Journal of Environmental Protection, 2011, 2, 115-123
doi:10.4236/jep.2011.22013 Published Online April 2011 (
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide
Contamination of Fish from the Densu River
Basin in Ghana
Joseph R. Fianko1,4,*, Augustine Donkor2, Samuel T. Lowor3, Paul O. Yeboah4, Eric T. Glover1,
Theodosia Adom5, Augustine Faanu6
1NNRI/GAEC, Legon, Accra; 2Department of Chemistry, University of Ghana, Legon, Accra; 3Cocoa Research Institute of Ghana,
Akim Tafo; 4School of Nuclear and Allied Sciences, University of Ghana, Legon, Accra; 5BNARI/GAEC, Legon, Accra; 6RPI/
GAEC, Legon.
Received August 19th, 2010; revised October 18th, 2010; accepted December 21st, 2010.
The Densu River Basin constitutes one of the largest agricultural areas in Ghana. The practice of using pesticides such
as organochlorines, organophosphates, carbamates, pyrethroids and several others in agriculture and public health
programs has raised concerns about potentially adverse effects on human health and the environment. In this study, a
field survey was conducted to assess farmers knowledge of safe handling and use of pesticides. Residues of pesticides
in fish samples as well as the potential health risk associated with exposure to these pesticides were also evaluated.
Data obtained from the field survey indicate that a very high proportion of farmers are at high risk of pesticide poison-
ing from occupational exposure. More than 90% of farm workers do not practice safety precaution during pesticide
formulation and application leading to considerable prevalence of pesticide related illness in this agricultural commu-
nity. Pesticide residues in fish samples varied greatly; from 0.10 µg·Kg-1 to 30.90 µg·Kg-1, consumption of fish and fi-
sheries product from the basin was no zero risk. The estimated dose for aldrin, methoxychlor, γ-chlordane, endrin al-
dehyde, endrin ketone, endrin, p'p'-DDT and δ- HCH do not pose a direct hazard to human health, although present in
fish samples since the values were lower than toxic thresholds as well as reference dose. However, γ- HCH, heptachlor,
α-endosulfan, endosulfan Sulphate, p'p'-DDE and dieldrin levels exceeded the reference dose, indicating a great poten-
tial for systemic toxicity in children who are considered to be the most vulnerable population subgroup.
Keywords: Ghana, Pesticide Residue, Exposure, Health Risk, Densu
1. Introduction
One of the most negative consequences of industrial de-
velopment in the world has been the use and disposal of
pesticide that are potentially hazardous to human health.
Severe health effects are associated with exposure to
pesticides in food. Although the presence of trace levels
of pesticides in food is considered as an indication that
contamination has occurred, the risk of adverse health
effects depends on their concentration, frequency of con-
tact and duration of exposure. Contamination results in
exposure to toxic substances for the resident populations
leading to harmful health effects. Ingestion of pesticide
in food has been linked with health conditions that are a
major source of morbidity and mortality and increased
risk of skin, bladder and lung cancer at very low concen-
trations [1-3]. The use of pesticides has led to an increased
production of food and fiber as well as profitability in
agriculture. However, their use has also been associated
with several concerns including the risks to human health,
the death of farm animals and the alteration of the local
environment [4,5] particularly in countries where regula-
tions are not strictly implemented and farmers’ knowl-
edge of safe handling procedures is inadequate.
All substances exert some degree of toxicity to various
forms of life, depending on the exposure level of the
substance. The risks of pesticide inputs to the environ-
ment also vary with the toxicological, physical and eco-
logical properties of the pesticide. Fish and processed
fish are major animal protein sources to human in Ghana.
A number of pesticides have been identified as likely to
cause disturbances to natural hormones in our bodies.
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana
Unfortunately, they are commonly found in food such as
fish. Consumption of contaminated fish and fisheries
products could therefore be a serious risk to human [1].
Excessive usage can have effects such as disruption of
neurological cellular functions, acute and chronic neuro-
toxicity, tissue or organ damage, irritation and chemical
burns [2]. The discovery of an association between subtle
neurologic effects and low-level lead exposure in chil-
dren as well as findings of developmental toxicity from
low-level intra-uterine exposure of polychlorinated bi-
phenyls has led many researchers to construct analogous
hypothesis related to pesticides [3,6]. Recent reports on
developmental neurotoxicity of the insecticide chlor-
pyrifos lend support to this area of investigation [6].
