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Objectives Foaming and spraying are common application techniques for biocidal products. In the past, inhalation and dermal exposure during spraying have been investigated extensively. Currently, however, no exposure data are available for foaming, hindering a reliable risk assessment for foam applications of biocidal products. The focus of this project was the quantification of inhalation and potential dermal exposure to non-volatile active substances during the foam application of biocidal products in occupational settings. In some settings, exposure during spray application was measured for comparative purposes. Methods The inhalation and dermal exposure of operators were investigated during the application of benzalkonium chlorides and pyrethroids by foaming and spraying, considering both small- and large-scale application devices. Inhalation exposure was measured by personal air sampling; potential dermal exposure was measured using coveralls and gloves. Results Potential dermal exposure was substantially higher than inhalation exposure. Changing from spraying to foaming reduced inhalation exposure to airborne non-volatile active substances, but had no relevant effect on potential dermal exposure. However, for potential dermal exposure, considerable differences were observed between the application device categories. Conclusions To our knowledge, this study presents the first comparative exposure data for the foam and spray application of biocidal products in occupational settings with detailed contextual information. The results indicate a reduction of inhalation exposure with foam application compared to spray application. However, special attention is necessary for dermal exposure, which is not reduced by this intervention. [ABSTRACT FROM AUTHOR]

The aerosol release during the professional application of two different isocyanate based two component spray systems was identified and the physicochemical properties of the released airborne aerosols were characterized. For this purpose, aerosol release fractions were measured using a mass balance method described by Schwarz and Koch. Besides the release of total aerosol mass special emphasis was directed to the content of free monomeric MDI (4,4′- and 2,4′-diphenylmethane diisocyanate) in three particle size fractions relevant for inhalation uptake: inhalable, thoracic, and respirable size fraction. Two products were investigated: a two component PUR (polyurethane) spray foam (Elastopor) and a polyurea spray coating (Elastocoat). The mass fraction of the applied products released with the overspray as inhalable aerosol is 6.3 × 10−4 (Elastopor) and 4.0 × 10−4 (Elastocoat). Of the released total overspray aerosol 75 or 80% were in the thoracic size range, and 26 or 47% in the respirable regime for the PUR spray foam or the polyurea spray coating, respectively. At the time point of release the content of monomeric MDI in the aerosol corresponds to the composition of the bulk product. However, analysis of air samples indicates that <1% of the spray foam aerosol mass release fraction is attributed to free monomeric 4,4′- and 2,4′-MDI. For the Spray Coating the monomeric MDI fraction is <0.1%. Higher oligomers of MDI and prereacted oligomeric reaction products make up a few percent of the aerosol. This results in a total fraction of 0.0023% (spray foam) and 0.00015% (spray coating), respectively, of the sprayed monomeric MDI that is transferred into an inhalable aged aerosol. This data demonstrates, that during professional spraying only a small fraction of the total applied mass is released as airborne aerosol. The potential distribution of the theoretically inhalable aerosol in the respiratory tract and a low residual monomer content is described, significantly contributing to a refined safety assessment of the spray applications at the workplaces. [ABSTRACT FROM AUTHOR]

A field study was carried out in order to derive a factor for the conversion of historic worker exposure data on airborne beryllium (Be) obtained by sampling according to the 37-mm closed faced filter cassette (CFC) ‘total' particulate method into exposure concentration values to be expected when sampling using the ‘Gesamtstaubprobenahmesystem' (GSP) inhalable sampling convention. Workplaces selected to represent the different copper Be work processing operations that typically occur in Germany and the EU were monitored revealing a broad spectrum of prevailing Be size distributions. In total, 39 personal samples were taken using a 37-mm CFC and a GSP worn side by side for simultaneous collection of the ‘total' dust and the inhalable particulates, respectively. In addition, 20 static general area measurements were carried out using GSP, CFC, and Respicon samplers in parallel, the latter one providing information on the extra-thoracic fraction of the workplace aerosol. The study showed that there is a linear relationship between the concentrations measured with the CFC and those measured with the GSP sampler. The geometric mean value of the ratios of time-weighted average concentrations determined from GSP and CFC samples of all personal samples was 2.88. The individual values covered a range between 1 and 17 related to differences in size distributions of the Be-containing particulates. This was supported by the area measurements showing that the conversion factor increases with increasing values of the extra-thoracic fraction covering a range between 0 and 79%. [ABSTRACT FROM AUTHOR]

We report on particle deposition in the tracheobronchial and pulmonary regions of the respiratory tract of the minipig and its dependence on particle size. Four animals breathing spontaneously via the nose were exposed for 1 h to known concentrations of three different polydisperse dry aerosols composed of bovine serum albumin (BSA) and an oxide of a rare earth element: Y2O3, Sm2O3, and Er2O3. The mass size distributions of the rare earth elements of the three test aerosols have mass median aerodynamic diameters of 0.9, 2.5, and, 4.3 μm, and geometric standard deviations of σg = 2.0, 1.8, and, 1.7. The extrathoracic, tracheobronchial, and pulmonary regions of the respiratory tract were dissected, separately lyophilized, and chemically digested by microwave-assisted high pressure digestion. The tracer element in each compartment was determined by inductively coupled plasma mass spectrometry. A mass balance equation relating the tracer mass found in the lung compartments to the tracer mass inhaled was solved by linear regression to obtain the deposition fraction as function of particle sizes for the tracheobronchial and the pulmonary lung region. Estimated values for the respiratory minute volume were used in this context. For coarse particles >6 μm, the deposition fraction is <5% for both compartments. The deposition fraction for particles with aerodynamic diameter of ~3 μm is 21% in the tracheobronchial airways and 40% in the pulmonary airways. [ABSTRACT FROM AUTHOR]

A response from the authors of the articles "Change in Agglomeration Status and Toxicokinetic Fate of Various Nanoparticles in vivo Following Lung Exposure in Rats" and "Dispersion and Retention of Dusts Consisting of Ultrafine Primary Particles in Lungs" in the 2012 issue is presented.