1. Mutation Research 627 (2007) 158–163
Cytogenetic damage in workers from a coal-fired power plant
Mustafa Celik a , Lale Donbak a,∗ , Fatma Unal b , Deniz Y¨ zbasıoglu b ,
u
H¨ seyin Aksoy
u b , Serkan Yılmaz b
a University of Kahramanmaras S¨ tc¨ Imam, Science and Arts Faculty, Department of Biology, Kahramanmaras, Turkey
u u
b University of Gazi, Science and Arts Faculty, Department of Biology, Ankara, Turkey
Received 25 July 2006; received in revised form 21 October 2006; accepted 10 November 2006
Available online 18 December 2006
Abstract
The aim of this study was to investigate the genotoxic risk to workers occupationally exposed to coal combustion products in
Afsin-Elbistan A power plant, located in south-eastern Turkey. We analysed chromosomal aberrations (CAs), polyploidy, sister-
chromatid exchanges (SCEs), and micronuclei (MN) in 48 male workers without a history of smoking, tobacco chewing, or alcohol
consumption. The results were compared with a control group of 30 healthy male individuals without exposure to any known
genotoxic agents. The mean frequencies of CA, polyploidy, SCEs (P < 0.01), and MN (P < 0.05) were significantly higher in
workers than in the control group, by the Mann–Whitney U-test. Spearman’s rho correlation analysis revealed a significant increase
in the frequency of CA and MN with increasing years of exposure (P < 0.05). However, there was no significant effect of age on
the cytogenetic markers analysed in both groups (P > 0.05). The data obtained from this study clearly showed chromosomal hazard
in the peripheral lymphocytes of workers exposed to coal combustion products in Afsin-Elbistan A power plant for several years.
This cytogenetic damage might be attributed to the cumulative effects of several substances due to chemical complexity of the coal
ash and gaseous emissions rather than a specific substance.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Sister chromatid exchange; Chromosomal aberrations; Micronucleus; Genotoxic risk; Coal-fired power plant; Coal combustion products
1. Introduction ash (which is removed at the bottom of the boiler).
Coal ash particles are a complex mixture, consisting of
Coal-fueled power plants are one of the major sources COx , NOx , SOx , amorphous silicon–aluminium–glass,
of environmental pollution because of release of coal quartz, unburned carbon, heavy metals (arsenic, boron,
combustion products. These products include flue gasses cadmium, chromium, copper, lead, selenium, iron, zinc,
and particulate materials like fly ash (which may be etc.), radioactive elements (uranium, thorium, radium,
collected from flue gas by means of electrostatic pre- radon), and polycyclic aromatic hydrocarbons (PAHs)
cipitators, but is released to the air via chimneys if there [1–3]. Most of these substances are also present in the
is no flue gas cleaning equipment present) and bottom gaseous emissions. The chemical content of coal ash
varies with the type of coal, amount of incombustible
substance in the coal, pulverization and combustion pro-
∗ Corresponding author at: Kahramanmaras S¨ tc¨ Imam Univer-
u u cesses and also precipitation techniques [4–6].
sitesi, Fen Edebiyat Fak¨ ltesi, Biyoloji B¨ l¨ m¨ , Avsar Yerleskesi,
u ou u
Kahramanmaras, Turkiye. Tel.: +90 344 2191000;
In earlier studies concerning the health risks of work-
fax: +90 344 2191042. ers from coal-fired power stations, prolonged, high
E-mail address: lale@ksu.edu.tr (L. Donbak). exposure to coal ash (>5 mg/m3 ) has been demonstrated
1383-5718/$ – see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.mrgentox.2006.11.003

2. M. Celik et al. / Mutation Research 627 (2007) 158–163 159
to cause lung function impairment and respiratory symp- Afsin-Elbistan A power plant during the waste ash dis-
toms [7,8]. In another study [9], a possible lung cancer posing process were investigated by analysing the CA,
risk has been observed among Italian electricity work- polyploidy, SCE, and MN frequencies in the periph-
ers. In a 29 year follow-up study in U.K. power station eral blood lymphocytes from workers as cytogenetic
workers [10], a significant increase of death due to pleu- biomarkers.
