Registration Dossier

Administrative data

Description of key information

The skin sensitization potential of test chemical was assessed in various experimental studies conducted on mose lymphoma. Based on the available data for the target and supporting studies, it can be concluded that the test chemical is not able to cause skin sensitization and thus cannot be considered as sensitizing. Comparing the above annotations with the criteria of CLP regulation, it can be classified under the category “Not sensitizing”.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
experimental data from various test chemicals
Justification for type of information:
Data is summarized based on the available information from various read across test chemicals.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: As mentioned below
Principles of method if other than guideline:
WoE report is based on 2 skin sensitization studies as - WoE 2 and WoE 3
Skin sensitization test was carried out to study the effects of the test chemical on rodents.
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)
Specific details on test material used for the study:
No data available
Species:
mouse
Strain:
other: 2.Not specified 3.CBA
Sex:
female
Details on test animals and environmental conditions:
2.Not specified
3.TEST ANIMALS
Source: No data
Age at study initiation: 7-12 weeks
Vehicle:
other: AOO (Acetone/olive oil, 80/20 v/v)
Concentration:
2. 5%, 10% and 25%
3.25 µL
No. of animals per dose:
2.Not specified
3.groups of female mice (number not specified)
Details on study design:
2.Not specified
3.Pre –screen tests : No data

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response:
A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). Dose response data were used to measure the relative skin sensitization potency of all of the chemicals that were positive. When the LLNA dose-response curve included concentrations that induced at least one SI greater than 3 and one SI less than 3, EC3 values were calculated by linear interpolation. For chemicals that induced an SI greater than or equal to 3 at all concentrations tested, an EC3 value was extrapolated from the two lowest doses used. For this extrapolation method to work, a dose response should be evident. The relative sensitizing potencies of the chemical allergens were categorized via a recently proposed arbitrary classification scheme.

TREATMENT PREPARATION AND ADMINISTRATION: groups of CBA female mice (7–12 weeks of age) were exposed topically on the dorsum of both ears to 25 µL of test material or to an equal volume of the relevant vehicle alone. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group.
Positive control substance(s):
not specified
Statistics:
2.Not specified
3.
Positive control results:
2.Not specified
3.
Parameter:
other: T/C ratio
Remarks:
2
Value:
1.2
Test group / Remarks:
Concentartion 5%
Remarks on result:
other: Not sensitizing
Parameter:
other: T/C ratio
Remarks:
2
Value:
1.4
Test group / Remarks:
Concentration 10%
Remarks on result:
other: Not sensitizing
Parameter:
other: T/C ratio
Remarks:
2
Value:
2.1
Test group / Remarks:
Concentration 25%
Remarks on result:
other: Not sensitizing
Parameter:
SI
Remarks:
3
Value:
2.8
Remarks on result:
other: Not sensitizing
Cellular proliferation data / Observations:
2.Not specified
3.
Interpretation of results:
other: Not sensitizing
Conclusions:
Based on all the observations and results, it was concluded that the test chemical is not sensitizing to skin.
Executive summary:

Various studies has been investigated for the test chemical to observe the potential for skin sensitization to a greater or lesser extent. The studies are based on in vivo experiments in mice for test chemical are summarized as below;

The dermal sensitization potential of the given test chemical was evaluated in a mouse local lymphnode assay (LLNA). Groups mice were exposed topically on the dorsum of both ears to 5%, 10% and 25% of the test material or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected intravenously with [H3] thymidine and activity measured as a function of isotope incorporation in draining auricular lymph nodes. The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value. A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). The values for Stimulation Indices at various test concentrations were 1.2, 1.4 and 2.1 which are below 3, hence EC3 value couldnot be calculated. Therefore, the given test chemical was considered to be not sensitizing to skin of mice.

In another study, the dermal sensitization potential of the given test chemical was evaluated in a mouse local lymphnode assay (LLNA). The study was performed as per OECD 429 Guidelines. Groups of female CBA mice (7-12 weeks of age) were exposed topically on the dorsum of both ears to 25µl of the test material or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group. The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value.A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). The values for Stimulation Indices at various test concentrations were 1.2, 1.4 and 2.8 which are below 3, hence EC3 value couldnot be calculated. Therefore, the given test chemical was considered to be not sensitizing to skin of mice.

All these studies lead to a conclusion that Test chemical is indeed not sensitizing to skin. Hence, comparing the above annotations with the criteria of CLP regulation, Test chemical can be classified under the category “Not Sensitizing”.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Various studies has been investigated for the test chemical to observe the potential for skin sensitization to a greater or lesser extent. The studies are based on in vivo experiments in mice for test chemical are summarized as below;

The dermal sensitization potential of the given test chemical was evaluated in a mouse local lymphnode assay (LLNA). Groups mice were exposed topically on the dorsum of both ears to 5%, 10% and 25% of the test material or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected intravenously with [H3] thymidine and activity measured as a function of isotope incorporation in draining auricular lymph nodes. The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value. A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). The values for Stimulation Indices at various test concentrations were 1.2, 1.4 and 2.1 which are below 3, hence EC3 value couldnot be calculated. Therefore, the given test chemical was considered to be not sensitizing to skin of mice.

In another study, the dermal sensitization potential of the given test chemical was evaluated in a mouse local lymphnode assay (LLNA). The study was performed as per OECD 429 Guidelines. Groups of female CBA mice (7-12 weeks of age) were exposed topically on the dorsum of both ears to 25µl of the test material or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group. The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value.A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). The values for Stimulation Indices at various test concentrations were 1.2, 1.4 and 2.8 which are below 3, hence EC3 value couldnot be calculated. Therefore, the given test chemical was considered to be not sensitizing to skin of mice.

All these studies lead to a conclusion that Test chemical is indeed not sensitizing to skin. Hence, comparing the above annotations with the criteria of CLP regulation, Test chemical can be classified under the category “Not Sensitizing”.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The skin sensitization potential of test substance were observed in various studies. From the results obtained from these studies it is concluded that the test chemical is not likely to cause skin sensitization and hence can be classified as “Not sensitizing”.