Semi-volatile (SV) aerosols still represent an important challenge to occupational hygienists due to toxicological and sampling issues. Particularly problematic is the sampling of hazardous SV that are present in both particulate and vapour phases at a workplace. In this study we investigate the potential evaporation losses of SV aerosols when using off-line filter-adsorber personal samplers. Furthermore, we provide experimental data showing the extent of the evaporation loss that can bias the workplace risk assessment. An experimental apparatus consisting of an aerosol generator, a flow tube and an aerosol monitoring and sampling system was set up inside a temperature controlled chamber. Aerosols from three n-alkanes were generated, diluted with nitrogen and sampled using on-line and off-line filter-adsorber methods. Parallel measurements using the on-line and off-line methods were conducted to quantify the bias induced by filter sampling. Additionally, two mineral oils of different volatility were spiked on filters and monitored for evaporation depending on the samplers flow rate. No significant differences between the on-line and off-line methods were detected for the sum of particles and vapour. The filter-adsorber method however tended to underestimate up to 100% of the particle mass, especially for the more volatile compounds and lower concentrations. The off-line sampling method systematically returned lower particle and higher vapour values, an indication for particle evaporation losses. We conclude that using only filter sampling for the assessment of semi-volatiles may considerably underestimate the presence of the particulate phase due to evaporation. Thus, this underestimation can have a negative impact on the occupational risk assessment if the evaporated particle mass is no longer quantified.

The ubiquitous use of phthalates in various materials and the knowledge about their potential adverse effects is of great concern for human health. Several studies have uncovered their role in carcinogenic events and suggest various phthalate-associated adverse health effects that include pulmonary diseases. However, only limited information on pulmonary toxicity is available considering inhalation of phthalates as the route of exposure. While in vitro studies are often based on submerged exposures, this study aimed to expose A549 alveolar epithelial cells at the air-liquid interface (ALI) to unravel the genotoxic and oxidative stress-inducing potential of dibutyl phthalate (DBP) with concentrations relevant at occupational settings. Within this scope, a computer modeling approach calculating alveolar deposition of DBP particles in the human lung was used to define in vitro ALI exposure conditions comparable to potential occupational DBP exposures. The deposited mass of DBP ranged from 0.03 to 20 ng/cm 2 , which was comparable to results of a human lung particle deposition model using an 8 h workplace threshold limit value of 580 μg/m 3 proposed by the Scientific Committee on Occupational Exposure Limits for the European Union. Comet and Micronucleus assay revealed that DBP induced genotoxicity at DNA and chromosome level in sub-cytotoxic conditions. Since genomic instability was accompanied by increased generation of the lipid peroxidation marker malondialdehyde, oxidative stress might play an important role in phthalate-induced genotoxicity. The results highlight the importance of adapting in vitro studies to exposure scenarios relevant at occupational settings and reconsidering occupational exposure limits for DBP.

During many measurements it is important to account for possible changes in the gas-particle distribution of aerosols containing semi-volatile organic compounds (SVOCs). If denuders are combined with currently used personal air samplers, a simultaneous differential sampling of the gas and particle phase is possible. Here we analysed the transmission efficiency of denuders based on multi-channel silicone rubber traps (setup: 9 cm long glass liner (ID 4 mm), containing 22 parallel silicone rubber tubes (55 mm long, ID 0.3 mm, OD 0.5 mm)) with polystyrene latex (PSL) particles for different scenarios. n-Hexadecane, dimethyl phthalate and diethylene glycol gases were used to measure the time-dependent gas phase collection efficiency of a denuder. Additionally, the evaporation of n-hexadecane aerosol particles passing through the denuders was investigated. Our results showed high transmission efficiencies from 91 to 100% (variation coefficients 3.69-9.65%) for the denuders operated vertically at a flow rate of 0.5 l min. With regard to the gas phase collection efficiency, nonpolar n-hexadecane gas was trapped with higher efficiency (87% after 22 h) than dimethyl phthalate gas (27% after 22 h), while for highly polar diethylene glycol the gas phase collection efficiency was 50% after 2 h. Regarding the evaporation of aerosol particles, smaller particles and lower flow rates led to higher particle volume reduction inside the denuders. In conclusion, the tested denuders are suitable for determining the gas-particle partitioning of SVOC aerosols of nonpolar substances and show above 90% transmission for all tested particle sizes.

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