Cytogenetic analysis of peripheral blood lymphocytes in workers exposed to benzene

In the present study, the method of cytogenetic analysis of peripheral blood lymphocytes was used to investigate 66 workers exposed to benzene, and 20 individuals selected from general population from the same locality, not exposed to particular mutagenic or carcinogenic agents (control group). Altogether, 8,600 metaphases were analysed. Frequencies of aberrant cells, including chromatide and chromosomal breaks, and chromatide and chromosomal exchanges, were scored in both groups. A very slight increase in aberrant cell frequencies (2.152% aberrant cells) was observed in the professional exposure group as compared to the control group (1.6% aberrant cells). Increased frequencies of aberrant cells were found in smokers of both the benzene-exposed and the control group. The differences were however not significant. In addition to cytogenetic examination, the workers underwent a general examination of their health condition (preventive examination). Benzene exposure seemed to have no injurious effect on the state of health of exposed workers. Biochemical and haematological tests gave normal values.     

Micronuclei in human peripheral blood lymphocytes exposed to mixed beams of X-rays and alpha particles

The purpose of this study was to analyse the cytogenetic effect of exposing human peripheral blood lymphocytes (PBL) to a mixed beam of alpha particles and X-rays. Whole blood collected from one donor was exposed to different doses of alpha particles ((241)Am), X-rays and a combination of both. All exposures were carried out at 37 °C. Three independent experiments were performed. Micronuclei (MN) in binucleated PBL were scored as the endpoint. Moreover, the size of MN was measured. The results show that exposure of PBL to a mixed beam of high and low linear energy transfer radiation led to significantly higher than expected frequencies of MN. The measurement of MN size did not reveal any differences between the effect of alpha particles and mixed beam. In conclusion, a combined exposure of PBL to alpha particles and X-rays leads to a synergistic effect as measured by the frequency of MN. From the analysis of MN distributions, we conclude that the increase was due to an impaired repair of X-ray-induced DNA damage.     

Cytogenetic analysis of peripheral blood lymphocytes in workers exposed to vinyl chloride

In the present study, the method of cytogenetic analysis of peripheral blood lymphocytes was used to examine 43 workers exposed to vinyl chloride monomer (average exposure 11.2 years) and 22 subjects selected from the same locality (control group). A total number of 8650 metaphases were analysed. All cytogenetic parameters examined were increased in the exposed group as compared to the control group and 3 parameters, chromatid breaks, percentage of aberrant cells and breaks per cell, were significantly increased (P less than 0.001).     

Micronuclei in peripheral blood lymphocytes and buccal epithelial cells of Polish farmers exposed to pesticides.

In this biomonitoring study, we investigated whether an occupational exposure to a complex mixture of chemical pesticides produced a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Forty-nine male workers exposed to pesticides, from an agricultural area of Malopolska Region in Southern Poland, together with 50 men from the same area without indication of exposure to pesticides that served as controls, were used in this investigation.No statistically significant differences in the frequencies of cytogenetic damage were detected between exposed and control individuals, for either type of cells. The multiple linear regression analysis in the case of lymphocytes indicated that the studied cytogenetic endpoints were inversely influenced by alcohol; whilst a negative binomial regression, in the case of buccal cells, indicated that the MN values were directly influenced by the ingestion of red meat. An inverse negative relationship between the cytokinesis-block proliferation index and age, and a significant increase of miscarriages due to the exposure to pesticides were also observed.     

Cytogenetic analysis of peripheral blood lymphocytes of workers occupationally exposed to styrene

The genetic risk run by workers occupationally exposed to styrene vapors was assessed in two different plants A and B, using the cytogenetic analysis of peripheral blood lymphocytes. In plant A engaged in the manufacture of polystyrene vessels the mean styrene exposure level was found to range between 70 and 150 mg . m-3, in plant B manufacturing sports boats, plastic slides for children and plastic guard-stones it reached the level of about 200 mg . m-3. The rate of aberrant cells (AB.C.) found in plant A workers (N = 36) at the time of first sampling was 1.38% and the value of break/cell (B/C) ratio was 0.015; at the second sampling the rate of AB.C. was 1.41% and the B/C ratio was 0.014. The group of matched controls (N = 19) was found to have 1.26% of AB.C. and 0.014 breaks per cell. Plant B workers (N = 22) exhibited at the first sampling 1.72% of AB.C. and their value of B/C ratio was 0.018, the group of matched controls (N = 22) had 1.36% of AB.C and the B/C ratio 0.015; the respective values at the time of second sampling were 2.81% for AB.C. rate and 0.029 for B/C ratio in the exposed and 1.89% for AB.C. rate and 0.021 for B/C ratio in the control group. It is concluded that styrene exposure levels below 100 mg . m-3 do not pose any serious genetic risk for the exposed population groups. The variations found in the degree of chromosome injury by smoking habits, drug intake pattern, or sex were not statistically significant.     

