from a study of the presence of 0 6·meG in the DNA of individuals notImowingly exposed to methylating agents. Total leukocyte DNA was isolatedfrom venous blood collected from non-smoking women as well as fromcord blood collected from their babies just after birth, and analysed for 0 6_

meG by a sensit ive assay capable of detecting the lesion at levels as lowas 0.02 fmoUg DNA. Each participant answered a questionnaire regardingher place of residence and work, eating habits and lifestyle . The adduct wasdetected in 30/35 mother and 28135 baby samples, at levels ranging 0.02­0.12 fmoUg DNA. There was a strong correlation between adduct levels inmother and baby samples. While multivariate analysis of the data did notreveal a significant effect of residence, workplace or eat ing habits, intake ofvitamin supplements during the last I month prior to sample collection wassignificantly assoc iated witb reduced adduct levels.

We arc now developing a fully automated Enzyme-Linked ImmunosorbcntAssay for the detection of 06-mcthylguanine in DNA. Preliminary experi­ments arc very promis ing and we strongly beheve that this method can beadopted in molecular epidimiology studies . The methodology and some ofthe results will be presented.

Keyword(s): 06.methylguanine; Biomarkers; Molecular Epidimiology

Ip XVI B.sl A molecular epidemiological study or genetic suscep­tibility to lunK cancer

Sarah Lewis I , Robert Niven 2, Nicola Cherry I , Phil ip Barbe~, DonaldCooper' , Andrew Povey'. JSchool of Epidemiol"?, and Health Sciences.University of Manchester, Manchester, England; NorthWest Lung Centre,HYthenshawe Hospital. Manchester, England; J Paterson Institutefor CancerResearch. Manchester, England

Polymorphisms in carc inogen metabolising enzymes have been shown toalter smok ing-induced lung cancer risk, presumably by modifying the for­mation of DNA damage. To test this hypothesis a molecular epidemiolog­ical study was initiated , to compare; tobacco smoke exposure , metabolicgenotypes and carcinogen-DNA adduct levels in individuals with lungcancer (cases) and individuals with non-malignant disease (controls) atbronchoscopy.

Each pat ient was interviewed, according to a standard questionnaire, forInformation on ; recent and lifetime tobacco smoke exposure, occupationalhistory, area of residence, alcohol consumption and family history of lungcancer. Peripheral blood and bronch ial lavage samples. taken from the rightupper lobe bronchus of the lung, were collected from participants. A pilotstudy of 50 individuals indicated that one third had lung cancer and thatapproximately 8oo!o were smokers or exsmokers, There was an increase inGSTMI null genotype (OR 3.8 CI 0.8-19.5) and an increase in the CYP2D6poor metaboliser gene (OR 2.25 CI 0.74--6.95) among lung cancer cases. Nodifferences were seen in the distribution of CYP2EI and GSTTI polymer­phisms in the two groups. Further recruitment into the ma in study is ongoingin order to obtain a study population of approximately 300 individuals. N7­methylguanine levels are currently being measured in bronchial DNA. andwill be compared with genotype and carcinogen exposure data in an attemptto confirm the initial hypothesis.

Ip XVI B.61 Occupational exposure to mutagens; monitoring ofrubber factory worken

Mana Duinslci l , RadosJav Fabryl , Elena Szabova" , Martina Somorovska",Helena Petrnvska I , Andrew Collins2. JInstitute of Preventive and ClinicalMedicine. Limbood U . 833 01 Bratislava. Slooak: Republic; 1Rowell Re­search Institute. Aberdeen AB21 9SB. UK

Worken in a rubber tyre factory, exposed to contam inants sucb as B(a)P,benzf1uoranthen, naphthalen, acetonaphthen, have been regularly examinedfor several years ; chromosomal aberrations in lymphocytes, mutagenicityof urine (using the Ames test) and various parameters of blood and urinewere assessed. A higher level of merkapturats in urine of employers wasfound, indicating an environmental exposure to toxicants with a1kylatingactivity. We have now extended this study by examining genotox icity with the

S-XVI: DNA adducts and buman cancers S161

modified comet assay in parallel with chromosome aberrations, micronucleusformation and sister chromatid exchange. 30 exposed workers from thisfactory were compared with 22 nonexposed administrative persons workingin the same factory as well as with 22 laboratory workers. Endogenousstrand breaks (includ ing alkali-labile sites). FPG and endonuclease 111­sensitive sites in were measured by the comet assay in lymphocyte DNA,as well as the sensitivity of lymphocytes to H202- induced damage. Exposedworkers had significantly higher levels of DNA breaks compared with office­workers or WIth laboratory workers . DNA damage measured using FPG andendonuclease III (predominantly oxidised bases) was similar in all threegroups . as was H202 ·induced damage. These results are consistent withattack on DNA by agents forming bulky adducts.

Th is work was supported by EC contract CIPA-CT94-0129.

Ip XVI B.71 PS3 mutational spectra In lung and bladder cancen.A study of urban bus driven and a reference KrouP

Lise R. Nielsen ", Grete K. Jacobserr', Helle Soll-Johanning I , BirgitteKorsholm' , Lourdes M. Pedersen', Lisbeth E. Knudsen", Otto M. Poulsen',Hakan Wallin I , Bjarn A. Nexa, I NationalInstitute ofOccupational Health,2100 Copenhagen. Denmark; 20entojle University Hospital. Hellerup, Den­mark

Mutational spectra in the p53 tumor suppressor gene may reflect specificcarcinogenic exposures. We determined p53 mutations in cancers of busdrivers and a reference group to examine an effect of traffic generated airpollut ion.

142 samp les of paraffin-cmbedded tumor tissue from cases of lung andbladder cancers in a retrospective cohort of 18,174 bus drivers and a groupof references were analysed for mutations in exons s-8 by SSCP analysisand sequencing. Occupational history and smoking status wasobtained for80 patients by telephone interviews. Only one patient had not been smoking.

The mutat ional frequencies were similar in bus drivers and references of53 lung squamous cell carc inomas (56% and 54%) and 37 lung adenocarci­nomas (33% and 40% ), and their mutational patterns were similar. G- -+ Ttransversions such as the lung specific codon 157 transversion were frequent,and small deletions were observed in lung squamous cell carcinomas. The G­-+ A transit ions found in 42 bladder tumors occurred predominantly at CpOsites in bus drivers but frequently at non-CpG sites in references, perhapsindicat ing a different exposure.

A unique spectrum of pS3 mutat ions was not found for bus drivers, andthe spectra for lung and bladder cancers in this study resemble the generalpatterns found for smokers.