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Administrative data

dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 428 (Skin Absorption: In Vitro Method)
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate
EC Number:
EC Name:
2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate
Cas Number:
Molecular formula:
2-ethylhexyl 10-ethyl-4,4-dioctyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecan-1-oate
Constituent 2
Reference substance name:
Dioctyltin bis(2-EHMA)
Dioctyltin bis(2-EHMA)
Details on test material:
Dioctyltin bis(2-EHMA) [CAS No. 15571-58-1]; colorless liquid, 99.73% (w/w) DOT(2-EHMA), 15.7% w/w tin, source: Crompton GmbH.

Test animals

other: rat and human epidermis

Administration / exposure

Type of coverage:
other: occluded and unoccluded
Duration of exposure:
24 hour(s)
Absorption was determined via both occluded and unoccluded applications to human and rat epidermis (100 µl/cm²; equivalent to a dose of 17,007 µg tin/cm²).
Details on study design:
Absorption of tin compouds was measured (not DOTE only).

Results and discussion

Any other information on results incl. tables

HUMAN EPIDERMIS: A dose of 17,007 ug tin/cm² was determined to alter the barrier function of the epidermis.  From the occluded and unoccluded applications, the rates of tin absorption over the 0-24 h exposure period were below the limit of quantification (0.001 ug/cm²/h).  In terms of  percent applied tin, 0.0001% was absorbed from the occluded dose,  and  0.0001% was absorbed from the unoccluded dose after  24 hours of exposure.

RAT EPIDERMIS: Absorption of tin through rat epidermis was much faster than through human epidermis.  From the occluded application, the  maximum rate of tin absorption (0.035 ug/cm²/h) occurred during 16-24 hours of exposure, and the mean rate of tin absorption over the whole  24-h exposure period was 0.021 ug/cm²/h.  From the unoccluded application, the maximum rate of tin absorption occurred during 12-24 hours of  exposure and was 0.033 ug/cm²/h.  The mean rate of tin absorption over the whole  24-h exposure period was 0.025 ug/cm²/h.  In terms of percent applied tin, 0.003% was absorbed from the occluded dose, and 0.004% was  absorbed from the unoccluded dose after 24 hours of exposure.  The overall recovery of tin from the test system after 24-h exposure was low and may be due to adsorption of the test substance to the glass  equipment used.  The recovery was 45.5% (human) and 25.2% (rat) of theapplied occluded doses, and 29.6% (human) and 30.5% (rat) were  recovered from the unoccluded test systems.  Of the recovered tin, 2.1% (human) and 5.5% (rat) were obtained from the surface of the epidermis and donor chamber.  The mean amounts of tin  absorbed by 24 hours were 0.010 ug/cm² (unoccluded) and 0.011 ug/cm² (occluded) through human epidermis and 0.641 ug/cm² (unoccluded)  and 0.547ug/cm² (occluded) through rat epidermis.  These results show that the absorption of tin from dioctyltin bis(2-ethylhexylmercaptoacetate) through rat epidermis significantly  overestimated absorption from human epidermis.  By 24 hours only a small amount of the applied tin (3% in human and 1% in the rat) is  associated with the epidermis and is not regarded as systemically available.

The recovery was 45.5% (human) and 25.2% (rat) of the applied occluded doses, and 29.6% (human) and 30.5% (rat) were recovered from the unoccluded test systems.

Applicant's summary and conclusion

Bioaccumulation potential cannot be judged based on study results.
Absorption of tin from DOT(EHMA) through rat epidermis significantly overestimates absorption through human epidermis.
Executive summary:

A dermal absorption study was carried out with DOT(2 -EHMA). Absorption of tin compounds was determined via both occluded and unoccluded applications to human and rat epidermis.

Of the recovered tin, 2.1% (human) and 5.5% (rat) were obtained from the surface of the epidermis and donor chamber.  The mean amounts of tin absorbed by 24 hours were 0.010 ug/cm² (unoccluded) and 0.011 ug/cm² (occluded) through human epidermis and 0.641 ug/cm² (unoccluded) and 0.547ug/cm² (occluded) through rat epidermis.

The results show that the absorption of tin from dioctyltin bis(2-ethylhexylmercaptoacetate) through rat epidermis significantly over-estimated absorption from human epidermis.  By 24 hours only a smallamount of the applied tin (3% in human and 1% in the rat)  is associated with the epidermis and is not regarded as systemically available.