Cytogenetic analysis of peripheral blood lymphocytes in glass workers occupationally exposed to mineral oils

Chromosome aberration tests were carried out in a group of 31 pressed glass makers operating an automatic line of press-and-blow machines known to release mineral oil mists containing relatively high concentrations of the mutagenic chemicals belonging to a class of polycyclic aromatic hydrocarbons (PAH). The workers were exposed to the mineral oil aerosol levels that did not exceed the Czechoslovak maximum allowable concentration limit of 5 mg . m-1 of air. The tests revealed that the frequency of aberrant cells (% AB.C.) and the value of breaks per cell (B/C) ratio found in mineral oil-exposed workers were increased significantly, accounting for 4.65 +/- 0.29% AB.C. (0.0532 B/C) vs. 1.13 +/- 0.19% AB.C. (0.0113 B/C) seen in matching controls. Also, a higher rate of dicentrics, reciprocal translocations and cells with pulverization was observed in this group of glass workers. These finding are considered as evidence suggesting that these workers might experience an increased risk of genetic injury due to exposure to mineral oil mists.     

Micronuclei frequency in peripheral blood lymphocytes of cancer patients: a meta-analysis

Micronuclei (MN) frequency is a biomarker of chromosomal damage, genome instability, and cancer risk that integrates acquired mutations and genetic susceptibility. To evaluate and summarize the evidence reporting association between cancer and MN formation, we performed a meta-analysis assessing the frequency of this biomarker in cancer patients. Findings from 37 publications were retrieved through an extensive search of the MedLine/PubMed database. Given the heterogeneity of the study design, all studies were re-classified into three groups: (i) baseline MN frequency of untreated cancer patients (25 studies), (ii) induced MN frequency in thyroid cancer patients undergoing radioiodine treatment (9 studies), and (iii) radiosensitivity of lymphocytes (12 studies) in untreated cancer patients. A meta-estimate of the frequency ratio (meta-FR) was computed in each group. A significant increase of MN frequency was found in untreated cancer patients (meta-FR=1.45; 95% Confidence Interval (95% CI): 1.28-1.64) and in thyroid cancer patients after radioiodine treatment (meta-FR=2.26; 95% CI: 1.90-2.68). The third meta-analysis showed a negative trend of meta-FR's when plotted vs. the dose used to study patients' radiosensitivity, possibly associated to a high rate of apoptosis. The results of this review substantiate the existing evidence about a role of MN in various steps of carcinogenesis. The relatively small numbers of papers suitable for the meta-analysis call for new and larger studies, possibly based on high-throughput techniques, to further understand the role of MN formation in the occurrence of genetic instability and cancer.     

Cytogenetic analysis of peripheral blood lymphocytes of occupational workers exposed to low levels of ionising radiation.

The incidence of chromosomal aberrations was analysed in peripheral blood lymphocytes of occupationally exposed people having cumulative doses of 500 mSv. The exposed individuals showed higher frequencies of dicentrics as well as acentrics than normal controls. Absorbed radiation dose was calculated by using in vitro dose response curve established for Cobalt-60 gamma rays. In the control constituting 17 healthy individuals, two dicentrics were detected among 3700 metaphases analysed. In the exposed group 27 dicentrics and one centric ring was detected among 8400 metaphases analysed. Due to small number of dicentrics scored in each individual, the dose estimate suffers from a large statistical uncertainty. The collective dose was found to be 1.89 Gy. This is in good agreement with the corrected physical doses, assuming a mean life of 10 years for the disappearance of lymphocytes. The physical doses accumulated during the last 10 years of occupation were also in good agreement with the biological dose estimate.     

Micronuclei frequency in lymphocytes of individuals occupationally exposed to pesticides.

Pesticides have been widely used in developing countries over the years. A large amount of these remains in the environment and organisms. Pesticide pollution is detrimental to human health. The effects can be seen on a short or a long-term basis and the symptoms can vary from headache to cancer. Only a minority of studies focuses on their genotoxic effect. This study assesses the genotoxic effect of the pesticides used at banana-packaging plants with binucleate micronuclei assay using cultured lymphocytes. The studied population included 32 exposed and 37 unexposed women from Costa Rica. There is no significant difference between the two groups. However, women who worked at the packaging plant and had stillbirths or spontaneous abortions were 1.45 times more (alpha = 0.06) likely to have an increased micronuclei frequency than their coworkers who lacked those disorders; this may indicate genetic susceptibility. In vitro pesticides studies and susceptibility biomarkers are needed to identify subgroups with higher risks.     

