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Volume 49(3-4):19-22, 2005
Acta Biologica Szegediensis
http://www.sci.u-szeged.hu/ABS
ARTICLE
Department of Biochemistry, Faculty of Basic Medical Sciences, University of Calabar, Calabar, Nigeria
Evaluation of toxicological implications of inhalation
exposure to kerosene fumes and petrol fumes in rats
Friday E Uboh, Monday I Akpanabiatu*, Eyong U Eyong, Patrick E Ebong, Offiong O Eka
ABSTRACT
Toxicological implications of exposure to ungraded concentrations of kerosene
and petrol fumes in albino Wistar rats were investigated after two weeks of 4 hours daily
inhalation. Serum aminotransferases (AST and ALT), alkaline phosphatase (ALP), total choles
-
terol (Chol), triglyceride (TG) levels and histological analysis of the liver tissues were used as
diagnostic markers to assess liver dysfunction. The mean levels of these markers determined for
the group of rats exposed to kerosene and petrol fumes (test groups), as compared with the
levels for the control group were significantly (p < 0.05) higher. ALT, AST and ALP levels of the
kerosene exposed group were raised by 191%, 161% and 204% while serum total cholesterol
and TG levels increased by 129% and 118%, respectively. The increases in the serum levels of
AST, ALT, ALP, Chol, TG in the petrol exposed group were 177%, 140%, 191%, 100% and 97%,
respectively, when compared with the controls. Histological analysis of the liver tissues of the
experimental test groups indicated degenerative changes in the ultrastructural integrity of the
hepatic cells. These results showed that frequent exposure to kerosene and petrol fumes may
be highly deleterious to the liver cells.
Acta Biol Szeged 49(3-4):19-22 (2005)
KEY WORDS
kerosene
petrol
fumes
liver enzymes
histopathology
serum lipids
Accepted April 15, 2005
*Corresponding author. E-mail: akpanabiatu@yahoo.com
19
Kerosene and petrol are distilled from crude petroleum and
vapours obtained from their evaporation may be considered
as kerosene and petrol fumes. These fractions of crude pe
-
troleum contain aliphatic, aromatic and a variety of other
branched saturated and unsaturated hydrocarbons (Henderson
et al. 1993; Kato et al. 1993; Anderson et al. 1995). It has
been demonstrated that after inhalation of equal concentra-
tions of petroleum vapour through chronic exposure, lower
concentrations of saturated hydrocarbons are detected in hu-
man and animal blood than that of the unsaturated aromatic
hydrocarbons (Zahlsen et al. 1993). Biological monitoring
of exposure to bitumen fumes during road-paving operations
indicated urinary excretion of 1-hydroxypyrene and thioethers
in the exposed workers (Burgaz et al. 1992).
Petroleum fumes are ubiquitous in our environment and
the common sources of contact or exposure are petrochemical
industries (refineries, oils fields, filling stations) and homes.
The applications of kerosene as cooking and lighting fuels in
the home have resulted in direct exposure of these products to
a good percentage of the populace. Moreover, the day-to-day
use of petrol outside the industrial settings is likely to have
the same effect on the users as kerosene since they have been
reported to contain most of the same hydrocarbons. However,
the most affected are those who occupationally exposed to
the fumes (Smith et al. 1993; Carballo et al. 1994; Rothman
et al. 1996).
Despite the high utilization of kerosene and petrol, our
knowlegde is sparse on the toxicological effects of inhaling
the composite fumes evaporating from kerosene and petrol.
However, mutagenic, genotoxic, carcinogenic, neurotoxic,
immunotoxic and haemotoxic effects of some petroleum and
petrochemical products’ constituents have been reported in
experimental studies on humans and animals (Sim 1980; Hu
and Wells 1994; Hallier et al. 1995). Hydrocarbons and other
constituents of petroleum and petrochemical products, like
other xenobiotics, are metabolized in the liver to a greater
extent (Sims 1980; Nelson et al. 1993). Ueng et al. (1998)
reported that exposure of rats to motorcycle exhaust and or-
ganic extracts of the exhaust particulate caused a dose- and
time-dependent increase in cytochrome P-450-dependent
monoxygenases and glutathione-S-transferase in the liver,
kidney and lung microsomes. Since kerosene and petrol con-
tain some of these constituents, chronic or frequent exposure
to their fumes may affect the normal liver functions.
The expression of toxicity of xenobiotics is usually de-
termined biochemically by the monitoring of some plasma
enzymes and lipids. A rise in AST, ALT, ALP, TG and choles-
terol are commonly measured as indices of the damage of the
liver cells (Abdel-Baset et al. 1997; Owu et al. 1998). In this
study we attempt to place on record the biotoxicity effects of
kerosene and petrol fumes on albino Wistar rats by measur-
ing some of these parameters. Histopathological changes in
the liver tissues of both the control and experimental animals
were also examined to support the biochemical findings.
20
Uboh et al.
Materials and Methods
Experimental animals
Young adult Wistar albino rats obtained from the animal
house of the College of Medical Science, University of Cala-
bar, Nigeria, were used for this study. Rats weighing 80-113
g were randomly selected into 3 groups (control, kerosene
and petrol, respectively) of eight animals each. Kerosene and
petrol were obtained from the Mobil Filling station, Calabar,
Nigeria. All experimental animals were housed in stainless
steel cages (60 cm x 30 x 45 cm) in a well-ventilated animal
house and had free access to water, and normal rat chow
obtained from Livestock Feeds, Calabar, Nigeria. The test
groups were exposed to kerosene and petrol fumes, respec-
tively, while the control group was kept in a section of the
experimental animal house free from petroleum fumes.
Exposure to kerosene and petrol fumes
The method of exposure employed in this study was by inha-
lation. The animal cages housing the test groups were placed
in exposure chambers measuring 150 cm x 90 cm x 210 cm.
