Abstract
Benzene is found in the environment as a contaminant from both human activities and
natural processes posing serious bio-hazards from chronic exposure. To study the health
hazards from chronic exposure to low levels of benzene, an all-male cohort of 390 individuals
were recruited. This cohort study included 75 healthy individuals that served as a control
group and 315 individuals occupationally chronically exposed to low-levels of benzene in
their daily activity during routine work in some petroleum industries.
Benzene itself was not detected in the blood or urine of all participants, but the levels of
its metabolites; phenol and muconic acid were higher in the blood and urine samples of the
group of benzene-exposed workers. Inspection of the results of the study clearly shows that
the benzene-exposed workers are under oxidative stress, as judged by higher
malondialdehyde, the end product of lipid peroxidation, and lower total antioxidant defense in
the blood of exposed workers. This was confirmed by lowered total and reduced glutathione
and elevated oxidized form. The effect on cellular membranes was reflected in increased
breakage of red blood cells (RBCs) membranes causing higher degree of hemolysis.
The data indicate, that chronic exposure to benzene, even at low variable levels, causes
biochemical and biophysical alterations that are detrimental to the health and well-being of
exposed workers.