Chromosome analysis in operating room personnel

Exposure to volatile anaesthetics is not followed by a massive induction of single-strand DNA breaks in operation theatre personnel

Volatile anaesthetics such as halothane, isoflurane and others were expected to produce a health challenge for operation room personnel because of prolonged occupational exposure to anaesthetic gases. To estimate a molecular background of adverse health effects, a cohort of 100 exposed individuals was studied by the single-cell gene electrophoresis (comet assay) test. DNA lesions in lymphocytes of the exposed group did not differ significantly compared with non-exposed blood donors. Then, the exposed group was further divided according to job position. A highest level of DNA lesions was established in nurses but without significant difference compared with other groups. When a time period of exposure was taken into account, a tendency to cumulate DNA lesions was found only in the group of anaesthesiologists. A very weak genotoxic effect established in this study is discussed in relation to DNA repair, adaptative response and potential self-elimination of sensitive individuals.

Determination of DNA damage after exposure to inhalation anesthetics in human peripheral lymphocytes and sperm cells in vitro by comet assay

In this study, genotoxic activities of four halogenated anesthetics (halothane, isoflurane, sevoflurane and desflurane) were investigated in human peripheral blood lymphocytes (PBLs) and sperm cells in vitro by alkaline comet assay. For this purpose, sperm or lymphocyte suspension was exposed to different concentrations (0.1 mM, 1 mM, 10 mM and 100 mM) of anesthetic agents and 1% dimethyl sulfoxide (DMSO) or phosphate-buffered saline (PBS) as controls. The DNA strand breaks as well as alkali-labile sites were measured as percentage tail intensity with comet assay. The results of this study demonstrate that all analyzed drugs were capable of inducing DNA damage on PBLs in a dose-dependent manner in vitro. However, the results in sperm cells were slightly different since we did not observe any genotoxic effect for desflurane in any of the exposure doses, and the genotoxic effect of halothane was not dose dependent. This experimental study points out to the presence of DNA damage after exposure to halogenated anesthetics in both PBLs and sperm cells, although this effect seems to be higher in PBLs.

Detection of premature segregation of centromeres in persons exposed to ionizing radiation

We have analyzed the frequency of premature centromeric division (PCD) in medical personnel professionally exposed to low doses of radiation. They had chromosome aberrations (CAs) involving dicentric chromosomes, ring chromosomes, acentric fragments, chromosome breaks, and chromatid breaks. The study included 30 exposed subjects and 23 controls who were each analyzed by a conventional cytogenetics procedure and subsequently by fluorescent in situ hybridization (FISH). The latter was applied particularly in order to verify PCD in a specific chromosome (chromosome 18) in both metaphases and interphase nuclei. The results revealed a significant difference (p < 0.001) in frequencies between the two groups (exposed and controls) for all the observed variables (CAs), metaphases with PCD (MPCD), total number of chromosomes with PCD (TPCD), number of PCD metaphases in acrocentric chromosomes (MAPCD), and the total number of acrocentric chromosomes with PCD (TAPCD). The doses of ionizing radiation absorbed by the subjects' bodies were measured with thermoluminescent dosimeters once a month during the duration of occupational exposure. They were expressed in mSv, as mean annual effective doses for the period of exposure. The Spearman rank test showed a high positive correlation between total life effective dose and frequency of CAs and PCD. Based on the results obtained in this study, we suggest that PCD, as a phenomenon manifesting chromosomal instability (CIN), should be considered as a suitable cytogenetic biomarker for individuals occupationally exposed to ionizing radiation.

Cytogenetic analysis in Chinese hamster cells chronically exposed to low doses of X‐rays

PURPOSE

It is important to develop simple experimental models to assess the induction of DNA damage and study the different factors involved under controlled conditions. This paper describes the cytogenetic analysis carried out in Chinese hamster cells (CHO) sequentially exposed to very low doses of X-rays.

