IPCS guidelines for the monitoring of genotoxic effects of carcinogens in humans. International Programme on Chemical Safety

The purpose of these guidelines is to provide concise guidance on the planning, performing and interpretation of studies to monitor groups or individuals exposed to genotoxic agents. Most human carcinogens are genotoxic but not all genotoxic agents have been shown to be carcinogenic in humans. Although the main interest in these studies is due to the association of genotoxicity with carcinogenicity, there is also an inherent interest in monitoring human genotoxicity independently of cancer as an endpoint. The most often studied genotoxicity endpoints have been selected for inclusion in this document and they are structural and numerical chromosomal aberrations assessed using cytogenetic methods (classical chromosomal aberration analysis (CA), fluorescence in situ hybridisation (FISH), micronuclei (MN)); DNA damage (adducts, strand breaks, crosslinking, alkali-labile sites) assessed using bio-chemical/electrophoretic assays or sister chromatid exchanges (SCE); protein adducts; and hypoxanthine-guanine phosphoribosyltransferase (HPRT) mutations. The document does not consider germ cells or gene mutation assays other than HPRT or markers of oxidative stress, which have been applied on a more limited scale.

A simple modified arthroscopic procedure for fixation of displaced tibial eminence fractures

SUMMARY

Avulsion fractures of the tibial eminence have been well described in children and adults with an increased in incidence resulting from road traffic and athletic accidents. According to the literature, only surgical treatment is advocated because of the high incidence of the nonunion and instability following conservative treatment. Open reduction can cause some morbidity and, therefore, arthroscopic techniques have been developed. The limitations of the techniques are related to technical difficulty and unstable fixation. We report a simple and effective method of fixation with the following advantages: (1) use of metallic suture for stable fixation, (2) the fixation device is easily removed in the office, (3) there is no need of additional instruments, and (4) the minimal size of the fixation device avoids damage to the anterior cruciate ligament insertion. This technique has been used in a series of 10 consecutive patients treated for avulsion fractures of the tibial spine since 1991, resulting in a high rate of excellent and good results without any case of nonunion fracture or related complication.

Pre-clinical evaluation of new antineoplastic agents in NSCLC cell lines: evidence of histological subtype-dependent cytotoxicity

The antiproliferative effect of paclitaxel, docetaxel, gemcitabine, topotecan, SN-38 and cis-platin was studied on 5 non-small cell lung cancer (NSCLC) cell lines, 3 of which were adenocarcinoma (ADK) and 2 squamous cell carcinoma (SCC). Cellular chemosensitivity was determined using the MTT in vitro assay after 48, 72 and 96 h of exposure to drug in concentration ranging from 0.001 to 100 microM. A concentration-dependent cell growth inhibition was observed for paclitaxel, gemcitabine, topotecan, SN-38 and cis-platin in all cell lines tested. Docetaxel showed a concentration-independent cytotoxicity and was 104 times more potent than cis-platin (IC50 = 0. 001 vs. 10 microM). Paclitaxel, gemcitabine, topotecan and SN-38 were 102 times more potent than cis-platin, with median IC50 = 0.1 microM at 72 h. The level of drug-induced cell growth inhibition appeared to be correlated, for some of the six drugs tested, with the tumor histological subtype. In particular, topotecan and cis-platin were more active in squamous cell carcinoma than in adenocarcinoma cell lines (p=0.006 and 0.001 respectively at 0.1 microM concentration), while paclitaxel was more active in ADK than in SCC cell lines (p=0.004 at 0.01 microM concentration). Ca-Lu-6, a cell line that, contrary to most other lung cancer cell lines, is wild-type for most oncogenes/tumor suppressor genes, was by far the most sensitive cell line used (p=0.002, 0.003, 0.01 for paclitaxel, topotecan and cis-platin respectively, at 1 microM concentration), showing a >50% growth inhibition to new drugs at a concentration of 0.01 microM. In conclusion, all these new compounds tested were found to be more potent than cis-platin in affecting cellular proliferation of six NSCLC cell lines studied. We suggest that the specific histological subtype and molecular pattern of the cell line being treated could affect the antiproliferative effect of these drugs.

[Computerized tomography of the meniscus with a stress device]

PURPOSE

We investigated the usefulness of a mechanical stress device to increase widening of the articular rima in CT studies of the meniscus on forced varus and valgus.

