Download assessment of impacts of hematological parameters of

SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
ASSESSMENT OF IMPACTS OF HEMATOLOGICAL PARAMETERS OF
CHRONIC IONIZING RADIATION EXPOSED WORKERS IN HOSPITALS
SAMAN SHAHID*1, NASIR MAHMOOD2, MUHAMMAD NAWAZ CHAUDHRY1,
SHAHARYAR SHEIKH3 AND NAUMAN AHMAD3
1
College of Earth and Environmental Science, University of the Punjab, Lahore, Pakistan.
Department of Allied Health Science and Chemical Pathology,University of Health Sciences, Lahore, Pakistan.
3
Department of Neurosurgery, Shaikh Zayed Hospital, Federal Postgraduate Medical Institute Lahore, Pakistan
*Corresponding author e-mail: [email protected]
2
Abstract
This study examined the impact on hematological parameters for medical workers that work on ionizing
radiation equipment. Comparison of mean values of CBC (complete blood count) parameters with the normal
range and comparisons based on the T-tests between radiation exposed (RE) workers and radiation unexposed
workers was done. Most of the parameters were below the normal range and were disturbed in majority of the
RE workers. Most affected parameter was MCH (mean corpuscular hemoglobin) which was found to be lower
in majority of radiotherapy workers. From T-test, statistically significant differences (p<0.05) were observed in
the mean values MCHC (MCH concentration) and lymphocytes (LYM). A decline was observed in plateletcount, hematocrit and lymphocytes, whereas, an increase was observed in neutrophils in association with
Annual average effectived dose (AAED) (0.29-1.91) mSv. These associations were although weak but
significant. Long term work on radiations at even low doses (<20 mSv) can impact health and results into an
altered immune response or anemia.
Introduction
There is a worldwide concern about the use of ionization radiations (IR) in the medical field such as X rays,
gamma (γ) rays and particles: α-particle, β-particle, protons and neutrons. Radiations are being extensively used
in diagnosis as well as in therapeutic use for cancer patients. Therefore, the frequent use of machines by
technicians such as X-ray diagnostic units as well as therapy units, CT-scans, PET (positron emission
tomography), SPECT (single photon emission computed tomography), gamma cameras, brachytherapy units,
60
Co teletherapy units, linear accelerators, dose calibrators, radioimmunoassay counters and different
radiopharmaceuticals pose health risks to occupational workers (Jabeen et al., 2010; Masood et al., 2013).
Ionization radiations influence human health as they break chemical bonds of the molecules and damage DNA
by the production of free radicals and hence proliferative cells can undergo apoptosis (Vakifahmetoglu et al.,
2008). Stem cells are found radiosensitive and their damage by radiations can result into non-performance of the
functional cells. Long term exposure to even low doses of radiation can affect proliferating cells (Fliedner et al.,
2012). Ionizing radiation exposure is sensitive for those tissues (i.e., bone marrow, the gastrointestinal tract and
skin) which turnover rapidly as well as to those tissues (i.e., central nervous system, lung, heart, liver, kidney
and gonads) which turnover slowly (Dainiak and Sorba, 1997). Hematopoietic system is one of the most
radiosensitive systems because its functional cells transport oxygen in the blood, which prevent immune system
against viruses, bacteria, etc. This system also provides blood coagulation to safe intact blood vessels
(Smirnova, 2010). This study examines the impact of ionizing radiations (IR) on the complete blood count
(CBC) parameters of hospital workers who work in radiotherapy (RT), radiology (RT) and nuclear medicine
(NM) departments. This research provides a study on radiation induced hematopoietic system alterations for the
hospital radiation exposed workers or technicians etc. for their health and safety measures concerns. It is known
that bone marrow system is highly radiosensitive and analysis of hematopoietic system for such workers is
highly emphasizing. Blood forming cells are located in bone-marrow and such cells are highly susceptible to
radiation damage (Edwards, 1977). This study not only provides various comparisons of CBC parameters
between radiation exposed workers with the control group (radiation unexposed workers) but also includes
correlation analysis with the control variable that is, Annual Average Effective Dose (AAED) in mSv
(millisievert: measure of radiation dose). Pakistan Nuclear Regulatory Authority (PNRA) follows International
Atomic Energy Agency (IAEA) and International Committee on Radiological Protection (ICRP) guidelines on
dose range limits for occupational radiation exposures (Jabeen et al., 2010). According to IAEA guidelines, the
annual effective dose should be controlled below 20mSv for radiation workers. In Pakistan, a Radiation
Dosimetery Laboratory (RDL) regularly monitors occupational exposure of all workers that the exposure may
not exceed the recommended limits by PNRA by Film Badge dosimeters (FBD) service mostly and remaining
by thermoluminiscent dosimeters (TLD) (Jabeen et al., 2010).
