Marcell Maceno

Health risk assessment of inhabitants exposed to PAHs particulate matter in air

The presence of polycyclic aromatic hydrocarbon compounds (PAHs) was investigated in the particulate matter of samples taken at six sampling sites in the city of Curitiba (southern Brazil). The concentrations of suspended particulate matter ranged from 11.02 to 177.27 ng/m3. The analysis showed that 14 of the 16 PAHs are considered a priority compound by the USEPA (US Environmental Protection Agency). The mixture of PAHs was predominantly composed of PAHs with 3 and 4 aromatic rings. Isomer pair ratios show that the main source of PAHs was from burning fossil fuels (gasoline and diesel oil), although other sources may have contributed also. Benzo(a)pyrene, (BaP), regarded one of the most toxic PAHs, was present in all samples, but with concentrations lower than the maximum concentrations defined by some EU Countries. The risk assessment was conducted using the toxic equivalent factor (TEF) considering the toxicity of the individual PAHs compared to BaP. The BaPeq for all samples was between 0.42–1.12 ng/m3. The equivalent BaPeq indicated low health risk associated with exposure to the total PAHs content in air. The incremental lifetime cancer risk (ILCR) model was used to find the risk level for workers close to the emitting pollution sources. Outdoor exposure showed no risk for the amount of PAHs emitted. The acceptable risk is 10−6; however, all results were lower than this value.

Polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter in Curitiba, Brazil and benzo(a)pyrene toxic equivalency factors (TEFs)

The concentration of PAHs in particulate matter was investigated in the city of Curitiba, located in south of Brazil. Urban atmospheric particulate matter was collected at six sampling sites whose characteristics were representative of the prevailing conditions. The concentration of particulate matter varied from 11.02 to 177.27 ng/m3. Particulate matter was basically composed of PAHs with 3 and 4 aromatic rings and it agrees with results of air quality monitoring performed in other cities around the world. Molecular ratios, such as (Benzo(ghi)Perilene/Indene(cd)Pyrene, B(ghi)P/I(cd)P, indicate that the source of PAHs is gasoline engines in the downtown area and diesel engines in surrounding sites representing a heavy traffic situation. It was also investigated the toxic level of particulate matter using the BaP equivalency factor. The BaPeq for all samples was between 0.42 to 1.12 ng/m3. The equivalency BaPeq indicated low health risk associated with exposure to the total PAHs content in environmental air.

Degradation of Organochlorine Compounds Using Zero Valent Iron (ZVI) Nano Particles Impregnated in Hydrophobic Modified Bentonite

The degradation of perchloroethylene (PCE) adsorbed on hydrophobic modified bentonite was investigated. The degradation occurred via reduction of iron particles with zero valence (ZVI) incorporated in hydrophobic surface of bentonite. We compared two different systems, one containing ZVI and another without ZVI. The degradation of PCE was accompanied by decreasing concentrations of PCE and the increase of resulting compounds such as trichloroethylene (TCE), 1,2-dichloroethylene, trans and cis forms, (1,2-cis-DCE and 1,2- trans-DCE). The results show that the PCE is rapidly adsorbed and in contact with ZVI particles is degraded to less toxic compounds, while in the systems without ZVI no significant decrease of PCE was observed, clearly demonstrating that the degradation process occurs through the reduction with ZVI. The rate constant for the system containing ZVI was 0.215 h−1, while for the system without ZVI it was only 0.031 h−1. The results agree with other research, however the reaction was conducted in columns and the clay was zeolite. It can be concluded that the system impregnated with ZVI is extremely interesting as an alternative application for removal of organic compounds containing chlorine due to their persistence and toxic effect on the microorganisms. The system can also be applied as barrier content.