Pesticides are widely used in agriculture and sanitation
for defense of pests in Ghana. Agriculture is a traditional
economic activity in the Densu River Basin. With the
intensification of agricultural production in Ghana, there
has been an increase usage of pesticides; however, little
attention is given to health hazards associated with their
use. Procedures recommended for the safe handling of
these pesticides have not been followed conscientiously.
Repeated pesticide application may put farmers at risk
with chemicals being dispersed, leaked or spilled and
entering the human body either directly or indirectly. A
higher proportion of pesticide poisoning and illness oc-
curs in remote agricultural areas where there are inade-
quate occupational safety standards, insufficient en-
forcement of pesticide-related legislation, poor labeling
of pesticide containers, illiteracy, inadequate protective
clothing and washing facilities as well as user’s lack of
knowledge of pesticide hazards [4,7].
The Densu river basin is primarily an agriculture area
with intense pesticide usage. Pesticides are extensively
used in the basin for pineapple, cocoa, vegetables, cereals
and fruit productions as well the control of vector-borne
diseases for public health. Economic activities in the ba-
sin also include fishing and industrial development. Fish
from the basin serves as the major source of income for
most of the inhabitants. Fish in the Densu basin also con-
stitutes an important source of protein for the inhabitants
in and around the basin as well as the entire country. Ag-
ricultural, domestic, municipal and industrial activities
have impacted negatively on the basin since effluents and
other storm water drains from these activities empty into
the basin. Bioaccumulation and bio-concentration of pes-
ticides in the fish species are capable of reaching toxic
levels in the fish even when exposure is low [4].
Human exposure to pesticides through fish and fish
products from the Densu River Basin may be excessive,
especially through ground application of pesticides in
cocoa, pineapple, cotton and vegetable farms; where
compounds of high toxicity are often used but no studies
have been done to assess the health risk associated with
the contamination of fish from the basin. Studies in other
parts of the country [2,8-12] related several disease con-
ditions such as headache, blurred vision, fever skin irrita-
tion, abdominal pains, cough, nausea and dizziness to
pesticide poisoning. The Densu River basin has a long
history of pesticide usage; consumption of fish and fish
products from the basin is on the increase, however, there
exists no amount of epidemiological data concerning the
risk of farmers and consumers of fish from the basin.
This study therefore seek to evaluate the potential health
risk associated pesticide contamination of fish from the
basin and to assess the knowledge, practices and attitudes
regarding safe use of pesticides, toxicity awareness and
symptoms among farmers in the Densu River basin.
2. Materials and Method
2.1. Field Investigation
A field survey was conducted in all communities within
the Densu River Basin (Figure 1) between March and
December 2007 during which a questionnaire was ad-
ministered to a total of 200 farm heads, farmers and farm
workers in the basin. The questionnaire focused on the
assessment of knowledge, attitudes and practices of these
farm workers regarding the safe use of pesticides, toxic-
ity awareness and the identification of most prominent
health related issues in the area. During the survey, fresh
fish samples were purchased from the two major fishing
communities (Nsawam and Weija) in the basin. The fish
samples were bought when still alive, directly from the
fishermen. The fish samples were immediately wrapped
in aluminum foil, appropriately labeled, transported to
the laboratory on ice and kept at –20˚C in a freezer prior
to extraction.
2.2. Sample Extraction
The extraction of pesticides from fish samples was per-
formed by solid dispersion method as described by the
US Food and Drug Administration, [13] and Akerblom
[14]. Two hundred grams of fish samples were homoge-
nized in a stainless steel blender. About 25 g portion of
the homogenized fish sample was grounded with 10 g
sand and about 35 g of Na2SO4 (anhydrous) in a mortar
to free-flowing powder. The powder was extracted in a
flask by shaking successively with ethyl acetate (50, 3 ×
20 ml). The combined extract was filtered through a cot-
ton wool and the solvent evaporated at 40˚C with rotary
evaporator to near dryness. The concentrate was recov-
ered with (3 × 1.5 ml) portions of cyclohexane. The or-
ganic phase was then subjected to clean-up.