ral cancer has been found. In contrast to these studies,
Petrelli et al. [11] did not observe any excess of death 2. Materials and methods
originating from the cancer among workers of a power
plant in Italy. The degree of cancer risk associated with 2.1. Subjects and sampling
combustion products in man has been reported to depend
Prior to the study, informed consent was obtained from
on the time of exposure, and on the types and concen-
each subjects and each individual’s lifestyle (e.g. occupational
trations of biologically active compounds present in the
and health history, habits) was determined by questionnaire
combustion emissions [12]. Several experimental stud- administration. Persons with medical treatment including
ies have indicated the mutagenic and genotoxic effects radiography and vaccination up to three months before collect-
of some constitutients of coal ashes or flue gasses such ing samples were not included in the study. Smokers, alcohol
as CO, NOx , SOx , quartz, heavy metals, and PAHs in dif- consumers, and Maras powder (a kind of smokeless tobacco)
ferent test systems [13–17]. However, only a few studies chewers were also excluded. A total of 48 male workers was
have been done on the genotoxic risks of workers occu- selected for the study, who were engaged in transportation of
pationally exposed in power plants, and have reported waste coal ash for disposal. The waste ashes are transported
increased genetic damage in the occupationally exposed to the dumping area of the coal reserves without wetting. The
groups [18,19]. workers have been exposed to coal ashes by inhalation and
dermal exposure due to heavy dust. However, previous mea-
Volatile and particulate emissions from coal-fired
surements of air quality in the power plant demonstrated that
power plants are serious problems for many developing
the workers have been also exposed to gaseous emissions such
countries, because of insufficient precipitation and desul- as NO, NO2 , NOx , SO2 , and silica as well as coal ashes. In 1995,
furication techniques, and the wastes requiring disposal the air quality measurements in the power plant were stopped,
[20,21]. In time, it may adversely impact environmen- so, the level of air-borne respirable fractions of coal combus-
tal quality and health of populations working and living tion products to which the workers were exposed in the years
around the power plants. Afsin-Elbistan A power plant, just before our study was unknown. The control group con-
located in south-eastern Turkey, may represent an exam- sisted of 30 healthy male subjects with no known exposure to
ple of such power plants. genotoxic agents such as radiation, chemicals, cigarette, Maras
Afsin-Elbistan A power plant, built in 1983, has powder, alcohol, etc. Control subjects were selected from the
four pulverized coal boiler units with a total capac- city, Kahramanmaras, the minumum distance between exposed
and control groups being 160 km. The mean years of potential
ity of 1360 MW. The power plant consumes about
exposure of workers in the power plant was 20.35 ± 0.49 years
48 × 103 tonnes of low quality lignite from Kıslakoy
(range, 6–23 years). The mean age of workers was 46.08 ± 0.54
basin and produces approximately 8 × 103 tonnes of coal years (range, 36–50 years), and of controls was 45.06 ± 0.59
fly ash and bottom ash per day. These waste ashes are years (range, 38–50 years).
transported to the dumping area of the coal reserves for
disposal. In a recent study [22], coal fly ash samples 2.2. Cytogenetic methods
from Afsin-Elbistan A power plant have been reported to
contain calcium oxide, quartz, hematite, and aluminium About 2 ml of venous blood from each persons was col-
oxide, accounting for 74–85% of the material. The other lected in heparinised tubes and immediately transported over
chemical components of coal fly ash were indicated to be ice to the laboratory. Duplicate lymphocyte cultures were set
Cl, Cr2 O3 , K2 O, MgO, MnO2 , MoO3 , Na2 O, NiO, P2 O5 , up by adding six drop whole blood to 2.5 ml of chromosome
SO3 , SrO, TiO2 , V2 O5 , ZrO2 , and CO2 . The workers of medium (Biochrom, Berlin, Germany), supplemented with
the power plant have been exposed to coal ashes and its 10 g/ml bromodeoxyuridine (Sigma, Taufkirchen, Germany).
