I. Sari-Minodier

Cytogenetic monitoring of industrial radiographers using the micronucleus assay.

Industrial radiography is the process of using either gamma-emitting radionuclide sources or X-ray machines to examine the safety of industrial materials. Industrial radiographers are among the radiation workers who receive the highest individual occupational radiation doses. To assess occupationally induced chromosomal damage, we performed the cytokinesis-block micronucleus (CBMN) assay in peripheral lymphocytes of 29 male industrial radiographers, exposed to ionizing radiation for 12.8 years+/-11.2, in comparison with 24 gender-, age-, and smoking habits-matched controls. The CBMN assay was combined with fluorescent in situ hybridization with a pan-centromeric DNA probe in 17 exposed subjects and 17 controls randomized from the initial populations. The mean cumulative equivalent dose, recorded by film dosimeters, was 67.2 mSv+/-49.8 over the past 5 years. The mean micronucleated binucleated cell rate (MCR) was significantly higher in the industrial radiographers than in the controls (10.7 per thousand +/-5.2 versus 6.6 per thousand +/-3.1, P=0.009); this difference was due to a significantly higher frequency of centromere-negative micronuclei (C-MN) in exposed subjects than in controls (8.5 per thousand +/-4.9 versus 2.2 per thousand +/-1.6, P<0.001). The two populations did not significantly differ in centromere-positive micronuclei (C+MN) frequency. These findings demonstrate a clastogenic effect in lymphocytes of industrial radiographers. MCR significantly positively correlated with age in the two groups. After correction for the age effect, MCR did not correlate with duration of occupational exposure. No correlation between radiation doses and MCR, C-MN, and C+MN frequencies was observed. In addition to physical dosimetry records, the enhanced chromosomal damage in lymphocytes of industrial radiographers emphasizes the importance of radiation safety programs.

Acentromeric micronuclei are increased in peripheral blood lymphocytes of untreated cancer patients

Increased micronucleated cell rates, dicentric chromosomes, and other chromosomal damages have been reported in lymphocytes of cancer patients prior to the initiation of chemotherapy, and/or radiotherapy. The cause of these chromosomal damages in these lymphocytes remains unclear. In the present work, we investigated whether these micronuclei mainly reflect structural or numerical chromosomal aberrations by applying the cytokinesis-blocked micronucleus (CBMN) assay in combination with fluorescent in situ hybridization (FISH) of a DNA centromeric probe on blood samples of 10 untreated cancer patients (UCPs), and 10 healthy subjects (HSs). Micronucleated binucleated lymphocyte rate was significantly increased in patients (mean+/-S.D.: 19.0 per thousand +/-14.1 versus 9.2 per thousand +/-4.6 in controls). Trinucleated cytokinesis-blocked cells were not significantly higher in patients than in controls. Acentromeric, centromeric, and multicentromeric micronucleus levels were two-fold higher in patients than in controls, but the difference was significant only with acentromeric micronuclei. The percentage of micronuclei containing one or more centromeres averaged 69.2, and 71.5% in patients, and controls, respectively. The percentage of micronuclei containing several centromeres was 44.7% in patients, and 54.6% in controls. Among centromere-positive micronuclei, the percentage of micronuclei containing several centromeres averaged 59.7% in patients, and 75.4% in controls. These results indicate that genetic instability in peripheral blood lymphocytes of UCPs occurs because of enhanced chromosome breakage. However, a substantial proportion of this genetic instability occurs because of defects in chromosome segregation.

Occupational Exposures Obtained by Questionnaire in Clinical Practice and Their Association With Semen Quality

In industrial countries, evidence suggests that semen quality has been steadily decreasing over the past 5 decades. We employed a short questionnaire to examine the association between self-reported physical or chemical occupational exposures and semen quality. The study included 402 men consulting for couple infertility (314 with oligospermia, asthenospermia, or teratospermia and 88 with normal semen; World Health Organization criteria). Exposure effects on global sperm quality and total sperm count, sperm motility, and sperm morphology were investigated. We found significant associations between semen impairment and occupational risk factors such as exposure to heavy metals (adjusted odds ratio [OR] = 5.4; 95% confidence interval [CI], 1.6-18.1), solvents (OR = 2.5; 95% CI, 1.4-4.4), fumes (OR = 1.9; 95% CI, 1.1-3.4), and polycyclic aromatic hydrocarbons (OR = 1.9; 95% CI, 1.1-3.5). Exposure to pesticides or cement was nearly significant (OR = 3.6; 95% CI, 0.8-15.8, and OR = 2.5; 95% CI, 0.95-6.5, respectively). Physical risk factors were associated with some sperm anomalies, such as mechanical vibrations with oligospermia and teratospermia as well as excess heat and extended sitting periods with impaired motility. Exposure to ionizing radiation and electromagnetic fields was not associated with semen impairment; these results, however, may be skewed, because very few subjects reported such exposure. Despite the small dataset, self-reported exposures were correlated with semen impairment. This approach may be recommended in routine clinical practice to seek relationships between occupational exposures to reprotoxic agents and impaired semen parameters. This knowledge would allow preventive measures in the workplace to be established and could be complemented by the use of biomarkers to better characterize exposure to chemical substances and their spermiotoxic effects.