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
136
Ionizing radiations (IR) can damage stem cells of hematopoietic system which is radiosensitive and as a
result alteration in the production of bone marrow stromal cells is observed which are important to regulate this
system. An exposure to IR can reduce bone marrow production where blood forming cells both immature and
rapidly dividing cells locate. Dividing cells of the hematopoietic system are highly radiosensitive which divide
rapidly and may show effects at even at low doses of long term ionizing radiations such as X-rays or γ-rays
(Smirnova, 2010). For the last 30 years, the fluoroscopically guided interventional procedures have increased Xray exposure. These occupational health concerns are quite important to the cardiologists, radiologists, surgeons
and other technicians working with the fluoroscopy techniques (Klein, 2009). Several studies suggest that
chronic exposure of low-dose radiation has a genotoxic effect on somatic DNA of professionally exposed
workers as well. A few studies focus on interventional cardiologists who work in cardiac catheterization
laboratories and are exposed to low doses of ionizing radiation (Andreassi et. al,. 2005; Roguin et. al., 2012;
Venneri et. al., 2009).
There were 92 radiation workers in this research who were working in different radiation departments
(diagnostic or therapeutical) and were exposed to x-rays or γ rays in the range of Annual Average Effective
Dose (AAED) 0.29-1.91 mSv. This study focus on those workers’ hematology through complete blood count
(CBC) test, who are being long-term exposed (although low dose) from radiation machines such as X-ray
machines or linac (linear accelerator). Health hazards from acute radiation dose impacts of radiations are
although, well documented but there is a little concern and unawareness in such workers related to the impacts
of chronic low-dose regular or periodic radiation exposure. Therefore, this research will be beneficial to initiate
awareness among occupational ionizing radiation workers and further to mitigate the effects.
Materials and Methods
Blood Sample Collection and Background Information: Blood samples (1-ml from each individual) of 147
non-smoker individuals were collected by taking volunteers and informed consents from radiation exposed (RE)
workers (n=92) and control group (n=55) who were radiation unexposed (RU) workers. The control group
individuals were not found to be exposed from any type of artificial or ionizing natural radiations. Blood was
collected in CBC vials and sent for a CBC test soon after its collection. Information regarding age, sex, duration
of radiation exposure, dietary habits and occupation was taken on a designated Performa. All individuals were in
having balanced food intake with non-alcoholic habits.
CBC (Complete Blood Count) Test: The collected blood was mixed well and inserted into the following
machines: Abacus+ and Medonic and CBC parameters were analyzed. Nine CBC parameters were considered
for this study and these were: hemoglobin (HB in g/L), white blood cells (WBC in 109/L), platelet count (PLT in
109/L), hematocrit (HCT in %), red blood cells (RBC in 1012/L), mean corpuscular hemoglobin (MCH in g/L),
mean corpuscular hemoglobin concentration (MCHC in %), lymphocytes (LYM in %) and neutrophils (NEUT
in %) were analyzed in all groups.
Statistical Analysis & Calculations: All statistical calculations were performed in software SPSS-21. All of
nine CBC parameters’ mean values and mean values of those CBC parameters which were either below the
normal range or above the normal range, were calculated for all groups, i.e., for RT (radiotherapy) workers
(n=20), RD (radiology) workers (n = 41), NM (nuclear medicine) workers (n = 31) and RU (radiation
unexposed) workers (n = 55). A T test (independent samples test) was conducted on the mean values of all nine
CBC parameters to analyze those parameters which show significant difference between all radiation exposed
(RE) workers (n = 92) and radiation unexposed (RU) workers (n = 55). Another T- test (independent samples
test) was conducted on those CBC parameters which were either in below or above with the normal range
between all radiation exposed workers (RE) i.e., from three different departments, i.e., radiotherapy, radiology
and nuclear medicine workers (total n = 92) and radiation unexposed (RU) workers (n = 55).
In Pakistan, annual average effective dose (AAED) range was recorded between 1.39-1.80 (mSv) for the
nuclear medicine department, 1.22-1.71 (mSv) for radiology department and 1.05 -1.45 (mSv) for radiotherapy
department during 2003-2007 (Jabeen et al., 2010) and AAED ranges were between 0.51-1.91 (mSv) for the
nuclear medicine department, 0.29-0.80 (mSv) for radiology department and 0.50-1.72 (mSv) for radiotherapy
department during 2007-2011 (Masood et al., 2013). The range of the duration of radiation exposure among
radiation workers was between 05-25 years during of the employment history. The AAED range 0.29-1.91
(mSv) was considered for the statistical analysis in this study. A Bivariate correlation analysis was conducted to
see the correlation between CBC parameters with an independent variable, i.e., AAED (mSv) for all radiation
exposed (RE) workers (n = 92). The r-values (Pearson coefficients) were obtained and analyzed to observe the
strength and direction (±) of the correlation between a respective significant CBC parameter and AAED (mSv)
as a control variable. The p-values obtained were checked for significance or non-significance of a CBC
parameter with the variable i.e., AAED (mSv).
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
137
Further, Linear Regression analyses were performed and R-square (coefficient of determination) values
were observed for the analysis of the proportion of variance in the dependent variables (CBC parameters) which
can be subjected to be predictable from the independent variable AAED (mSv). The Linear Regression analyses
were performed for variable AAED (mSv) to predict CBC parameters’ change. The measure of strength of CBC
parameter’s association was analyzed with an independent variable AAED (mSv) to analyze R (square) values,
model’s coefficients, t-test values and p-values in order to handle the estimation of an affected CBC parameter
which was significant in correlation with independent variable AAED (mSv). Finally, regression equations were
developed between independent variable AAED (mSv) and the respective dependent variable i.e., a specific
CBC parameter. Regression equations mentioned in scatter plots figures accordingly. Odds ratios were
calculated to find out the association of measure between radiation exposure and having an altered (low or high)
CBC parameter. Pearson chi-square test used to evaluate significance of a respective parameter through p-value
(p < α = 0.05).
