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Toxicological information

Dermal absorption

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Administrative data

Endpoint:
dermal absorption in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Expert judgement combined with experimental data.

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
The absorption, distribution and excretion of alkyl polyethoxylates by rats and humans.
Author:
Drotman, R.B.
Year:
1980
Bibliographic source:
Tox. Appl. Pharm. 52:38-44
Reference Type:
publication
Title:
In vivo percutaneous absorption of polyoxyethylene lauryl ether surfactants in hairless mice.
Author:
Nishiyama, T. et al.
Year:
1983
Bibliographic source:
J. Soc. Cosmet. Chem. 34:263–271

Materials and methods

Principles of method if other than guideline:
No guideline exists for this type of appraisal.
Alcohol ethoxylates radiolabelled in either the hydroxyl-bearing carbon or the α-carbon of the alkyl group were dosed orally or applied to the skin of rats and humans. Excreta from both species and tissue samples from the rats were assayed for 14C.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
other: partly

Test animals

Species:
other: rat and human

Administration / exposure

Type of coverage:
other: Various
Vehicle:
other: Various
Duration of exposure:
Various
Doses:
Various
No. of animals per group:
Various
Details on study design:
For further details on the various studies please refer to the HERA report on AEs (HERA report 2009).

Results and discussion

Percutaneous absorption
Parameter:
percentage
Absorption:
2 %
Remarks on result:
other: 0-24 h
Remarks:
Penetration rate of 0.0000092 cm/h is derived from measured data.

Any other information on results incl. tables

It was shown that the amount absorbed increased linearly with time. In the case of LAE containing ethylene oxide units larger than 2 mol, the LAE absorbed percutaneously was rapidly metabolized to CO2 and excreted in expired air. Therefore, the rate of percutaneous absorption could be calculated from the rate of expiratory excretion. This result coincided with the amount obtained from the slope of the percutaneous absorption curve as a function of time.

Moreover it could be shown that LAE-1 and LAE-2.6 penetrate the skin readily while LAE-10 is barely absorbed.

Most of the activity applied to human skin was removed by cleaning the application site with alcohol soaked gauze (i.e., 73.9% in subject 1; 87.5% in subject 2) and less than 2% (i.e., 1.82% in subject 1; 1.03% in subject 2) was detected in the urine. No radioactivity was found in the faeces or in form of CO2. Radioactivity in the blood was barely detectable. In subject 2, it was equivalent to 0.14 μg/g at 8 hours, 0.02 μg/g at 12 hours and 0.01 μg/g at 24 hours indicating that the vast majority of dermally absorbed AE was absorbed within the first 24 hours. The total recovery of radioactivity was 82.4% for subject 1 and 94.7% for subject 2. Urinary excretion was the primary route of elimination following dermal absorption.

Applicant's summary and conclusion

Conclusions:
The dermal penetration rate for alcohol ethoxylates was calculated on the basis of a dermal penetration study with 14C-labelled C12AE6 in human volunteers and assumes – conservatively - 2% absorption within the first 24 h following dermal application.