For the analysis of CA, polyploidy, and SCE, the cultures were
hazardous constituents and also volatile emissions due
incubated at 37 ◦ C for 72 h. At the 70th h of the incubation,
to inadequacy of measures for pollution control. Signif-
0.06 g/ml of colchicine (Sigma) was added to each culture
icant exposure to coal combustion products may occur for arresting the cell cycle at metaphase stage. The cells were
especially during the waste ash removal process because harvested by treating with 0.075 M KCl and methanol:glacial
of heavy dust. acetic acid (3:1) solution. The staining of air-dried slides
In the present study, the possible genotoxic risks was performed according to the modified Fluorescence Plus
of workers exposed to coal combustion products in Giemsa Method [23].

3. 160 M. Celik et al. / Mutation Research 627 (2007) 158–163
For the evaluation of MN frequencies, lymphocytes were (SPSS 10.0, SPSS Inc., USA). All P-values were two tailed and
incubated for 72 h at 37 ◦ C. After 44 h incubation, 6 g/ml of P-values of 5% or less were considered statistically significant
cytocalasin B (Sigma) was added to the tubes to block cytoki- for all tests carried out.
nesis. Following additional 28 h incubation at 37 ◦ C, the cells
were harvested according to the standard procedure [24].
3. Results
2.3. Cytogenetic analysis
The effects of exposure to coal combustion products
A total of 100 well-spread first-division metaphases includ- on the level of CA, polyploidy, SCE, and MN in 48
ing 46 ± 1 chromosomes was analysed for four categories male workers are presented in Tables 1 and 2, respec-
of CAs: chromatid breaks, chromosome breaks, dicentrics, tively. There was a significant (about 3-fold) increase in
and chromatid exchanges. Gaps (achromatid lesions) were not
the frequency of CA (P < 0.01) and also the percentage
scored as CAs. The criteria for distinguishing chromatid breaks
of cells with aberrations (AB.C; P < 0.01) in periph-
from gaps were the acentric piece displaced with respect to the
chromosome axis and the size of the discontinuity exceeded eral lymphocytes from exposed workers compared to
the width of the chromatid. Cells containing any type of chro- the control subjects. The most common type of aber-
mosomal aberrations were scored as aberrant cells (AB.C). ration in workers and controls was the chromatid break,
Metaphases were scored as polyploid if they contained three as shown in Table 1. The comparisons between workers
or four times the haploid number, all chromosomes were mor- and control groups with respect to the level of polyploidy
phologically similar and there was clearly visible cytoplasm. revealed a marked difference in the frequency of poly-
The number of polyploid metaphases among 100 metaphases ploidy (P < 0.01), which was higher in the exposed group
was recorded and expressed as % polyploid cells. Twenty- (Table 1).
five well-spread second-division metaphases were analysed for With regard to frequency of SCE, there was a sig-
determining the level of SCEs. The microscopic examination
nificant differences between the workers and controls
of CAs, polyploidy, and SCEs was performed at 1000× magni-
(P < 0.01) (Table 2). The mean value of SCE for exposed
fication under an oil immersion lens. For each subject, a total of
1000 binucleated lymphocytes was scored with a 40× magni- workers was 6.08, compared with 4.60 for the con-
fication lens, to determine frequency of micronuclei. All slides trol group. The exposed group also showed a slightly
were coded and cytogenetic analysis of slides from workers increased frequency of MN in binucleated lymphocytes,
and controls were carried out “blind” by the same person using about 25% higher than the mean for the control group
a Olympus-light microscope (CX21FS1). (P < 0.05).
