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Diss Factsheets

Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
4 March 2003 to 28 March 2003
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Version / remarks:
September 30, 1996
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
July 17, 1992
Deviations:
yes
Remarks:
the dose used to challenge was non-irritant
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The test was performed before LLNA was implemented.

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
469-070-1
EC Name:
-
Cas Number:
17861-60-8
Molecular formula:
C9H26O2Si3
IUPAC Name:
4-ethyl-2,2,4,6,6-pentamethyl-3,5-dioxa-2,4,6-trisilaheptane
Test material form:
liquid
Details on test material:
Other name: Baysilone TP 3886
Specific details on test material used for the study:
Density: 828 g/L at 20°C

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
Test animals:
Age:5 weeks at study start
Weight: not reported
Acclimatisation:13 days
Housing: group housed (maximum 10 animals/cage)
Diet: standard laboratory diet ad libitum
Water: tap water ad libitum

Environmental conditions:
Temperature: 20 +/-3°C
Humidity: 30-70%
Ventilation: 10 air changes/hour
Lighting: 12 hours light/dark cycle

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
maize oil
Concentration / amount:
10%
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
intradermal
Vehicle:
other: FCA/test substance in vehicle 1:1
Concentration / amount:
10%
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Day(s)/duration:
2
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
maize oil
Concentration / amount:
30%
Day(s)/duration:
1
Adequacy of challenge:
other: non-irritant concentration
No. of animals per dose:
Test group: 10 animals
Control group: 5 animals
Details on study design:
The dose levels were chosen following a preliminary irritation study using two animals per treatment route:
Intradermal injections at concentrations of 1,3,10, 30 and 100% and topical treatment at 30 and 100%.
Intradermal injection at concentrations of 30 and 100% produced abscesses
Topical treatment at 100% produced moderate and confluent erythema

Challenge controls:
Control groups were treated with FCA/physiological saline or vehicle only as appropriate during the induction phase and vehicle only during the challenge phase
Positive control substance(s):
yes
Remarks:
positive control study run concurrently using 20 and 10% dilution of hexylcinnamaldehyde in saline induced positive reactions in all animals.

Results and discussion

Positive control results:
The study with positive control alpha-hexylcinnamaldehyde (application of a 10% dilution) was run in March 2003 in the same test facility. All 5 test animals showed positive response at 24 and 48 hours, while the three animals in the negative control group did not show a reaction.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
negative control
No. with + reactions:
2
Total no. in group:
5
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
negative control
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
30%
No. with + reactions:
2
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
30%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
other:
Group:
positive control
Remarks on result:
positive indication of skin sensitisation
Remarks:
Positive control not run simultaneously

Any other information on results incl. tables

Maximum concentration not causing irritating effects in preliminary test: 30 %

Signs of irritation during induction:
Moderate erythema

Evidence of sensitisation of each challenge concentration:
Control group: 2 of 5 animals showed slight erythema after 24 hours; after 48 hours no effects were observed.

Test group: 2 of 10 animals showed slight erythema after 24 hours; after 48 hours no effects were observed.

Other observations:
None

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
In a guinea pig maximization study, performed according to OECD/EC guidelines and under GLP principles, none of the test animals showed positive signs of sensitisation. A positive control group demonstrated the sensitivity of the test system. Based on these findings, it is concluded that heptamethylethyltrisiloxane is not a skin sensitizer under the conditions of this study.
Executive summary:

The skin sensitization potential of heptamethylethyltrisiloxane was evaluated in female guinea pigs using the Maximization Test. Test substance concentrations used in the main study were based on an initial irritancy screen.

The first induction was performed by intradermal injection with 10% test substance suspension in maize oil and an emulsion of Freund's complete adjuvant (FCA)/10% test substance in maize oil. One week later, a second induction was made by topical application (48 hours) under an occlusive dressing of undiluted test material. Two weeks after the second induction, the animals were challenged by topical application of 30% test substance ointment in maize oil under an occlusive dressing for 24 hours.

Both test and control animals reacted slightly to the test substance and to the vehicle alone at 24 hours after challenge. The degree and incidence were comparable for both test and control groups and considered to be signs of primary skin irritation. None of the test animals showed positive signs of sensitisation. A positive control group demonstrated the sensitivity of the test system.

Based on these findings, it is concluded that heptamethylethyltrisiloxane is not a skin sensitizer under the conditions of this study