J. Nig. Soc. Phys. Sci. 5 (2023) 983

Journal of the
Nigerian Society

of Physical
Sciences

Health Risk Assessment of Heavy Metals in Sediment of
Tropical Freshwater Stream

Godwin O. Olutonaa,b,∗

aIndustrial Chemistry Programme, College of Agriculture, Engineering and Science, Bowen University, Iwo, Nigeria
bSchool of Basic Science, Kampala International University, Western Campus, Ishaka, Uganda

Abstract

An investigation of the heavy metals in the bed sediment of Asunle stream was carried out to assess how seriously the sediment is polluted
using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The potential health risk assessment was calculated for a lifetime
exposure (ingestion) based on the United State Environmental Protection Agency (USEPA) models to determine the carcinogenic and non-
carcinogenic risks for children and adults. The range of values (mg/kg) of heavy metals in bed sediment were: Fe (2850 – 7260), Mn (58 – 209),
Co (0.7 – 33), Ti (21.6 – 67), Ba (1.61 – 9.81), Zn (7.5 – 79), Cu (5.6 – 25), As (8 – 137), Al (273 – 2160), Y (24 – 49), and Sr (0.10 – 5.3).
As and Sr, values were below the background values for typical soil. The health risk assessment of heavy metals in the bed sediments revealed
that carcinogenic risk was almost insignificant while the non-carcinogenic risk was significant since their values were above the recommended
minimal risk level. The results also revealed that children are more vulnerable to hazards than adults. The chronic hazard quotient index for
exposure to these metals through ingestion exceeded the acceptable USEPA value of 1.0.

DOI:10.46481/jnsps.2023.983

Keywords: Contamination, Toxicology, Pollution, Public health, Asunle stream

Article History :
Received: 10 August 2022
Received in revised form: 02 December 2022
Accepted for publication: 19 December 2022
Published: 24 February 2023

© 2023 The Author(s). Published by the Nigerian Society of Physical Sciences under the terms of the Creative Commons Attribution 4.0 International license

(https://creativecommons.org/licenses/by/4.0). Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Communicated by: T. Owolabi

1. Introduction

Over time pollution from both point and non-point sources
have been a great challenge to water bodies [1] all over the
world, and sediment has been the reservoir of these pollutants.
The Obafemi Awolowo university dumpsite had been reported
to be polluted with the heavy metals and non-metals, metal-
loids, actinides and rare earth metals at varying degrees [2].
Leaching of these elements into the adjoining stream is inevitable
The distribution of metals in the sediment of a tropical stream

∗Corresponding author tel. no: +234 8132406932; +256 726393978
Email address: delog2@gmail.com (Godwin O. Olutona)

adjoining a university dumpsite, and runs through human settle-
ments with heavy agricultural activities can provide researchers
with proof of the anthropogenic impact on the ecosystem, and
thus aid in assessing the ecological risk to the aquatic habitats
and toxic risks on terrestrial habitat. The build-up of heavy
metals in sediment has significant environmental implications
on water quality and local inhabitants [3]. The impact of open
dumpsite on groundwater contamination with heavy metals was
investigated by Coker et al. [4]; their results revealed contam-
ination of groundwater as a result of leachate from the dump-
site.. Ogunfowokan et al. [5] earlier conducted an early wet
speciation study of heavy metals in the water and sediment of

1



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 2

the Asunle stream using atomic absorption spectroscopy (AAS).
Contamination factors of the study area were not fully explored.
This study is a follow-up monitoring of the perennial stream
with a comprehensive seasonal study and the use of ICP-OES
to further established the contamination levels of the adjoin-
ing stream to the Obafemi Awolowo University dumpsite. The
study further fully explored the pollution status of the stream.
Health risk assessment of the stream had not been conducted in
the previous study. The objectives of this study was to inves-
tigate the metal concentrations of the bottom sediments using
ICP-OES; their contamination factors and conduct the health
risk assessment.

2. Materials and Methods

2.1. Study area

Asunle, an adjoining stream is a periodic stream that has its
spring located about 100 m uphill from the Obafemi Awolowo
University (OAU), Ile-Ife refuse dumpsite (Figure 1).The uni-
versity dumpsite falls between Latitude 07° 32´N and Longi-
tude 4° 31´E. Geologically, the study area falls within the base-
ment complex of southwestern Nigeria. It forms part of African
crystalline shield with which consists predominantly of dolerites,
apitite, microgranite genesis, granite genesis, ultrasonic rocks,
mica and banded genesis. The characteristic of wastes gener-
ated in this dumpsite had been reported by Olutona et al[6] The
stream was about 100 m away from the major road that runs a
stretch of more than 10 km, cutting across three human settle-
ments [5]. It has the highest vegetation cover (about 90%) of all
the sites. Noticeable human activities along the stream are rig-
orous farming activities where cash crops (such as palm trees,
cola nut, and cocoa) and various food crops were planted. Oil
palm processing took place in all the human settlements along
this stream. Along the course of the stream, water from the
stream is used by the inhabitants who are predominantly farm-
ers for palm oil processing, irrigation of fruits and vegetables,
mixing and dilution of agrochemicals used for spraying of both
cash and food crops. Downstream, the water from the stream is
utilized for household purposes [6-7].

2.2. Sample Collection and Analysis

Five sites were chosen for this study along the course of
the stream. Sediment samples were collected on a monthly
basis for the period of eight (8) months (4 months dry and 4
months wet). Sediment sampling protocol described by IAEA
[8] was employed in this study. Sediment samples were col-
lected from the upstream (source as control), point of discharge
and downstream sampling points of receiving stream (Figure
1). Composite sediment samples (two samples) were randomly
collected (10-20 m apart) at 0-3 cm depth each month from
each location. Sediment samples were collected using stainless
steel scoop facing upstream. Excess water was drained from the
scoop. Black cellophane nylon beforehand cleaned with pure
acetone was used to collect the sediment samples. The sam-
ples were air dried for about five days and further dried at 50 ºC
in a vacuum oven to ensure that the samples were completely

Figure 1. A Map of Asunle an adjoining stream to Obafemi Awolowo Univer-
sity dumpsite

dried. The dried samples were crushed, ground and sieved with
500-micron plastic sieve. The samples were stored in clean
250 mL capacity amber bottles kept in the refrigerator until fur-
ther analysis was required. One (1 g) each of the samples was
acid digest using nitric acid (5 mL) and perchloric acid (1 mL)
acid. The digested samples were concentrated to a volume (<
2 mL) transferred into a volumetric flask (25 mL) and topped
up with distilled water. The digested solutions were analysed
using ICP-OES.

