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Diss Factsheets

Administrative data

Description of key information

Several studies and assessment reports from competent authorities are available for the skin sensitising properties of alpha-pinene, beta-pinene and limonene.

As a result from these studies all of these substance were identified as inducing skin sensitisation.

Even if the DPRA study of Terpene Dimers shows negative results, this information is not sufficient enought to dissipate the doubts. That´s why we follow the worts-case approach and classify the substance as skin senstitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
data from publication
Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
weight: 300-350 g
temperature: 25 oC
humidity: 50-70%
Route:
intradermal
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
7 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
14 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
0.8%
Day(s)/duration:
1 day
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
6
Details on study design:
For induction, 6 intradermal injections of 0.1 ml of compound and Freund's adjuvant were administered in the shaved scapular region. After 7 d, an occluded patch of 0.15 ml of compound was placed on the injection site for 48 h. In the control guinea pigs, the compound was replaced by the solvent. After 14 d, all the guinea pigs (including controls) were exposed to a challenge dose on the shaved flank for 24 h. Skin reactions were observed and scored.
Positive control substance(s):
no
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.8%
No. with + reactions:
0
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
not measured/tested
Interpretation of results:
GHS criteria not met
Conclusions:
In a Guinea-Pig Maximisation Test alpha-pinene was tested for its skin sensitising properties in female Hartley guinea pigs. None of the tested animals showed a positive response after challenge exposure. Therefore it can be concluded that alpha-pinene was not identified as a skin sensitizer in the Guinea-Pig Maximisation Test .
Executive summary:

In a Guinea-Pig Maximisation Test alpha-pinene was tested in female Hartley guinea pigs. None of the tested animals showed a positive response after challenge exposure. Therefore it can be concluded that alpha-pinene was not identified as a skin sensitizer in the Guinea-Pig Maximisation Test .

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA:J
Sex:
female
Details on test animals and environmental conditions:
age: 8-12 weeks
temperature: 25oC
humidity: 50-70%
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0,1, 25, 100%
No. of animals per dose:
4
Details on study design:
Groups of mice (4 for each group) received topical administration of 25 µl of various concentrations of the test chemicals on the dorsum of both ears, or the same volume of the relevant vehicle alone, daily for 3 consecutive days. Five days after initiation of exposure, all mice were injected via the tail vein with 250 µl phosphate-buffered saline (PBS) containing 20 µCi [3H] methyl thymidine. Five hours later, the mice were sacrificed and the draining auricular lymph nodes excised and pooled for each experimental group.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Positive control results:
HCA: EC3: 10.86%
Key result
Parameter:
SI
Value:
1
Test group / Remarks:
control
Key result
Parameter:
SI
Value:
1.03
Test group / Remarks:
1%
Key result
Parameter:
SI
Value:
1.65
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
2.59
Test group / Remarks:
100%
Interpretation of results:
GHS criteria not met
Conclusions:
α-pinene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance failed in all tested concentrations to induce a positive response. Even at the higest test concentration of 100 % a SI of 2.59 was estimated. Therefore it can be concluded that α-pinene did not induce an allergic reaction in the described LLNA-test.
Executive summary:

α-pinene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance failed in all tested concentrations to induce a positive response. Even at the higest test concentration of 100 % a SI of 2.59 was estimated. Therefore it can be concluded that α-pinene did not induce an allergic reaction in the described LLNA-test.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Assessment report from a highly reputed government agency.
Qualifier:
no guideline followed
GLP compliance:
no
Type of study:
other: review of data
Species:
mouse
Strain:
CBA:J
Sex:
not specified
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
1,25, 100%
No. of animals per dose:
1
Key result
Parameter:
SI
Value:
1.89
Test group / Remarks:
1%
Key result
Parameter:
SI
Value:
1.82
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
2.55
Test group / Remarks:
100%
Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Executive summary:

Citation from assessment report:

"Based on the available human data, the chemicals are considered to be skin sensitisers warranting hazard classification.

