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Diss Factsheets

Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics
Type of information:
other: theoretical approach
Adequacy of study:
key study
Reliability:
other: not applicable
Rationale for reliability incl. deficiencies:
other: Study is based on expert judgement.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report date:
2008

Materials and methods

Objective of study:
other: Assessment of toxicokinetic behaviour
GLP compliance:
no
Remarks:
not applicable

Test material

Constituent 1
Reference substance name:
-
EC Number:
481-490-7
EC Name:
-
Molecular formula:
multi-constituent.
IUPAC Name:
5,11,17,23,29,35,41,47-octa-tert-butyl-49,50,51,52,53,54,55,56-octahydroxy-2λ⁶,8λ⁶,14λ⁶,20λ⁶,26λ⁶,32λ⁶,38λ⁶,44λ⁶-octathianonacyclo[43.3.1.1³,⁷.1⁹,¹³.1¹⁵,¹⁹.1²¹,²⁵.1²⁷,³¹.1³³,³⁷.1³⁹,⁴³]hexapentaconta-1(49),3,5,7(56),9,11,13(55),15,17,19(54),21(53),22,24,27,29,31(52),33,35,37(51),39(50),40,42,45,47-tetracosaene-2,2,8,8,14,14,20,20,26,26,32,32,38,38,44,44-hexadecone; 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrahydroxy-2λ⁶,8λ⁶,14λ⁶,20λ⁶-tetrathiapentacyclo[19.3.1.1³,⁷.1⁹,¹³.1¹⁵,¹⁹]octacosa-1(25),3,5,7(28),9,11,13(27),15(26),16,18,21,23-dodecaen-2,2,8,8,14,14,20,20-octone
Details on test material:
- Name of test material (as cited in study report): TC4ASO2
- Substance type: multi-constituent
- Physical state: white powder
- Analytical purity: 97.8%
- Composition of test material, percentage of components: 92.9% 4-tert-Butylsulfonylcalix(4)arene (CAS 204190-49-8)
4.9% 4-tert-Butylsulfonylcalix(8)arene
- Lot/batch No.: AYUI-1Y
- Expiration date of the lot/batch: 07 October 2007
- Stability under storage conditions: Stable
- Storage condition of test material: At room temperature in the dark

Results and discussion

Any other information on results incl. tables

The test substance is a powder with a low water solubility
(2.97 mg/L). Since in general a substance needs to be
dissolved before it can be taken up from the gastro-
intestinal tract, it is unlikely that the test substance
will show a high systemic exposure after oral
administration. The absorption will furthermore be lowered
by the relatively large molecular weight (849.05/1698.12
g/mol) of this substance limiting the passage through
biological membranes. The lipophilic character of the test
substance varies with the pH (logPow = 5.4 at pH 1.8 and <
0.3 at neutral pH); the relevance of uptake by micellular
solubilisation by bile salts is therefore difficult to
predict, but may not be of particular importance as this is
only relevant for highly lipophilic compounds. For risk
assessment purposes the oral absorption of the test
substance is set at 10%. The results of the toxicity studies
do not provide reasons to deviate from this proposed oral
absorption factor.

Absorbed test substance might undergo metabolism and/or
conjugation (1). In view of the low water solubility of the
test substance (2.97 mg/L) a low potential for distribution
through the human body is anticipated. Although the logPow
can not clearly be established (pH dependent), the test
substance is not expected to be lipophylic under
physiological conditions and hence significant distribution
into cells is not expected and will be further limited by
the high molecular weight (849.05/1698.12 g/mol). Because of
its relatively high molecular weight, the test substance
and its conjugates will predominantly be excreted via the
bile.

Based on the particle size of the test substance, particles
< 100 µm, which have a potential to be inhaled, are present.

Particles might settle in the nasopharyngeal region
(particles with aerodynamic diameter > 1-5 µm), or reach the
tracheobronchial or pulmonary region (~7% of the particles
< 1 µm and ~83% < 5 µm). The low water solubility of the
test substance (2.97 mg/L) indicates a potential for
accumulation, while its anticipated low lypophilic character
(logPow < 0.3 at neutral pH) indicates a low potential for
absorption directly across the respiratory tract epithelium.

Particles might be engulfed by alveolar macrophages which
may thus be translocated to the ciliated airways or carried
into the pulmonary interstitium and lymphoid tissues.
Particles may also migrate directly to the pulmonary
interstitium where slow clearance is to be expected as
clearance depends on the rate at which the particles
dissolve. For risk assessment purposes the inhalation
absorption of the test substance is set at 50% as a worst
case assumption.

The test substance being a low water soluble solid with a
relatively high molecular weight has no real potential for
dermal absorption. Although the logPow could not clearly be
established (< 0.3 at neutral pH) the substance might well
be not sufficiently lipophilic to cross the stratum corneum.

As the logPow could not clearly be determined (< 0.3 at
neutral pH) it can not be established whether or not the
criterion for 10% dermal absorption as given in the TGD (2)
(MW > 500 and logPow < -1 or > 4) are met. Taking the
relatively high molecular weight into account and as it is
generally accepted that dermal absorption is lower compared
to oral absorption, 10% dermal absorption of the test
substance is proposed for risk assessment purposes. The
results of the toxicity studies do not provide reasons to
deviate from this proposed dermal absorption factor.

Based on the present available data, no additional
conclusions can be drawn on the distribution, metabolism and
excretion of the test substance after dermal and inhalatory
absorption.


REFERENCES

1.  A. Parkinson. In: Casarett and Doull's Toxicology, The
basic science of poisons. Sixth edition. Ed. C.D. Klaassen.
Chapter 6: Biotransformation of xenobiotics. McGraw-Hill,
New York, 2001.

2.   ECB EU Technical Guidance Document on Risk Assessment,
2003.

Applicant's summary and conclusion