MATERIALS AND METHODS

CHO cells were cultured for 14 passages. Irradiation treatment was performed once per passage, and three irradiation doses were employed: 2.5, 5.0 and 10.0 mSv.

RESULTS

Sequential irradiation of CHO cells did not increase the yield of chomatid- or chromosome-type aberrations. However, a significant increase of achromatic lesions (gaps) was found after the first or second X-ray dose, with all three irradiation doses employed.

CONCLUSIONS

The variation in the frequency of gaps as well as that in the mitotic index during the 14 cycles of radiation could be an indication of the induction of genomic instability. According to this, continuous rises and falls in the frequency of gaps as well as in the mitotic index reflects the simultaneous induction of endogenous DNA damage, cell death and cell survival.

Determination of DNA damage by alkaline halo and comet assay in patients under sevoflurane anesthesia

In this study, we report data on the possible genotoxic effect of inhalation anesthetic sevoflurane (SVF) by comparing two techniques, comet and alkaline halo assay, in peripheral blood lymphocytes (PBL) of patients before, during, and after anesthesia and in controls. DNA single strand breaks were detected in PBL of malignant breast cancer diagnosed patients (stage II–III), who were undergoing mastectomy. Blood samples were taken before the induction of anesthesia, at 120 min of SVF anesthesia, and on the postoperative fifth day. The nuclear spreading factor (NSF) for each cell was assessed by alkaline halo assay, and the total comet score (TCS) was evaluated by comet assay. A statistically significant increase ( P < 0.0001) was observed in the mean NSF at 120 min of anesthesia (38.24 ± 14.14) as compared with samples before anesthesia (12.33 ± 6.14), and the mean NSF was significantly decreased after the postoperative fifth day (17.89 ± 9.44). Similar results were obtained by the comet assay with significant increase ( P < 0.0001) in DNA damage at 120 min of anesthesia (79.66 ± 15.28) as compared with samples before anesthesia (36.30 ± 11.39). The DNA damage was almost with the preoperative damage rates after the fifth day of anesthesia (43.40 ± 12.19). In conclusion, the study points out a reversible genotoxic effect of SVF and the similar DNA damage levels obtained by comet and alkaline halo assay indicate that although halo assay has a completely different principle, it can conveniently be utilized for the assessment of DNA single strand breakage in individual mammalian cells with its experimental advantages.

Increased incidence of micronuclei assessed with the micronucleus assay and the fluorescence in situ hybridization (FISH) technique in peripheral blood lymphocytes of nurses exposed to nitrous oxide

It has been postulated that exposure to nitrous oxide and halogenated anaesthetics is associated with various adverse health effects such as neurological and reproductive abnormalities or impairment of hepatic functions. In spite of the quite well known genotoxic effects of exposure to nitrous oxide in vivo, the mechanisms of these effects are still not clear. The aim of this study was to assess the frequency of micronuclei and to identify the type of chromosomal damage (clastogenic or aneugenic) in peripheral blood lymphocytes of operating-room nurses exposed to nitrous oxide. The study group comprised 46 women working at departments where the concentration of nitrous oxide ranged from 14 to 2308 mg/m3. The control population was composed of 28 women employed in the same hospitals but in non-surgical departments. The clastogenic/aneugenic effect of nitrous oxide was evaluated in lymphocytes using the standard micronucleus (MN) assay in combination with the fluorescence in situ hybridization (FISH) technique with pancentromeric probes. The results show a significant increase of the MN frequency in lymphocytes of exposed nurses compared with the control group (4.36+/-2.23 versus 9.02+/-4.67). The multiple regression analysis revealed a statistically significant relationship (p=0.0009) between MN frequency and exposure status, indicating that the level of exposure was the main factor affecting chromosomal damage. As assessed by FISH analysis, the overall frequencies of centromere-positive MN in the control and exposed groups were 43 and 49%, respectively. The increase observed in the exposed group may suggest a slight, statistically insignificant pro-aneugenic effect of exposure to nitrous oxide.

