Environmental, dietary, maternal, and fetal predictors of bulky DNA adducts in cord blood: a European mother-child study (NewGeneris).

BACKGROUND: Bulky DNA adducts reflect genotoxic exposures, have been associated with lower birth weight, and may predict cancer risk. OBJECTIVE: We selected factors known or hypothesized to affect in utero adduct formation and repair and examined their associations with adduct levels in neonates. METHODS: Pregnant women from Greece, Spain, England, Denmark, and Norway were recruited in 2006-2010. Cord blood bulky DNA adduct levels were measured by the 32P-postlabeling technique (n = 511). Diet and maternal characteristics were assessed via questionnaires. Modeled exposures to air pollutants and drinking-water disinfection by-products, mainly trihalomethanes (THMs), were available for a large proportion of the study population. RESULTS: Greek and Spanish neonates had higher adduct levels than the northern European neonates [median, 12.1 (n = 179) vs. 6.8 (n = 332) adducts per 108 nucleotides, p < 0.001]. Residence in southern European countries, higher maternal body mass index, delivery by cesarean section, male infant sex, low maternal intake of fruits rich in vitamin C, high intake of dairy products, and low adherence to healthy diet score were statistically significantly associated with higher adduct levels in adjusted models. Exposure to fine particulate matter and nitrogen dioxide was associated with significantly higher adducts in the Danish subsample only. Overall, the pooled results for THMs in water show no evidence of association with adduct levels; however, there are country-specific differences in results with a suggestion of an association in England. CONCLUSION: These findings suggest that a combination of factors, including unknown country-specific factors, influence the bulky DNA adduct levels in neonates.

Micronuclei in cord blood lymphocytes and associations with biomarkers of exposure to carcinogens and hormonally active factors, gene polymorphisms, and gene expression: the NewGeneris cohort.

BACKGROUND: Leukemia incidence has increased in recent decades among European children, suggesting that early-life environmental exposures play an important role in disease development. OBJECTIVES: We investigated the hypothesis that childhood susceptibility may increase as a result of in utero exposure to carcinogens and hormonally acting factors. Using cord blood samples from the NewGeneris cohort, we examined associations between a range of biomarkers of carcinogen exposure and hormonally acting factors with micronuclei (MN) frequency as a proxy measure of cancer risk. Associations with gene expression and genotype were also explored. METHODS: DNA and protein adducts, gene expression profiles, circulating hormonally acting factors, and GWAS (genome-wide association study) data were investigated in relation to genomic damage measured by MN frequency in lymphocytes from 623 newborns enrolled between 2006 and 2010 across Europe. RESULTS: Malondialdehyde DNA adducts (M1dG) were associated with increased MN frequency in binucleated lymphocytes (MNBN), and exposure to androgenic, estrogenic, and dioxin-like compounds was associated with MN frequency in mononucleated lymphocytes (MNMONO), although no monotonic exposure-outcome relationship was observed. Lower frequencies of MNBN were associated with a 1-unit increase expression of PDCD11, LATS2, TRIM13, CD28, SMC1A, IL7R, and NIPBL genes. Gene expression was significantly higher in association with the highest versus lowest category of bulky and M1dG-DNA adducts for five and six genes, respectively. Gene expression levels were significantly lower for 11 genes in association with the highest versus lowest category of plasma AR CALUX® (chemically activated luciferase expression for androgens) (8 genes), ERα CALUX® (for estrogens) (2 genes), and DR CALUX® (for dioxins). Several SNPs (single-nucleotide polymorphisms) on chromosome 11 near FOLH1 significantly modified associations between androgen activity and MNBN frequency. Polymorphisms in EPHX1/2 and CYP2E1 were associated with MNBN. CONCLUSION: We measured in utero exposure to selected environmental carcinogens and circulating hormonally acting factors and detected associations with MN frequency in newborns circulating T lymphocytes. The results highlight mechanisms that may contribute to carcinogen-induced leukemia and require further research.

Bulky dna adducts in cord blood, maternal fruit-and-vegetable consumption, and birth weight in a European mother-child study (NewGeneris).

