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Description of key information

Skin sensitisation (Read-Across: undec-10-enal): sensitising, EC3 = 6.8% female mice, OECD TG 429, 2001

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Guideline study performed under GLP. The source and target substances must have an aldehyde group at the 1-carbon position and either a terminal (10-position) or an internal alkene (9-position or 8-position; with the terminal alkyl group no larger than an ethyl group and/or should not multiply substituted). The substance alkyl chain length of the substance should be more than 6 carbons in length and less than 14 carbons in length and fulfil the mono-alkene definition. The substance should not have any branched alkyl groups or side chains. The target and source share common structural elements in the same relative positions. The source and target have very similar physico-chemical properties and thus have similar expected toxicokinetic behaviour. The substances have similar in silico chemical reactivity predictions. This is observed within available in vivo toxicology testing where low level local and systemic toxicity is demonstrated and comparable between target and source. The substances therefore demonstrate chemical similarity. In the skin sensitisation endpoint, the target and source have common protein reactivity alert(s). The target and source therefore have common foreseen mode of action.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included in attachment to IUCLID section 13.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across is based on the hypothesis that the source and target substances have common structural features in the same relative positions. The source and target have similar physico-chemical, toxicological properties and because of common metabolism they share common or have similar breakdown products and therefore potential mechanisms of action. Further information is included in attachment to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source and target chemicals have comparable chemical similarity. Further information is included in attachment to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
The source substance is a chemically similar substance with common metabolism and common or similar degradants of the target substance. Further information is included in attachment to IUCLID section 13

4. DATA MATRIX
Further information is included in attachment to IUCLID section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
other: CBA/Jibm(SPF)
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: 7 - 12 weeks
- Weight at study initiation: 17.7 - 24.8 g
- Housing: In groups of four in Makrolon type-3 cages with standard softwood bedding
- Diet: standard pellet diet ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/- 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12 h light / 12 h dark

IN-LIFE DATES: 28-AUG-2001 to 12-SEP-2001
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
5, 10, 25, 50 and 75%
No. of animals per dose:
4 females
Details on study design:
TREATMENT PREPARATION AND ADMINISTRATION:
The test item in the main study was assayed at five consecutive concentrations that were selected by the sponsor.

TOPICAL APPLICATION
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 5 %, 10 %, 25 %, 50% and 75% in acetone:olive oil, 4:1 (v/v). The application volume, 25uI, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). A hair dryer was used to dry the ear's surface as quickly as possible to avoid loss of test item applied.

ADMINISTRATION OF 3H-METHYL THYMIDINE
3H-methyl thymidine (3HTdR) (specific activity, 2 Ci/mmol; concentration, 1 mCi/ml). Five days after the first topical application, all mice were administered with 250uL of 83.32 uCi/ml 3HTdR (equal to 20.83 uCi 3HTdR) by intravenous injection via a tail vein.

DETERMINATION OF INCORPORATED 3HTDR
Approximately five hours after treatment with 3HTdR all mice were euthanized by intraperitoneal injection of NARCOREN at a dose of at least 2 ml/kg body weight (equivalent to 320 mg sodium pentobarbitone/kg body weight). The draining lymph nodes were rapidly excised and pooled for each experimental group (8 nodes per group). Single cell suspensions (phosphate buffered saline) of pooled lymph node cells were prepared by gentle mechanical disaggregation through stainless steel gauze (200 um mesh size). After washing three times with phosphate buffered saline (approx. 10 ml) the lymph node cells were resuspended in 5 % trichloroacetic acid (approx. 3 ml) and incubated at approximately +4 degrees C overnight for precipitation of macromolecules. The precipitates were then resuspended in 5% trichloroacetic acid (1 ml) and transferred to glass scintillation vials with 10 ml of 'Ultima Gold' scintillation liquid and thoroughly mixed. The level of 3HTdR incorporation was then measured on a beta-scintillation counter. Similarly, background 3HTdR levels were also measured in two 1 ml-aliquots of 5 %trichloroacetic acid. The beta-scintillation counter expresses 3HTdR incorporation as the number of radioactivedisintegrations per minute (DPM).
Positive control substance(s):
mercaptobenzothiazole (CAS No 149-30-4)
Statistics:
The mean values and standard deviations were calculated in the body weight tables. The EC3 value was calculated according to the equation:
EC3 = (a-c) [(3-d)/(b-d)] + c
where EC3 is the estimated concentration of the test item required to produce a 3-fold increase in draining lymph node cell proliferative activity; (a, b) and (c, d) are respectively the co-ordinates of the two pair of data lying immediately above and below the S.l. value of 3 on the local lymph node assay dose response plot.
Positive control results:
2-MERCAPTO-BENZOTHIAZOLE showed an allergenic potency when tested at concentrations of 10 % and 25 %.
Parameter:
SI
Value:
1.7
Test group / Remarks:
5% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
5.3
Test group / Remarks:
10% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
7.5
Test group / Remarks:
25% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
8.7
Test group / Remarks:
50% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
8.8
Test group / Remarks:
75% in acetone/olive oil (4:1 v/v)
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see table 1 below

