The primary way styrene may enter the body is
by inhalation of contaminated air into the lungs. Studies indicate
that approximately two-thirds of the styrene inhaled into human
lungs is actually retained (ATSDR, 1991). The majority of retained
styrene is rapidly absorbed from the lungs into the bloodstream
where it can then be transported throughout the body.
A small portion of retained styrene leaves the
body unchanged through exhaled air. The majority of absorbed styrene
is rapidly broken down into other compounds (metabolites) and leaves
the body through the urine. Experimental studies indicate that,
once exposure has stopped, total elimination of styrene from the
body may take a few days up to a few weeks.
Short term inhalation of large amounts of styrene
is reported to adversely impact the central nervous system. Depression,
concentration problems, muscle weakness, tiredness, and nausea have
been reported in people, especially workers, who have inhaled large
amounts of styrene for short periods of time (ATSDR, 1991). Exposure
to styrene in the air may also irritate the mucous membranes of
the eyes, nose and throat.
Some studies of female workers indicate that
occupational exposure to elevated air levels of styrene, in a mixture
with other potentially hazardous chemicals, may be associated with
lower birth weight babies and an increased risk of spontaneous abortions
(miscarriages) (ATSDR, 1991). However, it is unknown what role styrene
itself may play in these effects.
Rapid recovery from the adverse effects associated
with short-term inhalation exposure to styrene vapors has been noted.
However, the potential effects of long-term human exposure to low
levels of styrene vapors are not currently known.
Experimental studies indicate that animals are
also impacted by inhalation of styrene vapors. Changes in the lining
of the nose of experimental animals have been noted up to several
weeks after exposure has stopped. Although long-term inhalation
of high levels of styrene has been associated with adverse liver
effects in animals, this effect has not been noted in humans (ATSDR,
Scant information is available regarding adverse
health effects associated with human ingestion of or dermal contact
with styrene. Liver, kidney, blood, immune system and nervous system
effects have been noted in experimental styrene ingestion studies
with laboratory animals. Irritation of the skin and eyes has been
noted in experimental dermal studies with rabbits. Styrene has been
classified as possibly carcinogenic to humans by the International
Agency for Research on Cancer.
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Last Updated: 1/31/03