Results
Analysis of Background Information: Background information for all individuals included in this study has
been presented in Table 1. Among all RT workers (n = 20), most of the workers were male (80%) and mostly
(50%) were from the age group (26-50 years). Among all RD workers (n = 41), most of the workers were male
(80.4%) and mostly (68%) were from the age group (26-50 years). Among all NM workers (n = 31), most of the
workers were male (77.4%) and mostly (67.7%) were from the age group (26-50 years). In the category of
radiation unexposed workers (n = 55) most of the individuals were male (62%) and mostly (62%) were from the
age group (26-50 years). Radiation unexposed workers were from miscellaneous profession, for example, office
workers, teachers, physicians, etc. All radiation exposed workers and radiation unexposed workers included
were from Lahore city.
Table 1. Background Information for Radiation Exposed (RE) Workers and Radiation
Unexposed (RU) Workers
*PP: Percentage Prevalence
Hematological Profiles:
Parameters
Occupationally Radiation
Exposed (RE) Workers (n=92)
Radiotherap
y (n=20)
PP*
%
Radiology PP
(n=41)
%
Age 18-25
3
15
10
24
26-50
51 &
above
Sex Male
10
7
50
35
28
3
68
7
16
80
33
Nuclear PP
Medicine %
(n=31)
5
16
21
5
67.7
16
Radiation
Unexposed (RU)
Workers (n=55)
Miscellaneo PP
us workers
%
Tota
l
PP
%
18
20
9
16
59
15
64
16
34
12
62
22
80.
24
77.4 73
79
34
62
4
Female
4
20
8
19.
7
22.6 19
21
21
38
5
Comparison of Mean Values of CBC Parameters with the Normal Range:
Table 2. shows nine CBC parameters’ mean values (indicated “total”), mean values of those CBC
parameters which were below the normal range (indicated “low”) and mean values of those CBC parameters
which were above the normal range (indicated “high”) of all four groups of individuals that is, RD workers, RT
workers, NM workers and RU workers. This Table (2) is explained on the basis of Table 3 in which percentages
of the all individuals have been mentioned who were having their one or more CBC parameter(s) in either low
or high range when compared with the normal range mentioned in Table 2.
Most affected CBC parameter was MCH, which was found in the lower range (mean=25. 87) in 60% of the
radiotherapy workers when compared with RD and NM departments as well as with the RU workers. The
second most affected CBC parameter was MCHC which was found in the lower range (mean=30.22) in 50% of
the radiotherapy workers when compared with RD and NM departments as well as with the RU workers. The
third most affected CBC parameter was LYM which was found in higher range (mean=49.43) in 39% of the
radiology workers when compared with RT and NM departments as well as with the RU workers. Overall in all,
40.2 % of all (n = 92) RE workers two CBC parameters were more affected in lower range, i.e., MCH
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
138
(mean=24. 99) and MCHC (mean=30.57) as compared to the controls the RU workers. It can also be observed
from the column labeled “total” in Table 2 that collective mean values of all CBC parameters are within the
normal range but there is a little shift towards lower range in the CBC parameter MCH (mean= 27.21 for RT,
mean=27.87 for RD and mean=27.84 for NM) in all three department’s workers whereas, and MCHC is also on
a slight lower range (mean=31.87) for RT workers only.
Table 2. Mean values of complete blood count (CBC) for radiation exposed (RE) workers and radiation
unexposed (RU) workers. Column labeled as “low” shows mean of CBC parameter below normal range, column
labeled as “high” shows mean of CBC parameter above normal range and column labeled as “total” shows mean
of CBC parameter of each individual. The number in the parenthesis describes the number of individuals whose
CBC parameters were found disturbed (low or high).
Table 3. Number of workers expressed in percentages whose CBC parameters were either in low
range/high range.