Table 1. Individual results

Test concentration % Group Measurement dpm   Calculation   Result - S.I.
dpm - BG Number of lymph nodes dpm per lymph node
- BG I 4 - - - -
- BGII 4 - - - -
- CG I 4146 4142 8 518 -
5 TG 2 7028 7024 8 878 1.7
10 TG 3 21816 21812 8 2727 5.3
25 TG 4 31132 31128 8 3891 7.5
50 TG 5 36016 36012 8 4502 8.7
75 TG 6 36335 36331 8 4541 8.8

BG = Background (1 mL 5% trichloroacetic acid) in duplicate

CG = Control Group

TG = Test Group

S.l. = Stimulation Index

EC3 was calculated as 6.8%

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
For the target substance: the expected EC3 is 6.8% and is considered to be weakly sensitising.
Executive summary:

The study was performed on a source substance to GLP and the method followed OECD 429 to assess the skin sensitisation potential of the test material in the CBA/Jibm(SPF) strain mouse following topical application to the dorsal surface of the ear. The test item in the main study was assayed at five consecutive concentrations that were selected by the sponsor. Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 5 %, 10 %, 25 %, 50% and 75% in acetone:olive oil, 4:1 (v/v). The application volume, 25 uL, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). Five days after the first topical application, all mice were administered with 250 uL of 83.32 uCi/ml 3HTdR (equal to 20.83 uCi 3HTdR) by intravenous injection via a tail vein. The mice were observed twice daily and any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded at the start of acclimatisation and prior to necropsy. No irritation or signs of systemic toxicity were observed in the animals examined. Body weights were within the range seen for controls over the study period. Mean DPM/animal values for the experimental groups treated with test substance concentrations 5, 10, 25, 50 and 75% were 7024, 21812, 31128, 36012 and 36331 DPM, respectively. The mean DPM/animal value for the vehicle control group was 4142 DPM. The SI values calculated for the substance concentrations 5, 10, 25, 50 and 75% were 1.7, 5.3, 7.5, 8.7 and 8.8, respectively. Under the conditions of this study the EC3 of the test substance has been calculated as 6.8% and is considered to be weakly sensitising.

The target substance is expected to have an EC3 6.8% and is considered to be weakly sensitising meeting Regulation (EC) 1272/2008: skin sensitising category 1B

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Guideline study performed under GLP. The source and target substances must have an aldehyde group at the 1-carbon position and either a terminal (10-position) or an internal alkene (9-position or 8-position; with the terminal alkyl group no larger than an ethyl group and/or should not multiply substituted). The substance alkyl chain length of the substance should be more than 6 carbons in length and less than 14 carbons in length and fulfil the mono-alkene definition. The substance should not have any branched alkyl groups or side chains. The target and source share common structural elements in the same relative positions. The source and target have very similar physico-chemical properties and thus have similar expected toxicokinetic behaviour. The substances have similar in silico chemical reactivity predictions. This is observed within available in vivo toxicology testing where low level local and systemic toxicity is demonstrated and comparable between target and source. The substances therefore demonstrate chemical similarity. In the skin sensitisation endpoint, the target and source have common protein reactivity alert(s). The target and source therefore have common foreseen mode of action.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
other: CBA/Jibm(SPF)
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: 7 - 12 weeks
- Weight at study initiation: 17.7 - 24.8 g
- Housing: In groups of four in Makrolon type-3 cages with standard softwood bedding
- Diet: standard pellet diet ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/- 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12 h light / 12 h dark

