Particle-induced oxidative damage is ameliorated by pulmonary antioxidants.

This investigation focuses on the application of an in vitro assay in elucidating the role of lung lining fluid antioxidants in the protection against inhaled particles, and to investigate the source of bioreactivity in urban PM10 collections from South Wales. The Plasmid Assay is an in vitro method of assessing and comparing the oxidative bioreactivity of inhalable particles. This method has provided the basis of limited toxicological studies into various inhaled xenobiotics including asbestos, and more recently PM10. Carbon Black M120 and Diesel Exhaust Particles (DEP) were tested as PM10 surrogates, DEP displaying the greatest oxidative bioreactivity. Both urban PM2.5 (fine fraction) and PM2.5-10 (coarse fraction) (Cardiff, S. Wales, UK) caused significant damage, the coarse fraction displaying higher oxidative capacity. The soluble components were found to be responsible for most of the bioreactivity in both PM sizes. Low molecular components of fresh lung lavage were found to offer most antioxidant protection, and surrogate Epithelial Lining Fluid (sELF) showed significant amelioration of DNA damage by the coarse fraction but less effect against the fine. Overall, the coarse, soluble fraction of PM10 is a great source of oxidative bioreactivity, but natural pulmonary low molecular weight antioxidants can significantly ameliorate its effects.

Montserrat volcanic ash induces lymph node granuloma and delayed lung inflammation.

OBJECTIVES: A substantial amount of Montserrat volcanic ash, containing up to 24% of cristobalite (w/w), a fibrogenic crystalline silica, has been generated since the first documented eruption in 1995. The bioreactivity of the ash and its two major components: cristobalite and anorthite have been studied in vivo for a year following intratracheal instillation into rats. METHODS: The rats (n=5) were instilled with a sterile vehicle solution (0.15 M NaCl) and/or three doses (1.0, 2.5 or 5.0 mg) of each of the dust, and were sacrificed at 13, 25 or 49 weeks post-instillation for quantitative biochemical and histopathological analyses in the lung and lymph nodes. RESULTS: Cristobalite caused inflammation in the lung and granuloma in the hilar lymph nodes associated with significant size augmentation at 13 weeks post-instillation (P<0.05) and cristobalite (5.0 mg) induced fibrosis in the lung at 49 weeks post-exposure. However, the Montserrat volcanic ash caused inflammation in the lung at 49 weeks post-treatment without any fibrogenic response although the ash (5.0 mg) triggered significant lymph node enlargement without significant changes in the lung at 13 weeks post-treatment (P<0.05). Dose and time independent responses in the anorthite-exposed lung and lymph nodes suggest that a single instillation of 5.0 mg of poorly soluble mineral dust does not induce any change in the lung or lymph nodes. CONCLUSION: The ash produces inflammatory reactions in lymph nodes at 13 weeks post-instillation in rats. These effects are seen much earlier than any inflammatory reaction in the lung. The onset of the lung inflammation is delayed until 49 weeks post-exposure. Despite the high cristobalite content of the ash, there is no evidence of any lung fibrogenic responses.

Characterisation of aerosol particulate matter from urban and industrial environments: examples from Cardiff and Port Talbot, South Wales, UK.

A high-volume cascade impact collector (1100 l/min air flow) was used to collect air samples in an industrial (Port Talbot) and an urban (Cardiff) site with the purpose of characterising both coarse (PM(10-2.5)) and fine (PM(2.5)) fractions comprising the total sample. PM(10-2.5) and PM(2.5) samples were collected by cascading air through two polyurethane foams on which particles impact and become deposited. Air sample collection rates are to some extent dependent on weather conditions, notably rainfall, humidity, and especially, wind direction, but samples show a very different and distinctive air particle composition between the two collection sites. Thus, although both Cardiff and Port Talbot are coastal sites and therefore have high contents in chlorides, Port Talbot is extremely rich in tiny Fe spherules (>30%, in both coarse and fine fractions) from a nearby steel plant. Mineralogical characterisation using SEM-EDX shows a clear fractionation between the particle composition in the PM fractions, with the coarse fraction being dominated by chlorides, sulphates (gypsum), and silicates, and the fine fraction having high proportions of ammonium sulphates and elemental and organic carbon compounds, most of the latter being linked to traffic pollution.

In vitro effects of water-soluble metals present in UK particulate matter.

The water-soluble metal content of 1950s London smogs and modern particulate matter (PM) are associated with adverse health effects. This study aimed to elucidate the bioreactivity of these metals alone and in mixtures and to investigate the comparative bioreactivities of a surrogate mixture and a PM sample. These revealed similar bioreactivities. A bioreactivity hierarchy of these metals was established: Fe2+ > Cu2+ > Fe3+ > VO2+ > Zn2+ > As3+ = Pb2+ = Mn2+ = VO3-. Secondary components (i.e., chlorides, sulfates, nitrates) did not affect metal bioreactivity, whereas oxidation state was important. Synergism was observed between zinc and various metal ions (Cu2+, Fe3+, VO2+). In conclusion, low-valence transition metals are key to PM bioreactivity.

The collection of PM10 for toxicological investigation: comparisons between different collecting devices.

A positive correlation has been established between increased levels of airborne particulate pollution and adverse health effects, the toxicological mechanisms of which are poorly understood. For toxicologists to unambiguously determine these mechanisms, truly representative samples of ambient PM10 are required. This presents problems, as PM10 collecting equipment commonly employed, such as the Tapered Element Oscillating Microbalance (TEOM), heat the inflow to exclude moisture or use fibrous filters, resulting in a PM10 sample that may have undergone significant chemical change on the filter surface or is contaminated by filter fibres. Other systems (i.e. Negretti and Partisol) can successfully collect PM10 without chemical alteration or filter contamination. Comparative collections from Port Talbot, S. Wales suggest that TEOMs and Negretti/Partisol systems collect different PM10's; the principle difference arising from the TEOM's heating chamber, which precipitates water-soluble ions and volatilises some organic components. This results in both the mass and composition of the PM10's being altered. Particle size distributions for Negretti and Partisol collections highlighted differences mainly attributed to different flow rates. The results of this work demonstrate that simple correlations between PM10 mass and adverse health effects are problematic. Furthermore, elucidation of the complex fractionation and chemical changes in different collectors is necessary.