2.3. Clean-Up of Sample Extracts
Conditioned 8-ml C-18 solid phase extraction (SPE) car-
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana
Copyright © 2011 SciRes. JEP
tridges were used for the sample clean-up [15]. Each fish
extract was percolated through the cartridges with a flow
rate of approximately 5 ml/min under vacuum pump. The
pesticides trapped in the cartridges were eluted with 6 ml
(2 × 3 ml) ethyl acetate. The sample extract was concen-
trated using the rotary evaporator aided with a water
chiller to 2 ml for GC analysis.
2.4. Analysis of Pesticides
Fish samples were analyzed in a gas chromatograph (Va-
rian CP-3800 gas chromatograph) equipped with Ni-63
electron capture detector (ECD) and Flame ionization
detector (FID). Extracts of samples were interspersed
with analytical standards of interest, placed on autosam-
pler with standards at the start, between every 15 samples
and the last of the GC sample run. The pesticide residue
components were identified by comparing their retention
times with those of the standard mixture of the pesticides.
Quantification was based on comparison with calibration
curves in the concentration range of 0 to 200 µg/L. The
gas chromatograph’s conditions were as follows: injector
temperature, 225˚C; injector mode, splitless; oven tem-
perature, programmed from 70˚C, held for 2 min to
180˚C at a rate of 25˚C/min, then from 180˚C to electron
capture detector temperature set at 300˚C at a rate of
10˚C/min, injector volume, 1.0 μL. The flame ionization
detector working conditions were oven temperature,
60˚C held for 2 min to 180˚C at a rate of 35˚C/min, then
increased to 270˚C at a rate of 2˚C/min, and finally in-
creased to 300˚C at a rate of 5˚C/min and held for 10
minutes. The injector mode was splitless and the injec-
tion volume 2 μL [15,16].
2.5. Quality Control/Quality Assurance
Quality control and quality assurance as prescribed by the
CODEX Alimentarus Committee were incorporated in the
analytical scheme. Quality assurance measures applied in
the laboratory included rigorous contamination control
procedures (strict washing and cleaning proce- dures),
monitoring of blank levels of solvents, equipment and
other materials, analysis of procedural blanks, re- covery
of spiked standards, monitoring of detector re- sponse and
linearity. During extraction, blanks and du- plicates were
included in the analysis and re-calibration standards run
frequently to check the integrity of the calibration curve.
Aliquot (100 ml) of each solvent was concentrated to 2 ml
and analyzed to check the contami- nation from the re-
agents [17]. Percentage recoveries in spiked samples were
68.5% - 102%, hence the results of the study were not
corrected for recoveries since all were within the normal
acceptable range of 65% - 120% [17,18].
Figure 1. Map of study area.
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana
2.6. Health Risk Estimation
To assess the risk of pesticide on consumers, the guide-
lines for potential risk assessment drawn up by the US
EPA were followed [19]. To evaluate the chronic risk
posed by pesticide exposures a reference dose (RfD) is
commonly used. This is the level at or below which daily
aggregate exposure over a lifetime will pose no appre-
ciable risk to human health. The Reference Dose (RfD) is
derived from the “no observable adverse effect levels”
(NOAEL) and it is reference point from which potential
health effects of a chemical at other doses may be esti-
mated. An aggregate daily exposure to a pesticide residue
at or below the RfD is generally considered acceptable
by the USEPA, [7,20,21].
Health risk estimates in this study were calculated
based on an integration of pesticide analysis data and the
consumption rate of fish in Ghana. The following as-
sumptions were adapted from the U.S Environmental
Protection Agency’s guidelines [19,21]:
1) Hypothetical body weight of 10 kg for children (0 -
1 yrs), 30 kg for children (1 - 11 yrs) and 70 kg for
2) Maximum absorption rate of 100% and a bioavail-
ability rate of 100%.
3) Food (fish) consumption rate in Ghana is 0.080
kg/day [22].