A popliteal lymph node (PLN) assay was conducted to assess the sensitisation potential of (–)-alpha-pinene. Female Wistar rats were treated by subcutaneous injection with 50 µL of (–)-alpha-pinene (0.5, 2.5 or 5 mg) into the right hind footpad while the contralateral footpad was injected with the vehicle (DMSO) alone. Weight and cellularity indices (WI and CI) for draining PLNs were determined 7 days after treatment. The chemical was positive (WI>2 and CI≤5) under these test conditions. In a secondary PLN assay (T-cell priming test), animals whose immune systems had been primed to the chemical (5 mg), were re-administered the chemical via subcutaneous injection (0.5 mg). Assessment of WI and CI were conducted 5 and 7 days following the second injection. The chemical was negative in the second test. The chemical induced a clear immuno-stimulatory response due to its irritant properties but it was not considered to be a sensitising agent (Friedrich et al., 2007).

The chemical alpha-pinene was assessed for its potential to produce skin sensitisation in a guinea pig maximisation test (GPMT). Female Hartley guinea pigs (6/dose group) were induced with 0.1 mL of the chemical at 4 % (in acetone: olive oil (v/v 4:1)). After 7 days, an occluded patch was applied to the shaved skin with 0.15 mL of the chemical. After 14 days, animals were exposed to a challenge dose (0.8 %) in the same vehicle as the induction dose. The chemical was negative for sensitisation under these test conditions (Wei et al., 2006).

A study was conducted to assess the sensitisation potential of the components of the Myoga (Zingiber Myoga Roscoe) plant, one of which is alpha-pinene. In a Local Lymph Node Assay (LLNA), alpha-pinene was topically-administered to the dorsum of both ears of 4 CBN/J mice. The chemical was applied at concentrations of 0, 1, 25 and 100 %. No EC3 value (the estimated concentration needed to produce a 3-fold increase in lymphocyte proliferation) could be determined up to 100 %, indicating that it was not a skin sensitiser under these test conditions (Wei et al., 2010).

The Quantitative Structure–Activity Relationship (QSAR) modelling for skin sensitisation using the OECD QSAR Toolbox (version 3.4) indicated that there were protein binding alerts for the predicted auto-oxidation metabolic products of alpha-pinene.

The chemical alpha-pinene is predicted to be a skin sensitiser using the VEGA skin sensitisation model (CAESAR). The chemical falls within the applicability domain of the model.

The chemical (–)- alpha-pinene is predicted to be a moderate skin sensitiser (predicted LLNA EC3%: 9.6) using Derek Nexus v5.0.2. The prediction is based on the triggered structured alert for terpenoids. The prediction strength is 'equivocal' (REACHb).

In the EU, the ECHA Guidance on the Application of the CLP Criteria (2013), the decision logic was used to determine the skin sensitising potential of alpha-pinene multiconstituent.

The chemicals (–)-beta-pinene and alpha-pinene are structurally-similar (both are bicyclic monounsaturated terpenes and are positional isomers). They also share very similar physico-chemical properties. (-)-beta-pinene has been classified as a Category1B skin sensitiser (based on an EC3 value of 29 %, obtained in a Local Lymph Node Assay) and is present in alpha-pinene multiconstituent above the generic concentration limit of 1 % for classification as skin sensitiser (REACHa).

It is expected that alpha-pinene multiconstituent will have the same weak potential for skin sensitisation. This, coupled with the available data, suggest classification of alpha-pinene for sensitisation is warranted.

Turpentine oil (CAS No. 8006-64-2), of which alpha-pinene is the primary constituent, is classified as hazardous with hazard category ‘Skin sensitisation – category 1’ and hazard statement ‘May cause an allergic skin reaction' (H317) in the Hazardous Chemical Information System (HCIS) (Safe Work Australia). Data for the mixture (including a positive Guinea Pig Maximisation test) support this classification (NICNASa)."

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
data from publication
Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
weight: 300-350 g
temperature: 25 oC
humidity: 50-70%
Route:
intradermal
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
7 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
14 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
0.8%
Day(s)/duration:
1 day
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
6
Details on study design:
For induction, 6 intradermal injections of 0.1 ml of compound and Freund's adjuvant were administered in the shaved scapular region. After 7 d, an occluded patch of 0.15 ml of compound was placed on the injection site for 48 h. In the control guinea pigs, the compound was replaced by the solvent. After 14 d, all the guinea pigs (including controls) were exposed to a challenge dose on the shaved flank for 24 h. Skin reactions were observed and scored.
Positive control substance(s):
no
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.8%
No. with + reactions:
0
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
not measured/tested
Interpretation of results:
GHS criteria not met
Conclusions:
In a Guinea-Pig Maximisation Test beta-pinene was tested for its skin sensitising properties in female Hartley guinea pigs. None of the tested animals showed a positive response after challenge exposure. Therefore it can be concluded that beta-pinene was not identified as a skin sensitizer in the Guinea-Pig Maximisation Test .
Executive summary:

In a Guinea-Pig Maximisation Test beta-pinene was tested in female Hartley guinea pigs. None of the tested animals showed a positive response after challenge exposure. Therefore it can be concluded that beta-pinene was not identified as a skin sensitizer in the Guinea-Pig Maximisation Test .

