exposure. Over this treatment time, anatase TiO(2) and Fe(2)O(3) nanoparticles also produced more intracellular ROS compared to the microsized particles. However, similar levels of DNA damage were observed in the comet assay after 24 h of exposure to anatase nanoparticles and microparticles. Rutile microparticles were found to induce more DNA damage than the nanosized particles. However, no significant increase in DNA damage was detected from nanosized and microsized iron oxides. None of the samples tested showed significant induction of micronuclei formation after 24 h of exposure. In agreement with previous size-comparison studies, we suggest that in vitro cytotoxicity and genotoxicity induced by metal oxide nanoparticles are not always higher than those induced by their bulk counterparts.

Bioaerosol sampling by a personal rotating cup sampler CIP 10-M

High concentrations of bioaerosols containing bacterial, fungal and biotoxinic matter are encountered in many workplaces, e.g. solid waste treatment plants, waste water treatment plants and sewage networks. A personal bioaerosol sampler, the CIP 10-M (M-microbiologic), has been developed to measure worker exposure to airborne biological agents. This sampler is battery operated; it is light and easy to wear and offers full work shift autonomy. It can sample much higher concentrations than biological impactors and limits the mechanical stress on the microorganisms. Biological particles are collected in 2 ml of liquid medium inside a rotating cup fitted with radial vanes to maintain an air flow rate of 10 l min(-1) at a rotational speed of approximately 7,000 rpm. The rotating cup is made of sterilisable material. The sampled particles follow a helicoidal trajectory as they are pushed to the surface of the liquid by centrifugal force, which creates a thin vertical liquid layer. Sterile water or another collecting liquid can be used. Three particle size selectors allow health-related aerosol fractions to be sampled according to international conventions. The sampled microbiological particles can be easily recovered for counting, incubation or further biochemical analysis, e.g., for airborne endotoxins. Its physical sampling efficiency was laboratory tested and field trials were carried out in industrial waste management conditions. The results indicate satisfactory collection efficiency, whilst experimental application has demonstrated the usefulness of the CIP 10-M personal sampler for individual bioaerosol exposure monitoring.

Personal thoracic CIP10-T sampler and its static version Cathia-T

A specific version of the personal aerosol sampler CIP 10 was designed, named CIP10-T, for sampling the conventional CEN thoracic fraction. A static sampler, named CATHIA, was also designed. It uses the same sampling head, but the size selected particles are collected onto a filter. The combined particle efficiency of the aspiration slot and the selector was measured in a horizontal wind tunnel at low air velocity, close to 16 cm s-1. The flow rate of both samplers was fixed at its nominal value, i.e., 71 min-1. Two different methods were used: the former was based on the Aerodynamic Particle Sizer (TSI); the latter used the measurement of particle size distribution of the collected samples by the Coulter technique. For the CIP10-T sampler, the particle collection efficiency onto the rotating cup was also measured. For both samplers bias and accuracy maps have been calculated, following the recommendations of a new CEN standard about sampler performance. The bias does not exceed 10% in absolute value for both samplers, within a large range of particle size distribution of the total aerosol. For the CIP10-T sampler, the accuracy map exhibits a large area where the accuracy is better than 10%, corresponding for example to 4 microns < or = MMAD < or = 14 microns for GSD = 2. For the same geometric standard deviation, the accuracy is still better than 20% for 15 microns < or = MMAD < or = 21 microns. For the CATHIA-T sampler, the accuracy map can be roughly divided into two parts. The accuracy remains better than 10% for MMAD < or = 12 microns, and it remains between 10 and 20% for coarser aerosols, with 13 microns < or = MMAD < or = 20 microns, provided GSD > or = 2.

A new experimental wind tunnel facility for aerosol sampling investigations

Abstract A new experimental wind tunnel facility for aerosol sampling investigations has been built and its performance evaluated. Subsequently, an experimental methodology using a polydisperse test aerosol of glass beads to measure entry, transmission and overall sampling efficiencies has been developed and tested. The new facility is composed of a horizontal cylindrical pipe of 5 m long and 30 cm in diameter. The measurement zone is located just at the exit, allowing to take benefit of the whole cross-sectional area inside a stabilised aerosol flow. The working air velocity range is 0.5–4.5 m s−1 Air velocity and turbulence profiles are uniform within 10%. Turbulence in the working section is controlled with a square mesh grid. The test aerosol is generated by a fluidized-bed generator and dispersed into the clean air flow upstream of the horizontal part. Generated particles are within a size interval extending from a few μm to about 80 μm in aerodynamic diameter. Tests of time and space stability of the test aerosol in the working section were carried out. They have shown a reasonably uniform spatial distribution and time stability considering the size range of generated particles. The experimental method allows to obtain, simultaneously with the same technique entry, transmission, and overall sampling efficiencies of samplers from several μm up to 70 μm in particle aerodynamic diameter with a good accuracy. It is based on the measurement of the distribution of particle number concentration vs particle aerodynamic diameter of deposited and sampled aerosols in a reference probe and in the test sampler. To evaluate both the new wind tunnel facility and the methodology, measurements of the different efficiencies were achieved using a cylindrical sharp-edged thin-walled probe as a test sampler. This evaluation was performed in three steps. At first, the reproducibility of transmission efficiency measurements of the probe working in isokinetic conditions was determined. It appears fairly good between 10 and 70 μm in particle aerodynamic diameter. Then, the methodology was applied to the assessment of the aspiration efficiency of a probe working in subisokinetic conditions. Finally, a consistency test of the data was proposed and applied to our data; it consists in comparing the mass fractions of collected samples (deposited on the internal sampler walls, collected onto filters) calculated from the efficiency data and the distributions of particle concentrations, with those which are directly recovered after each experiment and weighed. This test yields an indicator of the quality of the whole efficiency data set.