Consumption of contaminants in food was calculated
based on its concentration in the food and on an estimate
of the food consumption rates. Hence for each type of
exposure, the lifetime exposure dose (mg/kg/day) was
obtained by multiplying the residual pesticide concen-
tration (mg/kg) in the food of interest by the food con-
sumption rate in the country (liter/day or kg/day) and
dividing the product by the body weight (kg) [4,23]. The
hazard indices for children and adults were estimated as
ratios between estimated pesticide exposure doses and
the reference doses (RfD). Pesticide residue data from
fish samples (Table 1) were used for the health risk as-
sessment. It is important to note that the data used repre-
sent the maximum concentrations of pesticide residues in
fish samples. Because of the need for conservative ap-
proach in dealing with risk assessment of multiple chem-
ical compounds, it was more appropriate to consider the
maximum levels of specific detected pesticides instead of
their mean concentrations [4]. Moreover, an aggregate
daily exposure to a pesticide residue at or below the RfD
ia generally considered acceptable by the EPA (20, 21)
which are considered to be safe levels of exposure over
the lifetime.
Life Exposure Dose = Residue conc. in food of inter-
est X food consumption rate Body weight.
Hazard index = Estimated dose/reference dose.
Table 1. Detection frequency and pesticide and metabolite residue concentrations (fresh weight basis) in pooled whole body
homogenized fish samples. (N = 20).
Positive detection Concentration (µg·kg-1)
(% of samples) Min max mean
γ-HCH 75 0.10 17.65 4.94
δ-HCH 65 0.20 17.60 3.12
heptachlor 80 1.30 21.50 5.49
aldrin 50 0.10 2.90 0.65
γ-chlordane 70 0.25 10.15 3.02
α-endosulfan 60 0.15 16.50 3.56
p'p'-DDE 50 0.10 30.90 7.99
dieldrin 65 0.15 9.90 3.01
endrin 40 0.10 6.95 2.19
p'p'-DDT 55 0.10 12.50 4.01
endrin aldehyde 40 0.10 1.55 0.51
endosulfan Sulphate 25 0.10 10.85 3.80
endrin ketone 50 0.10 6.70 2.59
methoxychlor 60 0.10 12.60 2.27
N= number of samples
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana119
3. Results and Discussion
3.1. Field Survey
3.1.1. Availability of Pesticides
Most farmers interviewed in the study area derive over
85% of their income from farming. Pesticides and other
agrochemical sources were found to be within reach of
farmers. About 80% of farmers got their agrochemicals
within few kilometers from their home while a few of
them (20%) get their supplies from relatives in the cities.
The primary source of agrochemicals in the study area
was agrochemical shops (64%), followed by general
shops (14%) with Cooperative societies representing
12% of their source of supply and 10% from relatives
(Figure 2).
Most farmers stored agrochemicals in multipurpose
storage structures together with food containers and farm
implements. The type and amount of pesticides used in
different crops depended on the pest population and their
potential damages to the crop as well as farmers’ percep-
tion regarding pest management practices. Most of the
farmers (78%) apply pesticides in mixtures. There were
combinations of up to three pesticides in a single tank
mixture. Farmers did not have specific instructions either
from the label or from extension officers regarding these
tank mixtures. They reported that tank mixing was fa-
vourable because it saves time, labour and cost since
more than one pesticide could be applied in a single
3.1.2. Farmers’ Knowledge and Attitudes Regarding
Safe Use of Agrochemicals, Toxicity Awareness
and Symptoms
Results of the field survey regarding safe use of agro-
chemicals especially pesticides, toxicity awareness and
symptoms among farmers in the study area (Figure 1)
indicated that about 84% of farmers have ever used ag-
rochemicals, 92% do not wear gloves while 98% do not
Figure 2. Source of agrochemicals in the Densu River basin.
wear eye glasses or goggles when mixing or applying
agrochemicals with most of the farmers (80%) wearing
long cloths and shoes when applying the chemicals.
Among the respondents, 60% reported that they have
ever eaten food or drank water and 28% smoked when
mixing or applying pesticides. Most farmers (83%) had
received no training on pesticide and other agrochemical
use from the Ministry of Food and Agriculture or any
other organization. Farmers are generally less aware of
the potentially adverse impacts of pesticide deposition on
the environment; nonetheless, they are well aware of the
adverse effects of pesticides on human health (68%).
About two-third (73%) of the interviewees had ever
experienced various symptoms of pesticide poisoning.
