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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to the O.E.C.D. test guideline no. 429 with GLP compliance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report date:
2012

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid: viscous
Details on test material:
As per IUCLID5 Sections 1.1. 1.2. and 4.1.

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Harlan Laboratories UK Ltd., Oxon, UK. On receipt the animals were randomly allocated to cages. The animals were nulliparous and non-pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink-marking on the tail and a number written on a cage card. At the start of the study the animals were in the weight range of 15 to 23 g, and were eight to twelve weeks old.
The animals were individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes. Free access to mains tap water and food (2014C Teklad Global Rodent diet supplied by Harlan Laboratories UK Ltd., Oxon, UK) was allowed throughout the study.
The temperature and relative humidity were controlled to remain within target ranges of 19 to 25°C and 30 to 70%, respectively. Any occasi onal deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was approximately fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06.00 to 18.00) and twelve hours darkness.
The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
The test substance was applied at concentrations of 50, 25 and 10 % v/v
No. of animals per dose:
4
Details on study design:
Groups of four mice were treated with the test item at concentrations of 50%, 25% or 10% w/w in acetone/olive oil 4:1. The preliminary screening test suggested that the test item would not produce systemic toxicity or excessive local skin irritation at the highest suitable concentration. The mice were treated by daily application of 25 μl of the appropriate concentration of the test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test item formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette. A further group of four mice received the vehicle alone in the same manner.
Five days following the first topical application of the test item or vehicle (Day 6) all mice were injected via the tail vein with 250 μl of phosphate buffered saline (PBS) containing 3H-methyl thymidine (3HTdR: 80 μCi/ml, specific activity 2.0 Ci/mmol, ARC UK Ltd) giving a total of 20 μCi to each mouse. Five hours following the administration of 3HTdR all mice were killed by carbon dioxide asphyxiation. The draining auricular lymph nodes from the four mice were excised and pooled for each experimental group. For each group 1 ml of PBS was added to the pooled lymph nodes. A single cell suspension of pooled lymph
node cells was prepared by gentle mechanical disaggregation through a 200-mesh stainless steel gauze. The lymph node cells were rinsed through the gauze with 4 ml of PBS into a petri dish labelled with the project number and dose concentration. The lymph node cell suspension was transferred to a centrifuge tube. The petri dish was washed with an additional 5 ml of PBS to remove all remaining lymph node cells and these were added to the centrifuge tube. The pooled lymph node cells were pelleted at 1400 rpm (approximately 190 g) for ten minutes. The pellet was resuspended in 10 ml of PBS and re-pelleted. To precipitate out the radioactive material, the pellet was resuspended in 3 ml of 5% Trichloroacetic acid (TCA). After approximately eighteen hours incubation at approximately 4°C, the precipitates were recovered by centrifugation at 2100 rpm (approximately 450 g) for ten minutes, resuspended in 1 ml of TCA and transferred to 10 ml of scintillation fluid (Optiphase 'Trisafe'). 3HTdR incorporation was measured by b-scintillation counting. The "Poly QTM" vials containing the samples and scintillation fluid were placed in the sample changer of the scintillator and left for approximately twenty minutes. The purpose of this period of time in darkness was to reduce the risk of luminescence, which has been shown to affect the reliability of the results. After approximately twenty minutes, the vials were shaken vigorously. The number of radioactive disintegrations per minute was then measured using the Beckman LS6500 scintillation system (Beckman Instruments Inc, Fullerton, CA, USA). The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).
The test item will be regarded as a sensitiser if at least one concentration of the test item results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test item failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non-sensitiser".
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
Positive Control % Concentration Stimulation Index
_________________________________________________________
25 5.76
_________________________________________________________

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: see Remark
Remarks:
Test Substance % Concentration Stimulation Index ________________________________________________________ Vehicle na 10 3.52 25 1.75 50 5.57 ________________________________________________________
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see Remark
Remarks:
Test Substance % Concentration dpm ________________________________________________________ Vehicle 17114.18 10 60175.70 25 30012.57 50 95311.07 ________________________________________________________

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: expert judgment
Conclusions:
Inducing a Stimulation Index of 3.52 at a concentration of 10 % v/v the test substance is considered to be a skin sensitiser. The estimated EC3 value is 2.0% v/v or 500 ug/cm2.
Executive summary:

The test substance, 4,4'-Isopropylidenediphenol, oligomeric reaction products with 1-chloro-2,3-epoxypropane, reaction products with fatty acids, C18-unsatd., dimers was accessed for skin sensitization potential in an O.E.C.D. test guideline no. 429 LLNA study. Inducing a Stimulation Index of 3.52 at a concentration of 10 % v/v the test substance is considered to be a skin sensitiser. The estimated EC3 value is 2.0% v/v or 500 ug/cm2.