MATERIAL AND METHODS

September 1997 to October 1998, we examined 284 patients with symptoms and clinical signs of meniscal injury. CT was performed during forced varus and valgus, depending on the site of the suspected damage, in 70 of 284 patients. We used an FOV of 18 cm, with a potential difference of 140 kVp and power of 170 mA. The reconstruction matrix was 512 x 512 and acquisition time was 3 s. A set of 8-10 partially overlapping scans were acquired craniocaudally, with slice thickness of 1.5 mm and gap of 1 mm. The mechanical strainer was locked in the correct position and a second set of 4-5 images acquired at the meniscus. Then the patients were submitted to arthroscopy to check the radiological findings.

RESULTS

CT performed in forced varus and valgus had 96.8% specificity, 97.3% sensitivity and 97.1% diagnostic accuracy. Sensitivity was 100%, specificity 96% and diagnostic accuracy 98% in the medial meniscus, while we had 88.9%, 100% and 94.7% respectively in the external meniscus.

CONCLUSIONS

CT with a mechanical stress device was extremely useful in defining the meniscal loose edge. It also showed the exact shape and complexity of meniscal injury, even in the cases with narrow articular rima or those where conventional CT had performed poorly.

Final height of patients who underwent bone marrow transplantation for hematological disorders during childhood: a study by the Working Party for Late Effects-EBMT

Few data are available on the long-term effect of bone marrow transplantation (BMT) on growth. This study examines those factors that play a role in the final height outcome of patients who underwent BMT during childhood. Data on 181 of 230 patients with aplastic anemia, leukemias, and lymphomas who had BMT before puberty (mean age, 9.8 +/- 2.6 years) and who had reached their final height were analyzed. An overall decrease in final height standard deviation score (SDS) value was found compared with the height at BMT (P < 10(7)) and with the genetic height (P < 10(7)). Girls did better than boys, and the younger in age the person was at time of BMT, the greater the loss in height. Previous cranial irradiation + single-dose total body irradiation (TBI) caused the greatest negative effect on final height achievement (P < 10(4)). Fractionation of TBI reduces this effect significantly and conditioning with busulfan and cyclophosphamide seems to eliminate it. The type of transplantation, graft-versus-host disease, growth hormone, or steroid treatment did not influence final height. Irradiation, male gender and young age at BMT were found to be major factors for long-term height loss. Nevertheless, the majority of patients (140/181) have reached adult height within the normal range of the general population.

Exposure to agrochemicals and DNA adducts in Western Liguria, Italy

Pesticides are used to control pests and improve agricultural production. Despite their selectivity of action, a number of agrochemicals have been reported to be genotoxic using the (32)P-DNA postlabeling assay. Greenhouse floriculturists are suspected of being heavily exposed to agrochemicals during loading, mixing, and application of pesticides, as well as during manual activities by continuous contact with flowers and ornamental plants. We analyzed the DNA adduct formations in the white blood cells (WBCs) of 57 nonsmoker greenhouse floriculturists and 33 nonsmoker age-matched referents residing in the Western Liguria Region, Italy-the most important Italian greenhouse floriculture area. The averages of DNA adducts, expressed as relative adduct labeling (RAL), were 8.50 x 10(9) +/- 1.98 (SE) in floriculturists and 2.17 x 10(9) +/- 1.05 (SE) in referents. DNA adducts were significantly higher in floriculturists than in controls after adjustment for age and gender (P = 0.007). A specific adduct pattern, with up to six different spots, was observed in 60% of floriculturists, while no adducts were generally detected in controls. Our study represents an important contribution to the correct evaluation of the potential health risk associated with floriculture activity and supports the adoption of measures ensuring pesticide exposure reduction in greenhouses.

Specific K-ras2 mutations in human sporadic colorectal adenomas are associated with DNA near-diploid aneuploidy and inhibition of proliferation