The Agilent, Varian 710 ICP-OES equipped with axially-
viewed plasma available at the Department of Nano Science,
University of the Western Cape, Cape Town, South Africa was
used for metal analysis in this study. The axially-viewed plasma
cover all-important wavelength in the visible region from 177-
785 nm. The ICP-OES is equipped with CCD detector and op-
timized optical design that give excellent signal-to-noise per-
formance, ensuring low detection limit. The CCD features the
Clocked recombination System (CRS) for anti-blooming pro-
tection. To enhance the performance of the 710 series are the
accessories such as VGA for mercury and hydride forming el-
ements, the fast SPS auto sampler for unattended automation,
the SVS switch valve for rinsing and improve productivity, the
AGM for organic matrices and the USN for lower detection
limit with environmental sample.

The choice of ICP-OES is due to its analytical advantage
over other excitation sources originates from its capability for
efficient and reproducible vaporization, atomization, excitation
and ionization for a wide range of elements in various sam-
ple matrices. This is basically due to high temperature 6000-
7000K, in the observation zones of the ICP which is much
higher than the maximum temperature of flames or furnaces
(3300K). This instrument also makes it capable of exciting re-
fractory elements and renders it less prone to matrix interfer-
ences. Similarly, the choice of axial rather than radial view ICP-
OES is due to the fact that the axial view provides better LODs
than radial view. This may be attributed to longer viewing path

2



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 3

available down the axis of the plasma, thus a better sensitivity
of 5-10 fold improvement in the LOD can be achieved.

2.3. Calculation of Pollution Assessment Indices

In this study, geo-accumulation index, enrichment factor,
contamination factor and pollution index have been applied to
assess heavy metals distribution and contamination in the sedi-
ment samples from Asunle Stream.

2.3.1. Enrichment Factor (EF)
Enrichment factor (EF) analysis is a method used to differ-

entiate between the metals originating from anthropogenic ac-
tivities and those from natural sources and to assess the degree
of anthropogenic influence [9]. The EF is defined as follows:

EF =

[
Cx

CAl

]
sample[

C x
CAl

]
background

(1)

Where, [Cx/CAl] sample is the ratio of metal [Cx] to that of
Al [CAl] in the soil /sediment sample and [Cx/CAl] background
is the ratio of metal and Al concentration of the geochemical
background. The geochemical background values of metals are
not available. Thus, the geochemical average shale values given
by Turekian and Wadepohl [10] were adopted. Seven contami-
nation categories are recognized based on enrichment factor as
follows [11]:

2.3.2. Geo-accumulation Index
The geo-accumulation index (I-geo) values were calculated

for different metals as introduced by Muller[12] as follows:

I-geo = log2{
Cn

[1.5 Bn]
} (2)

where Cn is the measured concentration of the heavy metal
‘n’ in the sample and Bn is the geochemical background value
of element ‘n’ and 1.5 is the background matrix correction fac-
tor.

2.3.3. Contamination Index
The calculation of contamination index of metals in the sed-

iment samples was done using the relationship:

Contamination Index (CI) =
Metal concentration in the soil
Background value o f the metal

(3)

2.3.4. Pollution Load Index
Each location was evaluated for the extent of metal pollu-

tion by employing the method based on the pollution load index
(PLI) developed by Thomilson et al. [13] as follows:

PLI = n
√

CF1 × CF2 × CF3 × CF4 . . . . . . .CFn (4)

where n is the number of metals studied and CF is the con-
tamination factor calculated as described in equation 3.

2.4. Health Risk Assessment

The basic formulas and values used for the calculation of
ingestion and inhalation of soil as described by Grezetic et al.
[14] are shown below.

Chronic Daily Intake (CDI) for carcinogenic risk (ingestion
of soil):

Carcinogenic CDI (mg/kg/day) = CS xI F x
EF
AT

(5)

where IF =
IRAdult× EDAdult

BWAdult
+

IRChild × EDChild
BWChild

(6)

lNon-carcinogenic: CDI (mg/kg/day)

= CS × I N × EF ×
ED

BW
× AT (7)

3. Results and Discussion

3.1. Validity of Analytical Method Adopted for Heavy Metal
Analysis

The linear calibration curve for each metal was plotted and
each near unity. Blank and internal standard were also con-
ducted to authenticate the results and to check for background
contaminants. Table 1 presents the limits of detection (LOD)
and quantification (LOQ) of the elements.

3.2. Heavy Metals in Asunle Stream Sediment

This section of the study presents the metal content in the
Asunle stream bed sediment. Generally, the concentrations of
metals in the bed sediment were significantly lower at p < 0.05
when compared with either those of the dumpsite soils or the
lateral soil sampling towards the receiving stream. The data
obtained (Table 2) were subjected to Duncan Multiple range test
to establish possible differences in all the sampling periods. The
statistical analysis showed that except for Fe, Mn, Ba, Cu, and
Y, all other metals had significant difference in all the sampling
periods.

Biologically, iron (Fe) plays a crucial role in the transport
and storage of oxygen, and also in electron transport [15 ]. It
is safe to say that, with only a few possible exceptions in the
bacterial world, there would be no life without iron [16]. The
monthly mean level of Fe ranged from 2850 ± 1600 mg/kg in
August to 7260 ± 5400 mg/kg in February. These values were
below the background value of 47,200 mg/kg in shales [10] and
26,000 mg/kg elemental concentration of typical soil [17].

Manganese is an indispensable element in human food with
a normal nutritional intake considered to be nearly 2 –5 mg/day
[18]. It is a constituent of certain enzymes and can also activate
many enzymes [19]. Manganese monthly mean levels ranged
from 58 ± 50 mg/kg in August to 210 ± 210 mg/kg in February.
These values were below the background value of 850 mg/kg in
shales [10] and 550 mg/kg elemental concentration of typical
soil [17].

Cobalt means levels ranged from 0.73 ± 1.74 mg/kg in De-
cember to 33 ± 21 mg/kg in August. The values obtained in the

3



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 4

Table 1. Validation of analytical methods
Fe Mn Cr Ni Co Ti Zr Zn Cu Be

λ (nm) 238.2 257.6 267.7 221.6 238.89 336.12 343.82 213.86 324.75 313.04
%RSD 0.71 1.41 1.05 1.07 0.01 0.84 0.67 0.59 0.67 0.86
LOD 0.006 0.003 0.0009 0.03 0.018 0.0012 0.015 0.00 0.002 0.001
LOQ 0.06 0.03 0.009 0.3 0.18 0.012 0.15 0.00 0.02 0.01

dry season were low when compared to the background level of
19 mg/kg in shales [10] and 9.1 mg/kg elemental concentration
of typical soil [17]. The monthly mean levels of Ti ranged from
21.6 ± 5.6 mg/kg in November to 67 ± 77 mg/kg in February.
These values were below the background value of 4600 mg/kg
in shales [10]. Barium monthly mean values ranged from 1.61
± 3.94 mg/kg in July to 10 ± 16 mg/kg in February. These val-
ues obtained were below the background value of 580 mg/kg in
shales [10].

