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Estimation of Excess Lifetime Cancer Risks at the Niger Delta
University Sculpture Garden, Wilberforce Island, Bayelsa State,
Nigeria
Biere, Peter E
1*
, Aluko, Tolulope O.
2
and Emumejaye, Kugbere
3
1
Department of Physics, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
2
Department of Physics Education, Federal College of Education (Tech.) Akoka, Lagos State, Nigeria
3
Department of Physics, Delta State University of Science and Technology, Ozoro, Nigeria
*Corresponding author
DOI : https://doi.org/10.51583/IJLTEMAS.2025.1401023
Received: 27 January 2025; Accepted: 04 February 2025; Published: 17 February 2025
Abstract: The exposure rates at the Niger Delta University sculpture gardens have been measured and excess lifetime cancer risk
has also been determined. Measurement of exposure rate was carried out in a total of twenty points around the garden using a
portable hand-held radiation detector, radalert 100X. Results show averages of exposure rate, absorbed dose, annual effective
dose and excess lifetime cancer risk as 0.012 mRh
-1
, 107.9 nGyh
-1
, 0.132 mSvy
-1
and 0.162 x 10
-3
respectively. All averages,
except for absorbed dose rate, were below world average. The results show low radiation level in the materials used in sculptures
at the garden. However, this low level can pose specific health risks after prolonged exposure. There is the need to begin to apply
caution in the consideration of materials used for building the sculptures so as to avoid the introduction of radioactive elements
into the garden. Conclusively. the study suggests that the Niger Delta University sculpture garden is relatively safe for public use.
Keywords: exposure rate, sculpture garden, excess lifetime cancer risk.
I. Introduction
Ionizing radiations like alpha, beta particles, x-rays as well as gamma rays, possess enough energy to ionize atoms or molecules
by detaching electrons from them, which can lead to significant alterations in their chemical structure. This process of ionization
can cause serious biological damage, including DNA mutations, cellular dysfunction, and even cell death, which underscores the
importance of studying this type of radiation (Baeyens, et al. 2023; Tuan, et al, 2023; Buciuman, et al, 2024). Unlike alpha and
beta particles, gamma rays are not particles but high-energy photons, meaning they can travel long distances and penetrate most
materials, including human tissue (IAEA, 2004; Tabrah, 2010; IAEA, 2024). Because of their high penetration capability, gamma
rays are used extensively in medical imaging and cancer treatment, where they can be precisely targeted to destroy malignant
cells (Hosam and Amal, 2023). However, their ability to penetrate deeply into the body also makes them particularly dangerous,
as they can ionize atoms within living cells even at lower energy levels, potentially leading to mutations, cancer, and other health
issues (Mavragani, et al., 2019; Omoruyi, et al., 2023). Research has consistently shown that exposure to elevated gamma
radiation intensity can potentially cause acute radiation syndrome, with symptoms ranging from nausea and vomiting to severe,
life-threatening organ damage (ICRP, 2019). Radiation is everywhere in the environment and in the things that make up the
environment.
Sculpture as an expressive medium that involves the manipulation of materials such as stone, metal, wood, or clay to create a
tangible artistic representation in the environment (Nithiku, 2010; Gilmore, 2020;). Sculpture gardens, often celebrated for their
artistic and aesthetic appeal, provide a serene environment where art and nature coexist. However, beneath the beauty and
tranquility, there exists a potential radiation risk to human health, particularly through prolonged exposure to certain materials
used in sculptures. The estimation of excess lifetime cancer risk in a sculpture garden is a significant concern that arises from the
potential exposure to harmful substances that may be associated with certain sculptural materials and their degradation over time.
Studies such as those by Akpoveta and Osakwe (2010) and Ogbodo et al., (2023) have highlighted the general environmental
health concerns in the Niger Delta but have not addressed the particular risks posed by localized and culturally significant spaces
like the Sculpture Garden. This gap in research necessitates an investigation into excess lifetime cancer risks that may be
associated with the unique environmental factors present in the Sculpture Garden at Niger Delta University.