We further analysed the data with respect to years of
2.4. Statistical analysis exposure and age of the individuals, to investigate the
association between the cytogenetic markers and inde-
The data points for statistical analysis were the mean fre- pendent variables. Spearman’s rho analysis indicated a
quencies of each endpoint for each individual. Comparison positive correlation between the years of exposure and
of mean values of the percentage of cells with aberrations, fre-
CA (P < 0.05) or MN (P < 0.05) (Table 3). The level
quencies of aberrations per cell, percent polyploid metaphases,
SCE/cell, and MN per 1000 cells between the exposed and
of SCE was not significantly enhanced with the years
control group was assessed by the Mann–Whitney U-test. of exposure, although there was a trend towards an
Spearman’s rho correlation test was used for evaluation of increase in frequency of SCE with the years of expo-
the association between cytogenetic markers and independent sure (P > 0.05). In neither workers nor controls did the
variables of age and years of exposure. Statistical calculations incidence of cytogenetic markers, show a significant cor-
were carried out using the SPSS software package programme relation with age (P > 0.05; Table 3).
Table 1
Frequencies of CA and polyploidies in lymphocytes of workers and control subjects
Group N Age ± S.E.a SCAsb Total SCA CA/cell ± S.E. AB.Cc ± S.E. % Polyploidy ± S.E. %
B B Dic CE
Workers 48 46.08 ± 0.54 106 28 13 10 158 0.033 ± 0.015d 3.12 ± 0.19d 0.52 ± 0.09d
Controls 30 45.06 ± 0.59 22 3 0 3 28 0.009 ± 0.008 0.93 ± 0.13 0.10 ± 0.05
a S.E.: Standard error.
b SCAs: Structural chromosomal aberrations; B :chromatid break; B :chromosome break; Dic:dicentric chromosome; CE: chromatid exchange.
c AB.C: Cells with aberrations.
d P < 0.01.

4. M. Celik et al. / Mutation Research 627 (2007) 158–163 161
Table 2 ers were significantly higher in exposed workers than in
Frequencies of SCE/cell and MN in lymphocytes of workers and con- controls.
trol subjects
Bauman and Horvat [18] reported considerably
Group N Age ± S.E.a SCE/cell ± S.E. MN ± S.E. ‰ increased CA levels in the peripheral lymphocytes of
Workers 48 46.08 ± 0.54 6.08 ± 0.12c 8.20 ± 0.61b workers occupationally exposed in a power station burn-
Controls 30 45.06 ± 0.59 4.60 ± 0.11 6.56 ± 0.43 ing coal, which contained between 14 and 100 ppm
a S.E.: Standard error.
uranium, as compared to control group. Leonard et al.
b P < 0.05. [19], scored chromosome aberrations in 59 workers from
c P < 0.01. coal-fueled power plants and in 89 workers from nuclear-
power plants and reported a significant elevation in acen-
tric chromosome fragments and dicentric chromosomes
Table 3
Correlation analysis of cytogenetic markers in both types of workers compared to the control group.
Moreover, the number of abnormal cells was signifi-
Cytogenetic markers Workers Controls
cantly greater in workers of conventional plants than in
ra P r P those of nuclear-power plants. In the study of Kleinjans
CA/cell et al. [31], peripheral lymphocytes of 22 workers occupa-
CA vs. age 0.143 >0.05 0.040 >0.05 tionally exposed to coal fly ash in a coal fly ash process-
CA vs. years of exposure 0.329 <0.05 ing plant showed a considerably higher incidence of SCE
Polyploidy (%) than in control subjects. About two year after coal fly ash
P vs. age 0.019 >0.05 0.000 >0.05 exposure-reducing measures had been taken in this coal
P vs. years of exposure 0.082 >0.05 fly ash processing plant, Stierum et al. [32], conducted a
SCE/cell study in a group of 18 male workers and 18 male control
SCE vs. age 0.124 >0.05 0.135 >0.05 subjects, to evaluate the effect of these measures with
SCE vs. years of exposure 0.217 >0.05 respect to genotoxic risk. In contrast to previous study
MN (‰) of Kleinjans et al. [31], no increased SCE frequencies
MN vs. age 0.022 >0.05 0.111 >0.05 were found in workers potentially exposed to coal fly ash
MN vs. years of exposure 0.287 <0.05 when compared to the control group. In addition, no dif-
a Correlation coefficient. ferences were observed between the exposed and control