Among the clinical symptoms of pesticide poisoning
which they reported were nausea, headaches, blurred
vision, dizziness, diarrhoea, tingling or burning of skin,
abdominal pains, sweating, hypertension and eye irrita-
tion. While most farmers believe in the slogan ‘‘the more
pesticides the better’’ (76%), only a minority recognize
the need to apply a balanced dosage to their crops (38%).
Furthermore, farmers prefer to spray their crops after
noticing insects or weeds in the field and generally re-
frain from preventive spraying, particularly in the more
remote villages. Farmers sometimes mix active ingredi-
ents in ways not recommended by the manufacturers
(64%). The number of farmers that adhere to the usage
instructions provided on the agrochemical packaging is
considerably lower than expected (only 12% of the total
number of farmers interviewed).
The data obtained from the survey indicated that a
very high proportion of farmers are at high risk of pesti-
cide poisoning from occupational exposure (Figure 3).
Survey analysis indicated that more than 90% of farmers
do not wear protective devices nor apply safety measures
during pesticide mixing and application. Pesticide expo-
sure may be exacerbated by the fact that a good propor-
tion of these agricultural workers eat, drink and or smoke
during pesticide application. As a result of pesticide ex-
posure, about 73% of farmers experience various kinds
of discomfort including abdominal cramps, excessive
salivation, nausea, confusion, eye irritation etc. Several
pesticides (organochlorines, organophosphates, car-
bamate) have been linked to severe human health condi-
tions including neurological damage, hypertension, car-
diovascular diseases and skin disorders [5,16]. Some
pesticides have been found to cause infertility, sterility
and birth defects; others have been linked to allergies,
hematologic disorders, mutagenicity and cancer [2,4,8].
It is therefore not surprising that a good proportion of the
farmers interviewed reported that over the past ten years
they had suffered severe health problems including fever,
skin irritation, skin diseases, respiratory problems, head-
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana
ache, abdominal pain, diarrhoea and asthma since they
had used most of these pesticides.
Farmers apply agrochemicals without adequate per-
sonal protection and in an unsafe manner; moreover,
even if they have sufficient income to take protective
measures, it is made a matter of lower priority compared
to funeral expenses, child education, litigation etc. In
addition, labourers are also hired for agrochemical ap-
plication without providing them with the necessary pro-
tective clothing. Shirt and trousers, for example, are fre-
quently worn for extensive periods of time after being
contaminated. That seems almost inconceivable as most
farmers are aware of the negative effects of pesticides on
their health. One reason for not wearing protective
clothing, even if it were available, is that the tropical
climate makes the wearing of full protective gear imprac-
tical because of the potential for body heat stress.
Studies conducted by the International Labour Or-
ganization (ILO) suggest that pesticide misuse causes
14% of occupational injuries in agriculture and, in some
countries, as much as 10% of fatalities [24]. Other con-
tributory factors may include lack of capacity (manpower
and financial resources) to advice on and enforce na-
tional laws, approved codes of conduct. Lack of washing
facilities to shower after spraying and for regular wash-
ing of clothes; clothes may be washed in sources of
drinking water. Reuse of containers for food and drink
storage as well as no facilities for safe disposal. In Ghana,
regulation and management of the production, trade and
use of agrochemicals is inadequate while there is no ac-
cess to standards and regulations enforced in importing
countries. Poor information, complex label instructions
in foreign languages, poor literacy and lack of training in
application procedures or hazard awareness, combining
different products, applying on crops for which a product
is not intended may all contribute to the misuse of pesti-
cides by farmers.
The tank mixture of pesticides observed in this study
indicates that farmers lack basic knowledge in pesticide
application. Usually labeled instructions do not cover
mixtures of three or more pesticides and give no infor-
mation on the compatibility of inert ingredients. It has
been observed that there was an interaction between fun-
gicides, insecticides and water mineral content that in-
fluenced the efficacy of individual pesticide against fun-
gal pathogens and insect mortality and some tank mix-
tures induced phytotoxicity on tomato [25]. Mixtures of
insecticides generally result in the simultaneous devel-
opment of resistance strains [26]. Farmers interviewed
did not consider that unspecified tank mixing of pesti-
cides could be less effective and cause adverse effects to
their health or the environment; instead, the tank mixing
was carried out to save time, labour cost and with antici-
pation of high efficacy in pests and diseases control. The
tank mixtures observed in this study indicated that they
were purely on individual thinking and feelings as well
as advice from some retailers and not on label instruct-
tions or advice from extension workers.