Study area
The garden is located at main campus, Niger Delta University, Yenagoa, Bayelsa State, Nigeria. It is specifically located at the
Fine and Applied Art Department in the Faculty of Arts, the main campus of the university, it is known as the sculpture garden,
and it consists of different sculptures and materials. It is an outdoor space specifically designed to showcase sculptures and
artworks in a natural setting. The sculptures are made up of different materials like stone, metals, wood, and even glass and are
exposed to all elements of weather such as rain, wind, and sunlight which can gradually wear down the sculpture over time. The
university campus itself is situated on the edge of Nun River Forest Reserve, nestled within a humid tropical rainforest marked by
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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heavy rainfall periodic flooding, and multilayered flora (Mohammed et. al, 2007). In this region, pockets of sandstone exist
between diapiric structures towards the delta or (base of coastal slope), this alternating sequence of sandstones and shale
progressively transition to basically sand-stone (Dorrik and Melissa, 2000; Worden and Burley, 2009; Beck et. al., 2024). The
primary real risk in the Niger Delta is the interceded shale within the Agbada formation. Below are pictures showing sections of
the sculpture garden.
Plates 1, 2 and 3 are pictures of sections of the sculpture garden
II. Material and method
The material used in the course of this research is the radiation alert inspector, the Radalert 100X, a factory-calibrated radiation
detection instrument, to measure x-rays, beta, alpha and gamma radiation (Omojola, et. al., 2021; Ononugbo and Anekwe, 2020).
This device features an audible alarm for radiation levels exceeding the set threshold, enabling the screening of environmental
contamination and radioactivity sources. Data logging and computer connectivity allow for efficient data recording and analysis.
Utilizing a Geiger tube and mica window, the Radalert 100X detects ionizing radiation displays results on an LCD screen. The
garden was divided into two sections for the purpose of this study. One section has more sculptures than the other. Measurement
was performed at 20 points, 10 points a section. The meter was turned on and positioned at waist level for 120 seconds during
each measurement after which the radiation counts were recorded in mRh
-1
.
III. Calculation
Equations 1, 2, and 3 were used to convert exposure rate, ER to absorbed dose (Rafique et. al, 2014), then to annual effective dose
(Aluko, et. al., 2023) then eventually to excess lifetime cancer risk (Biere et. al., 2024) respectively.
I mRh
-1
= 8700 nGyh
-1
1
AEDE = D x 8760 h x 0.7 SvGh
-1
x 0.2 x 10
-3
2
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ELCR = AEDE x DL x RF 3
Where D is the absorbed dose rate in 𝑛𝐺𝑦𝑦
−1
, 8760 h is the total hours a year, CF is the dose conversion factor from the absorbed
dose to effective dose in Sv/Gy. CF = 0.7 Sv/Gy. OF is the occupancy factor, OF = 0.2 as put forward by UNSCEAR, 2008.
AEDE is annual effective dose equivalent. DL is duration of life (55.2yrs) in Nigeria (WHO, 2018) and RF is risk factor for low-
level background radiation, thought to cause stochastic effects, ICRP 103 assigns 0.05 Sv
-1
for public exposure (ICRP, 2007).
IV. Results
Table 1: Radiological values in section with more sculpture in the garden
S/N
ER (mRh
-1
)
D (nGyh
-1
)
AEDE (mSvy
-1
)
ELCR x 10
-3
1
0.012
104.4
0.128
0.157
2
0.011
95.7
0.117
0.144
3
0.012
104.4
0.128
0.157
4
0.016
139.2
0.171
0.209
5
0.016
139.2
0.171
0.209
6
0.017
147.9
0.181
0.222
7
0.023
200.1
0.245
0.301
8
0.011
95.7
0.117
0.144
9
0.017
147.9
0.181
0.222
10
0.023
200.1
0.245
0.301
Average
0.015
137.5
0.168
0.206
Table 2: Radiological values in section with less sculpture in the garden
S/N
ER (mRh
-1
)
D (nGyh
-1
)
AEDE (mSvy
-1
)
ELCR x 10
-3
1
0.009
78.3
0.096
0.118
2
0.009
78.3
0.096
0.118
3
0.012
104.4
0.128
0.157
4
0.006
52.2
0.064
0.079
5
0.006
52.2
0.064
0.079
6
0.009
78.3
0.096
0.118
7
0.012
104.4
0.128
0.157
8
0.007
60.9
0.075
0.092
9
0.009
78.3
0.096
0.118
10
0.011
95.7
0.117
0.144
Average
0.009
78.3
0.096
0.118
Table 3: Grand average of all parameters in the sculpture garden and world average
ER (mRh
-1
)
D (nGyh
-1
)
AEDE (mSvy
-1
)
ELCR x 10
-3
0.015
137.5
0.168
0.206
0.009
78.3
0.096
0.118
0.012
107.9
0.132
0.162
0.013
59.0
1.0
0.29
* UNSCEAR, 2000
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Figure 1: exposure rate in area with more sculptures versus world average
Figure 2: exposure rate in area with less sculptures versus world average
Figure 3: graph of ELCR averages versus World average
0
0.005
0.01
0.015
0.02
0.025