Tobacco consumption and benzo(a)pyrene-diol-epoxide–DNA adducts in spermatozoa: in smokers, swim-up procedure selects spermatozoa with decreased DNA damage

OBJECTIVE To analyze the distribution of benzo(a)pyrene-diol-epoxide (BPDE)-DNA adducts in spermatozoa selected and nonselected by a swim-up procedure with relation to smoking habits. DESIGN Comparative study. SETTING Public university and public university hospital. PATIENT(S) Seventy-nine men (37 smokers and 42 nonsmokers) who visited an infertility clinic for diagnostic. INTERVENTION(S) Tobacco and environmental exposure assessment, semen sample analysis, swim-up procedure, BPDE-DNA adduct immunolabeling. MAIN OUTCOME MEASURE(S) BPDE-DNA adduct quantification in selected (SEL-SPZ) and nonselected (NONSEL-SPZ) spermatozoa. Data were normalized by using a normalized fluorescence value (NFV). RESULT(S) The mean NFV (±SD) in SEL-SPZ was significantly higher in smokers than in nonsmokers (18.9±11.5 vs. 10.5±10.4, respectively). Within smokers, a paired analysis (SEL-SPZ and NONSEL-SPZ) showed that NFV was significantly lower in SEL-SPZ than in NONSEL-SPZ (20.0±11.3 vs. 31.5±16.0, respectively). Conversely, within nonsmokers, the mean NFV was higher in SEL-SPZ than in NONSEL-SPZ (10.3±10.6 vs 4.3±7.1, respectively). CONCLUSION(S) Tobacco consumption is associated with BPDE-DNA adducts in spermatozoa. In smokers, semen processing by swim-up recovers potentially fertilizing spermatozoa that show a significantly lower amount of BPDE-DNA adducts compared with NONSEL-SPZ. Further study is needed to improve the spermatozoa selection in smoking patients requiring assisted reproductive technologies.

Sperm mRNAs and microRNAs as candidate markers for the impact of toxicants on human spermatogenesis: an application to tobacco smoking

Abstract Spermatozoa contain a complex population of RNAs including messenger RNAs (mRNAs) and small RNAs such as microRNAs (miRNA). It has been reported that these RNAs can be used to understand the mechanisms by which toxicological exposure affects spermatogenesis. The aim of our study was to compare mRNA and miRNA profiles in spermatozoa from eight smokers and eight non-smokers, and search for potential relationships between mRNA and miRNA variation. All men were selected based on their answers to a standard toxic exposure questionnaire, and sperm parameters. Using mRNA and miRNA microarrays, we showed that mRNAs from 15 genes were differentially represented between smokers and non-smokers (p < 0.01): five had higher levels and 10 lower levels in the smokers. For the microRNAs, 23 were differentially represented: 16 were higher and seven lower in the smokers (0.004 ≤ p < 0.01). Quantitative RT-PCR confirmed the lower levels in smokers compared to non-smokers for hsa-miR-296-5p, hsa-miR-3940, and hsa-miR-520d-3p. Moreover, we observed an inverse relationship between the levels of microRNAs and six potential target mRNAs (B3GAT3, HNRNPL, OASL, ODZ3, CNGB1, and PKD2). Our results indicate that alterations in the level of a small number of microRNAs in response to smoking may contribute to changes in mRNA expression in smokers. We conclude that large-scale analysis of spermatozoa RNAs can be used to help understand the mechanisms by which human spermatogenesis responds to toxic substances including those in tobacco smoke.

Evaluation of micronucleated lymphocytes, constitutional karyotypes and anti-p53 antibodies in 21 children with various malignancies

The implication of environmental carcinogens in childhood cancer is still unknown. To assess a possible link between DNA damage and alterations of the tumor suppressor gene p53, blood samples of 21 children with malignancies were examined for the presence of micronuclei in lymphocytes using the cytokinesis blocked micronucleus assay (CBMA). The constitutional karyotypes were analyzed for chromosome abnormalities and the presence of anti-p53 antibodies in blood sera was evaluated by an enzyme-linked immuno sorbent assay (ELISA). A control group of 20 children was also included. The rates of micronucleated cells were 5.1 per thousand+/-3.9 and 2.4 per thousand+/-2.3 for the cancer and control groups, respectively. The difference between the groups were statistically significant (P<0.05 by the Mann-Withney rank sum test). Two children in the cancer group showed extensive chromosome breakage in lymphocytes. The sera of two other children from the cancer group and of one child from the control group contained anti-p53 antibodies. Chromosome breakage and anti-p53 antibodies from the five children were associated with increased micronucleated cell rates. The results of the present study suggest that genotoxic events can occur in the lymphocytes of children with a cancerous state.

