Genotoxic and mutagenic activity of environmental air samples from different rural, urban and industrial sites in Flanders, Belgium.

The present study reports mutagenic and genotoxic activities associated with ambient air collected at 15 sites characteristic for urban, industrial or rural conditions in Flanders. Airborne particulates (PM10) and semi-volatile compounds were collected on quartz filters (QF) and polyurethane foam (PUF) cartridges using a high-volume sampling device. The mutagenic and genotoxic potency of the organic extracts--Soxhlet extraction with acetone--was determined by use of the Salmonella mutagenicity standard plate-incorporation assay and the Vitotox assay, respectively. Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the extracts were determined by reversed-phase high-performance liquid chromatography (HPLC). Ambient air samples contained significant PAH levels and mutagenic activities at all 15 sites: direct mutagenicity of up to 47 revertants per cubic meter was found in the QF extracts and more limited activity of up to 11 rev m(-3) in the PUF extracts. Metabolic activation of PUF extracts resulted in an important increase in mutagenic activity, up to 30 rev m(-3), but no such increase was observed for QF extracts. The highest values were observed outside large cities at industrial sites and at a rural site contaminated by pollution from a chemical plant at a distance of 4 km. Also at the background location near the North Sea a significant mutagenic activity was measured in the QF extracts (+S9: 9 rev m(-3); -S9: 7 rev m(-3)). Apparently, there is in Flanders a significant background exposure level to airborne mutagenicity, even in areas with limited or no nearby pollution sources. Based on the concentrations of 10 mutagenic PAHs and supposing additivity of their specific mutagenicities, only a few percent (mean 3%) of the observed indirect mutagenic activity could be explained. This implies that most mutagenic activity originated from other substances that were not identified or measured in our chemical analysis. This underscores the importance of bio-monitoring measurements.