Cytogenetic tests performed on operating room personnel (the use of anaesthetic gases)

OBJECTIVES

Personnel exposure to anaesthetic gases in the health sector, whether in the operating room, recovery room, or in the context of outpatient clinics, may entail a health risk. The goal of this research was to study the cytogenetic effects of chronic exposure to small doses of pollutants in operating theatres.

METHODS

Results of cytogenetic analyses [structural chromosomal aberrations (SCAs), sister chromatid exchange (SCE) and micronucleus (MN) test] of anaesthetists and other personnel handling anaesthetic gases, who only occasionally work in zones of ionizing radiation, were compared with results from radiologists, occupationally exposed to ionizing radiation only, and with the results obtained from a group of Slovene citizens who were never exposed to genotoxic agents.

RESULTS

This study involved 153 workers handling anaesthetic gases. The average frequency of SCAs in the group working with anaesthesia was 2.693. The result was statistically significantly higher than in the group of radiologists and Slovene citizens. The frequency of SCE and MN was also statistically significant. A number of authors, who used the same cytogenetic tests, found similar results in the group of anaesthetist.

CONCLUSION

The results of our study indicate that exposure to anaesthetic gases induced changes in human chromosomes.

Occupational hazards of inhalational anaesthetics

Occupational exposure to inhalational anaesthetics has often been associated with health hazards and reproductive toxicity, but the available evidence is weak and comes mostly from epidemiological studies that have been criticized. Studies based on registered data generally showed no association between occupational exposure to inhalational anaesthetics and reproductive effects. Animal studies also showed a lack of carcinogenicity, organ toxicity and reproductive effects with trace concentrations, as observed in operating rooms. The exception may be nitrous oxide, which in some, but not all, studies showed teratogenicity in rats chronically exposed to concentrations of 1000 p.p.m. and higher, such as may occur in unscavenged operating rooms lacking a mechanical ventilation system. Occupational exposure has also been associated with impairment of psychological functions, but these effects do not occur with trace concentrations. All in all, the scientific evidence for hazards is weak. Nonetheless, it is good practice to limit levels of exposure.

Effects of chronic exposure to anaesthetic gases on some immune parameters

A cross-sectional survey was carried out to evaluate the relation between occupational exposure to low levels of anaesthetic gases (nitrous oxide and isoflurane) and immune parameters. Fifty-one anaesthetists were recruited among different Services of Anaesthesiology and Reanimation. The control group consisted of non-exposed physicians, similar for gender, age, and job grade. Total number of lymphocytes, lymphocyte subpopulations and the natural killer (NK) cytotoxic activity were measured. Information on personal and professional characteristics and on short- and long-term exposure was collected. Percentages of T cells (CD3) decreased significantly in anaesthetists compared to controls, whereas numbers of NK cells (CD16+ CD3-) increased. After correction for confounders, short-term (last 2 weeks) exposure was associated with a decrease in percentages of total T and T helper (CD4) cells. Furthermore, T helper percentages were significantly reduced with increasing individual exposure score evaluated on the basis of working days and levels of anaesthetic gases in operating rooms. A significant X-ray-associated increase of numbers and percentages of NK cells was lastly observed. Despite limited present exposure to anaesthetic gases, a specific derangement in lymphocyte subpopulations, with T lymphocytes more affected than B, has been observed.

Occupational exposure to trace concentrations of waste anesthetic gases

The relationship between exposure to trace concentrations of waste anesthetic gases in the operating room and the possible development of adverse health effects has concerned health care professionals for numerous years. Results of studies have been conflicting. In the late 1960s and early 1970s, some US and European epidemiological studies of operating room personnel showed an increase in the incidence of adverse health effects, including spontaneous abortion and development of congenital abnormalities in offspring. However, subsequent analysis of these studies by 2 independent groups showed that the apparent increase in adverse health effects was most likely due to flaws in these studies' methods and data collection. A later prospective study showed no causal relationship between exposure to trace concentrations of waste anesthetic gases and adverse health effects. Each institution should have a waste anesthetic gas management program that includes scavenging of waste anesthetic gases, work practices to reduce contamination, documented maintenance and regular checking of all equipment, and education of all personnel on this subject. A mechanism for reporting work-related health problems should be in place in each institution.