BACKGROUND: Tobacco-smoke, airborne, and dietary exposures to polycyclic aromatic hydrocarbons (PAHs) have been associated with reduced prenatal growth. Evidence from biomarker-based studies of low-exposed populations is limited. Bulky DNA adducts in cord blood reflect the prenatal effective dose to several genotoxic agents including PAHs. OBJECTIVES: We estimated the association between bulky DNA adduct levels and birth weight in a multicenter study and examined modification of this association by maternal intake of fruits and vegetables during pregnancy. METHODS: Pregnant women from Denmark, England, Greece, Norway, and Spain were recruited in 2006-2010. Adduct levels were measured by the 32P-postlabeling technique in white blood cells from 229 mothers and 612 newborns. Maternal diet was examined through questionnaires. RESULTS: Adduct levels in maternal and cord blood samples were similar and positively correlated (median, 12.1 vs. 11.4 adducts in 108 nucleotides; Spearman rank correlation coefficient = 0.66, p < 0.001). Cord blood adduct levels were negatively associated with birth weight, with an estimated difference in mean birth weight of -129 g (95% CI: -233, -25 g) for infants in the highest versus lowest tertile of adducts. The negative association with birth weight was limited to births in Norway, Denmark, and England, the countries with the lowest adduct levels, and was more pronounced in births to mothers with low intake of fruits and vegetables (-248 g; 95% CI: -405, -92 g) compared with those with high intake (-58 g; 95% CI: -206, 90 g). CONCLUSIONS: Maternal exposure to genotoxic agents that induce the formation of bulky DNA adducts may affect intrauterine growth. Maternal fruit and vegetable consumption may be protective.

Development and validation of a direct sandwich chemiluminescence immunoassay for measuring DNA adducts of benzo[a]pyrene and other polycyclic aromatic hydrocarbons.

We have developed and validated a sandwich chemiluminescence immunoassay (SCIA) which measures polycyclic aromatic hydrocarbon (PAH)-DNA adducts combining high throughput and adequate sensitivity, appropriate for evaluation of adduct levels in human population studies. Fragmented DNA is incubated with rabbit antiserum elicited against DNA modified with r7,t8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) and subsequently trapped by goat anti-rabbit IgG bound to a solid surface. Anti-single-stranded (ss) DNA antibodies binds in a quantity proportional to the adduct levels and is detected by chemiluminescence. The BPDE-DNA SCIA has a limit of detection of 3 adducts per 10(9) nucleotides with 5 µg DNA per well. We have validated the BPDE-DNA SCIA using DNA modified in vitro, DNA from benzo[a]pyrene (BP)-exposed cultured cells and mice. The levels of adduct measured by SCIA were lower (30-60%) than levels of bulky DNA adducts measured in the same samples by (32)P-postlabelling. The BPDE-DNA SCIA also detected adducts produced in vivo by PAHs other than BP. When blood DNA samples from maternal/infant pairs were assayed by BPDE-DNA SCIA, the adduct levels obtained were significantly correlated. However, there was no correlation between (32)P-postlabelling and SCIA values for the same samples. The SCIA can be extended to any DNA adduct and is expected to provide, when fully automated, a valuable high-throughput approach in large-scale population studies.

STrengthening the Reporting of OBservational studies in Epidemiology: Molecular Epidemiology STROBE-ME. An extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change, susceptibility, and clinical outcomes are used as proxies for investigating the interactions between external and/or endogenous agents and the body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as STrengthening Reporting of Observational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology - Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE Statement implementing 9 existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

STrengthening the Reporting of OBservational studies in Epidemiology--Molecular Epidemiology (STROBE-ME): an extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change, susceptibility and clinical outcomes are used as proxies for investigating interactions between external and / or endogenous agents and body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as the STrengthening Reporting of OBservational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology - Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE statement implementing nine existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

STrengthening the Reporting of OBservational studies in Epidemiology - Molecular Epidemiology (STROBE-ME): an extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change, susceptibility and clinical outcomes are used as proxies for investigating interactions between external and/or endogenous agents and body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as the STrengthening Reporting of OBservational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology -Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE statement implementing nine existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

STrengthening the reporting of OBservational studies in Epidemiology-Molecular Epidemiology (STROBE-ME): an extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change, susceptibility, and clinical outcomes are used as proxies for investigating the interactions between external and/or endogenous agents and the body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as STrengthening Reporting of Observational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology-Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE Statement implementing 9 existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

STrengthening the Reporting of OBservational studies in Epidemiology - Molecular Epidemiology (STROBE-ME): an extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change, susceptibility and clinical outcomes are used as proxies for investigating the interactions between external and/or endogenous agents and the body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as the STrenghtening Reporting of Observational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology - Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE Statement implementing 9 existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

STrengthening the Reporting of OBservational studies in Epidemiology--Molecular Epidemiology STROBE-ME: an extension of the STROBE statement.