Recent studies indicate that p21ras proteins mediate their multiple cell functions through interactions with multiple effectors and that the number of new effectors is growing. We recently reported that K-ras2 mutations in human colorectal adenomas were associated with chromosome instability and proliferation changes. In the present study, we extend these previous observations. Hereditary and multiple (n > or = 5) adenomas and adenomas with early cancer were excluded. Dysplasia was moderate in 91 cases and high in 25, and the median adenoma size was 1.5 cm. K-ras2 spectrum analysis was done by sequence-specific oligonucleotide hybridization using nuclear suspensions provided by analysis and sorting of multiparameter flow cytometry. In particular, tissue inflammatory cells were separated for DNA diploid tumors, whereas DNA aneuploid epithelial subclones were analyzed separately. K-ras2 mutations and DNA aneuploidy were both detected in 29 of 116 (25%) cases. DNA aneuploid index was in the near-diploid region in the majority of cases. DNA aneuploidy was strongly associated with G-->C/T transversions. An association was also found between low S-phase values and G-->A transitions. These findings were confirmed using multivariate logistic regression analysis to account for the effects of size, dysplasia, site, type, age, and sex. These data suggest that specific K-ras2 mutations in a subgroup of human sporadic colorectal adenomas play a role in chromosome instability and, contrary to expectations, are associated with inhibition of proliferation.

Effects of cardio-pulmonary bypass on vancomycin plasma concentration decay

The objective of the study was to investigate possible changes in vancomycin serum levels induced by cardio-pulmonary bypass (CPB). Ten cardiac patients (seven males, three females, aged between 56 and 81), who underwent cardiac surgery requiring CPB, took part in the study. Vancomycin (15 mg kg-1) was intravenously infused over 60 min before anaesthesia and blood samples were taken at appropriate times after drug administration (0, 0.5, 1, 6, 8 h), after starting CPB (0, 5, 30 and 60 min) and after aortic unclamping (0, 5, 30, 60, 120 min). Drug serum concentrations were determined by means of a fluorescence polarization immunoassay. The area under the concentration-time curve (AUC) measured during CPB were compared with the AUC extrapolated in the same interval by fitting a two-compartment pharmacokinetic model to drug concentrations obtained before and after CPB. Five minutes after starting CPB vancomycin serum levels decreased, on average, by 40.9% and remained steadily lower than the expected values over the next 60 min. In the same interval, the measured AUC was 31.7% lower than the expected AUC. In no instance did serum levels fall below the MIC for most common pathogens (1-2 mg l-1). At aortic unclamping serum levels slightly rebounded but tended to remain lower than the expected concentrations over the next 120 min. In conclusion, during CPB vancomycin serum levels invariably decreased but, at the dose employed (15 mg kg-1), remained in a potentially effective range for antimicrobial prophylaxis.

Urinary excretion of 1-hydroxypyrene as a marker for exposure to urban air levels of polycyclic aromatic hydrocarbons

A cross-sectional study was conducted among 94 traffic police officers from the Municipality Police of Genoa, Italy, exposed to airborne pollutants and 52 referent subjects exposed to indoor air pollution levels to investigate the relationships between exposure to ambient air polycyclic aromatic hydrocarbons (PAHs) and urinary excretion of 1-hydroxypyrene (1-OH-P). The effects of smoking, lifestyle factors such as exposure to ETS, and diet, along with the role played by the cytochrome P4501A1 (CYP1A1), and glutathione S-transferase M1 and theta metabolic susceptibility gene polymorphisms were examined. The geometric mean of benzo(a)pyrene air measurements (an index compound of PAH levels) was 70 times higher in traffic police officers (3.67 ng/m3) than in referents (0.05 ng/m3). The urinary concentration of 1-OH-P was clearly associated with cigarette smoking and, to a lesser extent, with exposure to ETS and particulate PAH pollution. No association was detected between 1-OH-P excretion and diet. Women exhibited a higher excretion level than did men, and an apparent effect of age was due to differences in cigarette smoking habits. Exposure to PAHs resulted in higher levels of 1-OH-P excretion in all groups except heavy smokers. Overall, no significant role of any metabolic polymorphism was detected. However, stratification of study subjects according to their smoking habits revealed higher levels of excretion of 1-OH-P in subjects smoking < or =15 cigarettes/day carrying the CYP1A1 polymorphism. No such effect was seen either with nonsmokers or with people smoking more than 15 cigarettes/day. These findings are suggestive of a gene-environment interaction, in which subjects with the CYP1A1 polymorphism, relative to subjects without it, have higher levels of 1-OH-P in their urine at low doses of exposure to PAHs.

Local-Regional Recurrence of Renal Cell Carcinoma following Nephrectomy. Our Experience

Introduction

Locally recurrent renal cell carcinoma (RCC) after nephrectomy is uncommon (1.3% of our cases) and prognosis is poor. There is as yet no standard treatment, but radical surgery is classed by many authors as the best therapeutic approach given the relative ineffectiveness of chemo-immunotherapy and radiotherapy. The surgical approach and follow-up protocol that we adopt are described.