Zinc is an indispensable element essential for the life pro-
cesses of several enzymes. Zn impedes at diverse levels in the
endocrine system and lipids and carbohydrate metabolism [20].
At higher levels zinc may be carcinogenic [21]. The monthly
mean values of Zn ranged from 7.53 ± 9.31 mg/kg in August
to 79 ± 46 mg/kg in January. These values were below the
background value of 95 mg/kg in shales [10] and 60 mg/kg el-
emental concentration in typical soil except values obtained in
December and January that were above the elemental concen-
tration in typical soil[17].

Copper is a vital metal to human life at modest levels op-
erational as part of some enzymes e.g., tyrosine (necessary for
the formation of melanin pigments), cytochrome oxidase, su-
peroxid dismutase, and amine oxidases. It is essential for the
utilization of iron in the formation of haemoglobin [22]. Cu
monthly mean values ranged from 5.63 ± 7.16 mg/kg in July to
25 ± 43 mg/kg in February. The values were below 45 mg/kg
background value in shales7 and 25 mg/kg elemental concentra-
tion in atypical soil [17]. Arsenic is a metalloid, poisonous [23]
classified as carcinogenic, and harmful to human healthiness.
In addition to natural origin, it can also be predominant in the
soil in an area where there are mining-related activities; munic-
ipal sewage, coal burning, agrochemicals, fertilizers, vehicular
emissions and wood preservative chemicals and industrial ef-
fluents [24-26]. The monthly mean values of As ranged from
8.42 ± 21 mg/kg in December to 137 ± 100 mg/kg in August.
Except for December, the values obtained were above the back-
ground value of 13 mg/kg in shales7 and 7.2 mg/kg elemental
concentration in atypical soil [17].

The monthly mean values of Al ranged from 273 ± 288
mg/kg in August to 2160 ± 610 mg/kg in January. The values
were below 80,000 mg/kg background value in shales [10]. Yt-
trium was only above the detection limit in January and Febru-
ary and ranged between 24 ± 60 mg/kg and 49 ± 120 mg/kg.
The values were above the background value of 26 mg/kg in
shales7. Strontium ranged from 0.10 ± 0.17 mg/kg in June to
5.25 ± 2.45 mg/kg in January. The values were below the back-
ground value of 300 mg/kg in shales [10].

Figure 2. Seasonal levels of heavy metals in sediment of Asunle stream

3.3. Seasonal Levels of Heavy Metals of Asunle Stream Sedi-
ment

Seasonal variation of heavy metals of Asunle stream sed-
iment is presented in Figure 2. The data obtained revealed
that all the metals with exception of Co and As were generally
higher in the dry season. Moreover, the concentrations of Fe
and Al were exceptionally higher than all other metals in both
seasons. Higher levels of these metals in dry season might be
due to the slower movement of water in the stream during the
dry season resulting in greater settlement chances of the metal-
bound sediment particles. Also, the lower levels of the metals
in the bed sediment during the wet season compared to the dry
season might be due to dilution arising from high precipitation.

3.3.1. Principal Component Analysis of Heavy Metals in Sedi-
ment of Asunle Stream

The principal component analysis (PCA) of heavy metals
in the bed sediment (Figure 3), the total variance for the two
components was explained by 55.32%. The first component ac-
counted for 39.23% of the explained variance in which Fe, Al,
Ba and Mn recorded high positive loadings of 0.86, 0.79, 0.78
and 0.72, respectively. The second component accounted for
16.09% of the explained variance and only As had the highest
loading 0.74. In terms of association, four groups can readily
be identified. These are Zn, Sr, Cu and Al; Mn, Ba, Fe and Ti;
As and Co; and Y. The metals that are associated probably have
a common origin or source.

3.4. Pollution assessment indices
3.4.1. Geo-accumulation Index of Heavy Metals in Sediment of

Asunle Stream
The geo-accumulation index of heavy metals in the bed sed-

iment of Asunle Stream is presented in Table 3. The results ob-
4



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 5

Table 2. Monthly levels of heavy metals in sediment of Asunle stream
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Nov 3530a
±1900

68a

±45
1.87a
±3.67

21.6a

±5.6
BDL 49abc

±31
8.87a

±11
14bc

±34
1270d

±650
BDL 2.53ab

±1.31
Dec 5130a

±3100
110a

±65
0.7a

±1.7
32ab

±12
2.9a

±7.0
69bc

±64
18a

±32
8bc

±21
1650a

±770
BDL 3.9ab

±3.8
Jan 6850a

±3600
124a

±95
2.9a

±5.3
31ab

±12
5.96a

±12
79c

±46
14a

±25
15c

±37
2160a

±610
24a

±60
5.3b
±2.5

Feb 7260a
±5400

209a

±210
5.0a

±8.6
67b

±77
9.81a

±16
31ab

±49
25a

±43
33ab

±46
1070ab

±740
49a

±120
2.7ab

±4.5
May 4970a

±3900
96a

±118
25b

±14
59ab

±43
7.73a

±19
12a

±16
24a

±36
114bc

±39
1430bc

±1300
BDL 0.44ab

±1.10
Jun 4970a

±3000
124a

±150
21b

±13
28ab

±15
3.1a

±7.6
16a

±16
13a

±15
46ab

±86
997ab

±550
BDL 0.10a

±0.17
Jul 3320a

±2500
74a

±68
31b

±18
25ab

±17
1.6a

±3.9
8.6a

±9.5
5.6a

±7.2
62ab

±95
701abc

±600
BDL BDL

Aug 2850a
±1600

58a

±50
33b

±21
27.4ab

±4.8
BDL 7.5a

±9.3
13a

±14
137a

±100
273c

±290
BDL 3.2ab

±8.1
The alphabet in each column denotes mean that are significantly different (p < 0.05)

BDL = Below detection Limit

Figure 3. PCA of heavy metals in sediment of Asunle stream

tained revealed that the sediments were practically unpolluted
with the metals during both seasons. Arsenic, however, demon-
strated a moderate to heavily pollution status of the sediments
during the dry season.

3.4.2. Enrichment Factor/Index of Heavy Metals in Sediment of
Asunle Stream

The Enrichment Factor (EF) for the heavy metals in the bed
sediments is presented in Table 4. These values were obtained
using the geochemical background values in average shale [10].
The enrichment status of the soil based on Taylor [11] propo-
sition revealed that the sediment was not enriched with Ti, Ba
and Sr. On the other hand the enrichment of the sediment with
Fe, Mn during the two seasons and Co in dry season were mod-
erately severe. Enrichment of Zn in wet season and Cu in dry
season were severe. Similarly, enrichment of the sediment with
Zn and Y in dry season and Cu in wet season were very severe
while those of Co in wet season and As in both seasons were
extremely severe.

