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EC number: 267-122-6
CAS number: 67801-01-8
and metabolism of the test substance was not examined. The test item
shares high structural similarity to an analogue substance, since both
are Ba-salts and differ in one additional ethyl-group only. Both
substances are poor soluble in water and octanol and dissolve most
likely in an acidic environment (e.g. stomach). Therefore, it is
acceptable to derive information on toxicokinetic from experimental data
of the analogue substance.
Pigment Red 53:1 (D&C
Red No 9) is of very low solubility and tends to re-agglomerate in
aequeous solution. Experimental data on inorganic Barium salts indicates
that the solubility increases in the acidic environment of the stomach
as Barium chloride is of high solubility in water. To what extent this
happens depends on the actual pH in the stomach. Dissolved Ba2+is
detected rapidly in the blood after ingestion. It is eliminated to a
higher extent in the feces than in the urine and is also incorporated
into the bone and detected in tissues.
In the course of an in vitro skin penetration
study, the percutaneous absorption of D & C Red No. 9 through human skin
was found to be very low. With all four vehicles, total absorption was
less than 0.1% of the applied dose and the maximum flux rate achieved
was less than 0.1 mug/cm2/24 hours. The vast majority of the unabsorbed
material remained on the surface of the skin and was found in the skin
wash. This amount varied from 85-103 %. Very little colorant was found
in the epidermis or dermis, less than 0.3% in all cases. Total drug
recovery averaged 83-103% of the applied dose.
Regarding the inhalation
route, only acute data is available. After inhalation of PR 53:1, all
animals survived until scheduled necropsy. Hunched posture, wet and
stained fur and noisy respiration were observed. All effects, unless
staining, resolved with in 2-3 days and animals appeared to be normal.
Subacute, subchronic and
chronic repeated dose toxicity data are available for Pigment Red 53:1
Ba salt. In the majority of this studies, changes in red blood count,
hemosiderosis in liver and spleen as well as fibrosis in and
discoloration of the spleen were observed. These effects indicate that metabolites
of the test article (1-amino-2-naphtol) cause methemoglobinamia leading
to disturbances of iron metabolism and subsequently increased iron
deposition in liver and spleen (hemosiderosis). Moreover, the substance
or metabolites are attached at methemoglobin and transported via red
blood cells into the spleen which acts as a filter for old or damaged
erythrocytes. During degradation of methemoglobin, the substance or
metabolite is released and affects spleenic mesenchymal tissue leading
to fibrosis, scars and necroses.
Azo reduction of
1-amino-2-naphthol-based azo dyes was reported to be catalysed by human
intestinal microflora [Xu, H., et al.: Anaerobic metabolism of
1-amino-2-naphthol-based azo dyes (dyes) by human intestinal microflora.
Appl Environ Microbiol, 2007.73(23): p. 7759 -7762].
In conclusion, the absorption
of the pigment via skin is very low. In the course of the acute
inhalation study neither stained urine nor specific toxic effects or
mortalities were observed indicating a very limited uptake of the
substance via the respiratory system. The poor solubility of the test
item and the property to stick together in aequeous solution support
this assumption. Repeated dose toxicity tests revealed some effects
which suggest a cleavage of the azo bond and a subsequent release of
amino-naphthol. Amino-naphthol might cause met-hemoglobin formation and
be responsible for hematotoxicity and damage of the splenic tissue.
Uptake of small amounts of barium after dissociation in gastric acid is
likely. Effects on CNS, kidney, GIT or other target organs were not
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