groups for frequencies of gene mutations at the hypox-
anthine guanine phosphoribosyltransferase (hprt) locus,
4. Discussion for MN frequencies or for urinary mutagen excretion.
The observed elevation in the frequency of CA and
Coal combustion products from power plants have SCE in the workers of Afsin-Elbistan A power plant was
shown evidence of carcinogenic and genotoxic effects in consistent with the observations in the previous studies
different test systems, ascribed mainly to heavy metals, of Bauman and Horvat [18] and Leonard et al. [19]. We
PAHs, and silica [3,13,25–28]. Previous studies con- also found a significant increase in MN level of power
cerning the health risk of workers engaged in coal-fired plant workers. However, no published data concerning
power plants have reported an association between the the effects of occupational exposure in coal-fired power
exposure to coal combustion products and different type plants on the MN level is available.
of diseases such as lung function impairment, respira- In the present study, the frequency of CA and MN
tory symptoms, mesothelioma, lung and pleural cancer increased with the increasing years of exposure to coal
[7–10,29,30]. Advanced combustion techniques, emis- combustion products (P < 0.05) (Table 3). These results
sion control technologies, and waste disposal procedures were in aggreement with the findings in other occupa-
have been developed for limiting human exposure to tionally exposed groups [33–35]. No correlations were
combustion products. However, these technologies are found between age and CA, polyploidy, SCE, or MN
not in routine use in some old power plants especially in in exposed workers or control subjects, although ageing
less developed or developing countries due to their high effect on cytogenetic markers has been demonstrated by
cost. several other studies [36–38]. In our study, the lack of
In this study, the possible genotoxic risks to workers correlation might be attributed to the narrow age range,
from Afsin-Elbistan A power plant were investigated by 36–50 years old.
analysing the frequency of CA, polyploidy, SCE and MN In conclusion, our findings demonstrated that occu-
in peripheral blood lymphocytes. Levels of all four mark- pational exposure to coal combustion products in

5. 162 M. Celik et al. / Mutation Research 627 (2007) 158–163
Afsin-Elbistan A power plant was associated with signif- [12] P.R. Band, J.J. Spinelli, R.P. Gallagher, W.J. Threlfall, V.T. Ng, J.
icantly higher levels of CA, polyploidy, SCE, and MN Moody, D. Raynor, L.M. Svirchev, D. Kan, M. Wong, Identifica-
tion of occupational cancer risks using a population-based cancer
in peripheral blood lymphocytes of workers compared registry, Recent Results Cancer Res. 120 (1990) 106–121.
with controls. These cytogenetic changes might origi- [13] P.J.A. Borm, Toxicity and occupational health hazards of coal fly
nate from the cumulative effect of the many chemical ash (CFA). A review of data and comparison to coal mine dust,
compounds that are present in the coal ash and gaseous Ann. Occup. Hyg. 41 (1997) 659–676.
emissions rather than a specific substance. Further, coal [14] B.Z. Zhong, Z.W. Gu, J. Stewart, T. Ong, Micronucleus formation
induced by three polycyclic aromatic hydrocarbons in rat bone
ashes provide a surface for interactions of several agents
marrow and spleen erythrocytes following intratracheal instilla-
and this may lead to alterations in its genotoxic properties tion, Mutat. Res. 326 (1995) 147–153.
as reported in coal dust [13]. In the power plant, expo- ¨
[15] S. Ozturk, S. Vatansever, K. Cefle, S. Palanduz, K. Guler, N. Erten,
sure reducing measures should be taken to limit health O. Erk, M.A. Karan, C. Tascıoglu, Acute wood or coal expo-
risks of workers and also of the general population living sure with carbon monoxide intoxication induces sister chromatid
exhange, J. Toxicol. Clin. Toxicol. 40 (2002) 115–120.
around the power plant.
[16] O. Andersen, Effects of coal combustion products and metal com-
pounds on sister chromatid exchange (SCE) in a macrophagelike
Acknowledgements cell line, Environ. Health Perspect. 47 (1983) 239–253.
[17] B.Z. Zhong, S.C. Stamm, S. Robbins, D. Bryant, W. Lan, W.F.