Micronuclei in peripheral lymphocytes and exfoliated urothelial cells of workers exposed to 4,4′-methylenebis-(2-chloroaniline) (MOCA)

4,4′-Methylenebis-(2-chloroaniline) (MOCA) is used in the manufacture of polyurethane. The IARC classifies MOCA as a probable human carcinogen. Suggested changes to guidelines for health surveillance of MOCA-exposed workers in Australia include a reduction in acceptable levels of urinary MOCA to below 15 μmol/mol creatinine. Twelve male workers aged 24 and 42 years were recruited into this study from four work locations where MOCA is used. Exfoliated urothelial cells from prework urine samples on a midweek work day were assessed for micronucleus (MN) frequencies. Postwork urine samples were analysed for total MOCA. Blood samples collected on the same day were cultured for 96 h and cytochalasin-B-blocked cells were scored for MN. Eighteen male control subjects (23–59 years) provided corresponding urine and blood samples. Median urinary MOCA concentrations were 6.5 μmol/mol creatinine (range 0.4–48.6 μmol/mol creatinine) in postwork samples of MOCA-exposed workers. MOCA was not detected in urine of control workers. Mean MN frequencies were higher in urothelial cells and lymphocytes of MOCA workers (14.27±0.56 and 13.25±0.48 MN/1000 cells) than in controls (6.90±0.18 and 9.24±0.29 MN/1000 cells). The mean number of micronucleate cells was also higher in both tissues of exposed workers (9.69±0.32 and 8.54±0.14 MN cells/1000 cells) than in controls (5.18±0.11 and 5.93±0.13 MN cells/1000). There was no correlation between postwork urinary MOCA concentrations and MN frequencies in either tissue. This study suggests that exposures to MOCA in South Australia are similar to those of a decade ago and are at levels similar to those currently acceptable in Australia. These are associated with genotoxic effects in urothelial cells and peripheral blood lymphocytes. It may be prudent to reduce MOCA exposures in line with proposed guidance values.     

Genomic damages in peripheral blood lymphocytes and association with polymorphisms of three glutathione S-transferases in workers exposed to formaldehyde

DNA and chromosome damages in peripheral blood lymphocytes were evaluated in 151 workers occupationally exposed to formaldehyde (FA) and 112 non-FA exposed controls. The effects of polymorphisms in three glutathione-S-transferase (GSTs) genes on the DNA and chromosome damages were assessed as well. Alkaline comet assay and cytokinesis-block micronucleus (CBMN) assay were used to determine DNA and chromosome damages, respectively. The genotypes of GSTP1 (Ile105Val), GSTT1, and GSTM1 were assayed. The mean 8-h time-weighted average (TWA) concentrations of FA in two plywood factories were 0.83 ppm (range: 0.08–6.30 ppm). FA-exposed workers had higher olive tail moment (TM) and CBMN frequency compared with controls (Olive TM, 3.54, 95%CI = 3.19–3.93 vs. 0.93, 95%CI = 0.78–1.10, P < 0.01; CBMN frequency, 5.51 ± 3.37 vs. 2.67 ± 1.32, P < 0.01). Olive TM and the CBMN frequency also had a dose-dependent relation with the personal FA exposure. Significant association between FA exposure history and olive TM and CBMN frequency were also identified. The level of olive TM was slightly higher in FA-exposed workers with GSTM1 null genotype than those with non-null genotype (3.86, 95%CI = 3.31–4.50 vs. 3.27, 95%CI = 2.83–3.78, P = 0.07) with adjustment of covariates. We also found that FA-exposed workers carrying GSTP1 Val allele had a slightly higher CBMN frequency compared with workers carrying only the wild-type allele (6.32 ± 3.78 vs. 5.01 ± 2.98, P = 0.05). Our results suggest that the FA exposure in this occupational population increased DNA and chromosome damages and polymorphisms in GSTs genes may modulate the genotoxic effects of FA exposure.     

