Investigations into the health effects and genotoxicity of bitumen fumes on the respiratory tract of occupational exposed individuals

Status:

completed 01/2009

Aims:

Global gene expression profiles of lymphozytic RNA, DNA-adducts in lymphozytic DNA

Activities/Methods:

DNA from white blood cells of workers exposed to bitumen fumes and aerosols was analyzed for DNA-adducts by the 32P-postlabeling assay and compared with representative controls. Specifically, the polycyclic aromatic hydrocarbons (benzo[c]chrysene-9,10-dihydrodiol-11,12-epoxid, benzo[g]chrysendiolepoxid, dibenzo[a,l]pyrendiolepoxid, benzo[c]chrysene-1,2-dihydrodiol-3,4-epoxid, benzo[a]pyrenediolepoxid und benzo[c]phenanthrenediol-epoxid were used to synthesize reference-DNA-adducts and used as references for an analysis of blood samples. Moreover, a MALDI-TOF/TOF mass spectrometry method was employed to further search for DNA-adducts in DNA extracts of blood cells of exposed workers. Finally, candidate genes were analyzed for mutations and sequence variations possible induced by exposure to bitumen fumes and aerosols and are known to be risk factors for lung cancer.

Results:

Based on the 32P-postlabeling assay, up to 12 DNA adducts were identified in DNA-extracts from white blood cells. The number and amount of DNA-adducts varied considerably, but two thirds of individuals had no or only a few DNA-adducts at low concentrations. None of the aforementioned reference DNA-adducts could be identified in DNA-extracts of individuals by MALDI-TOF/TOF mass spectrometry. Unknown DNA-adducts were, however, identified and analysis is still in progress. Possibly, the identified DNA-adducts may be induced by other factors such as smoking and lifestyle.
Furthermore, dHPLC and capillary sequencing of DNA evidenced sequence variations particularly in non coding introns, nonetheless are important for gene regulation. Indeed, most of the sequence variations were identified as known single nucleotide polymorphisms (SNP), but no evidence was obtained that suggests specific mutations to be induced by bitumen fumes and aerosols in lymphocytic DNA.

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