Advances in laboratory techniques have led to a rapidly increasing use of biomarkers in epidemiological studies. Biomarkers of internal dose, early biological change susceptibility and clinical outcomes are used as proxies for investigating the interactions between external and/or endogenous agents and body components or processes. The need for improved reporting of scientific research led to influential statements of recommendations such as the STrengthening Reporting of OBservational studies in Epidemiology (STROBE) statement. The STROBE initiative established in 2004 aimed to provide guidance on how to report observational research. Its guidelines provide a user-friendly checklist of 22 items to be reported in epidemiological studies, with items specific to the three main study designs: cohort studies, case-control studies and cross-sectional studies. The present STrengthening the Reporting of OBservational studies in Epidemiology -Molecular Epidemiology (STROBE-ME) initiative builds on the STROBE statement implementing 9 existing items of STROBE and providing 17 additional items to the 22 items of STROBE checklist. The additions relate to the use of biomarkers in epidemiological studies, concerning collection, handling and storage of biological samples; laboratory methods, validity and reliability of biomarkers; specificities of study design; and ethical considerations. The STROBE-ME recommendations are intended to complement the STROBE recommendations.

Smoking-related O4-ethylthymidine formation in human lung tissue and comparisons with bulky DNA adducts.

Tobacco smoke contains many alkylating agents that can react with DNA to produce O(4)-ethylthymidine (O(4)-etT) and several other types of promutagenic base modifications. Our aims were (i) to confirm results of a pilot study (Godschalk, R., Nair, J., Schooten, F. J., Risch, A., Drings, P., Kayser, K., Dienemann, H. and Bartsch, H. (2002) Comparison of multiple DNA adduct types in tumor adjacent human lung tissue: effect of cigarette smoking. Carcinogenesis, 23, 2081-2086) on the formation of O(4)-etT in smokers' lung; (ii) to explore associations between levels of O(4)-etT and smoking status and (iii) to investigate whether a correlation exists between levels of O(4)-etT and bulky (polycyclic aromatic hydrocarbons-derived) DNA adducts. Archived DNA samples originated from histologically normal peripheral lung tissues of 64 Hungarian lung cancer patients, who underwent lung resection. O(4)-etT was determined by an immunoenriched (32)P-postlabelling-high-performance liquid chromatography method. Levels of bulky DNA adducts were determined by the nuclease P1 adduct-enriched (32)P-postlabelling. O(4)-etT levels ranged from 0.01 to 3.91 adducts/10(8) thymidines. In the combined group of subjects who smoked until surgery or gave up smoking at most 1 year before it, the mean level of O(4)-etT was 1.7-fold (P = 0.015) and of bulky DNA adducts 2.2-fold (P < 0.0001) higher than in long-term ex-smokers (LES) and never-smokers (NS) combined. We found no significant correlation between the individual levels of the two DNA adduct types. No dose-response was detected between O(4)-etT formation and smoking dose. In one-third of LES, O(4)-etT levels were above the 2.0-fold mean level of adducts found in NS, indicating its high persistence. Our results confirm the smoking-related formation of O(4)-etT in human lung DNA that should be explored as biomarker. Its long persistence in target tissue implicates a role of this potentially miscoding lesion in tobacco smoking-associated cancers.

Recovery of bulky DNA adducts by the regular and a modified 32P-postlabelling assay; influence of the DNA-isolation method.