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA:J
Sex:
female
Details on test animals and environmental conditions:
age: 8-12 weeks
temperature: 25oC
humidity: 50-70%
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0,1, 25, 100%
No. of animals per dose:
4
Details on study design:
Groups of mice (4 for each group) received topical administration of 25 µl of various concentrations of the test chemicals on the dorsum of both ears, or the same volume of the relevant vehicle alone, daily for 3 consecutive days. Five days after initiation of exposure, all mice were injected via the tail vein with 250 µl phosphate-buffered saline (PBS) containing 20 µCi [3H] methyl thymidine. Five hours later, the mice were sacrificed and the draining auricular lymph nodes excised and pooled for each experimental group.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Positive control results:
HCA: EC3: 10.86%
Key result
Parameter:
SI
Value:
1
Test group / Remarks:
control
Key result
Parameter:
SI
Value:
1.89
Test group / Remarks:
1%
Key result
Parameter:
SI
Value:
1.82
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
2.55
Test group / Remarks:
100%
Interpretation of results:
GHS criteria not met
Conclusions:
β-pinene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance failed in all tested concentrations to induce a positive response. Even at the higest test concentration of 100 % a SI of 2.55 was estimated. Therefore it can be concluded that β-pinene did not induce an allergic reaction in the described LLNA-test.
Executive summary:

β-pinene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance failed in all tested concentrations to induce a positive response. Even at the higest test concentration of 100 % a SI of 2.55 was estimated. Therefore it can be concluded that β-pinene did not induce an allergic reaction in the described LLNA-test.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Assessment report from a highly reputed government agency.
Qualifier:
no guideline followed
GLP compliance:
no
Type of study:
other: review of data
Species:
mouse
Strain:
CBA:J
Sex:
female
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
5, 10, 25, 50, 100%
No. of animals per dose:
5
Key result
Parameter:
SI
Value:
2.29
Test group / Remarks:
5%
Key result
Parameter:
SI
Value:
1.16
Test group / Remarks:
10%
Key result
Parameter:
SI
Value:
2.23
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
7.17
Test group / Remarks:
50%
Key result
Parameter:
SI
Value:
14.7
Test group / Remarks:
100%
Key result
Parameter:
EC3
Value:
29
Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Executive summary:

Citation from assessment report:

"Based on the weight of evidence from the available animal, human and in silico data, the chemicals are skin sensitisers and warrant hazard classification.

Hydroperoxide species originating from auto-oxidation are thought to be the major contributors.

In a local lymph node assay (LLNA) performed in accordance with OECD TG 429, female CBA/J mice (5/dose) received topical applications of 5.0, 10, 25, 50 or 100 % (v/v) beta-pinene in acetone/olive oil on three consecutive days. The reported stimulation indices (SI) were 2.29, 1.16, 2.23, 7.17, 6.47 and 14.7 for concentrations of 5.0, 10, 25, 50 and 100 % respectively. The reported concentration producing a three-fold increase in lymphocyte proliferation (EC3) was 29 %, indicating weak sensitisation potential (REACH).

In a non-guideline LLNA, CBN/J (1/dose) mice received topical applications of 1, 25 and 100 % of the beta-pinene in acetone/olive oil on three consecutive days. The reported stimulation indices (SI) were 1.89, 1.82 and 2.55 for the concentrations 1, 25 and 100 %, respectively. As all SI values were below 3, an EC3 value could not be determined and the chemical was; therefore; considered a non-sensitiser (Wei et al., 2010).

No structural alerts for skin sensitisation were present for beta-pinenes (OECD QSAR Toolbox v3.4). However, when auto-oxidation was simulated, mechanistic alerts, including alerts for protein binding via nucleophilic addition and free radical formation were present for the metabolites.