Genetic damage in operating room personnel exposed to isoflurane and nitrous oxide

OBJECTIVES

To evaluate genetic damage as the frequency of sister chromatid exchanges and micronuclei in lymphocytes of peripheral blood of operating room personnel exposed to waste anaesthetic gases.

METHODS

Occupational exposure was measured with a direct reading instrument. Venous blood samples were drawn from 10 non-smokers working in the operating room and 10 non-smoking controls (matched by age, sex, and smoking habits). Lymphocytes were cultured separately over 72 hours for each assay with standard protocols. At the end of the culture time, the cells were harvested, stained, and coded for blind scoring. The exchanges of DNA material were evaluated by counting the number of sister chromatid exchanges in 30 metaphases per probe or by counting the frequency of micronuclei in 2000 binucleated cells. Also, the mitotic and proliferative indices were measured.

RESULTS

The operating room personnel at the hospital were exposed to an 8 hour time weighted average of 12.8 ppm nitrous oxide and 5.3 ppm isoflurane. The mean (SD) frequency of sister chromatid exchanges was significantly higher (10.2 (1.9) v 7.4 (2.4)) in exposed workers than controls (p = 0.036) the proportion of micronuclei (micronuclei/500 binucleated cells) was also higher (8.7 (2.9) v 6.8 (2.5)), but was not significant (p = 0.10).

CONCLUSION

Exposure even to trace concentrations of waste anaesthetic gases may cause dose-dependent genetic damage. Concerning the micronuclei test, no clastogenic potential could be detected after average chronic exposure to waste anaesthetic gas. However, an increased frequency of sister chromatid exchanges in human lymphocytes could be detected. Although the measured differences were low, they were comparable with smoking 11-20 cigarettes a day. Due to these findings, the increased proportion of micronuclei and rates of sister chromatid exchanges may be relevant long term and need further investigation.

Chromosome aberrations in operating room personnel

BACKGROUND

Long-term occupational exposure to volatile anesthetic agents may result in various adverse health effects. Additionally, certain surgical procedures involve exposure to the other agents such as X rays. Identification of chromosome damages in peripheral blood lymphocytes serves as a useful indicator of exposure to mutagenic agents.

METHODS

The frequency of chromosomal aberrations was assayed in peripheral lymphocytes obtained from 129 subjects working in operating theatres and 41 control subjects.

RESULTS

The results show an increased rate of chromosome aberrations in the exposed subjects. The differences in frequency of chromosome aberrations between particular job tasks were not distinct. Acentric fragments in anesthesiologists and dicentrics in surgeons seem to stand out.

CONCLUSIONS

As the findings do not differ significantly between the exposed groups, one can hardly distinguish radiation and anesthetics effects from one another.

Increased frequency of micronucleated kidney cells in rats exposed to halogenated anaesthetics

Six halogenated anaesthetics were tested for their ability to induce micronuclei formation in the rat kidney. A statistically significant increase in the frequency of micronucleated cells was detected in rats given a single p.o. dose of 4 mmol/kg of halothane (3.48 x baseline), chloroform (3.32 x baseline), trichloroethylene (3.24 x baseline), sevoflurane (2.98 x baseline), and isoflurane (2.95 x baseline). In contrast, the response was substantially negative in rats given the same dose of enflurane. As compared to controls, rats treated with halothane and trichloroethylene displayed a reduction in the frequency of binucleated cells presumably due to a toxicity-induced inhibition of cellular proliferation. These findings suggest a potential genotoxic activity of halogenated anaesthetics for the rat kidney.