CBC
Parameters
Occupationally (Medical) Radiation Exposed (RE) Workers
(n=92)
Radiotherapy
(n=20)
Radiology
(n=41)
Total Radiation
Exposed (RE)
Workers (n=92)
Low%
High%
Nuclear Medicine
(n=31)
Low%
High%
Low%
High%
Low%
High %
20
-
7.3
-
6.5
-
9.8
-
WBC (109/L)
5
5
9.8
7.3
-
3.2
5.4
PLT (109/l)
HCT (%)
15
15
-
17.1
7.3
2.4
5
6.5
3.2
-
11
8.7
RBC (1012/L)
10
5
-
19.5
3.2
19.4
3.3
MCH (g/L)
60
-
31.7
-
38.7
6.5
40.2
MCHC (%)
50
-
41.5
2.4
32.3
3.2
LYM (%)
5
5
2.4
39
3.2
NEUT (%)
25
-
17.1
-
6.5
HB (g/L)
Radiation
Unexposed (RU)
Workers (n=55)
Low%
High%
-
-
5.4
-
1.8
2.2
2.2
7.3
5.5
-
16.3
-
9.1
2.2
29.1
3.6
40.2
2.2
9.1
1.8
16.1
3.3
32.6
-
20
-
15.2
-
1.8
-
Key (Tables 2 and 3): HB: Hemoglobin, WBC: White Blood Cells, PLT: Platelet Count, HCT: Hematocrit,
CBC
Occupationally Radiation Exposed (RE) Workers (n=92)
Total Radiation
Radiation Exposed
Normal
Para- Radiotherapy (n=20)
Exposed (RE)
(RU) Workers (n=55)
Range
Radiology (n=41)
Nuclear Medicine
meters
Workers (n=92)
(n=31)
Low
High
Total Low
High
Total Low
High Total
Low
High
Total
Low High Total
HB
10.07
13.1 11 (3)
13.965 9.95
13.906 10.35
13.7
14.13 11.5-17.0
(g/L)
(4)
6
(2)
(9)
7
WBC
3.66 11.45 6.67 2.46 12.33 (3) 7.27
12.91 7.21
2.7 (5) 12.27
7.12
12.5 7.29 4.0-11.0
(109/L)
(1)
(1)
(4)
(1)
(5)
(1)
PLT
114.6
230. 106.42
445 230.21
653 (1) 245.67 108.9 549
235. 120 (4)
231.8 150-400
(109/L)
(3)
9
(7)
(1)
(10)
(2)
57
7
HCT
31.6
41.1 27.7 51.7 (2) 42.64 31.45
41.76
30.13 51.7 (2) 42.0
35.46
41.7
36-50
(%)
(3)
6
(3)
(2)
(8)
2
(3)
RBC
3.58 5.96 (1) 4.85
6.13 (8) 5.10 3.75 (1) 5.72 (6) 5.02 3.63 (3) 5.96
5.02
5.95 4.96
3.8-5.5
(1012/L) (2)
(15)
(5)
MCH- 25.87
27.2 24.63
27.87
24.5 32.5 (2) 27.84
24.99 32.5
27.7
25.7
35
28.6
28-32
(g/L)
(12)
1
(13)
(12)
(37)
(2)
(16)
(2)
MCHC 30.22
31.8 30.54 38.2 (1) 32.32 30.97 36.6 (1) 33.28
30.57 37.4
32.5
31.26
36.6 33.81
32-36
(%)
(10)
7
(17)
(10)
(37)
(2)
5
(5)
(1)
LYM
19.5 48.65 36.8 19.4
49.43 38.93 15.7 (1) 52.18
35
18.2 (3) 49.66
37.1
43.27 33.87
20-40
(%)
(1)
(1)
(1)
(16)
(5)
(30)
4
(11)
NEUT
(%)
28.16
(5)
-
50.3 19.44 (7)
2
-
51.36 18.5 (2)
-
54.39
22.42
(14)
-
52.1
6
34.2 (1)
-
54.95
RBC: Red Blood Cells, MCH: Mean Corpuscular Hemoglobin, MCHC: MCH Concentration, LYM:
Lymphocytes, NEUT: Neutrophils
40-80
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
139
Table 4. T test analysis of significantly different mean CBC values between radiations exposed (RE)
workers and radiation unexposed (RU) workers.
Blood
t-test for Equality of Means
Parameters
95% Confidence Interval of
the Difference
t
p-value
Lower
Upper
( < 0.050)
0.000
MCHC
-4.688
-1.795593
-0.730613
0.027
LYM
2.238
0.381714
6.159037
0.005
LYM (high)
2.943
1.997080
10.777466
Table 5. Correlation analysis between Annual Average Exposed Dose AAED (mSv) with CBC parameters
in radiation exposed (RE) workers.
PLT
Pearson Correlation
-0.240*
p-value (<0.050)
0.021
* Correlation is significant at the 0.05 level (2-tailed).
mSv
HCT
-0.235*
0.024
LYM
-0.232*
0.026
NEUT
0.254*
0.014
Table 6. Risk Estimate and Chi-Square Tests
Parameter
MCHC (low)
Odds Ratio
for Exposed
Workers
Value
6.842
NEUT (low)
ANC (low)
95% Confidence Interval
(CI)
Pearson ChiSquare
df
p-value ( < 0.05)
Lower
2.488
Upper
18.811
Value
16.574
1
0.000
9.692
1.238
75.910
6.745
1
0.009
6.897
1.540
30.891
8.139
1
0.004
*df: degree of freedom
Most of the radiation exposed (n = 92) workers (9.8%) had low HB (mean=10.35) as compared to RU
workers (0%). Most of RE workers (5.4%) had low WBC (mean=2.7) as compared to RU workers (0%). Most
of RE workers (11%) had low PLT (mean=108.9) as compared to RU workers (7.3%). Most of RE workers
(8.7%) had low HCT (mean=30.13) as compared to RU workers (5.5%). Most of RE workers (16.3%) had high
RBC (mean=5.96) as compared to RU workers (9.1%). Most of RE workers (40.2%) had low MCH
(mean=24.99) as compared to RU workers (29.1%). Most of RE workers (40.2%) had low MCHC
(mean=30.57) as compared to RU workers (9.1%). Most of RE workers (32.6%) had high LYM (mean=49.66)
as compared to RU workers (20%). Overall, seven CBC parameters: HB, WBC, PLT, HCT, MCH, MCHC and
NEUT were in the lower range of radiation exposed (RE) workers and two CBC parameters RBC and LYM are
in high range as compared with the mean values CBC of non-radiation exposed (RU) workers. It is observed of
course, that majority of RE workers had their CBC parameters affected because of the long term use of radiation
works in the hospitals.