Figure 3. Agrochemical usage and impacts, toxicity awareness and symptoms among farmers in Densu River Basin.
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana121
The preventive measures that farmers were not prac-
ticing as compared to curative application that requires
application after observing pest problem may probably
be due to lack of extension services that could offer ap-
propriate advice. The trend of pesticide use by farmers
over the years was probably based on farmers’ knowl-
edge on agrochemical application in relation to effect-
tiveness of agrochemicals, pests, farm size, prices and
weather condition. The risk of long-term effects of the
pesticides that were being used in the study area is high
especially due to exposure to carcinogens, possible car-
cinogens and suspected endocrine disruptors.
3.2. Health Risk Estimates
Table 1 represents the pesticide residue data from the
fish samples analyzed while Table 2 represents the esti-
mated dose values and health hazards associated with
pesticide residues in fish from the Densu Basin. Hazard
indices were computed for children between the ages of 0
- 1years, 1 - 11years and adults for aldrin, methoxychlor,
γ-chlordane, endrin aldehyde, endrin ketone, endrin, p'p'-
- DDT, γ-HCH, DDE, δ-HCH, ,heptachlor, α-endosulfan,
endosulfan sulphate, and dieldrin.
Data analysis of health risk estimates indicate that al-
drin, methoxychlor, γ-chlordane, endrin aldehyde, en-
drin ketone, endrin, p'p'-DDT, γ-HCH, DDE and δ-HCH
do not pose direct hazard to human health, although pre-
sent in fish samples. However, heptachlor, α-endosulfan,
endosulfan sulphate, and dieldrin levels exceeded the
reference dose in children between the ages of 0 - 1 years,
indicating a great potential for systemic toxicity in chil-
dren who are considered to be the most vulnerable popu-
lation subgroup. In children between the ages of 0 - 1
years, the hazard indices of 2.64, 1.720, 1.736 and 0.792
(Table 2) were computed for α-endosulfan, heptachlor,
endosulfan sulphate and dieldrin respectively and were
found to be of health risk to them since the estimated
dose exceeded the recommended reference dose.
For children between the ages 1 – 11 years, heptachlor,
α-endosulfan and endosulfan posed health hazard to them
since they recorded significant health indices of 0.573,
0.880 and 0.576 respectively. The estimated dose of
heptachlor (0.057 µg/kg/day) was quite closer to the ref-
erence dose of 0.10 µg/kg/day in children between the
ages of 1 - 11 years resulting in possible health hazard on
exposure to fish or fish products from the basin.
Table 2. Estimated dose values and Hazard indices of pe sticide exposure in contaminated fish from the Densu River Basin.
Estimated dose (µg/kg/day) Hazard index
Pesticide Reference dose
µg/kg/day 0-1yrs 1-11yrs Adult 0-1yr 1-11yr Adult
γ-HCH 0.30 0.141 0.047 0.020 0.471 0.157 0.067
δ-HCH 3.00 0.141 0.047 0.020 0.047 0.016 0.007
heptachlor 0.10 0.172 0.057 0.025 1.720 0.573 0.246
aldrin 0.10 0.023 0.008 0.003 0.232 0.077 0.033
γ-chlordane 0.50 0.081 0.027 0.012 0.1624 0.054 0.023
α-endosulfan 0.05 0.132 0.044 0.019 2.64 0.880 0.377
p'p'-DDE 0.50 0.247 0.082 0.035 0.4944 0.165 0.071
dieldrin 0.10 0.079 0.026 0.011 0.792 0.264 0.113
endrin 0.20 0.056 0.019 0.008 0.278 0.093 0.040
p'p'-DDT 0.50 0.100 0.033 0.014 0.2 0.067 0.029
endrin aldehyde 0.20 0.012 0.004 0.002 0.062 0.021 0.009
endosulfan Sulphate 0.05 0.087 0.029 0.012 1.736 0.579 0.248
endrin ketone 0.20 0.054 0.018 0.008 0.268 0.089 0.038
methoxychlor 5.00 0.1018 0.034 0.014 0.020 0.007 0.003
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana
Although residue levels of these pesticides are below
the maximum permissible intake of Codex Committee on
pesticides residues [1], there was no zero risk because
there were pesticides present in fish. Most of the detected
compounds are generally persistent, volatile, lipophilic
and bioaccumulative both in the environment and at each
trophic level of the food chain. Contaminants can thus
reach high concentrations through biomagnifications in
the tissues of predators including humans, which are high
on the food chain [27]. They are prone to long range
transport and deposition and can result in adverse envi-
ronmental and human health effects at locations near and
far from the source.