Materials and methods

Between January 1985 and December 1996, 7 patients (2 M - 5 F; mean age 63 - range 47–72), nephrectomised for RCC, underwent further surgery of the homolateral renal cavity. The stage of the primary neoplasm was pT3G3N0 in 3 patients, pT3G2N0 in 2, pT3G1N0 in 1 and pT2G2N0 in 1. Recurrence appeared on average at 30 months (12–84), with a diameter varying between 14 to 40 mm. Patients were staged again by median laparotomic access; no remote metastases were found. Three patients received adjuvant therapy with biological response modulators.

Results

Histological results confirmed recurrence of the primitive tumour in all cases and metastatised lymph node tissue was found in just one case. Four patients were still alive (2 disease-free, 2 with lung and multi-organ metastases respectively) after a mean follow-up of 24 months (15–54) following removal of the local recurrence. Two patients died at 13 and 27 months after surgery due to progression of the disease, whilst 1 patient died from uncorrelated pathology after 30 months. Of the above 4 live patients, 3 developed a single metastasis at 5, 8 and 21 months after treatment of the first local recurrence and underwent further radical surgery (2 in the pelvic pouch, 1 vaginal). They also received adjuvant therapy with biological response modulators after the 2nd operation. The disease progressed, however, and only 1 patient is alive with multiple metastasis.

Conclusions

Surgery of local recurrences of RCC presents no particular difficulties, whilst allowing excellent control of the neoplasm and survival free from advancing diseases. The role that adiuvant therapy (immunomodulators) plays is not yet certain, but could be associated with surgical removal, considering the possible co-existence of micrometastases that cannot clinically be shown.

Treatment of Ureteral Stones: Intracorporeal Or Extracorporeal Lithotripsy?

Over the last 15 years the treatment of ureteral stones has been considerably revolutionised thanks to new, less invasive technologies compared to traditional surgery. The urologist is, however, faced with a dilemma: whether to cure the patient with easy-to-perform extracorporeal lithotripsy (ESWL) without anesthesia in Day Surgery, but which often requires more than one session to clear the stones completely, or to carry out ureteroscopy and intracorporeal lithotripsy, which resolves most cases in just one treatment but is more invasive in that it requires general anesthesia and hospitalisation. The authors present their experience and compare the two methods.

32P-postlabeling detection of aromatic adducts in the white blood cell DNA of nonsmoking police officers

Atmosphere in urban areas may be polluted by a number of combustion sources, including industries, vehicle traffic, and residential heating. Traffic police constitute a group of workers that is highly exposed to urban pollutants, especially those from motor vehicle exhaust. We conducted a biomonitoring study to simultaneously measure in 34 nonsmoking police officers and in 36 nonsmoking office workers, as referents, the individual benzo(a)pyrene [B(a)P] exposure using personal samplers and the formation of DNA adducts in peripheral WBCs using 32P-postlabeling techniques. Our results show that the police officers were exposed to significantly higher levels of B(a)P than were referents (P < 0.0001). No seasonal variation of the atmospheric levels of B(a)P was found throughout the year. The median relative adduct labeling x 10(-8) values of the controls and exposed police officers were 0.94 (range, 0.1-3.7) and 1.3 (range, 0.1-5.5), respectively, using the nuclease P1 technique. Although the DNA adduct levels of police officers were globally higher than those of referents (P < 0.05), the difference was entirely due to the summer difference [median values 0.80 (range, 0.1-1.8) and 2.8 (range, 0.7-5.5), respectively (P < 0.001)]. In winter, the DNA adduct levels were substantially identical, and in midseason, there was only a very small increase in police officers, with respect to controls (statistically not significant). Moreover, a more significant seasonal variation of bulky aromatic DNA adduct levels was observed in WBC DNA samples of police officers (P < 0.05) compared to those of referents. The seasonal variation of bulky aromatic adduct levels could be correlated with the reported seasonal variation of aryl hydrocarbon hydroxylase inducibility in human lymphocytes.