CBC Parameters Related to Intradepartmental Comparisons between Radiotherapy, Radiology and Nuclear
Medicine Workers
Results from both Tables 2 and 3 indicated that the majority of RD, RT and NM workers had their CBC
parameters were in the low range. Most of the RT workers (20%) had low HB (mean= 10) as compared to RD
workers (7.3%) and NM workers (6.5%). Most of RD workers (9.8%) had low WBC (mean=2.46) as compared
to RT workers (5%) and NM workers (0%). Most of the RD workers (17.1%) had low PLT (mean=106.4) as
compared to RT workers (15%) and NM workers (0%). Most of RT workers (15%) had low HCT (mean=31.6)
as compared to RD workers (7.3%) and NM workers (6.5%). Most of the RD workers (19.5%) had high RBC
(mean=6.13) as compared to RT workers (5%) and NM workers (19.4%). Most of the RT workers (60%) had
low MCH (mean=25.87) as compared to RD workers (31.7%) and NM workers (38.7%). Most of the RT
workers (50%) had low MCHC (mean=30.22) as compared to RD workers (41.5%) and NM workers (32.3%).
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
140
Most of the RD workers (39%) had high LYM (mean=49.43) as compared to RT workers (5%) and NM workers
(16.1%). Most of the RT workers (25%) had low NEUT (mean=28.16) as compared to RD workers (17.1%) and
NM workers (6.5%).
Overall, in both radiology and radiotherapy personnel most of the CBC parameters had been affected as
compared to nuclear medicine department personnel. In the majority of radiotherapy (RT) workers, following
five CBC parameters were found in lower range: HB, HCT, MCH, MCHC and NEUT. While in majority of
radiology (RD) workers following two CBC parameters were found in lower range: WBC and PLT and two
CBC parameters were in higher range: RBC and LYM. It can be concluded that blood parameters had been
more altered in radiotherapy and radiology workers as compared to nuclear medicine workers. Moreover,
majority of CBC parameters were either low or high for the RT, RD and NM workers as compared to RU
workers.
Comparisons based on the T tests Between Radiation Exposed (RE) Workers and Radiation Unexposed (RU)
Workers
Comparisons based on the T test (Table 4) were conducted to find out those CBC parameters which show
the significance of difference between radiation exposed (RE) personnel (n = 92) and radiation unexposed (RU)
personnel (n = 55). The descriptive of T test shows that significant differences were existed in the mean values
of CBC parameters: MCHC, and LYM between those who were exposed to radiation (n=92) and those who
were not exposed to radiation (n = 55). The results of this T test indicated that the difference between the mean
scores of those exposed to radiation and those not exposed to radiation for MCHC is t= -4.688 standard
deviation units (95% CI: -1.79 to -0.73; p trend: 0.000 < α; α=0.05) and for LYM is t = 2.238 standard deviation
units (95% CI: 0.38 to 6.15; p trend: 0.027 < α; α=0.05). Whereas, another T test shows that significant
differences existed in the mean high values of the LYM between those who were exposed to radiation (n = 92)
and those who were not exposed to radiation (n=55). The results of this second T-test indicated that the
difference between the mean scores of those exposed to radiation and those not exposed to radiation for mean
high values of LYM is at t=2.943 standard units (95% CI: 1.99 to 10.77; p trend: 0.005 < α; α = 0.05).
Correlation Analysis between Annual Average Exposed Dose (AAED) and CBC Parameters
Correlation analyses were performed for the CBC parameters to see the strength of the association with
AAED (mSv) as a control variable. Table 5 showed that the correlation is significant at p < α (α = 0.05) for
following four CBC parameters: PLT (p = 0.021 < α), HCT (p = 0.024 < α), LYM (p = 0.026 < α) and NEUT (p
= 0.014 < α) with the Annual Average Effect Dose (AAED) overall range 0.29-1.91 (mSv) for all three
departments: radiotherapy (RT), radiology (RD) and nuclear medicine (NM) during the years 2003-2011. It is
observed that following three significant CBC parameters, i.e., PLT (r = -0.240), HCT (r = -0.235) and LYM (r
= -0.232) were having weak negative relationships with Annual Average Effective Dose (AAED) in mSv.
Whereas, parameters NEUT (r = +0.254) was having a weak positive relationship with Annual Average Effect
Dose (AAED) in mSv.
