Bioreactivity of metal components found in air pollution particles

• Main Author: Merolla, Luciano L. P
• Format: Dissertation
• Language: English
• Published: Cardiff University 2006

A correlation was found between individual metal content and in vitro bioreactivity of particulate samples (in both ambient PM samples from Port Talbot and ROFA samples). Global factors such as particulate origin and seasonal variation were also identified as playing a role. A bioreactivity hierarchy of metals was then established: Fe2+Cu2+Fe3+VO2+Zn 2+ As3+=Pb2+=VO3- indicating the importance of oxidation state and suggesting a role for redox mechanisms. Strong synergistic effects were observed between Zn 2+ and various bioreactive metal ions (Cu2+, Fe 3+, VO2+) in vitro. However, this effect was limited to ions which could be readily reduced to a more active form (no synergy with Fe2+). In vivo, the surrogate water-soluble metal mixtures gave rise to a transient (7-14 day) metal ion concentration and valence dependent increase in lung:body weight ratio, protein levels (pulmonary oedema) and differential cell counts (inflammation) in a dose and time dependent manner. Light microscopy of the lung tissue revealed an acute phase response to the installation of the metal mixture with peripheral damage and inflammation followed by bronchiolisation, hyperplasia and increased collagen deposition in repair. There was evidence of organ-specific changes in RNA production in both the heart and lung. In both organs, the primary responses revolved around up regulating redox-specific, stress mechanisms and metabolism pathways, suggesting activation of xenobiotic biotransformation systems.