IN-LIFE DATES: 28-AUG-2001 to 12-SEP-2001
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
5, 10, 25, 50 and 75%
No. of animals per dose:
4 females
Details on study design:
TREATMENT PREPARATION AND ADMINISTRATION:
The test item in the main study was assayed at five consecutive concentrations that were selected by the sponsor.

TOPICAL APPLICATION
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 5 %, 10 %, 25 %, 50% and 75% in acetone:olive oil, 4:1 (v/v). The application volume, 25uI, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). A hair dryer was used to dry the ear's surface as quickly as possible to avoid loss of test item applied.

ADMINISTRATION OF 3H-METHYL THYMIDINE
3H-methyl thymidine (3HTdR) (specific activity, 2 Ci/mmol; concentration, 1 mCi/ml). Five days after the first topical application, all mice were administered with 250uL of 83.32 uCi/ml 3HTdR (equal to 20.83 uCi 3HTdR) by intravenous injection via a tail vein.

DETERMINATION OF INCORPORATED 3HTDR
Approximately five hours after treatment with 3HTdR all mice were euthanized by intraperitoneal injection of NARCOREN at a dose of at least 2 ml/kg body weight (equivalent to 320 mg sodium pentobarbitone/kg body weight). The draining lymph nodes were rapidly excised and pooled for each experimental group (8 nodes per group). Single cell suspensions (phosphate buffered saline) of pooled lymph node cells were prepared by gentle mechanical disaggregation through stainless steel gauze (200 um mesh size). After washing three times with phosphate buffered saline (approx. 10 ml) the lymph node cells were resuspended in 5 % trichloroacetic acid (approx. 3 ml) and incubated at approximately +4 degrees C overnight for precipitation of macromolecules. The precipitates were then resuspended in 5% trichloroacetic acid (1 ml) and transferred to glass scintillation vials with 10 ml of 'Ultima Gold' scintillation liquid and thoroughly mixed. The level of 3HTdR incorporation was then measured on a beta-scintillation counter. Similarly, background 3HTdR levels were also measured in two 1 ml-aliquots of 5 %trichloroacetic acid. The beta-scintillation counter expresses 3HTdR incorporation as the number of radioactivedisintegrations per minute (DPM).
Positive control substance(s):
mercaptobenzothiazole (CAS No 149-30-4)
Statistics:
The mean values and standard deviations were calculated in the body weight tables. The EC3 value was calculated according to the equation:
EC3 = (a-c) [(3-d)/(b-d)] + c
where EC3 is the estimated concentration of the test item required to produce a 3-fold increase in draining lymph node cell proliferative activity; (a, b) and (c, d) are respectively the co-ordinates of the two pair of data lying immediately above and below the S.l. value of 3 on the local lymph node assay dose response plot.
Positive control results:
2-MERCAPTO-BENZOTHIAZOLE showed an allergenic potency when tested at concentrations of 10 % and 25 %.
Parameter:
SI
Value:
1.7
Test group / Remarks:
5% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
5.3
Test group / Remarks:
10% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
7.5
Test group / Remarks:
25% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
8.7
Test group / Remarks:
50% in acetone/olive oil (4:1 v/v)
Parameter:
SI
Value:
8.8
Test group / Remarks:
75% in acetone/olive oil (4:1 v/v)
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see table 1 below

Table 1. Individual results

Test concentration % Group Measurement dpm   Calculation   Result - S.I.
dpm - BG Number of lymph nodes dpm per lymph node
- BG I 4 - - - -
- BGII 4 - - - -
- CG I 4146 4142 8 518 -
5 TG 2 7028 7024 8 878 1.7
10 TG 3 21816 21812 8 2727 5.3
25 TG 4 31132 31128 8 3891 7.5
50 TG 5 36016 36012 8 4502 8.7
75 TG 6 36335 36331 8 4541 8.8