Regression Analysis: Four regression models were developed and scatter plots were generated (Figs. 1-4) in
order to estimate the effect of an independent variable AAED (mSv) on respective four CBC parameters (PLT,
HCT, LYM and NEUT) which were significant for both in male and female workers’ samples in correlation
analysis (as dependent variables). Regression analysis indicated that 5.8% of variance (R-square=0.058) in PLT,
5.5% (R-square=0.055) in HCT, 5.4% (R-square=0.054) in LYM and 6.5% (R-square=0.065) in NEUT can be
predicted from the variable AAED (mSv). It is now concluded that for every unit increase in AAED (mSv),
there is -37.774 unit decrease in PLT, -2.401 unit decrease in HCT, and -5.129 unit decrease in LYM is
predicted. Whereas, NEUT is found to be higher by 7.181 points for every increase of one point on the variable
AAED (mSv). In all these analyses, variable AAED (mSv) is found to be different than zero (p < α = 0.05).
Odds Ratio and Pearson Chi-Square Test: Odds ratios were calculated to find out the association of measure
between radiation exposure and having an altered (low or high) CBC parameter. The odds of developing low
MCHC were 6.84 times higher, the odds of developing low NEUT were 9.69 times higher and the odds of
developing a low ANC were 6.89 times higher for those who were radiation exposed compared to those who
were not exposed to occupational radiations. Only parameters, i.e., MCHC (low), NEUT (low) and ANC (low)
were found significant at p < α = 0.050 (Table 6).
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
Fig. 1. Scatter plot: PLT vs. AAED (mSv) = x
Model equation: PLT= y = 281.266 + (-37.774) x
R=-0.240, R Square= 0.058 (p-value<0.05), N=92
(PLT: platelet count; AAED: annual average effective dose; mSv millisievert)
Fig. 2. Scatter plot: HCT vs. AAED (mSv) = x
Model equation: HCT = y= 44.929 + (-2.401) x
R=-0.235, R Square=0.055 (p-value<0.05), N=92
(HCT: hematocrit; AAED: annual average effective dos; mSv millisievert)
141
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
142
Fig. 3. Scatter plot: LYM vs. AAED (mSv) = x
Model equation: LYM = y= 43.350 + (-5.129) x
R=-0.232, R Square= 0.054 (p-value<0.05), N=92
(LYM: lymphocytes; AAED: annual average effective dose; mSv millisievert)
Fig. 4. Scatter plot: NEUT vs. AAED (mSv) = x
Model equation NEUT = y= 43.470 + (7.181) x
R=-0.254, R Square= 0.065 (p-value<0.05), N=92
(NEUT: neutrophils; AAED: annual average effective dose; mSv millisievert)
Discussion
It is well known that dividing cells of the hematopoietic system are highly radiosensitive (Smirnova, 2010).
Role of the functional cells of the lymphopoiesis and granulocytopoiesis system is very important for immune
protection against infections. Thrombocytopoiesis is one of the most radiosensitive hematopoietic cell lines in
humans. Radiation injury or damage of hematopoiesis system can lead to hemorrhage and anemia (Smirnova,
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
143
2010). However, these alterations are dependent on an effective radiation dose range and exposure time (Ismail
and Jaafar, 2011). It is found in this study that radiation exposed (RE) workers’ CBC parameters had been more
altered as compared to the control group i.e., radiation unexposed (RU) workers. Erythropoietic system
produces mature erythrocytes for the circulation. There is a swift proliferation of the two immature forms of
erythropoietic system, i.e., erythroblast and basophilic proerythroblasts and they found to be more sensitive as
compared to other immature forms, i.e., polychromatic erythroblast, normoblast and reticulocytes and therefore,
as a result cell apoptosis can be occurred by Radiations (NATO handbook, 1996). Myelopoietic marrow cell
renewal system produces mature granulocytes i.e., neutrophils, eosinophils, and basophiles, for the circulating
blood. Neutrophils have an important role in preventing infections. Stems cells and those cells which are found
in developing phases, i.e., dividing and differentiating are more radiosensitive. That’s why, myeloblast,
progranulocytes and myelocyte stages are more radiosensitive as compared to the other immature forms i.e.,
metamyelocyte and band forms. Thrombopoietic cell renewal produces platelets, which are produced by
megakaryocytes in the bone marrow in the peripheral circulating blood. Platelets and mature megakaryocytes
are relatively radioresistant but the stem cells and immature megakaryocytic stage is very radiosensitive and
they can be declined by higher doses of ionizing radiations (NATO handbook, 1996).
Table 3 indicate percentage of those individuals which were having either lower or higher values of their
respective CBC parameter compared to the normal range. Overall, there were four most affected CBC
parameters, i.e., most affected CBC parameter was only MCH, which was found low in majority of RT workers
(60%), the second most affected parameter was MCHC which was found low in majority of RT workers (50%),
third most affected parameter was LYM which was found high in majority of RD workers (39%). It indicates
that overall, radiotherapy workers were more affected for CBC parameters MCH and MCHC probably because
of the extensive use of gamma rays and energetic particles for therapeutic purposes for patients. These personnel
can be accidentally exposed to the radiations from linac-based radiotherapy machines. This may happen if the
worker receives primary beam radiations or this could be the secondary beam from patient scatter-radiations
(Fondevila, 2009). Radiation induced anemia is due to the hemolysis of red blood cells, called hemolytic-anemia
(NATO handbook, 1996). This suggested that the Impact of IR is significant as evidenced by a reduction in the
MCH, MCHC and an increase of LYM. The radiation causes anemia in the radiation workers due to apoptosis at
the stem cell level within the bone marrow. The stem cells are precursors to all blood cell lines and hence a
reduction can be noted in the number of cells getting to mature. As a result of hypoxia, the bone marrow gets
stimulation for the production of the red blood cells. It is evident that hematopoietic system is the most sensitive
of radiation and cells which divide rapidly or are relatively non-specialized may incline to show effects at lower
doses of radiation (Jefferson Lab, 2012). Lower doses of occupational ionizing radiations are found to influence
the hematopoietic system in exposed workers and among the other radioresistant mature forms, lymphocytes are
found most radiosensitive (Edwards, 1977).