In domain skin sensitisation predictions for beta-pinenes using OASIS–TIMES 2.27.19 were negative for the unmetabolised chemicals. Several auto-oxidised metabolites of beta-pinene were predicted to be weak sensitisers which were supported by mechanistic alerts for hydroperoxide free radical decomposition and Michael type addition on conjugated systems with electron withdrawing groups."

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
data from publication
Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
weight: 300-350 g
temperature: 25 oC
humidity: 50-70%
Route:
intradermal
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
7 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
4%
Day(s)/duration:
14 days
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
0.8%
Day(s)/duration:
1 day
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
6
Details on study design:
For induction, 6 intradermal injections of 0.1 ml of compound and Freund's adjuvant were administered in the shaved scapular region. After 7 d, an occluded patch of 0.15 ml of compound was placed on the injection site for 48 h. In the control guinea pigs, the compound was replaced by the solvent. After 14 d, all the guinea pigs (including controls) were exposed to a challenge dose on the shaved flank for 24 h. Skin reactions were observed and scored.
Positive control substance(s):
no
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.8%
No. with + reactions:
2
Total no. in group:
6
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
not measured/tested
Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
In a Guinea-Pig Maximisation Test R-(+)-limonene was tested for its skin sensitising properties in female Hartley guinea pigs. 2 of the 6 tested animals showed a positive response after challenge exposure. Therefore it can be concluded that R-(+)-limonene was identified as a skin sensitizer in the Guinea-Pig Maximisation Test .
Executive summary:

In a Guinea-Pig Maximisation Test R-(+)-limonene was tested in female Hartley guinea pigs. Two of the six tested animals showed a positive response after challenge exposure. Therefore it can be concluded that R-(+)-limonene was identified as a skin sensitizer in the Guinea-Pig Maximisation Test .

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
not specified
Remarks:
publication
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA:J
Sex:
female
Details on test animals and environmental conditions:
age: 8-12 weeks
temperature: 25oC
humidity: 50-70%
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0,1, 25, 100%
No. of animals per dose:
4
Details on study design:
Groups of mice (4 for each group) received topical administration of 25 µl of various concentrations of the test chemicals on the dorsum of both ears, or the same volume of the relevant vehicle alone, daily for 3 consecutive days. Five days after initiation of exposure, all mice were injected via the tail vein with 250 µl phosphate-buffered saline (PBS) containing 20 µCi [3H] methyl thymidine. Five hours later, the mice were sacrificed and the draining auricular lymph nodes excised and pooled for each experimental group.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Positive control results:
HCA: EC3: 10.86%
Key result
Parameter:
SI
Value:
1
Test group / Remarks:
control
Key result
Parameter:
SI
Value:
1.6
Test group / Remarks:
1%
Key result
Parameter:
SI
Value:
2.31
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
7.09
Test group / Remarks:
100%
Key result
Parameter:
EC3
Value:
35.8
Interpretation of results:
GHS criteria not met
Conclusions:
Limonene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance induced a positive response and the EC3 value was 35.8%.
Therefore it can be concluded that limonen induced an allergic reaction in the described LLNA-test.
Executive summary:

Limonene was assessed in the local lymph note assay (LLNA) for its skin sensitising properties in CBA/J female mice. The substance induced a positive response and the EC3 value was 35.8%.

Therefore it can be concluded that limonen induced an allergic reaction in the described LLNA-test.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Assessment report from a highly reputed government agency.
Qualifier:
no guideline followed
GLP compliance:
no
Key result
Parameter:
SI
Remarks on result:
other: Assessment report from competent authority, results are only summarised.
Interpretation of results:
GHS criteria not met
Executive summary:

Citation from assessment report:

"Although d‑limonene was once considered the main allergen in citrus fruits, data from more recent studies in animals have revealed air‑oxidizedd‑limonene,rather than unoxidized d‑limonene,to be the sensitising agent. When limonene (unspecified form and unknown purity of the testmaterial) was tested in four different sensitisation assays with guinea‑pigs (Open Epicutaneous Test,Maximization Test, Draize's Test, and a test with Freund's Complete Adjuvant),it was sensitising in all but Draize's Test*(Klecak et al., 1977). In another study in mice,d‑limonene did not induce sensitisation*(Maisey & Miller, 1986). Hydro­peroxides and other oxidation products of d-limonene formed on exposure to the air have proved to be potent contact allergens when tested with Freund's Complete Adjuvant in guinea‑pigs, whereas unoxidized d-limonene did not cause any sensitisation(Karlberg et al., 1991;Karlberg et al., 1992).