Xin, J.K. Ma, W.Z. Whong, T.M. Ong, Studies on the mutagenic-
We would like to thank Rasit Is, the manager of the ity of mild gasification products of coal and their subfractions by
Afsin-Elbistan A power plant, and Hasan Beyazıt, the the Salmonella/microsomal assay, Environ. Res. 72 (1997) 32–44.
doctor of the power plant, for their kindly contribution [18] A. Bauman, D. Horvat, The impact of natural radioactivity
to the study. from a coal fired power plant, Sci. Total Environ. 17 (1981)
75–81.
[19] A. Leonard, G. Deknudt, E.D. Leonard, G. Decat, Chromosome
References aberrations in employees from fossil-fueled and nuclear-power
plants, Mutat. Res. 138 (1984) 205–212.
[1] D.J. Swaine, F. Goodarzi, Environmental Aspects of Trace Ele- [20] A. Popovic, D. Djordjevic, P. Polic, Trace and major element
ments in Coal, Kluwer, Dordrecht, 1997. pollution originating from coal ash suspension and transport pro-
[2] H.C. Zhou, B.S. Jin, Z.P. Zhong, Y.J. Huang, R. Xiao, D.J. Li, cesses, Environ. Int. 26 (2001) 251–255.
Investigation of polycyclic aromatic hydrocarbons from coal gasi- [21] A. Baba, A. Kaya, Leaching characteristics of solid wastes from
fication, J. Environ. Sci. (China) 17 (2005) 141–145. thermal power plants of western Turkey and comparison of toxi-
[3] E.S. Rubin, Toxic releases from power plants, Environ. Sci. Tech- city methodologies, J. Environ. Manage. 73 (2004) 199–207.
nol. 33 (1999) 3062–3067. [22] S. Ural, Comparison of fly ash properties from Afsin-Elbistan
[4] Y. Chen, N. Shah, F.E. Huggins, G.P. Huffman, Transmission elec- coal basin, Turkey, J. Hazard. Mater. 119 (2005) 85–92.
tron microscopy investigation of ultrafine coal fly ash particles, [23] G. Speit, S. Haupter, On the mecanism of differential giemsa
Environ. Sci. Technol. 39 (2005) 1144–1151. staining of bromodeoxyuridine-substituted chromosomes. II.
[5] B. Apicella, R. Barbella, A. Ciajolo, A. Tregrossi, Comparative Differences between the demonstration of sister chromatid dif-
analysis of the structure of carbon materials relevant in combus- ferantiation and replication, Hum. Genet. 70 (1985) 126–129.
tion, Chemosphere 51 (2003) 1063–1069. [24] A. Rothfus, P. Sch¨ tz, S. Bochum, T. Volm, E. Eberhardt, R.
u
[6] J.H. Yan, X.F. You, X.D. Li, M.J. Ni, X.F. Yin, K.F. Cen, Per- Kreirenberg, W. Vogel, G. Speit, Induced micronucleus frequen-
formance of PAHs emission from bituminous coal combustion, J. cies in peripheral lymphocytes as a screening test for carriers of
Zhejiang Univ. Sci. 5 (2004) 1554–1564. a BRCA 1 mutation in breast cancer families, Cancer Res. 60
[7] A.D. Oxman, D.C. Muir, H.S. Shannon, S.R.T. Stock, E. Hnizdo, (2000) 390–394.
H.J. Lanfe, Occupational dust exposure and chronic obstructive [25] G.L. Fisher, Biomedically relevant chemical and physical prop-
pulmonary disease, Am. Rev. Respir. Dis. 148 (1993) 38–48. erties of coal combustion products, Environ. Health Perspect. 47
[8] C.J. Schilling, I.P. Tams, R.S.F. Schilling, A. Nevitt, C.E. Rossiter, (1983) 189–199.