3.4.3. Contamination Factor with Respect to Temporal Varia-
tion of Heavy Metals in Sediments of Asunle Stream

The monthly and seasonal contamination factors (CFs) for
each metal were calculated according to Equation 3. and pre-
sented in Table 5. Four groups of classification of CF were
described by Nase et al. [27]; and Mmolawa et al.,[28]. These
are: CF < 1 (low contamination); 1≤ CF < 3 (moderate con-
tamination); 3 ≤ CF < 6 (considerable contamination), and CF
> 6 (very high contamination).

The results of contamination factor of temporal variation
of metals in bed sediment of Asunle river revealed that the
mean value varied between 0.0007(Ti) and 0.60 (Zn) in wet and
0.003(Sr) and 6.9(As) in dry. These results indicated that the
contamination due to Fe, Mn, Ti, Ba, Zn, Cu, Al, Sr in both
seasons and Co in the dry season were low. The sediment was
moderately contaminated with Co in the wet season and As in
the dry season while the contamination of the sediment with re-
spect to As in the wet season stood between considerable con-
tamination and high contamination. The contamination status
of the sediments with respect to the metals in decreasing order
in dry season was: As > Y > Zn > Cu > Mn > Co > Al > Sr >
Ba > Ti while in wet season, the order was: As > Co > Cu >
Zn> Mn > Fe > Al > Ti > Ba > Sr.

3.4.4. Contamination Factor with Respect to Temporal Varia-
tion of Heavy Metals in Sediments of Asunle Stream

The monthly and seasonal contamination factors (CFs) for
each metal were calculated according to Equation 3. and pre-
sented in Table 5. Four groups of classification of CF were
described by Nase et al. [27]; and Mmolawa et al.,[28]. These
are: CF < 1 (low contamination); 1≤ CF < 3 (moderate con-
tamination); 3 ≤ CF < 6 (considerable contamination), and CF
> 6 (very high contamination).

The results of contamination factor of temporal variation
of metals in bed sediment of Asunle river revealed that the

5



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 6

Table 3. Geo accumulation index of heavy metals in the sediment of Asunle stream
Cn I-geo Class Pollution In-

tensity
Dry Wet Bn Dry Wet Dry Wet Dry Wet

Fe 5690 4030 47200 -3.64 -4.14 0 0 PU PU
Mn 128 87.9 850 -3.32 -3.86 0 0 PU PU
Co 2.64 27.7 19 -3.43 -0.04 0 0 PU PU
Ti 38 34.8 4600 -7.50 -7.63 0 0 PU PU
Zn 57.2 11.2 95 -1.40 -2.10 0 0 PU PU
Cu 16.6 13.9 45 -2.03 -2.28 0 0 PU PU
Ba 4.66 3.11 580 -2.27 -8.13 0 0 PU PU
Al 1540 850 80000 -6.29 -7.14 0 0 PU PU
As 17.8 89.8 13 -0.13 2.20 0 3 PU MP-HP
Sr 3.58 0.97 300 -6.97 -8.86 0 0 PU PU
Y 18.32 - 26 -1.09 - 0 0 PU -

Key
PU= Practically Unpolluted, MP-HP = moderately to Heavy Polluted

Table 4. Enrichment factor of heavy metals in sediment of Asunle stream
Cn Enrichment Factor
Dry Wet Bn Dry Wet

Fe 5690 4030 47200 6.27 8.03
Mn 128 87.9 850 7.83 9.74
Co 2.64 27.7 19 7.22 137
Ti 38 34.8 4600 0.43 0.71
Ba 4.66 3.11 580 0.42 0.50
Zn 57.2 11.2 95 31.3 11.1
Cu 16.6 13.9 45 19.1 29
As 17.8 89.8 13 71 650
Y 18.3 - 26 36.6 ND
Sr 3.58 0.97 300 0.62 0.30

Key
Enrichment status: < 1 = No Enrichment, 1-3 = Minor, 3-5 Moderate, 5-10 = Moderately severe, 10-25= Severe, 25-30 = Very

severe, and > 50 = Extremely Severe.

mean value varied between 0.0007(Ti) and 0.60 (Zn) in wet and
0.003(Sr) and 6.9(As) in dry. These results indicated that the
contamination due to Fe, Mn, Ti, Ba, Zn, Cu, Al, Sr in both
seasons and Co in the dry season were low. The sediment was
moderately contaminated with Co in the wet season and As in
the dry season while the contamination of the sediment with re-
spect to As in the wet season stood between considerable con-
tamination and high contamination. The contamination status
of the sediments with respect to the metals in decreasing order
in dry season was: As > Y > Zn > Cu > Mn > Co > Al > Sr >
Ba > Ti while in wet season, the order was: As > Co > Cu >
Zn> Mn > Fe > Al > Ti > Ba > Sr.

3.5. Spatial Variation of Heavy Metals in Sediment of Asunle
Stream

The spatial variation of metals in bed sediments of the Asunle
stream is presented in Table 6. The results obtained when sub-
jected to ANOVA showed that all the metals in all locations
were significantly different (p < 0.05) from one another with

respect to Co, Ti, As, and Sr. This clearly indicated the non-
uniformity in the levels of the metals found in the bed sediment.
This could be due to uneven anthropogenic inputs of these met-
als, differential distribution by the flowing stream, the unequal
sequestering influence of sediment components to precipitate
the metals along the watercourse, etc. Similarly, the data were
also subjected to Duncan Multiple range tests to establish pos-
sible differences in the mean values of metals in each location.
The statistical analysis showed that except for Co, As and Sr,
virtually all the metals had significant differences in all the lo-
cations investigated.