Bulky DNA adducts are widely used as biomarkers of human exposure to complex mixtures of environmental genotoxicants including polycyclic aromatic hydrocarbons. The 32P-postlabelling method is highly sensitive for the detection of bulky DNA adducts, but its relatively low throughput poses limits to its use in large-scale molecular epidemiological studies. The objectives of this study were to compare the impact of DNA-sample preparation with a commercial DNA-isolation kit or with the classical phenol-extraction procedure on the measurement of bulky DNA adducts by 32P-postlabelling, and to increase the throughput of the 32P-postlabelling method--whilst maintaining radio-safety--by reducing the radioisotope requirement per sample. The test DNA samples were prepared from MCF-7 cells treated with benzo[a]pyrene and from human peripheral blood lymphocytes, buffy coat, and peripheral lung tissue. The modified 32P-postlabelling procedure involved an evaporation-to-dryness step after the enzymatic digestions of the DNA, and radio-labelling with a reduced amount of [γ-32P]ATP substrate in a reduced reaction volume compared with the regular method. Higher levels of DNA adducts were measured in the MCF-7 cells and in the lung-tissue samples after isolation with the kit than after solvent extraction. A seven-fold higher level of adducts was detected in the buffy-coat DNA samples isolated with the kit than with the phenol extraction procedure (p<0.001). Reduction of the amount of [γ-32P]ATP from 50 µCi to 25 µCi (>6000 Ci/mmol specific radioactivity) per sample in the modified 32P-postlabelling procedure was generally applicable without loss of adduct recovery for all test samples prepared with both DNA isolation methods. The difference between the bulky DNA-adduct levels resulting from the two DNA-isolation procedures requires further systematic investigation. The modified 32P-postlabelling procedure allows a 50% reduction of radioisotope requirement per sample, which facilitates increased throughput of the assay whilst maintaining radio-safety.

SHMT1 1420 and MTHFR 677 variants are associated with rectal but not colon cancer.

BACKGROUND: Association between rectal or colon cancer risk and serine hydroxymethyltransferase 1 (SHMT1) C1420T or methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms was assessed. The serum total homocysteine (HCY), marker of folate metabolism was also investigated. METHODS: The SHMT1 and MTHFR genotypes were determined by real-time PCR and PCR-RFLP, respectively in 476 patients with rectal, 479 patients with colon cancer and in 461 and 478, respective controls matched for age and sex. Homocysteine levels were determined by HPLC kit. The association between polymorphisms and cancer risk was evaluated by logistic regression analysis adjusted for age, sex and body mass index. The population stratification bias was also estimated. RESULTS: There was no association of genotypes or diplotypes with colon cancer. The rectal cancer risk was significantly lower for SHMT1 TT (OR = 0.57, 95% confidence interval (CI) 0.36-0.89) and higher for MTHFR CT genotypes (OR = 1.4, 95%CI 1.06-1.84). A gene-dosage effect was observed for SHMT1 with progressively decreasing risk with increasing number of T allele (p = 0.014). The stratified analysis according to age and sex revealed that the association is mainly present in the younger (< 60 years) or male subgroup. As expected from genotype analysis, the SHMT1 T allele/MTHFR CC diplotype was associated with reduced rectal cancer risk (OR 0.56, 95%CI 0.42-0.77 vs all other diplotypes together). The above results are unlikely to suffer from population stratification bias. In controls HCY was influenced by SHMT1 polymorphism, while in patients it was affected only by Dukes' stage. In patients with Dukes' stage C or D HCY can be considered as a tumor marker only in case of SHMT1 1420CC genotypes. CONCLUSIONS: A protective effect of SHMT1 1420T allele or SHMT1 1420 T allele/MTHFR 677 CC diplotype against rectal but not colon cancer risk was demonstrated. The presence of SHMT1 1420 T allele significantly increases the HCY levels in controls but not in patients. Homocysteine could be considered as a tumor marker in SHMT1 1420 wild-type (CC) CRC patients in Dukes' stage C and D. Further studies need to clarify why SHMT1 and MTHFR polymorphisms are associated only with rectal and not colon cancer risk.

Relationship between TP53 tumour suppressor gene mutations and smoking-related bulky DNA adducts in a lung cancer study population from Hungary.

Lung cancer rate in Hungary is one of the highest in the world among men and also very high among women, for reasons not clearly understood yet. The aim of the study was to explore characteristics of DNA damage and TP53 gene mutations in lung cancer from Hungary. Tissue samples from 104 lung resections for lung cancer patients, both men and women, operated on for non-small cell lung cancer, specifically, primary squamous cell carcinoma or adenocarcinoma were studied. Of the cases, 37% smoked up to the surgery, 24% stopped smoking within 1 year before the surgery, 26% stopped smoking more than a year before the surgery and 13% never smoked. TP53 mutations were detected by denaturant gradient gel electrophoresis, automated capillary electrophoresis single-strand conformation polymorphism and sequencing. Bulky DNA adduct levels were determined by (32)P-post-labelling in non-tumorous lung tissue. In total, 45% (47/104) of the cases carried TP53 mutation. The prevalence of TP53 mutations was statistically significantly associated with duration of smoking, tumour histology and gender. Smokers had approximately twice as high bulky adduct level as the combined group of former- and never-smokers (10.9 +/- 6.5 versus 5.5 +/- 3.4 adducts/10(8) nucleotides). The common base change G --> T transversion (8/43; 19%) was detected exclusively in smokers. For the first time, we demonstrate that most carriers of G --> T transversions had also a high level of bulky DNA adducts in their non-tumourous lung tissue. Our study provides evidence for a high burden of molecular alterations occurring concurrently in the lung of lung cancer patients.