B. Wilkinson, A survey into the respiratory effects of prolonged [26] V.B. Vouk, W.T. Piver, Metallic elements in fossil fuel combus-
exposure to pulverised fuel ash, Br. J. Ind. Med. 45 (1988) tion products: amounts and form of emissions and evaluation of
810–817. carcinogenicity and mutagenicity, Environ. Health Perspect. 47
[9] F. Forastiere, N. Pupp, E. Magliola, S. Valesini, F. Tidei, C.A. (1983) 201–225.
Perucci, Respiratory cancer mortality among workers employed [27] S.C. Stamm, W. Lan, B.Z. Zhong, W.Z. Whong, T. Ong, Muta-
in thermoelectric power plants, Scand. J. Work. Environ. Health genicity of mild gasification products in Salmonella typhimurium,
15 (1989) 383–386. Mutat. Res. 320 (1994) 261–271.
[10] L. Nichols, T. Sorahan, Mortality of UK electricity generation [28] IARC Monographs on the evaluation of the carcinogenic risk of
and transmission workers, 1973–2002, Occup. Med. (Lond.) 55 chemicals to humans. Vol 68, Silica, some silicates, coal dust, and
(2005) 541–548. para-aramid fibrils. Genova: IARC Pres., 1997.
[11] G. Petrelli, F. Menniti Ippolito, S. Spila Alegiani, G. Magarotto, [29] P. Crosignani, F. Forastiere, G. Petrelli, E. Merler, E. Chellini, N.
F. Taroni, Mortality among workers of three thermoelectric power Pupp, S. Doneli, G. Magarotto, E. Rotondo, C. Perucci, Malignant
plants in northern Italy: a retrospective cohort study, Med. Lav. mesothelioma in thermoelectric power plant workers in Italy, Am.
85 (1994) 397–401. J. Ind. Med. 39 (2001) 436–437.

6. M. Celik et al. / Mutation Research 627 (2007) 158–163 163
[30] G. Cammarano, P. Crosignani, F. Berrino, G. Berra, Cancer mor- [34] L. Donbak, E. Rencuzogulları, A. Yavuz, M. Topaktas, The geno-
tality among workers in a thermoelectric power plant, Scand. J. toxic risk of undergroung coal miners from Turkey, Mutat. Res.
Work. Environ. Health 10 (1984) 259–261. 588 (2005) 82–87.
[31] J.C. Kleinjans, Y.M. Janssen, B. Van Agen, G.J. Hageman, [35] F.Y. Wu, F.J. Tsai, H.W. Kuo, C.H. Tsai, W.Y. Wu, R.Y. Wang,
J.G. Schreurs, Genotoxicity of coal fly ash, assessed in vitro in J.S. Lai, Cytogenetic study of workers exposed to chromium
Salmonella typhimurium and human lymphocytes, and in vivo compounds, Mutat. Res. 464 (2000) 289–296.
in an occupationally exposed population, Mutat. Res. 224 (1989) [36] J. Shaham, R. Gurvich, Z. Kaufman, Sister chromatid exchange in
127–134. pathology staff occupationally exposed to formaldehyde, Mutat.
[32] R.H. Stierum, G.J. Hageman, I.J. Welle, H.J. Albering, J.G. Res. 514 (2002) 115–123.
Schreurs, J.C. Kleinjans, Evaluation of exposure reducing mea- [37] S.K. Fatima, P.A. Prabhavathi, P. Padmavathi, P.P. Reddy, Anal-
sures on parameters of genetic risk in a population occupationally ysis of chromosomal aberrations in men occupationally exposed
exposed to coal fly ash, Mutat. Res. 319 (1993) 245–255. to cement dust, Mutat. Res. 490 (2001) 179–186.
[33] D. Elavarasi, V. Ramakrishnan, T. Subramoniam, A. Ramesh, [38] D. Pinto, J.M. Ceballos, G. Garcia, P. Guzman, L.M. Del Razo,
K.M. Cherian, C. Emmanuel, Genotoxicity study in lymphocytes E. Vera, H. Gomez, A. Garcia, M.E. Gonsebatt, Increased cyto-
of workers in wooden furniture industry, Curr. Sci. 82 (2002) genetic damage in outdoor painters, Mutat. Res. 467 (2000)
869–873. 105–111.