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EC number: 229-722-6
CAS number: 6683-19-8
In an in situ study on GI absorption the results indicate that only
trace amounts, if any, of test material were absorbed in a 3-hour
period. Based on physico-chemical properties and the hazard profile, the
substance is not considered to be absorbed. There is no potential for
The test substance (molecular weight > 1177 g/mol) is a white
powder with a calculated Log Pow of 23, a water solubility of <0.1 mg/L
at 20°C and a vapor pressure of 1.33 E-10 Pa at 20°C (estimated).
Based on the physico-chemical data (low water solubility, molecule size,
Log Pow) it is assumed that there is no or only very slow absorption
after oral ingestion of the test article. This is supported by an old in
situ absorption study. Here it could be shown that only trace amounts,
if any, of test material were absorbed in a 3-hour period. In addition,
the available acute oral toxicity studies did not reveal any signs of
systemic toxicity and resulted in LD50 values of greater than 5000 mg/kg
or higher. Furthermore, in the available 90-day feeding study with dogs
using dose levels of 1000, 3000, 10000 ppm, no effects on body weight,
food consumption, ophthalmology, clinical pathology, organ weights, and
on histopathology were reported with a NOAEL of greater than 10000 ppm.
In addition, a 2-year chronic feeding study with rats is available,
which showed no findings of toxicological relevance up to the highest
dose level of 10000 pm. The lack of systemic toxicity in these studies
suggests poor bioavailability upon oral ingestion. In support of these
findings are the results of an old absorption study performed with rat
intestinal loops according to the Levine technique. This study showed
that the test article was only absorbed in trace amounts, if at all,
after a 3h exposure period. In addition, the diameter of the chemical
was determined to be 17.9Å. According to a publication by Opperhuizen et
al, a lipophilic particle with a diameter of greater than 9.5 Å has only
limited ability to cross biological membranes (Opperhuizen et al, 1985).
A second assessment found in ECHA Guidance on information requirements
and chemical safety assessment, Chapter R.11, concludes that a substance
is possibly not considered to be bioaccumulative if the average maximum
diameter is greater than 17 Å and the molecular weight is larger than
1100. Based on this information, it can be assumed that the test article
is not likely to cross biological membranes and has no bioaccumulation
potential. Therefore, in line with all toxicological data available,
systemic availability can be excluded.
Dermal absorption is equally unlikely, due to the size of the
chemical, the Log Pow of 22 and the very low water solubility. Highly
lipophilic substances that come into contact with the skin can readily
penetrate the lipid rich stratum corneum but are not well absorbed
systemically. Although they may persist in the stratum corneum, they
will eventually be cleared as the stratum corneum is sloughed off.
Furthermore, dermal uptake of chemicals with a molecular weight >500 is
not favored (ECHA GD 7c). This is in line with the available toxicity
data after dermal exposure. In an acute dermal toxicity study no
indications of systemic availability after dermal application were
detected. In conclusion, dermal penetration is expected to be very low.
In two inhalation toxicity studies, no effects were reported up to
the highest doses tested. Given its low water solubility, systemic
availability after exposure to dust particle of the test substance is
expected to be low. In addition, particle size distribution analysis
revealed a mass median diameter of 140.8 µm, therefore, the majority of
generated particles will not penetrate into the broncho-alveolar tract.
In view of the absence of relevant findings and the expected low
bioavailability, it can be assumed that the test substance is rapidly
excreted. Since the test substance has a molecular weight larger than
500 g/mol and a low solubility in water, it is expected to be excreted
predominantly via the feces (ECHA GD 7c).
The physico-chemical data suggest that the test article cannot
cross biological membranes and therefore absorption after oral, dermal
and inhalative exposure is expected to be negligible. This is supported
by the findings of available toxicity studies, which clearly
demonstrated absence of systemic toxicity. The test article has not
bioaccumulation potential and rapid excretion via the feces is expected.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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