To determine the induction of 8-hydroxy-2'-deoxyguanosine (8-OHdG) by fine (<2.5 microm)
and coarse (10-2.5 microm) particulate matter (PM) sampled over time at one sampling
location, and to relate the observed effects to the hydroxyl radical (*OH) generating
activities and transition metal content of these samples, and to meteorological parameters.
Weekly samples of coarse and fine PM were analysed for H(2)O(2) dependent *OH formation
using electron spin resonance (ESR) and formation of 8-OHdG in calf thymus DNA using
an immuno-dotblot assay. Immunocytochemistry was used to determine 8-OHdG formation
in A549 human epithelial lung cells. To determine temporal effects, samples from six
weeks in summer and six weeks in autumn/winter were compared using ESR and the dotblot
assay. Concentrations of leachable V, Cr, Fe, Ni, and Cu were determined by inductively
coupled plasma mass spectrometry.
Both PM fractions elicited *OH generation as well as 8-OHdG formation in calf thymus
DNA and in A549 cells. 8-OHdG formation in the naked DNA was significantly related
to *OH generation, but not to metal concentrations except for copper. A significantly
higher *OH generation was observed for coarse PM, but not fine PM collected during
the autumn/winter season; this was not due to differences in sampled mass or metal
content. Specific weather conditions under which increased *OH formation in the coarse
mode was observed suggest that other, as yet unknown, anthropogenic components might
affect the radical generating capacity of PM.
Both coarse and fine PM are able to generate *OH, and induce formation of 8-OHdG.
When considered at equal mass, *OH formation shows considerable variability with regard
to the fraction of PM, as well as the sampling season. The toxicological implications
of this heterogeneity in *OH formation by PM, as can be easily determined by ESR,
need further investigation.