4. Conclusions
It is clear from the results of the study that the farming
communities in the Densu Basin of Ghana do not follow
appropriate safety precautions with regard to agro-
chemical application. Substantial amounts of agro-
chemicals especially pesticides are inappropriately used
by these farmers leading to several clinicopathological
conditions including nausea, vomiting, blurred vision,
abdominal cramps, dizzineaa, diarrhea and headache.
The estimated dose for aldrin, methoxychlor, γ-chlordane,
endrin aldehyde, endrin ketone, endrin, DDE, p'p'-DDT,
γ-HCH and δ-HCH do not pose a direct hazard to human
health, although present in fish samples since the values
were lower than toxic thresholds as well as reference
dose and may indicate minimum risk to human. However,
heptachlor, α-endosulfan, endosulfan sulphate, and diel-
drin levels exceeded the reference dose, indicating a
great potential for systemic toxicity in children who are
considered to be the most vulnerable population sub-
group. Although residue levels of these pesticides are
below the maximum permissible intake, there was no
zero risk because there were pesticides present in fish
and other matrices. Human exposure during pesticide
application is exacerbated by water, food and environ-
mental contamination and there exists a potential risk for
systemic and carcinogenic health effects associated with
agrochemical usage in the Densu Basin.
[1] F. Sun, S. S. Wong, G. C. Li and S. N. Chen, “A Pre-
liminary Assessment of Consumer’s Exposure to Pesti-
cide Residues in Fisheries Products,” Chemosphere, Vol.
62, No. 4, 2006, pp. 674-680.
[2] F. O. Mensah, F. A. Yeboah and M. Akman, “Survey of
the Effect of Aerosol Pesticide Usage on the Health of
Farmers in the Akomadan and Afrancho Farming Com-
munity,” Journal of Ghana Science Association, Vol. 6,
No. 2, 2004, pp. 44-48.
[3] R. A. Fenske, J. C. Kissel, C. Lu, D. A. Kalman, N. J.
Simcox, E. H. Allen and M. C. Keifer, “Biologically
Based Pesticide Dose Estimates for Children in Agricul-
tural Community,” Environmental Health perspectives,
Vol. 108, No. 6, 2000, pp. 515-520.
[4] B. P. Tchounwou, B. A. Ashour, D. A. Ragheb and A. A.
Romeh, “Health Risk Assessment of Pesticide Usage in
Menia El-Kamh Province of Sharkia Governorate in
Egypt,” International Journal of Molecular Sciences, Vol.
3, No. 10, 2002, pp. 1082-1094.
[5] G. M. Calvert, W. T. Sanderson, M. Barnet, J. M. Blon-
dell and L. N. Melher, “Surveillence of Pesticide-Related
Illness and Injury in Humans,” In: Handbook of Pesticide
Toxicology, 2nd Edition, Academic Press, New York,
[6] K. D. Whitney, F. J. Seildler and T. A. Stotkin, “Devel-
opmental Neurotoxicity of Chlorpyrifos: Cellular Mecha-
nisms,” Toxicology and Applied Pharmacology, Vol. 134,
No. 1, 1995, pp. 53-62.
[7] D. J. Snelder, M. D. Maasipiquena and G. R. de Snoo,
“Risk Assessment of Pesticide Usage by Smallholder
Farmers in the Cagayan Valley (Philippines),” Crop Pro-
tection, Vol. 27, No. 3-5, 2008, pp. 747-762.
[8] J. W. Ntow, “Pesticide Residues in Volta Lake, Ghana,”
Lakes and Reservoirs: Research and Management, Vol.
10, No. 4, 2005, pp. 243-248.