Table 2 has two columns labeled “low” and “high” for each group which define CBC parameters’ mean
values which were in low range or in high range as compared to the normal range. Whereas, Table 3 has two
columns “low%” and “high%” to mention percentage of the individuals who were having low values or high
values of their respective CBC parameter compared to the normal range. Findings from such “low” and “high”
indicated for the comparison between total RE workers (n=92) and RU workers (n=55) that most of the CBC
parameters i.e., HB, WBC, PLT, HCT, MCH, MCHC & NEUT were found low in majority of RE workers
whereas, RBC and LYM were found high in majority of RE workers as compared to RU workers. That is, most
of the CBC parameters have been affected by the radiations and mostly were found in the lower range. Ionizing
radiations (IR) can damage, stem cells of the hematopoietic system and as a result can alter the production of
bone marrow stromal elements which are important to maintain this system. An exposure to IR can reduce bone
marrow production where blood forming cells, both immature and rapidly dividing cells located. Therefore IR
induces a decline in circulating hematopoietic cells and further redistribution and apoptosis (programmed cell
death) of mature cells of the blood can be occurred. Mature blood cells from the bone marrow are transported
out of the bone marrow in order to enter into the blood stream and hence they perform their respective functions.
Such cells are resistant to ionizing radiation, but their precursor cells (the pluripotent stem cells) are quite
susceptible to radiations. Stimuli like hypoxia because of IR, causes a release of erythropoietin from kidney
leading to RBC production. Furthermore, the stimulus to the bone marrow causes higher production of the red
blood cells. The retic count increased after IR as a result of compensatory mechanism started in the bone
marrow. MCHC is not increased because of hemolysis of RBCs as a result of radiations. The cell counts
increase, but MCHC does not increase correspondingly. Ionizing radiations cause apoptosis in the homeopathic
stem cells, which consider precursors to all blood cells and hence there could be a hampering in the provision of
mature cells into the blood stream and then there would be a development of plenty of immature cells in the
bone marrow (Dainiak, 2002). A study by Caciari et al., (2012) indicating that the mean of total white blood cell
were significantly decreased in exposed workers as compared to the controls.
The lymphocytes have been found to be the most radiosensitive cells (IAEA, 1997). At low doses, ionizing
radiation can affect the immune system by suppressing it or stimulating it whereas; relatively higher doses of
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
144
radiation can suppress immune responses because of the destruction of cells (UNSCEAR, 2012; IAEA, 2011). It
was reported that T-lymphocytes were affected to the individuals who were exposed to ionizing radiation and
hence and altered immune response was reported (Godekmerdan et al., 2004). The immune system has an
important role in fighting with the cancerous disease and radiations can increase or decrease this system which
can lead to the cancer development. Leukocytes are among the most sensitive lymphocytes to ionizing radiation
and hence radiations can lower white blood cells and platelets and, as a result, there would be a lowered
immunity to viruses or bacteria. Because lymphocytes are highly radiosensitive and therefore immune system is
susceptible to ionizing radiations (UNSCEAR, 2012; Godekmerdan et al., 2004). In a study it was found that the
subgroups of peripheral blood lymphocytes were affected for those who were operating X-ray machines for a
long time (Godekmerdan et al., 2004; Hrycek et al., 2002). Level of CD4+ T lymphocytes in this exposed group
was significantly lower than in the control group (Hrycek et al., 2002). Therefore, it can be concluded that
ionizing radiation can modulate the immune system response.
Intradepartmental comparisons, i.e., between RT, RD and NM revealed that workers of both RD and RT
departments had more CBC parameters affected as compared to NM department workers. In RT workers, five
CBC parameters, i.e., HB, HCT, MCH, MCHC and NEUT were in the lower range as compared to RD and NM
workers. Whereas, in RD workers, four CBC parameters were affected, i.e., WBC and PLT were in the low
range and LYM and RBC were in the higher range as compared to NM and RT workers. It means both RT and
RD workers had more CBC parameters affected as compared to NM workers. Therefore, it can be stated that
both RT and RD workers are more affected in their CBCs as compared to NM workers. It is known that
radiation workers are prone to significantly alter their blood parameters and they can be further suffered from
leukopenia, anemia or leukemia (Edwards, 1977). Moreover, a long term exposure to the radiations for medical
workers indicated that they may have effects on their immune system (Oskouii et al., 2013). Finding of the T
test indicated that two mean values of following CBC parameters: MCHC and LYM were found significantly in
their difference between total RE workers (n=92) and RU workers (n=55) among mean values of the all
remaining CBC parameters. A second T test was conducted between all CBC parameters’ mean low values and
mean high values between RE workers (n=92) and RU workers (n=55). Finding of the second T test indicated
that mean of high values of LYM was found significant in their difference among total RE workers (n=92) and
RU workers (n=55). LYM (high) explained that as a result of IR, the compensatory mechanism has started in
the bone marrow to cover the reduced number of lymphocytes.