The total metal burden at the control point (Location 0) was
generally low compared to other locations. This could be since
this location is situated upstream some distance away from the
dumpsite. The source of metal pollution at Location 0 might
be traced to natural sources, agro-allied chemicals used by the
farmers and deposition of metal containing fly ash coming from
incineration of solid waste. Location 1 is the closest point on
the stream bank from the dumpsite. It is at a lower gradient with
respect to the dumpsite. This could explain why the potentially

6



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 7

Table 5. Contaminant factor of heavy metals in sediment
Season Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Nov Dry 0.07 0.08 0.10 0.005 - 0.52 0.20 1.08 0.02 - 0.008
Dec 0.11 0.13 0.04 0.007 0.005 0.73 0.41 0.65 0.02 - 0.01
Jan 0.15 0.15 0.15 0.007 0.01 0.83 0.32 1.18 0.03 0.94 0.02
Feb 0.15 0.25 0.27 0.01 0.02 0.33 0.55 2.57 0.01 1.88 0.009
Mean 0.12 0.15 0.14 0.007 0.009 0.60 0.37 1.37 0.02 0.71 0.01
May Wet 0.11 0.11 1.34 0.01 0.01 0.13 0.53 8.78 0.02 - 0.001
Jun 0.11 0.15 1.09 0.006 0.005 0.17 0.29 3.53 0.01 - 0.0003
Jul 0.07 0.09 1.64 0.005 0.003 0.09 0.13 4.77 0.009 - -
Aug 0.06 0.07 1.76 0.006 ND 0.08 0.28 10.52 0.003 - 0.01
Mean 0.09 0.11 1.46 0.007 0.005 0.12 0.31 6.9 0.01 - 0.003

toxic metals burden of this location had generally higher val-
ues than other locations. From Location 1, there was a general
decrease in concentrations of the metals downward the stream
with exception of Location 4 which had a higher metal concen-
tration than Location 1. This occurrence might be due to the
flat topography of Location 4 which could encourage better and
more effective sedimentation of metal containing particulates.

The Fe concentrations having a range of 1620 ± 630 mg/kg
at Location 0 to 8310 ± 2700 mg/kg at Location 4 were below
the background value of 47200 mg/kg in shales [10], and 26000
mg/kg elemental concentration of a typical soil[17]. Manganese
is a vital nutrient and naturally occurring element, useful in
steelmaking, fireworks, fertilizers, chemicals, glass, and dry-
cell batteries production, textile and leather industries. Its pres-
ence in soil results in vegetable and animal foods reliably con-
taining varying amounts of the mineral [29]. Manganese mean
concentration ranged from 18 ± 18 mg/kg at Location 0 to 244
± 110 mg/kg at Location 4. The values obtained were below the
background value of 850 mg/kg in shales [10], and 550 mg/kg
elemental concentration in a typical soil[17].

Cobalt in sediment could be of natural and anthropogenic
origins. The anthropogenic sources could be as a result of phosphate-
based fertilizer application, smelting, sewage sludge, alloys,
and mining. In water, cobalt is basically settled in the bottom
sediment while some may be adsorbed by suspended solids in
the water column [29]. Cobalt ranged from 10 ± 11 mg/kg at
Location 3 to 23 ± 22 mg/kg at Location 2. These values were
very low with exception of Location 1 and 2 compared to 19
mg/kg in shales [10]. The mean concentrations of Co in all the
locations were above 9.1 mg/kg elemental concentration of a
typical soil [17].

The mean range value of Ti was between 18.3 ± 7.1 mg/kg
at Location 5 and 59 ± 67 mg/kg at Location 2. These values
were below the 4600 mg/kg background value in shales [10].
Barium levels ranged from 0.65 ± 1.9 mg/kg at Location 5 to
16 ± 17 mg/kg at Location 4. These values were below the
background value of 580 mg/kg in shales [10].

Zinc is abundant in the environment, instituting 20–200 ppm
(by weight) of the Earth’s crust [29]. The mean concentration of
Zn ranged from 13 ± 16 mg/kg at Location 0 to 84 ± 69 mg/kg
at Location 1; the values were below the background value of
95 mg/kg in shales [10], and 60 mg/kg elemental concentration

of a typical soil [17] with exception of Location 1.
Copper found their way into water bodies by natural weath-

ering of soil and rocks or anthropogenic sources [29]. Copper
mean concentrations ranged from 5.9 ± 4.3 mg/kg at Location
3 to 17 ± 30 mg/kg at location 0. The values of Cu at all lo-
cations were lower except at Location 1 when compared with
the background value of 45 mg/kg in shales[10], and 25 mg/kg
elemental concentration in a typical soil[17].The levels of As in
the bed sediment ranged from 9 ± 26 mg/kg at Location 2 to 83
± 80 mg/kg at Location 4. The mean values of As were higher
than the background value of 13 mg/kg in shales[10] except at
Location 2 where the value was higher.

The mean concentrations of Al ranged from 667 ± 400 mg/kg
at Location 3 to 1590 ± 970 mg/kg at Location 1. The mean
values of Al were low compared with the background value of
80,000 mg/kg in shales[10]. Yttrium was only above the de-
tection limit at Location 0 and the value was above the back-
ground value of 26 mg/kg in shales [10] Strontium in bed sed-
iment ranged from 0.8 ± 1.3 mg/kg at Location 0 to 4.4 ± 4.9
mg/kg at Location 1. The mean values of Sr obtained in this
study were far below the background value of 300 mg/kg in
shales[10].

Generally, the metals contamination levels in the bed sedi-
ment were wide-ranging significant among the stream site sam-
pling locations. Potential toxic metals in bed sediments are ei-
ther lithogenic or anthropogenic. The total metal burden at the
control point was generally low compared to other locations.
However, this could not be totally attributed to the lithogenic
effect since there was the possibility of atmospheric distribu-
tion as a result of incineration of dumped solid waste. The total
metal burden in the bed sediments of Locations 1 to 5 showed
the influence of anthropogenic inputs because of the leaching of
these metals from the dumpsite into the receiving stream. Since
bed sediment acts as both carrier and source of contamination in
the aquatic environment. High contaminations of the bed sedi-
ment with metals may have adverse effects on aquatic habitats;
hence, remediation of the bed sediment is highly required.

3.5.1. Contaminant Factor of Heavy Metals with Respect to
their Spatial Variation in Sediment of Asunle Stream

Table 7 is presentation of monthly and seasonal contamina-
tion factors (CFs) for each heavy metal. The results revealed

7



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 8

Table 6. Spatial variation of heavy metals in sediment of Asunle stream
Site Fe Mn Co Ti Ba Zn Cu As Al Y Sr Total

metal
burden

0 1620a

±630
18a

±18
10a

±14
40ab

±19
BDL 13a

±16
17a

±30
41a

±73
1280abc

±730
55a

±110
0.8a

±1.3
3090

1 7440cd

±3400
117bc

±100
21a

±24
59b

±67
6.54a

±13
84b

±69
51b

±32
61a

±100
1590bc

±970
BDL 4.4a

±4.9
9430

2 3030ab

±1700
43ab

±300
23a

±22
29ab

±14
BDL 32a

±26
8.50a

±14
9.31a

±26
896ab

±580
BDL 3.4a

±6.9
4070

3 4960bc

±2900
172cd

±130
10a

±11
25ab

±10
BDL 31a

±39
5.9a

±4.3
70a

±77
667a

±400
BDL 0.99a

±1.18
5940

4 8310d

±2700
244d

±110
10a

±14
47ab

±36
16b

±17
25a

±20
6.63a

±11
83a

±80
2020c

±960
BDL 2.00a

±2.54
10800

5 3820ab

±3100
54ab

±52
17a

±16
18.3a

±7.1
0.7a

±1.9
21a

±29
2.1a

±5.2
58a

±75
722a

±760
BDL 2.01a

±2.9
4710

The alphabet in each column denotes a mean value that is significantly different at p < 0.05 from each other.

that the contamination of bed sediment with respect to Fe, Mn,
Ti, Ba, Zn, Al, Sr, and Zn were low. Co at Locations 1 and 2
as well as Cu in Location 2 exhibited moderate contamination.
Similarly, Y had moderate contamination. Arsenic contamina-
tion varied between considerable and high contaminations ex-
cept Location 2 which exhibited low contamination.

