Formation of PAH-DNA adducts after in vivo and vitro exposure of rats and lung cells to different commercial carbon blacks.
OBJECTIVE
The current study was designed to test the possible release and bioavailability of polycyclic aromatic hydrocarbons (PAHs) from a set of commercial carbon blacks (CBs) as well as the ability of these PAHs to form bulky DNA adducts.


METHODS
In four commercial CBs (Printex 90, Sterling V, N330, Lampblack 101), leaching of PAH was examined through (1) release of parent PAHs in saline with or without surfactant, and (2) PAH adducts in lung epithelial cells (A549) or in rat lungs after exposure to two CBs (Printex 90, Sterling V) for 13 weeks (50 mg/m(3)). In vitro experiments were done with original and extracted particles, as well as organic extracts of CB in DMSO. As positive controls, B[a]P (0.03 microM) and a mixture of 16 PAHs (0.1 microM) were used.


RESULTS
No leaching of PAHs was measured in saline or surfactant-containing saline. In vitro incubations with CB particles (30-300 microg/cm(2)) revealed no adduct spots except for Sterling V. However, the spot was not concentration dependent and remains unidentified. Lung DNA from rats after inhalation of Printex 90 or Sterling V showed no spots related to PAH-DNA adduct formation compared to sham-exposed rats.


CONCLUSIONS
The results suggest that PAHs are very tightly bound to these CBs. Only using organic extracts or particles of low-surface Sterling V, with high PAH content, PAHs may become available to form PAH-DNA adducts. However, the in vitro conditions showing this effect will not be encountered in vivo and renders this mechanism in particle-induced lung cancer at in vivo exposures highly unlikely.
Borm
Paul J A
PJ
Particle Research, Institut für Umweltmedizinische Forschung (IUF) at the Heinrich-Heine University, Dusseldorf, Germany. p.borm@hszuyd.nl
Cakmak
Gonca
G
Jermann
Erich
E
Weishaupt
Christel
C
Kempers
Pascal
P
van Schooten
Frederik Jan
FJ
Oberdörster
Günter
G
Schins
Roel P F
RP
D000818:Animals; D001682:Biological Availability; D002244:Carbon / Q000737:chemistry / Q000493:pharmacokinetics*; D002460:Cell Line; D018736:DNA Adducts / Q000096:biosynthesis*; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D013501:Surface-Active Agents / Q000737:chemistry
D018736:DNA Adducts; D011084:Polycyclic Aromatic Hydrocarbons; D013501:Surface-Active Agents; C095911:polycyclic aromatic hydrocarbons-DNA adduct; D002244:Carbon