[9] F. A. Yeboah, F. O. Mensah and A. K. Afreh, “The
Probable Toxic Effects of Aerosol Pesticides on Hepatic
Function among Farmers at Akomadan/Afrancho Tradi-
tional Area of Ghana,” Journal of Ghana Science Asso-
ciation, Vol. 6, No. 2, 2004, pp. 39-43.
[10] E. Adetola, J. K. Ataki, E. Atidepe, D. K. Osei and A. B.
Akosa, “Pesticide Poisoning – a Nine Year Study (1989
– 1997),” Department of Pathology, University of
Ghana Medical School and Ghana Standards Board Ac-
cra, 1999.
[11] E. E. K. Clarke, L. S. Levy, A. Spurgeon and I. A. Cal-
vert, “The Problems Associated with Pesticide Use by Ir-
rigation Workers in Ghana,” Occupational Medicine, Vol.
47, No. 5, 1997, pp. 301-308.
[12] P. O. Yeboah, G. M. S. Klufio, G. A. Dixon and A. You-
deowe, “TCDC Oriented Subregional Workshop on Pes-
ticides Management Report,” FAO, 1989, pp. 8-9.
[13] FDA, “Multiresidue Method,” Pesticides Analytical Ma-
nual, Vol. 1, No. 94-1, 1994, from 2905a (6/92).
[14] M. Akerblom, “Environmental Monitoring of Pesticide
Residues. Guidelines for the SADC Region. SADC/
ELMS,” Monitoring techniques, Series 3, Lesotho, 1995.
[15] J. L. Zhou, H. Hong, Z. Zhang, K. Maskaoui and W.
Chen, “Multi-Phase Distribution of Organic Micropol-
lutants in Xiamen Harbour, China,” Water Research, Vol.
34, No. 7, 2000, pp. 2132-2150.
Copyright © 2011 SciRes. JEP
Health Risk Associated with Pesticide Contamination of Fish from the Densu River Basin in Ghana123
[16] USEPA, “Test Methods for Evaluating Solid Wastes
SW-846,” Volume IA-Laboratory Manual: Physical and
Chemical Methods, US EPA Office of Solid Waste and
Emergency Response, Washington D.C., 1994.
[17] FAO/WHO, “Codex Maximum Residue Limits for Pesti-
cides,” FAO, Rome, 2007.
[18] A. Hill, “Quality Control Procedures for Pesticide Resi-
dues Guidelines for Residues Monitoring in the European
Union,” 2nd Edition Document No. SANCO/3103/2000,
European Commission, 2000.
[19] USEPA, “Guidelines for Ecological Risk Assessment,”
Washington, US EPA, Report No. EPA/630/ R-95/002F,
[20] USEPA, “Lamda-Cyahalothrin Pesticide Tolerances, Fin-
al Rule,” Federal Register (Rules and Regulations), Vol.
67, No. 188, 2002a, pp. 60902-60915.
[21] USEPA, “Integrated Risk Information System,” USEPA,
Office of Health and Environmental Assessment. Wash-
ington D.C., 1996.
[22] FAO. FAO fisheries and Aquaculture, Ghana, 2001. sector/F1-cp
[23] USEPA, “Exposure Assessment Handbook,” USEPA,
Office of Health and Environmental Assessment, Wash-
ington D.C., 1989.
[24] Codex, “Codex Classification of Food and Animal Feed (Co-
dex Alimentarius) Pesticide Residues in Food,” Rome, 2005.
[25] Z. K. Smit, D. Indjic, S. Belic and M. Miloradov, “Effect
of Water Quality on Physical Properties and Biological
Activity of Tank Mix Insecticide-Fungicide Spray,” Pro-
ceedings of the Second Balkan Symposium on Vegetables
and Potatoes, International Society Horticultural Science,
Leuven, Belgium, Vol. 579, 2002, pp. 551-556.
[26] A. V. F. Ngowia, T. J. Mbisea, A. S. M. Ijania, L. Lon-
donb and O. C. Ajayic, “Smallholder Vegetable Farmers
in Northern Tanzania: Pesticides Use Practices, Percep-
tions, Cost and Health Effects,” Crop Protection, Vol. 26,
No. 11, 2007, pp. 1617-1624.
Copyright © 2011 SciRes. JEP