3.5.2. Pollution Load Index (PLI) of the Sediments
PLI was employed to adequately compare whether all the

locations suffer contamination or not. The PLI was intended at
providing an extent of the degree of the total contamination of
the sampling locations along the course of the stream. Table
8 shows the result of the PLI for the eleven metals studied at
the various locations. Based on the results, the overall degree
of contamination in all the locations was of the order: Loca-
tion 1 > Location 4 > Location 3 > Location 0 > Location 5 >
Location 2. Results of PLI indicated that no location was pol-
luted with Fe, Mn, Ti, Ba, Zn, Al and Sr. However, Location
0 was polluted with As and Y; Location 1 with Co, Cu and As;
Location 2 with Cu only; and Location 3, 4 and 5 with As only.

3.6. Correlation Analysis of Heavy Metals in Sediment of Asunle
Stream

The determination of the correlation analysis is to quan-
tify the strength of association observed between two variables.
This association is likely to better illustrate the causal relation-
ship between the variables. Two-tailed correlation analysis be-
tween various metals detected in the lateral sampling of sedi-
ment toward the receiving stream is presented in Table 9. The
result obtained revealed that Fe was positively correlated with
Mn, Ti, Ba, Zn, Cu, Al and Sr. Manganese positively correlated
with Ti, Ba and As, Ti positively correlated with Ba, Cu, Al and
Sr; Ba correlated positively with Al; Zn positively correlated
with Cu and Al; Cu and Al and Sr are positively correlated,
and Fe and Sr are positively correlated. However, Co nega-
tively correlated with Zn and Al while Zn negatively correlated
with As and As in turn negatively correlated with Sr. Corre-
lation analysis obtained in this study was similar to the values

obtained from the dumpsite soil [2]. The association between
these metals could be attributed to a common source, hence,
positive correlations among these metals were controlled by
features such as, anthropogenic factors, properties and soil gen-
esis [5]. The strong association among Fe, Ba, Zn, Al could be
attributed to the degradation of e-waste materials in the dump-
site that was leached into the stream.

3.7. Health Risk Assessment of Heavy Metals in Sediment of
Asunle Stream

The model used to calculate the exposure of humans to po-
tentially toxic metals in the sediments is based on those devel-
oped by the United States Environmental Protection Agency.
The chronic daily intake for carcinogenic risk (oral) in the bot-
tom sediment of the Asunle stream is showed in Table 10. The
chronic daily intake for Fe ranges from 0.31 – 3.87 mg/kg/day.
There is no available MRL data for Fe.

Manganese is an essential component of steel. Inorganic-
Mn is equally used in the manufacture of dry cells, fireworks,
and glass various chemicals, leather and textile, and fertilizer.
Manganese found their way into water bodies majorly via the
erosion of rocks and soils, mining works, and leaching e-waste
material dumped in landfills [29]. The chronic daily intake of
Mn for carcinogenic (oral) in the sediment of the Asunle stream
ranged from 0.006 – 0.1 mg/kg/day. Literature has no stipulated
MRLs values for various stages of toxicity for oral exposure to
Mn, though neurobehavioral disorder has been established in
literature from intermediate- and chronic-duration oral expo-
sure to excess inorganic-Mn, hence, an interim guidance value
of 0.16 mg Mn/kg/day is recommended by ATSDR for commu-
nity health assessments [30]. The level of Mn recorded in this
study are below any alerting values.

Cobalt, is vital for beings with dietary allowance of 0.1 µg,
and mean regular consumption from food is valued to be 5 – 40
µg/day [31]. The chronic daily intake for Co in the bed sedi-
ment ranged from 0.0002 – 0.004 Co mg/kg/day. The minimal
risk level (0.01 mg Co/kg/day) has been stipulated for average

8



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 9

Table 7. Contaminant factor of heavy metals in spatial variation in sediment of Asunle stream
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

0 0.03 0.02 0.54 0.009 ND 0.13 0.39 3.18 0.02 2.11 0.003
1 0.16 0.14 1.09 0.01 0.01 0.90 1.13 4.73 0.02 ND 0.01
2 0.06 0.05 1.20 0.006 ND 0.33 0.19 0.72 0.01 ND 0.01
3 0.11 0.20 0.53 0.006 ND 0.32 0.13 5.39 0.008 ND 0.003
4 0.18 0.29 0.54 0.01 0.03 0.27 0.15 6.35 0.02 ND 0.007
5 0.08 0.06 0.89 0.004 0.001 0.22 0.05 4.44 0.009 ND 0.007

Table 8. Pollution load index of heavy metals across the sampling locations
Sites Fe Mn Co Ti Ba Zn Cu As Al Y Sr
0 0.03 0.02 0.54 0.009 ND 0.13 0.39 3.18 0.02 2.11 0.003
1 0.16 0.14 1.09 0.010 0.01 0.90 1.13 4.73 0.02 ND 0.01
2 0.06 0.05 1.20 0.006 ND 0.33 0.19 0.72 0.01 ND 0.01
3 0.11 0.20 0.53 0.006 ND 0.32 0.13 5.39 0.008 ND 0.003
4 0.18 0.29 0.54 0.010 0.03 0.27 0.15 6.35 0.02 ND 0.007
5 0.08 0.06 0.89 0.004 0.001 0.22 0.05 4.44 0.009 ND 0.007
Mean 0.10 0.13 0.80 0.008 0.007 0.36 0.34 4.14 0.015 0.35 0.007

length oral contact to cobalt [29]. The CDI values obtained in
this study is below the MRL value for Co, hence there is no
cause for alarm. Barium, an alkaline earth metal, with a vari-
ability of usages such as getters in electronic tubes, rodenticide,
colorant in paints, and x-ray contrast medium [30]. The min-
imal risk level (0.2 mg Ba/kg/day) has been stipulated for av-
erage length oral exposure to barium. With the CDI of Ba in
bed sediment ranging from 0.0002 – 0.001 mg/kg/day, the CDI
value obtained in this present study was several folds (200 –
1000) below the recommended MRL.