Two highly perforated 1000 ml cans containing 500 ml of
kerosene were placed in the exposure chamber and the ani-
mals were allowed to inhale the fumes evaporating from the
cans. The same procedure was adopted for the petrol fumes.
In both cases, exposure lasted for 4 h daily for a period of 2
weeks. The time of exposure was 9.00 am to 1.00 pm, after
which the animals were transferred to fumes-free section of
the experimental animal house.
Collection of blood samples and liver tissues for
analysis
The animals were anesthetized with chloroform 24 h after the
last exposure and blood samples collected by cardiac puncture
into plain sample tubes. Serum samples were separated 1 h
after extraction of blood by centrifugation at 3000 g for 5
min and stored in a refrigerator. Biochemical analyses on the
serum samples were done 24 h after sample collection. The
liver tissues were collected and processed according to the
method reported by Akpanabiatu et al. (2003).
Biochemical analyses were carried out for the measure-
ment of serum alanine (ALT) and aspartate aminotransferases
(AST), alkaline phosphatase (ALP), cholesterol (Chol) and
triglyceride (TG) levels. Laboratory kit reagents (Randox
laboratory Ltd, UK) were used for all biochemical analyses
and the absorbances were read using a UV-Vis spectropho
-
tometer (DREL 3000 HACH). Statistical analysis was carried
out by employing Student’s t-test to compare the mean values
of the test groups with the controls (p < 0.05 was used as a
level of significance).
Results and Discussion
The serum enzymes activities of the controls and the animals
exposed to kerosene and petrol fumes are shown in Table 1.
The activity of ALT was significantly higher in animals ex-
posed to the kerosene and petrol fumes when compared to the
controls. The level of serum ALT activity has been reported to
be increased as a result of liver injury in patients developing
severe hepatotoxicity (Beckett et al. 1989). ALT might have
leaked from damaged cells, due to increased permeability of
the hepatocellular membrane, or due to necrosis, indicating
organ dysfunction (Mclntyre and Rosalki 1992).
The activity of AST was also significantly higher in
the animals exposed to kerosene and petrol fumes when
compared to the control animals. Increased activity of AST
has been reported in CCl
4
-intoxicated experimental animals
(Abdel-Baset et al. 1997). This increase may be due to the
abnormal dynamic properties of cellular membranes follow-
ing exposure to hydrocarbon fractions present in kerosene and
petrol fumes. Metabolism of aliphatic and aromatic hydro-
carbons which are the major constituents of petroleum fumes
as well as other xenobiotics have resulted in changes in the
cell membrane due to reactive free radical species (Leighton
et al. 1985; Bondy et al. 1995). The ratio of AST/ALT is
also an important index for the measurement of toxicity. The
decrease in the ratios in the animals exposed to kerosene
and petrol fumes showed that the liver is likely to be most
affected tissue.
Alkaline phosphatase activity in the animals exposed to
kerosene and petrol fumes were significantly higher (p < 0.05)
as compared to the control animals. This implies that dam-
ages may have occurred in the liver cells, since the activity of
this enzyme in the serum is reported to be increased in liver
damage (Abdel-Baset et al. 1997). Alkaline phosphatase is
involved in the transport of metabolites across the cell mem-
branes, protein synthesis, synthesis of certain enzymes, secre-
tory activities and glycogen metabolism. The increase in this
enzyme activity may not be unconnected with a disturbance
in the transport of metabolites or alteration in the synthesis of
certain enzymes as in other hepatotoxic conditions (Sharma
et al. 1995).
Group ALT (U/L) AST (UL) AST/ALT ALP (UL) Chol (mmol/l) TG (mmol/l)
Control 10.37±0.86 11.40±1.50 1.10 90.95±5.55 1.54±0.26 1.02±0.05
Kerosene fumes 30.12±0.58 29.72±1.37 0.99 276.24±3.36 3.53±0.33 2.22±0.05
Petrol fumes 28.70±1.06 27.33±3.06 0.95 264.67±0.36 3.08±0.36 2.01±0.09
Table 1. Effects of exposure to kerosene and petrol fumes on serum ALT, AST, ALP, Chol and TG levels of Wistar albino rats.
21
Inhalation exposure to kerosene and petrol fumes
The attendant effect of the exposure of experimental
animals to kerosene and petrol fumes is that the reactive in-
termediates generated may have disrupted the cell membranes
leading to enzyme leakage and tissue damage. Histological
analysis of the liver tissues of the experimental animals (Fig.
1) indicates that frequent exposure to kerosene and petrol
fumes affects the structural integrity of the liver cells. This
implies that the liver is one of the major target organs of
kerosene and petrol fumes-induced injury. The cumulative
oxidative damage is therefore likely to be one of the under
-
lying mechanisms responsible for the hepatotoxic effects of
kerosene and petrol fumes, as observed in this study.
The significant increase (p < 0.05) in the levels of serum
total cholesterol and triacylglycerol observed in this work
is an indication that inhalation exposure to kerosene and
petrol fumes also affect lipid metabolism. On one hand, lipid
metabolism is affected once there is liver damage since the
disturbance of cell membrane integrity is likely to cause some
membrane lipids to be released into circulation, while on the
other hand, it causes the tissue to compromise its effective-
ness in regulating lipid metabolism. There is a likelihood that
exposure to kerosene and petrol fumes predisposes the subject
to atherosclerotic condition.
In conclusion, the results of this work suggest that re-
peated exposure to kerosene and petrol fumes may elicit
hepatotoxicity, thereby impairing the normal liver function.
Petroleum workers therefore should have regular medical
check-up to ascertain their health condition. Further work
is ongoing on the influence of kerosene and petrol fumes on
oxidative metabolism.
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