Validation of biomarkers for the study of environmental carcinogens: a review.

There is a need for validation of biomarkers. Our aim is to review published work on the validation of selected biomarkers: bulky DNA adducts, N-nitroso compounds, 1-hydroxypyrene, and oxidative damage to DNA. A systematic literature search in PubMed was performed. Information on the variability and reliability of the laboratory tests used for biomarkers measurements was collected. For the evaluation of the evidence on validation we referred to the ACCE criteria. Little is known about intraindividual variation of DNA adduct measurements, but measurements have a good repeatability irrespective of the technique used for their identification; reproducibility improved after the correction for a laboratory factor. A high-sensitivity method is available for the measurement of 1-hydroxypyrene in urine. There is consensus on validation of biomarkers of oxidative damage DNA based on the comet assay and chromatographic measurement in blood while urinary measurements by chromatographic assays are well validated, and ELISA-based assays appear to lack specificity. Immunoassays for the quantification of adducts of N-nitroso compounds are useful for large epidemiological studies, given their sensitivity, the small amount of DNA required and their potential for rapid and high-throughput analysis.

Glutathione S-transferase enzyme polymorphisms in a Hungarian myelodysplasia study population.

GSTM1, GSTT1 and GSTP1 Ile105Val that are members of the GST gene family encode for Phase II drug/xenobiotic metabolizing enzymes, primarily with detoxifying function, and are polymorphic in humans. GSTM1 and GSTT1 homozygous deletion genotypes do not express the enzymes. It has been hypothesised that individuals with homozygous deletion of the GSTM1 and/or GSTT1 gene may have lower detoxification capacity towards genotoxic agents therefore those individuals may be at increased risk of myelodysplastic syndrome which is a preleukemic condition. Genetic polymorphism of GSTM1, GSTT1 and GSTP1 Ile105Val was investigated in a case-control study in a Hungarian patient population comprising 86 patients with myelodysplastic syndrome and 99 hospital-based controls. There were no statistically significant differences between cases and controls for the GSTM1, GSTT1 and GSTP1 Ile105Val genotype frequencies for any of the three genes separately and in various combinations. This suggests that these genetic polymorphisms may not be strong risk factors, if any, for myelodysplastic syndrome.

Correlation between biomarkers of human exposure to genotoxins with focus on carcinogen-DNA adducts.

Correlations among biomarkers, an important issue in biomarker research, provide enhanced insight and understanding of the complexity of molecular mechanisms initiated by environmental genotoxic agents in the human organism. Occupational and environmental exposures mostly represent mixtures of genotoxic agents, whereas the specificity of biomarker measurements varies widely. Here, we give an overview of the correlation studies with particular emphasis on DNA adduct biomarker analysis of exposure to polycyclic aromatic hydrocarbons (PAHs) and/or tobacco smoke. We have collected data on correlations between different DNA adduct detection methods, DNA adduct structures and DNA adduct levels in human tissues. Data are also presented on the correlation between DNA adducts and other biomarkers of exposure and of early biological effects, including protein adducts, urinary metabolites and cytogenetic end points. In numerous studies, 32P-postlabelling and immunoassay measurements of DNA adducts recognized the difference between exposure groups similarly; however, at the individual level, there was, in general, not a statistically significant correlation between the two determinations. Inconsistency was found regarding the correlation between the levels of total bulky adducts and specific single DNA adduct structures. A number of studies found a positive correlation between DNA adduct levels in target and surrogate tissues, although stratification for exposure level may have influenced the results. Characteristically, there was a positive correlation between DNA adduct levels in tumour and normal tissue pairs. In general, there was a lack of correlation between DNA adducts and urinary PAH metabolites, but after stratification for particular genetic polymorphisms correlation may have emerged between the two biomarkers of exposure. The correlations with cytogenetic biomarkers were very complex, with examples of both positive correlation and lack of correlation. Exploration of correlations among biomarkers contributes to the further progress of molecular cancer epidemiology and to the selection of the optimal biomarkers for the investigation of human exposure to carcinogens.