Zinc, a vital metal has a recommended daily allowance be-
tween 5 mg (infant) to 15 mg for infants and adults, respec-
tively [14]. Detrimental health effects of Zn range between 100
to 250 mg/day [32]. ATSDR [30] recommended minimal risk
level of 0.3 mg/kg/day for both intermediate and chronic dura-
tion. The CDI for Zn in bed sediment ranged from 0.00008 to
0.009 mg/kg/day. The Zn level recorded in this study are far
below the recommended limits, hence, not cause for immediate
health concern.

Copper, an indispensable nutrient is vital in carbohydrate,
and drug metabolism, haemoglobin formation, catecholamine
biosynthesis, the cross-linking of collagen, elastin, and hair ker-
atin, and the antioxidant defence mechanism[30]. Some of the
evidence of Cu deficit are: anaemia, leukopenia, and osteoporo-
sis. The recommended minimal risk level of both intermediate
and chronic duration is 0.01 mg/kg/day. The value obtained in
this study ranged from 0.0009 to 0.003 mg/kg/day which are
far below the recommended value and pose no health threat to
humans.

Arsenic is a metalloid, and very poison. Arsenic main route
of exposure is via food and drinking water. Dietary exposures
to arsenic in female ranges between 1.01, and 1,081 µg/day
and mean (50.6 µg/day); male ranges between 0.21 and 1,276
µg/day, and mean (58.5 µg/day) [30]. The minimal risk level of
0.005 and 0.0003 mg As/kg/day has been resultant for acute and
chronic duration oral exposure to inorganic arsenic. The CDI of

As in bed sediment ranged from 0.004 to 0.01 mg/kg/day (Table
10). The values obtained in this study were above the recom-
mended minimal risk level; hence, the risk of cancer is possible.

Aluminium, the third most abundant element of the earth’s
crust. There is appreciable amount of human data on the tox-
icity of Al because of oral exposure for instance, dialysis en-
cephalopathy syndrome (a degenerative neurological syndrome),
and Alzheimer’s disease [30]. The minimal risk level for both
intermediate and chronic duration is 1.0 mg/kg/day. The CDI
of Al for carcinogenic (oral) in bed sediment ranged from 0.03
– 0.24 mg/kg/day. These values were below the minimum risk
level; hence no health risk is implied. The levels of Strontium
in fresh waters ranges between 0.5 and 1.5 mg/L. The daily ex-
posure is estimated to be 3.3 mg/day (0.046 mg/kg/day): from
inhalation (400 ng/day), drinking water (2 mg/day), and diet
(1.3 mg/day) [30]. The minimal risk level of Sr in bed sediment
ranged from 0.00001 to 0.0006 mg/kg/day. Thus, the values
obtained in this study were also below the minimal risk level.

Table 11 presents the descriptive statistics of the cancer risk
assessment of the heavy metals in bed sediment of Asunle stream.
These values depicted non-hazard for both young and adult.
The sequence of the total cancer risk of the studied metals are
Fe > Al > Mn >As > Ti > Ba > Zn > Co > Y > Sr > Ba.
Given the available toxicological profile of the studied metals,
it is obvious that all the studied metals may not inevitably have
any adverse effect on human. The levels obtained in this study
are below the RAIS oral chronic reference dose (mg/kg/day).

The chronic daily intake for non-carcinogenic risk of both
children and adult of metals in the bed sediment of Asunle
stream are presented in Table 12 and 13. The level of human
health risk caused by non-carcinogenic pollutants in children
(x 106 mg/kg/day) (Table 12) ranged as follows: Fe (2910 -
51240), Mn (59.08 – 127.19), Co (0.75 – 34.19), Ti (22.05 –
60.23), Ba (1.65 – 7.90), Zn (7.69 – 80.66), Cu (5.75 – 24.59),
Al (8.61 -139.83), As (279.40 – 8210), Y (25.02.A20), and Sr
(0.10 – 5.37). Similarly, the level of human health risk caused

9



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 10

Table 9. Correlation analysis of metals in sediment of Asunle stream
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Fe 1.00
Mn 0.875** 1.00
Co -0.266 -0.279 1.00
Ti 0.481** 0.371** -0.052 1.00
Ba 0.719** 0.686** -0.079 0.677** 1.00
Zn 0.466** 0.226 -0.389** 0.274 0.225 1.00
Cu 0.341* 0.175 -0.109 0.590** 0.284 0.535** 1.00
As 0.040 0.083 0.365* 0.013 0.023 -0.307* -0.108 1.00
Al 0.646** 0.449** -0.346* 0.444** 0.650** 0.544** 0.282 -0.224 1.00
Y -0.149 -0.145 -0.173 0.001 -0.076 -0.103 -0.064 -0.061 0.064 1.00
Sr 0.345* 0.226 -0.066 0.292* 0.250 0.596** 0.485** -0.335* 0.366* -0.072 1.00

** Significant at p < 0.01 level (two-tailed); * significant at p < 0.05 level n= 528

Table 10. Chronic Daily Intake for Carcinogenic (oral) in Sediment of Asunle Stream
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Nov 3.87 0.007 0.0002 0.002 - 0.005 0.0009 0.002 0.14 - 0.0003
Dec 0.56 0.01 0.0008 0.004 0.0003 00.008 0.002 0.0009 0.18 - 0.0004
Jan 0.75 0.01 0.0003 0.003 0.0007 0.009 0.002 0.002 0.24 0.003 0.0006
Feb 0.80 0.02 0.0006 0.007 0.001 0.003 0.003 0.004 0.12 0.005 0.0003
May 0.55 0.01 0.003 0.006 0.0008 0.001 0.003 0.01 0.16 - 0.0005
Jun 0.55 0.01 0.003 0.003 0.0003 0.002 0.001 0.005 0.11 - 0.00001
July 0.36 0.008 0.003 0.003 0.0002 0.0009 0.0006 0.007 0.08 - -
Aug 0.31 0.006 0.004 0.003 - 0.00008 0.001 0.01 0.03 - 0.0004

Table 11. Cancer Risk Assessment of Heavy Metals in Sediment of Asunle Stream
Fe Mn Co Ti Ba Zn Cu Al As Y Sr

Min 0.62 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.00
Max 7.74 0.04 0.01 0.01 0.00 0.02 0.01 0.02 0.48 0.01 0.01
Mean 1.94 0.02 0.004 0.008 0.0009 0.007 0.003 0.01 0.27 0.002 0.002∑