The Effect of Workload on Biological Monitoring of Occupational Exposure to Toluene and N-Hexane: Contribution of Physiologically Based Toxicokinetic Modeling

A physiologically based toxicokinetic model was used to examine the impact of work load on the relationship between the airborne concentrations and exposure indicator levels of two industrial solvents, toluene and n-Hexane. The authors simulated occupational exposure (8 hr/day, 5 days/week) at different concentrations, notably 20 ppm and 50 ppm, which are the current threshold limit values recommended by ACGIH® for toluene and n-hexane, respectively. Different levels of physical activity, namely, rest, 25 W, and 50 W (for 12 hr followed by 12 hr at rest) were simulated to assess the impact of work load on the recommended biological exposure indices: toluene in blood prior to the last shift of the workweek, urinary o-cresol (a metabolite of toluene) at the end of the shift, and free (nonhydrolyzed) 2,5-hexanedione (a metabolite of n-hexane) at the end of the shift at the end of the workweek. In addition, urinary excretion of unchanged toluene was simulated. The predicted biological concentrations were compared with the results of both experimental studies among human volunteers and field studies among workers. The highest predicted increase with physical exercise was noted for toluene in blood (39 μg/L at 50 W vs. 14 μg/L at rest for 20 ppm, i.e., a 2.8-fold increase). The end-of-shift urinary concentrations of o-cresol and toluene were two times higher at 50 W than at rest (for 20 ppm, 0.65 vs. 0.33 mg/L for o-cresol and 43 vs. 21 μg/L for toluene). Urinary 2,5-hexanedione predicted for 50 ppm was 1.07 mg/L at 50 W and 0.92 mg/L at rest (+16%). The simulations that best describe the concentrations among workers exposed to toluene are those corresponding to 25 W or less. In conclusion, toxicokinetic modeling confirms the significant impact of work load on toluene exposure indicators, whereas only a very slight effect is noted on n-hexane kinetics. These results highlight the necessity of taking work load into account in risk assessment relative to toluene exposure.

Association entre anomalies spermatiques et environnement professionnel chez les hommes consultant pour infertilité de couple

Alteration of sperm parameters related to occupational exposures is the subject of several studies, often on a case-control approach. The study populations usually comprise men consulting in infertility clinics for couple infertility. The objective of this review is to identify, from these case-control studies, the main occupational factors that may be associated with altered sperm parameters. We selected 13 articles in the PubMed database. Participation in these studies varied from 61 to 2619 subjects, with great methodological heterogeneity, particularly in the characterization of exposure. The main occupations that appear significantly associated with a risk of altered sperm parameters are workmen, painters, farmers, welders, plumbers and technicians. When analysis focuses on occupational exposures, a significant result is reported for solvents, heavy metals, heat, vibrations and non-ionizing radiation. None of the selected studies has found a link with exposure to pesticides.

Risque génotoxique et exposition au formaldéhyde en laboratoire d'anatomo-pathologie : métrologie atmosphérique et biogénotoxicologie

Resume Objectif Le but de l’etude est d’evaluer les effets genotoxiques associes a l’exposition au formaldehyde aupres de sujets travaillant dans des laboratoires hospitaliers d’anatomo-pathologie. Methodes L’exposition au formaldehyde a ete mesuree au moyen de badges de prelevements passifs portes a proximite des voies respiratoires de 59 travailleurs pendant 15 minutes et 8 heures. L’evaluation des mutations chromosomiques a ete realisee a l’aide du test des micronoyaux avec blocage de la cytodierese au niveau des lymphocytes de 59 exposes et de 37 temoins apparies pour l’âge, le sexe et le tabagisme. Le test des micronoyaux a ete associe a l’hybridation in situ fluorescente d’une sonde pancentromerique chez 18 exposes et 18 temoins tires au sort dans les populations initiales. Resultats et discussion Les concentrations moyennes en formaldehyde etaient de l’ordre de 2,0 ppm (0,1 a 20,1 ppm) et de 0,1 ppm (0,1 a 0,7 ppm) pour des temps de prelevements respectivement de 15 minutes et de 8 heures. Les taux de lymphocytes binuclees micronuclees etaient plus eleves chez les sujets exposes que chez les temoins (16,9 ‰ ± 9,3 versus 11,1 ‰ ± 6,0 ; p = 0.001). Les taux de micronoyaux centriques etaient plus eleves chez les sujets exposes que chez les temoins (17,3 ‰ ± 11,5 versus 10,3 ‰ ± 7,1) mais la difference n’etait pas significative. Les taux de micronoyaux acentriques etaient similaires entre les deux populations exposee et temoin. Conclusion L’elevation des dommages chromosomiques, lies principalement a la perte de chromosomes entiers, dans les lymphocytes des sujets travaillant dans des laboratoires d’anatomo-pathologie souligne la necessite de mettre en œuvre des programmes de prevention appropries.