Site Comparison of Selected Aerosol Samplers in the Wood Industry

Several samplers (IOM, CIP 10-I v1, ACCU-CAP, and Button) were evaluated at various wood industry companies using the CALTOOL system. The results obtained show that compared to the CALTOOL mouth, which can be considered to be representative of the exposure of a person placed at the same location under the same experimental conditions, the concentrations measured by the IOM, CIP 10-I v1, and ACCU-CAP samplers are not significantly different (respectively, 1.12, 0.94, and 0.80 compared to 1.00), the Button sampler (0.86) being close to the ACCU-CAP sampler. Comparisons of dust concentrations measured using both a closed-face cassette (CFC) and one of the above samplers were also made. In all, 235 sampling pairs (sampler + CFC) taken at six companies provided us with a comparison of concentrations measured using IOM, CIP 10-I v1, ACCU-CAP, and Button samplers with concentrations measured using a CFC. All the studied samplers collected systematically more dust than the CFC (2.0 times more for the IOM sampler, 1.84 times more for the CIP 10-I v1 sampler, 1.68 times more for the ACCU-CAP sampler, and 1.46 times more for the Button sampler). The literature most frequently compares the IOM sampler with the CFC: published results generally show larger differences compared with the CFC than those found during our research. There are several explanations for this difference, one of which involves CFC orientation during sampling. It has been shown that concentrations measured using a CFC are dependent on its orientation. Different CFC positions from one sampling session to another are therefore likely to cause differences during CFC-IOM sampler comparisons.

Assessment of the Pulmonary Genotoxicity of Bitumen Fumes in Big Blue® Transgenic Rats

Occupational and environmental exposures to bitumen fumes during road paving or roofing activities represent a safety issue since this complex mixture of volatile compounds and particles contains carcinogenic polycyclic aromatic hydrocarbons (PAH). However, epidemiological and experimental animal studies failed to draw unambiguous conclusions concerning bitumen fumes toxicity. In order to gain better insights on their genotoxic potential, we used an experimental device able to generate bitumen fumes at 170°C (upper range used during road paving operations) with a total particulate matter of 112 ± 13 mg/m3 and a mass median aerodynamic diameter of 4.6 μ m. The nose-only exposure of Big Blue® transgenic rats was performed 6 h/day for 5 consecutive days. Biological exposure to this aerosol was monitored by measuring the rat urinary levels of 1-hydroxypyrene and lungs were collected at various time-points after the end of treatment for further analysis. As determined by the 32P post-labeling method, no DNA bulky adduct was found in control animal lungs, while one was detected in exposed rats 3 and 30 days after the end of treatment, suggesting that this genetic alteration was rather stable. However, there was no correlation between the amount of DNA adduct and the level of urinary of 1-hydroxypyrene. The pulmonary mutagenic properties of bitumen fumes were determined by analyzing the mutation frequency and spectrum of the neutral reporter gene cII inserted into the transgenic rodent genome. Thirty days after exposure, the cII mutant frequency was similar in control and exposed rat lungs. However, a modification of the mutation spectrum was noticeable in treated animals. The most striking difference was an increase of G:C to T:A and A:T to C:G transversions in exposed rodents. In addition, the increased occurrence of G:C to T:A transversions at CpG dinucleotides in treated animals was consistent with DNA adduction by PAH. Even though these data failed to demonstrate a clear pulmonary mutagenic potential of bitumen fumes in our experimental conditions, the analysis of the mutational spectrum provides a sensitive measure of a quantitative increase of specific mutations which may be associated with DNA adduct formation. The weak mutagenic response might also be related to the small inhalable fraction of bitumen fume particles reaching the deep lung. In conclusion, these results could give insights on the mechanism of action of bitumen fumes and provide additional information concerning human risk assessment associated with bitumen exposure.