1 2 3 4 5 6 7 8 9 10
ER (mR/h)
Points
ER (mR/h) World average
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
1 2 3 4 5 6 7 8 9 10
ER (mR/h)
Points
ER (mRh-1) World average
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1 2 3 4 5 6 7 8 9 10
ELCR x 10^3
Points
ELCR x 10-3 ELCR x 10-3 World average
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V. Discussion
In the section with more sculptures, average ER recorded is 0.015 mRh
-1
, with a minimum of 0.011 mRh
-1
and a maximum of
0.023 mRh
-1
, indicating relatively low exposure rate within the area. However, the slight variation suggests potential exposure
risks that warrant further monitoring, especially at points where ER reaches the maximum level. Absorbed dose D, values range
from (95.7 - 200.1) nGyh
-1
, with an average of 137.5 nGyh
-1
. This range indicates variability in radiation exposure within the
measured locations, which could be influenced by local geological conditions or anthropogenic activities. The average D is above
acceptable limits compared to global standards (UNSCEAR, 2008); the higher readings indicate the need for targeted studies to
ascertain the sources of increased radiation. AEDE values averaged 0.168 mSvy
-1
, with a minimum of 0.117 mSvy
-1
and a
maximum of 0.245 mSvy
-1
. These effective doses suggest that the radiation exposure is relatively low but still significant enough
to raise health concerns if sustained over long periods (UNSCEAR, 2008). The ELCR values range from (0.14 - 0.30) x 10
-3
, with
average 0.21 x 10
-3
. While these values are indicative of potential risk, they fall within acceptable limits for radiation exposure,
however, they highlight the importance of continues assessment, particularly for vulnerable populations in densely populated
areas.
In the section with fewer sculpture, ER averaged at 0.009 mRh
-1
, indicating a relatively low level of radiation exposure in that
section of the sculpture garden. The minimum recorded value of 0.006 mRh
-1
and maximum of 0.012 mRh
-1
suggest a consistency
in low radiation levels, which is beneficial for both the environment and public health, as excessive exposure can lead to harmful
biological effects. Absorbed Dose D, shows an average of 78.3 nGyh
-1
, with a minimum of 52.2 nGyh
-1
and a maximum of 104.4
nGyh
-1
. The average value fall within acceptable limit for natural background radiation, reinforcing the safety of this area for
recreational activities and gatherings. Annual Effective Dose Equivalent (AEDE) averaged 0.096 mSvy
-1
, but ranged (0.064 -
0.128) mSvy
-1
indicating that individuals in this area receive a relatively minor effective dose from environmental radiation
sources. This low dose is critical in assessing potential health risks associated with prolonged exposure. The Excess Lifetime
Cancer Risk (ELCR) value averages 0.118 x 10
-3
, with a range from (0.079 - 0.157) x 10
-3
. The values indicate very low cancer
risk. Table 3, shows the grand total of all measured parameters which indicates relatively low levels, implying that the risks
remain within a manageable threshold. Figure 3 shows all excess lifetime cancer risk obtained in the whole garden to be less than
the world average, except for two points in the section which has more sculpture.
Conclusion
The measurement of exposure rate in the Niger Delta University sculpture garden has been done. Results show averages of
exposure rate, absorbed dose, annual effective dose and excess lifetime cancer risk as 0.012 mRh
-1
, 107.9 nGyh
-1
, 0.132 mSvy
-1
and 0.162 x 10
-3
correspondingly. All values determined are less than world average values except for absorbed dose rate. This
suggests that the sculpture garden is generally safe for public use. However, fluctuations observed in readings highlight the fact
that radiation level across the garden is not evenly distributed with the section with more sculptures having relatively higher
values. Thus, the necessity for continuous monitoring. The ELCR values, although within acceptable limits with only about 20%
of obtained values above world average, 0.29 x 10
-3
, indicate a slight increase in excess lifetime cancer risk and underscoring the
importance of protecting vulnerable populations who may be exposed frequently to these environments. The results have shown
minimal elevation radiation levels, in environmental materials used in sculptures present in the garden. This low level can pose
specific health risks such as skin damage, eye irritation, and potential long-term effects like an increased risk of cancer due to
prolonged exposure. Therefore, caution should be taken to avoid the introduction of radioactive elements in relaxation areas like
the sculpture garden.
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