Sister chromatid exchange induction in peripheral blood lymphocytes of traffic police workers

Traffic police workers, as a population exposed to urban atmosphere, were compared with a control population exposed to indoor air pollution levels. Sister chromatid exchanges (SCEs) as a biomarker of effect were measured in peripheral blood lymphocytes of 54 exposed subjects and 35 controls, and environmental concentration of polynuclear aromatic hydrocarbon (PAH) tracer compounds was detected by personal air samplers. The mean exposure level to benzo[a]pyrene in our group of traffic policemen (3.4 mg/m3) was in the range that has been estimated in urban areas in Europe during the last 10 years. No difference in SCE levels was found between exposed workers (7.36, SD 1.35) and controls (7.47, SD 1.28). No correlation was observed between SCE/cell and airborne PAH concentration in the traffic worker population. A positive regression of SCE on exposure estimate was found only in the non-smoking group of police workers. Our findings suggest that exposure to urban air pollution does not induce relevant cytogenetic effects.

Our experience in the treatment of rheumatoid knee by arthroscopic synovectomy

The authors present the results obtained in the treatment of rheumatoid knee by arthroscopic synovectomy. A total of 29 knees operated on in 25 patients after a mean follow-up of 38 months based on the Laurin evaluation scale were re-examined. There was significant improvement for pain, synovitis, and overall function (mean values pre- and postoperative 2.07 vs 0.98; 2.14 vs 0.84, 2.37 vs 1.26, respectively); there were no, substantial variations in joint movement (2.47 vs 2.58). By dividing the patients into the 4 Larsen radiographic classes, the worst results were observed in patients in classes 3 and 4. In this series of patients complications of significance were not observed. Thus, we consider arthroscopic synovectomy to be the treatment of choice for rheumatoid knee because of the intrinsic advantages of minimum disease rate, rapid functional recovery, with expectations of results inversely proportional to the stage of progression of the disease.

Our experience in the arthroscopic treatment of fracture-avulsion of the tibial spine

The authors present their experience in the arthroscopic treatment of fracture-avulsion of the intercondyloid eminence in the adult with a variation in the original method. In fact, an ACUFEX tibial guide is used for reconstruction of the ACL positioning 2 Kirschner wires with hole at the margins of the fragment, successively sliding the metal wire through the hole. Successive traction on the outside of the wires allows the metal wires to be arranged dome-like to stabilize the avulsed fragment. The distal ends of the wires are stabilized with a metal pull-out in the area corresponding to the anteromedial surface of the tibia. In the 10 patients treated by this method, evaluated after a minimum follow-up of 6 months, we obtained overall satisfactory clinical and functional results. There was significant residual ligamentous laxity in 2 patients with no clinical symptoms of instability. Variations in arthroscopic technique described in the literature are analyzed.

Role of Bilateral Pelvic Lymphadenectomy in Prostatic Cancer

Objectives: to identify a group of patients with prostate cancer for whom open staging pelvic lymph node dissection (PLND) could be superfluous. Methods: the medical records of all patients presenting with prostate cancer from January 1992 to December 1996 were reviewed. A total of 118 patients with clinically localized disease were selected to undergo radical retropubic prostatectomy (RRP) preceded by open PLND. Final nodal status was correlated with the value of the preoperative serum prostate specific antigen (PSA) concentration, clinical stage (TNM), and grading (by OMS) to evaluate the predictivity of nodal involvement. We identified 3 groups: PSA <10 ng/ml, T1–2, G1-2, = 1st very low risk, PSA 10 −15, T1-2 - G1-2 = 2nd low risk, PSA <15 T3 or G3 or PSA >15 every T and G = 3rd high risk. Results: overall, only 21 patients (18%) had lymph node metastases. Lymph node involvement was significantly correlated with elevated serum PSA values, high grading, and advanced clinical stage. 35 patients belonged to the first 2 groups, presenting with low PSA and favorable clinical stage and grade, none with lymph node involvement. These patients could have avoided PLND with a very low risk of missing something. Conclusions: open staging PLND may no longer be justified on a routine basis in patients undergoing radical retropubic prostatectomy.

“Steinstrasse” or stone street after extracorporeal lithotripsy

The aim of this work has been to check the frequency and to assess which manoeuvres are necessary in treating the steinstrasse after ESWL in situ. From September 1989 to May 1996, 2400 patients were treated with extracorporeal lithotripsy, 86 (3.6%) developed a steinstrasse in the days immediately after treatment. Only 40% of cases had specific urinary obstruction symptoms. In 52 patients (60%) the steinstrasse was spontaneously eliminated within 4 weeks, while in the remaining 34 an auxiliary treatment was necessary (second ESWL, percutaneous nephrostomy, ureteroscopic management). These therapies required further hospital admittance but didn't cause statistically significant differences in the stone-free rate at 6 months (96% and 97%, p < 0.001). Our experience would indicate that the incidence of steinstrasse after ESWL in situ is quite low (3.6%) and the necessity for auxiliary treatment is extremely rare (1.4%).