Correlation analysis showed that the following four significant at p < α (α = 0.05) CBC parameters, i.e.,
PLT, HCT and LYM had weak negative associations with AAED (mSv) whereas two significant at p < α (α =
0.05) CBC parameter NEUT had a weak positive association with AAED (mSv). All other CBC parameters
were not found significant in correlation with AAED (mSv) and therefore not included in correlation
associations. This suggested that, PLT, HCT and LYM may decline with the annual average dose of exposure
ranging 0.29-1.91 (mSv). These parameters, though weak, but were found significant in association with AAED
(mSv). Rotations can decrease granulocytes, lymphocytes, and platelets, due to decline in hematopoietic stem
and progenitor cells and hence there would be a delayed re-population and individuals can be vulnerable to
infections (NATO handbook, 1996; Dainiak, 2002). Moreover, radiation-induced apoptosis and redistribution of
lymphocytes would be occurred from the circulation of the lymph-nodes as they're highly radiosensitive cells
found in the capillary bed (Dainiak, 2002).
It has been observed that long term use of ionizing radiations of radiation workers can affect their immune
system even at low doses of radiations as leukocytes and lymphocytes are highly radiosensitive (UNSCEAR,
2012; Gridley et al., 2002; Kłuciński et al., 2005). Granulocytes may show an initial increase (i.e.,
granulocytosis: demargination of granulocytes) before they deplete and there would a gradual decline in the
HCT and red cell count occurs after the exposure of moderate doses (Dainiak, 2002; Storer, 1966). A decline in
HCT (hematocrit) and increase in neutrophils are indicated by correlation analysis with the radiation dose range
0.29-0.91 (mSv) in our study. It is known that ionizing radiation affects bone marrow and lymphocytes can
decline along with a temporary sharp increase in granulocytes (Division of Environmental Health, A Fact
Sheet). This suggests that radiations can disturb immunity of those workers who are long term exposed to low
doses of ionizing radiation (Zykova et al., 1984; Soldatov and Ushakov, 1995). Because white blood cells,
lymphocytes are the most sensitive to X-ray radiations therefore, lymphopenia can be happen depends on the
absorbed dose (Anderson and Warner, 1976). It was reported in some studies, that lymphocytes of radiation
workers were slightly lower than the control group although the difference was not statistically significant.
Radiological workers were found under the influence of the gradual decline of neutrophils, leukopenia and
lymphopenia; due to the modulations or alterations in leukocytes (Hrycek and Stieber, 1994; Klajnowicz, et al.,
1998). Another investigation also indicated that the absolute number of peripheral blood lymphocytes was
slightly lower than for radiology department workers as compared to the control group but there was no
statistical significance found (Hrycek et al., 2002). Regression models were developed and scatter plots were
generated for four significant CBC parameters found in correlation with AAED (mSv) in order to estimate the
effects of an independent variable AAED (mSv) on respective significant CBC parameter as the dependent
SHAHID ET AL (2014), FUUAST J. BIOL., 4(2): 135-146
145
variable. It was discovered in this study, that the odds of developing low MCHC were 6.84 times higher and the
odds of developing low NEUT were 9.69 times higher for those who were radiation exposed compared to those
who were not exposed to occupational radiations. It has been discussed that the decreased number of circulating
lymphocytes and granulocytes by radiations can lead to infections and long term work on radiations can induce
anemia. Therefore, long-term damage caused by IR can induce various hematological diseases etc. (Andreassi
et. al,. 2005; Roguin et. al., 2012; Venneri et. al., 2009).
Conclusion
Hematopoietic system is found to be sensitive for radiation workers because mostly CBC parameters were
observed suppressed, however a weak (though significant) association has been linked with the AAED (0.291.91 mSv). Changes in blood parameters have been noted. Although these workers were working under <20mSv
of radiation doses, this may lead that long term use of radiations can show harmful effects on blood parameters.
Significant differences were found with the parameters: MCHC and LYM by the T-test. Radiotherapy and
radiology workers were more affected than nuclear medicine workers. The corresponding safety measures
should be kept in mind for such workers saving the workers from any accidental exposure. Furthermore, regular
checkups of radiation workers and effective monitoring of all blood parameters should be under taken in order
to diagnose an early change in their entire health. The long-term impacts of low ionizing radiation doses on the
immune functions in relation to human health should be evaluated. It has been discussed that the decreased
number of circulating lymphocytes and granulocytes by radiations can lead to infections and long term work on
radiations can induce anemia.
Declaration of Interest and Acknowledgement
The authors report no conflict of interest. This research was supported by a grant from Higher Education
Commission (HEC), Islamabad Pakistan.
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