CDIkS Fk 15.5 0.148 0.024 0.062 0.007 0.059 0.027 2.12 0.082 0.016 0.012

by non-carcinogenic pollutants in adult (x106 mg/kg/day) (Ta-
ble 13)ranged as follows: Fe (2480 – 6300), Mn (50.22 – 182.05),
Co (0.63 – 215.30), Ti (18.75 – 53.09), Ba (1.39 – 8.52), Zn
(6.54 – 68.56), Cu (4.89 – 21.43), Al (7.31 - 28.98), As (8.66
– 1880), Y (21.27 – 42.38), and Sr (0.00 – 4.56). The implica-
tion of these values is that the number of deaths that could be
attributed to non-carcinogenic pollutant in each million is very
high, hence the risk is of great concern. According to the United
State Environmental Protection Agency (USEPA), the accept-
able health risk level is 10−6 – 10−4 per year[13]. Besides, the
CDI values for non-carcinogenic (oral) in children was slightly
higher than the value obtained in adult. This also suggests that
the children are more vulnerable to hazard than adults.

From each chronic non-carcinogenic exposure, the separate
chronic hazard index (HI) was first calculated from the ratios
of the chronic daily intake (CDI) to the chronic reference dose
(RfD) for the individual metals and then the obtained results
summed up as described in the equation:

Chronic Hazard Index =
∑n

k=1 CDIk /R f Dk [17]
where the hazard index is a unit less number that is ex-

pressed as the probability of an individual suffering an adverse

effect. Table 14 presents the total chronic hazard quotient for
both children and adults in the bed sediment. Generally, the
hazardous index (HI) for ingestion of sediment by children is
greater in comparison to that of adults. Consequently, the total
chronic hazard quotient index of oral exposure to contamina-
tion in the bed sediment for adult and children are far above 1,
great hazard for both young and old is depicted.

4. Conclusion

Along with several other metals, the determination of rare-
earth metals and some other metals that have not been reported
in earlier studies of the dumpsite was done. Values of metals
present in the various matrices revealed that potentially toxic
metal contamination had occurred to varying degrees that could
cause health hazards. In some cases, the extent of contamina-
tion had reached the pollution levels that gave cause for con-
cern. The geo-accumulation index, enrichment factor and con-
taminant factor revealed that the soil and sediment samples were
heavily polluted with such contaminants as As, Cu and Be. The
effective management of the water bodies and other aqueous

10



Olutona / J. Nig. Soc. Phys. Sci. 5 (2023) 983 11

Table 12. CDI for Non-Carcinogenic (oral) for Children in Sediment of Asunle Stream (x106 mg/kg/day)
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Nov 3610 69.05 1.91 22.1 - 50.38 9.06 14.28 1290 - 2.59
Dec 51240 112 0.75 32.95 2.92 70.84 18.76 8.61 1690 - 3.93
Jan 7000 127 2.97 32.1 6.09 80.66 14.68 15.65 2210 25.02 5.37
Feb 7420 127 2.97 32.1 6.09 80.66 14.68 15.65 2210 25.02 0.28
May 5080 98.1 26.1 60.23 7.90 12.65 24.59 116.71 1460 - 0.45
Jun 5080 126 21.2 28.43 3.18 16.69 13.56 46.95 1020 - 0.10
July 3390 76.1 31.9 25.47 1.65 8.75 5.75 63.38 717 - -
Aug 2910 59.1 34.2 27.96 - 7.69 12.86 139.83 279 - 3.30

Table 13. CDI for Non-carcinogenic risk (oral) for Adult in Sediment of Asunle Stream
Fe Mn Co Ti Ba Zn Cu As Al Y Sr

Nov 3060 58.69 1.62 18.75 - 42.83 7.71 12.14 1100 - 2.19
Dec 4460 95.81 0.634 28.02 2.48 60.22 15.95 7.31 1430 - 3.34
Jan 5950 108.11 215.3 27.26 5.18 68.56 12.47 13.30 1880 21.27 4.56
Feb 6300 182.05 4.38 58.09 8.52 27.02 21.43 2898 930 42.38 2.35
May 4320 83.36 22.14 51.20 6.72 10.75 20.90 99.20 1240 - 0.38
Jun 4320 107.34 18.05 24.16 2.70 14.19 11.53 39.90 8.66 - 0.09
July 2880 64.67 27.09 21.65 1.39 7.44 4.89 53.88 609 - -
Aug 2480 50.22 29.07 23.76 - 6.54 10.93 118.86 237 - 2.81

Table 14. Total Chronic Hazard Quotient Index (x 106) of the Heavy Metals in the Sediment of Asunle Stream
Minimum Value Maximum Value Mean Value
Child Adult Child Adult Child Adult

Mn 1284.35 1091.75 2765.00 3957.61 2161.96 2038.72
Co 37.30 3.70 1709.50 10766.00 762.16 1989.28
Ba 0.00 0.00 39.50 42.60 17.39 16.87
Zn 384.50 327.00 8345.00 3430.00 2990.81 1484.94
Cu 143.75 122.25 614.75 535.75 175441.70 330.66
As 28700.00 24366.67 466100.00 9660000.00 175441.70 1351079.00

matrices is vital to ensuring the safety of the receiving water
bodies as well as public health. Regular monitoring of persis-
tent organic pollutants is highly required. Future studies should
be targeted on the assessment of these contaminants in the aquatic
biota, crops, farmers and rural dwellers of the surrounding com-
munities in this environment. Studies should be focused on the
assessment of these contaminants in different biological sam-
ples, plant uptakes, farmers, and rural dwellers in this environ-
ment to ascertain the extent of bioaccumulation of these con-
taminants. Remediation of heavy metals in this water body is
highly recommended.

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Appendix

Supplementary Data/Appendix
Variable Value used
AT – averaging time for non-
carcinogens
AT – averaging time for carcino-
gens
BWAdult – body weight adult
BW Child −− body weight child
CS – concentration in soil or sedi-
ment
EF – exposure frequency
ET Indoor – Exposure time indoor
ET Outdooor- Exposure time out-
door

365 days/year/ ED
Child or adult

565days/year/70
years
70 kg
15 kg
chemical specific
(mg/kg)
350 days/year
0.683
0.073

DF – dilution factor indoor
IN – inhalation rate
PEF – particulate emission factor,
climate specific
VF- volatilization factor, chemical
specific
IF – intake factor
IR Adult – ingestion rate adult
IR Child – ingestion rate child
ED Child – exposure duration
childhood
ED Adult – exposure duration
adulthood

0.4
20 m3/day
m3/kg

m3/kg

-
0.0001 kg/day
0.0002 kg/day
6 years

24 years (for
general case:30
years)

12