Present role of surgery

The advent of more advanced endoscopic methods and extracorporeal lithotripsy (ESWL) plus the increasing use of radiological means such as ultrasound, which has allowed the bloodless treatment of small stones, have gradually reduced the number of traditional surgical operations. In one decade surgery has dropped from 63% (1983-1985) to 3.6% (1993-1995) in stone cases, mainly following unsuccessful ESWL or endoscopic methods. It is rarely first choice in lumbar calculosis unlike in voluminous obstructing iliac calculosis, while it is exceptional in cases of pelvic stones. Surgery may be “necessary”, however, with associated ureteral stenosis or anatomical alterations preventing endoscopic or percutaneous approaches and contemporaneousness of surgical operations. Occasionally circumstances, such as working conditions or the psychological state of the patient, “condition” the choice for an immediate, final solution by a single procedure. Lastly, surgery should be reserved today for selected cases and when used, should be highly competitive, from all points of view, compared to all other methods.

Teicoplanin concentrations in serum, pericardium, pericardial fluid and thoracic wall fat in patients undergoing cardio-pulmonary bypass surgery

The concentrations of teicoplanin in serum, pericardium, pericardial fluid and thoracic wall fat were measured in patients undergoing cardio-pulmonary bypass (CPB) after the administration of a single i.v. 12 mg/kg dose. Five minutes after the start of CPB, teicoplanin serum concentrations decreased by, on average, 35% (95% confidence interval (CI): 28-42%) and remained significantly lower than the expected values over the subsequent 60 min period. After aortic unclamping drug concentrations rebounded but remained significantly lower than the expected values in the next 60 min. Immediately before CPB, penetration of teicoplanin in pericardium and thoracic wall fat was 0.44 (95% CI: 0.23-0.65) and 0.05 (95% CI: 0.03-0.7), respectively, and increased at the end of CPB to 0.90 (95% CI: 0.55-1.25) and 0.17 (95% CI: 0.05-0.29), respectively. MICs for most staphylococcal strains were attained during CPB procedure in pericardium but not in thoracic wall fat. However, since staphylococcal infections involve the interstitial space it is likely that penetration into fat cells is not important for antimicrobial prophylaxis. In this respect, it is worth noting that drug concentration in pericardial fluid, which should reflect the interstitial concentration, was higher than the MIC for most staphylococcal strains. Although no infective complications were observed in our limited series of patients, larger clinical trials are needed to assess whether the dose regimen employed is effective in preventing post-CPB surgery infections.

Airborne levels of polycyclic aromatic hydrocarbons: 32P-postlabeling DNA adducts and micronuclei in white blood cells from traffic police workers and urban residents

An epidemiologic study on 94 traffic police officers exposed to airborne polycyclic aromatic hydrocarbons (PAH) and 52 age-matched urban residents working in confined spaces considered as referent subjects without occupational exposure to PAH was conducted to characterize individual exposure to benzo(a)pyrene (BaP), benzo(b)-, and benzo(k)fluoranthene (BbF and BkF) and the occurrence of DNA adducts and micronuclei in white blood cells (WBC). The study's findings indicated that mean concentrations of PAH in the city air were 10 to 30 times higher among the traffic police officers compared with referent subjects (4.55 +/- 3.44 ng/m3 and 0.15 +/- 0.30 ng/m3 of BaP among police officers and referents, respectively). 32P-postlabeling DNA adducts in WBC obtained from police officers (1.48 +/- 1.35 RAL/10(8)) were significantly higher than in referent subjects (1.01 +/- 0.63 RAL/10(8), P = 0.007), suggesting a possible role of exposure to airborne PAH in the DNA damage. The frequency of micronuclei was significantly increased (P = 0.02) in referent subjects (4.49 +/- 2.0% cells) compared with police officers (3.75 +/- 1.65% cells) due to the large proportion of females in the former group. Comparison of the mean micronuclei frequencies among 82 male police officers (3.73 +/- 1.6% cells) and referents (4.03 +/- 1.61% cells) failed to reveal a statistically significant difference (P = 0.38). Our findings support the evidence of a noxious effect of the exposure to airborne PAH found in large cities on the occurrence of DNA adducts in WBC, whereas there seems to be no effect on the cytogenetic risk assessed as micronuclei frequency.