Micronuclei in peripheral blood and bone marrow cells of mice exposed to 42 GHz electromagnetic millimeter waves

The genotoxic potential of 42.2 +/- 0.2 GHz electromagnetic millimeter-wave radiation was investigated in adult male BALB/c mice. The radiation was applied to the nasal region of the mice for 30 min/day for 3 consecutive days. The incident power density used was 31.5 +/- 5.0 mW/cm2. The peak specific absorption rate was calculated as 622 +/- 100 W/kg. Groups of mice that were injected with cyclophosphamide (15 mg/kg body weight), a drug used in the treatment of human malignancies, were also included to determine if millimeter-wave radiation exposure had any influence on drug-induced genotoxicity. Concurrent sham-exposed and untreated mice were used as controls. The extent of genotoxicity was assessed from the incidence of micronuclei in polychromatic erythrocytes of peripheral blood and bone marrow cells collected 24 h after treatment. The results indicated that the incidence of micronuclei in 2000 polychromatic erythrocytes was not significantly different among untreated, millimeter wave-exposed, and sham-exposed mice. The group mean incidences were 6.0 +/- 1.6, 5.1 +/- 1.5 and 5.1 +/- 1.3 in peripheral blood and 9.1 +/- 1.1, 9.3 +/- 1.6 and 9.1 +/- 1.6 in bone marrow cells, respectively. Mice that were injected with cyclophosphamide exhibited significantly increased numbers of micronuclei, 14.6 +/- 2.7 in peripheral blood and 21.3 +/- 3.9 in bone marrow cells (P< 0.0001). The drug-induced micronuclei were not significantly different in millimeter wave-exposed and sham-exposed mice; the mean incidences were 14.3 +/- 2.8 and 15.4 +/- 3.0 in peripheral blood and 23.5 +/- 2.3 and 22.1 +/- 2.5 in bone marrow cells, respectively. Thus there was no evidence for the induction of genotoxicity in the peripheral blood and bone marrow cells of mice exposed to electromagnetic millimeter-wave radiation. Also, millimeter-wave radiation exposure did not influence cyclophosphamide-induced micronuclei in either type of cells.     

Cytogenetic biomonitoring of Spanish greenhouse workers exposed to pesticides: micronuclei analysis in peripheral blood lymphocytes and buccal epithelial cells

In the present study, we evaluate whether or not occupational exposure to a complex mixture of pesticides results in a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Sixty four greenhouse workers from Almería (Southeastern Spain), together with 50 men from the same area, without indication of exposure to pesticides, that served as controls were used in this investigation. The results obtained indicate that there are no statistically significant differences in the MN frequencies between the two groups. Each donor was assessed for the presence or absence of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1), to look for relationships between the genotypes and the cytogenetic reponses. According to the GSTT1 genotype, there is a difference between both groups only for the cytokinesis-block proliferation index (CBPI). Neither GSTM1 nor smoking habit and age showed any effect in the overall analysis.     

Analysis of chromosomes in peripheral blood lymphocytes of styrene-exposed workers

A group of 11 workers exposed to an average of 253 mg.m-3 styrene had no elevation of the frequencies of chromosomal aberrations in their peripheral lymphocytes when compared to 11 healthy persons.     

Cytogenetic analysis of chromosomal aberrations of peripheral lymphocytes in workers occupationally exposed to nickel.

The authors carried out a cytogenetic examination of chromosomal aberrations of peripheral lymphocytes (100 cells evaluated in each sample) with simultaneous monitoring of the level of exposure by means of determination of nickel in the urine, serum and hair. The series included 21 workers occupationally exposed to nickel at two workshops producing NiO (6 persons) and NiSO4 (15 persons) in a chemical plant. At the same time a comparable control group, i.e., 19 workers of the same chemical plant but without any direct occupational nickel exposure (clerks, service men, etc.), were examined in the same way. In the exposed group chromosomal aberrations of peripheral lymphocytes were detected with an average value of 6.41 +/- 1.9% (range 2-14%); in the group producing NiO it was, on the average, 9.5 +/- 3.2% (range 7-14%) whereas in the NiSO4 production workers it was only 5.2 +/- 1.9% (range 2-10%). There was a dependence of chromosomal aberrations of peripheral lymphocytes on the exposure time and on the nickel content of the biological material. Significantly increased values (in contrast to the normal value of chromosomal aberrations of peripheral lymphocytes, up to 2%) were detected in the control group as well (average value of 4.05 +/- 2.27%, range 1-10%). The authors explain this fact by the nickel-polluted environment of the whole observed chemical plant.     

Sister-chromatid exchanges in lymphocytes of workers exposed to trichloroethylene

To detect mutagenic effects of trichloroethylene (TCE) on humans, sister-chromatid exchanges (SCEs) were analyzed in lymphocytes of 22 workers occupationally exposed to TCE and 22 matched controls. Although urinalysis in the workers revealed their obvious exposure to TCE, no increase in SCE frequencies was found in lymphocytes of the workers. SCE analysis in lymphocytes could not detect mutagenic effects by occupational exposure to TCE on humans.