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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:
18th April 2017- 18th May 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
A Buehler test was used for R&D purposes and worldwide acceptance, so an LLNA should not ethically be completed based on animal welfare reasons. LLNA frequently gives false positives for irritating substances therefore Buehler test was used. The testing will also be submitted to other regulatory agencies that do not accept LLNA testing.

Test material

Constituent 1
Chemical structure
Reference substance name:
Potassium hydrogen 2-octadecenylsuccinate
EC Number:
296-086-4
EC Name:
Potassium hydrogen 2-octadecenylsuccinate
Cas Number:
92218-39-8
Molecular formula:
C22H40O4.K
IUPAC Name:
hydrogen potassium 2-octadec-1-en-1-ylsuccinate

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
Young adult, male Hartley guinea pigs from a USDA licensed supplier were used. The animals
weighed 370-496 grams at the start of the study.A total of 32 animals were utilized.
Twenty test animals, ten negative control animals, and two pilot animals were used.
Prior to use, all animals were acclimated for at least five days. Animals were individually housed
in wire mesh suspension cages. The animals were maintained on a 12-hour cycle light controlled
room, at a temperature of 64° - 79°F and a relative humidity of 30-70%. The animals were
maintained according to the recommendations contained in the National Academy Press 2011:
“Guide for the Care and Use of Laboratory Animals.” The animals were supplied Purina Guinea
Pig Chow and tap water ad libitum during both acclimation and test periods. Tox Monitor
Laboratories has daily access to feed analysis; water analysis from the city of Chicago is on file.
There were no contaminants in either the feed or the water that would be expected to affect the
outcome of this study.
Animals were evaluated during the pre study acclimation period for signs of disease or physical
abnormalities and only animals that appeared healthy were used on the study. Only animals with
skin sites that were free from defects or alterations in coloration or texture were used. The
animals to be tested were selected from the population of animals available for this study. The
animals were randomly caged according to Standard Operating Procedures.

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, semiocclusive
Vehicle:
other: Deionized water
Concentration / amount:
0.4ml of 100% concentration of test substance
Day(s)/duration:
6 hours
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, semiocclusive
Vehicle:
other: Deionized water
Concentration / amount:
0.4ml of 50% concentration of test substance
Day(s)/duration:
6 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
20 animals
Details on study design:
A pilot study was conducted using 2 animals to determine the concentration that produced mild dermal irritation at the application site which is then used for the inductions dose and the highest non irritating concentration of the test substance is then used as the challenge dose. The application site is prepared by removing hair from the back and sides of the trunk and four sites are selected for the irritation screening, 0.4ml of 25%, 50%, 75% and 100% of the test substance were applied to the test site and secured with micropore tape and further secured with kendal adhesive tape then left for 6 hrs after which the tape is removed and the irritation scores are taken a day after.

Similarly, application sites were prepared on test animals by shaving off hair and test substance is applied and secured with tape for 6hours after which tape is taken off and excess material wiped off. The test substance was administered to 20 young adults’ male Guinea pigs by dermal application at a dose volume of 0.4ml per application site for the Inductions and challenge. The dose was based upon the appropriate amount of material sufficient to saturate the cotton pad in the Hilltop Chamber and allow for good skin contact of the test substance. Animals are scored for Irritation (erythema) at 24 and 48hours after completion of exposure. All animal body weight are taken before and after the study. In the challenge study, 6 negative control animals were challenged with the test substance.



Challenge controls:
6 naive controls, 4 animals were kept for a re-challenge if necessary.
Positive control substance(s):
yes

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50% of test substance
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
50% of test substance
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
50% concentration of Test substance
No. with + reactions:
0
Total no. in group:
6
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
50% of test substance
No. with + reactions:
0
Total no. in group:
6
Remarks on result:
no indication of skin sensitisation
Group:
positive control
Remarks on result:
not measured/tested

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Following primary challenge of test substance, at 50% concentration, the incidence of grade 1 response or greater in the test group (0 of 20) was compared to that of the naive control group (0 of 6). The incidence and severity of these responses were not significantly greater than those produced by the naive control group indicating that sensitization had not been induced Therefore, the test substance does not meet the criteria set for skin sensitization.
Executive summary:

The test substance was tested for dermal sensitization potential utilizing a Buehler Technique Guinea Pig Sensitization Protocol. The test substance was evaluated for sensitization potential by applying 0.4 ml at a 100% concentration directly into Hilltop Chambers® and applying them to the clipped left shoulder of twenty albino guinea pigs in the following manner: The animals were held gently, and the chambers were applied as quickly as possible to the clipped left shoulder. The chambers were secured with Micropore tape and further secured with Kendall adhesive tape. Approximately six hours later, the tape and chambers were removed. Two additional induction doses were conducted following the same procedure, at weekly intervals. Two weeks after the final application the animals received a topical primary challenge dose (6 hour contact), at 50% concentration, on a naive site located on the right shoulder. Animals were scored for irritation at 24 and 48 hours after initiation of the primary challenge application. Ten guinea pigs served as a naive control group, and remained untreated through the induction phase. Six naive control animals received only the primary challenge dose, at a 50% concentration. The four remaining guinea pigs were designated for a re-challenge, if necessary. Following primary challenge at 50% concentration, the incidence of grade 1 response or greater in the test group (0 of 20) was compared to that of the naive control group (0 of 6). The incidence and severity of these responses were not significantly greater than those produced by the naive control group therefore indicating that no sensitization had been induced.

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