 5.
What health effects can DBP cause in laboratory animals?
If DBP
is swallowed, about 90% is rapidly absorbed
and excreted in the urine within 48 hours. Very little is eliminated
via the faeces. About 60% of a dose
of DBP applied to the skin of rats is absorbed into the blood and
is excreted via urine within 7 days and about 12% via faeces. Human
skin absorbs DBP more slowly than rat skin.
There is no information on absorption after the
inhalation
of DBP.
After absorption
into the blood, DBP
passes to the liver and from there can be excreted into the gut
via bile, and absorbed into the blood again. In this way it “recirculates”
in the body. But DBP does not accumulate in the tissues.
The major part of DBP is broken down in the gut before absorption
of some DBP and its breakdown products into the blood. DBP and its
main breakdown product have been shown to cross the placenta and
reach the embryo but it does not accumulate in the embryo.
A single dose,
of DBP which is breathed in, swallowed, or absorbed
through the skin has a low toxicity.
DBP as appeared not to be irritating to the skin, eye or airways
nor sensitising to skin. However, a 28-day study on rats showed
that inhalation
of DBP can cause local effects in the upper
respiratory tract, but no sign of inflammation.
Repeated oral exposure
to DBP mainly affects the blood, liver and kidney. No effects were
seen at a dose of 152 mg/kg body weight/day. Some studies in rats
show effects on the testis at 250 mg/kg body weight.
Several laboratory tests show that DBP does not cause damage to
the inherited genetic
material in cells (chromosomes
and DNA).
DBP
has not been tested in mice or rats to see if it causes cancer,
but, as has been observed with DEHP
and DINP,
it might be expected to cause liver tumours
in rodents. However, the mechanism by which the phthalates
affect the liver in rodents does not apply in humans. Thus, there
does not seem to be concern about cancer in humans.
DBP is toxic
to the embryo and fetus and causes malformations at high doses
that are also toxic to the mother. There were no adverse effects
on the embryo and fetus at 100 mg/kg body weight (NOAEL).
There is also evidence from studies on rats that DBP affects aspects
of development that are dependent on male hormones
in male offspring at oral doses of 100 mg/kg body weight or more.
There were no effects at 50 mg/kg body weight/day.
In a rat reproduction study, specifically designed
to identify substances affecting hormones,
slight toxicity
to the embryo was seen at 52 mg/kg body weight. Thus, based on all
available studies an overall lowest observed adverse effect level
(LOAEL)
of 52 mg/kg body weight can be established for oral exposure
to DBP.
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