It has been suggested that limonene has a quenching effect (inhibition of the sensitising capacity of another substance) on the induction of skin sensitisation to citral. No effect was found in trials on guinea pigs or in the murine local lymph node assay (LLNA)(European Union, 2000)."

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH


1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Terpene dimers is primarily a mixture of terpene dimer with no more than trace quantities of unreacted monomer. The raw materials (monoterpene) react by cationic polymerisation.

Raw materials:
(R)-p-mentha-1,8-diene (D-limonene): EC: 227-813-5; ratio: 1 ~ 50
Pin-2(3)-ene (racemic mixture) (alpha-pinene); EC: 201-291-9; ratio: 15 ~ 45
(-)-pin-2(10)-ene (beta-pinene); EC: 242-060-2; ratio: 1 ~ 50

The reaction products terpene dimers are dimeric species of reactants covalently coupled twice. In other words, these species are structurally similar, i.e. they contain the same repeating reactant. It however has to be kept in mind that most of physical and chemical properties are altered significantly as a result of this increase in molecular weight going from the reactant to dimeric species. For example, the vapour pressure is very significantly reduced.

2. ANALOGUE APPROACH JUSTIFICATION
Overall, it can be assumed that the change in physical properties from starting materials to dimeric reaction products, results in a substance with significantly reduced hazardous properties.
Therefore read-across from the starting materials to terpene dimers is fully justified.
Although alpha- and beta-pinene are not classified for skin sensitisation, as a worst case assumption, the substance terpene dimers will be classified as skin sensitiser as the starting material D-limonene is classified for skin sensitisation.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Reliable safety assessment of the World Health Organization.
GLP compliance:
no
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Published data
Species:
guinea pig
Strain:
not specified
Sex:
not specified
Key result
Reading:
other: not stated
Group:
test chemical
Dose level:
not stated
Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
When limonene (unspecified form and unknown purity of the test material) was tested in four different sensitization assays with guinea-pigs (Open
Epicutaneous Test, Maximization Test, Draize’s Test, and a test with Freund’s Complete Adjuvant), it was sensitizing in all but Draize’s Test.
Executive summary:

When limonene (unspecified form and unknown purity of the test material) was tested in four different sensitization assays with guinea-pigs (Open

Epicutaneous Test, Maximization Test, Draize’s Test, and a test with Freund’s Complete Adjuvant), it was sensitizing in all but Draize’s Test.

Overall, it can be assumed that the change in physical properties from starting materials to dimeric reaction products, results in a substance with significantly reduced hazardous properties.

Therefore read-across from the starting materials to terpene dimers is fully justified.

Although alpha- and beta-pinene are not classified for skin sensitisation, as a worst case assumption, the substance terpene dimers will be classified as skin sensitiser as the starting material D-limonene is classified for skin sensitisation.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Terpene dimers is primarily a mixture of terpene dimer with no more than trace quantities of unreacted monomer. The raw materials alpha-pinene, beta-pinene and limonene react by cationic polymerisation.

The raw materials are:

(R)-p-mentha-1,8-diene (D-limonene): EC: 227-813-5; ratio: 1 ~ 50

Pin-2(3)-ene (racemic mixture) (alpha-pinene); EC: 201-291-9; ratio: 15 ~ 45

(-)-pin-2(10)-ene (beta-pinene); EC: 242-060-2; ratio: 1 ~ 50

The reaction products terpene dimers are dimeric species of reactants covalently coupled twice. In other words, these species are structurally similar, i.e. they contain the same repeating reactant.

Based on the read across assumption of structural similarity the substance terpene dimers is regarded as skin sensitising substance.

As the starting materials are all classified as skin sensitising substances, the substance terpene dimers will be classified as skin sensitiser too. This can be regarded as a worst case assumption.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

According to the CLP Regulation (EU GHS Regulation (EC) No 1272/2008) classification and labelling is required for skin sensitisation of terpene dimers, based on reliable data from the read across source substances alpha-pinene, beta-pinene and limonene.

As the starting materials for terpene dimers are all classified as skin sensitising substances, the substance terpene dimers will be classified as skin sensitiser too.

Even if the DPRA study of Terpene Dimers shows negative results, this information is not sufficient enought to dissipate the doubts. That´s why we follow the worts-case approach and classify the substance as skin senstitiser.