BG = Background (1 mL 5% trichloroacetic acid) in duplicate

CG = Control Group

TG = Test Group

S.l. = Stimulation Index

EC3 was calculated as 6.8%

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of this study, the EC3 of the item has been calculated as 6.8% and is considered to be weakly sensitising.
Executive summary:

The study was performed to GLP and the method followed OECD 429 to assess the skin sensitisation potential of the test material in the CBA/Jibm(SPF) strain mouse following topical application to the dorsal surface of the ear. The test item in the main study was assayed at five consecutive concentrations that were selected by the sponsor. Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 5 %, 10 %, 25 %, 50% and 75% in acetone:olive oil, 4:1 (v/v). The application volume, 25 uL, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). Five days after the first topical application, all mice were administered with 250 uL of 83.32 uCi/ml 3HTdR (equal to 20.83 uCi 3HTdR) by intravenous injection via a tail vein. The mice were observed twice daily and any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded at the start of acclimatisation and prior to necropsy. No irritation or signs of systemic toxicity were observed in the animals examined. Body weights were within the range seen for controls over the study period. Mean DPM/animal values for the experimental groups treated with test substance concentrations 5, 10, 25, 50 and 75% were 7024, 21812, 31128, 36012 and 36331 DPM, respectively. The mean DPM/animal value for the vehicle control group was 4142 DPM. The SI values calculated for the substance concentrations 5, 10, 25, 50 and 75% were 1.7, 5.3, 7.5, 8.7 and 8.8, respectively. Under the conditions of this study the EC3 of the test substance has been calculated as 6.8% and is considered to be weakly sensitising.

Endpoint:
skin sensitisation: in vitro
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
an in vitro skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
In accordance with REACH Regulation (EC) 1907/2006 as amended: Annex VII, section 8.3: the in chemico or in vitro / ex vivo study does not need to be conducted based on existing data sufficient for classification and labelling being already available based on REACH Annex XI: Section 1.5 – grouping of substances and read-across approach. According to ECHA Guidance on Information Requirements and Chemical Safety Assessment (Chapter R.7a: Endpoint Specific Guidance, R.7.3, July 2017) the study does not need to be conducted.
Reason / purpose:
data waiving: supporting information
Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Key study: OECD TG 429 - LLNA, 2001 : Read-Across SOURCE (undec-10 -enal): The study was performed to GLP and the method followed OECD 429 to assess the skin sensitisation potential of the test material in the CBA/Jibm(SPF) strain mouse following topical application to the dorsal surface of the ear. The test item in the main study was assayed at five consecutive concentrations that were selected by the sponsor. Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 5 %, 10 %, 25 %, 50% and 75% in acetone:olive oil, 4:1 (v/v). The application volume, 25 uL, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals). Five days after the first topical application, all mice were administered with 250 uL of 83.32 uCi/ml 3HTdR (equal to 20.83 uCi 3HTdR) by intravenous injection via a tail vein. The mice were observed twice daily and any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded at the start of acclimatisation and prior to necropsy.No irritation or signs of systemic toxicity were observed in the animals examined. Body weights were within the range seen for controls over the study period. Mean DPM/animal values for the experimental groups treated with test substance concentrations 5, 10, 25, 50 and 75% were 7024, 21812, 31128, 36012 and 36331 DPM, respectively. The mean DPM/animal value for the vehicle control group was 4142 DPM. The SI values calculated for the substance concentrations 5, 10, 25, 50 and 75% were 1.7, 5.3, 7.5, 8.7 and 8.8, respectively. Under the conditions of this study the EC3 of the test substance has been calculated as 6.8% and is considered to be weakly sensitising. These results indicate that the test substance could elicit a SI ≥ 3. Under the conditions of this study, the test substance would be considered to be classified as skin sensitizer (Category 1B) under Regulation (EC) No 1272/2008.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The substance meets classification criteria under Regulation (EC) No 1272/2008 for skin sensitisation category 1B: H317

 

The weight of evidence indicates that the substance has the potential for a low frequency of sensitisation occurrence in humans and/or low to moderate potency in animals (EC3 >2%) and can be presumed to have the potential to produce sensitisation in humans via the dermal route.