Hexamethylene diacrylate

Endpoint summary

Description of key information

skin sensitizing (no GLP guideline studies exist and all publication deviate from standard procedures)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

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 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

additional intradermal challenge to boost reactions, simultaneous challenge with several acrylates and methacrylates, potential repetition of induction procedure - deviations likely increased the number of positive reactions

Principles of method if other than guideline:

The guinea pig maximization (GPM)-test was performed in accordance with the original description by Magnusson and Kligman (J Invest Dermatol 1969: 52: 268-276 and Magnusson B, Kligman AM. Allergic contact dermatitis in the guinea pig. Identification of contact allergens. Springfield III: CC Thomas Publisher, 1970).

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Older study available

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 300-400 g

Route:

intradermal and epicutaneous

Vehicle:

other: Induction: Mixture of olive oil and acetone (9:1); Challenge: Petrolatum

Concentration / amount:

Pretest:
The concentrations used for the pretest are not reported.

Main Test:
Intradermal induction: 1 % (w/w) test substance in olive oil/acetone (9:1)
Epicutaneous induction: 25 % in petrolatum
Intradermal Challenge: 1 % (w/w) in petrolatum
Epicutaneous Challenge: 0.2 % (w/w) in petrolatum

Route:

intradermal and epicutaneous

Vehicle:

other: Induction: Mixture of olive oil and acetone (9:1); Challenge: Petrolatum

Concentration / amount:

Pretest:
The concentrations used for the pretest are not reported.

Main Test:
Intradermal induction: 1 % (w/w) test substance in olive oil/acetone (9:1)
Epicutaneous induction: 25 % in petrolatum
Intradermal Challenge: 1 % (w/w) in petrolatum
Epicutaneous Challenge: 0.2 % (w/w) in petrolatum

No. of animals per dose:

30 animals: 15 animals in the test group and 15 animals in the control group

Details on study design:

PRETEST:
3 animals were used to evaluate the optimal concentration for intradermal and topical induction. The animals were not subsequently used in the sensitization experiments. No further data were given.

MAIN STUDY:
The details of the test design were as described in Björkner et al. 1984 (Contact Dermatitis, Vol 10: 286-304) and can be summarized as follows:
INDUCTION EXPOSURE
Intradermal application:
- No. of exposures: 3 pairs of injections are made simultaneously (2x 50 µl of Freund´s Complete Adjuvant (FCA) alone, 2x 50 µl of test substance alone and 2x 50 µl of the test agent emulsified in the adjuvant).
- Test groups: 15 animals
- Control group: 15 animals. The control animals were sensitized in the same way as the experimental group but without the test material.
- Site: Shoulder region
- Frequency of applications: One time

Epicutaneous application:
- Time of application: 1 week after the injections
- Exposure period: 48 hours
- Test groups: 15 animals
- Control group: 15 animals
- Site: Shoulder region; the same area which was used for injections
- Frequency of applications: One time

CHALLENGE EXPOSURE
- Two challenges were conducted.
- The amount of test material was approximately 0.015 g.
- The first challenge using 6 different (meth) acrylates including HDDA was 2 weeks after the epicutaneous induction.
- 48 h later, the animals additionally received a booster dose of HDDA intradermally in the same concentration and vehicle as used for the intradermal induction, but without FCA.
- The second challenge was one week after the first challenge and also consisted of 6 different (meth)acrylates: HDDA and 5 new substances (different from challenge 1)
- Control group: 15 animals. When the sensitized animals were challenged, the control animals were also patch-tested with the same chemicals and the same concentrations. As a booster dose, the control animals received olive oil intradermally.
- Site: clipped, shaved flank of the animal.
- Evaluation (hr after challenge): 24 hours after removal of the patch.

REMARK:
- If no animals or just a few showed positive reactions, the GPM test procedure was repeated once more.
- In all animals, challenge with hydroquinone (0.1 % w/w in alcohol), which is a possible additive in acrylate products, was performed. The authors reported that challenge with hydroquinone gave no response in any tested animal.

Positive control substance(s):

no

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

0.2 % (w/w) in petrolatum

No. with + reactions:

9

Total no. in group:

15

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 0.2 % (w/w) in petrolatum. No with. + reactions: 9.0. Total no. in groups: 15.0.

Reading:

rechallenge

Hours after challenge:

48

Group:

negative control

Dose level:

0.2 % (w/w) in petrolatum

No. with + reactions:

0

Total no. in group:

15

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 48.0. Group: negative control. Dose level: 0.2 % (w/w) in petrolatum. No with. + reactions: 0.0. Total no. in groups: 15.0.

Group:

positive control

Remarks on result:

not measured/tested

Cross reactivity for 1,6 -Hexandioldiacrylate was checked by challenge reactions with 1,4 -butandioldiacrylate (BUDA), diethyleneglycoldiacrylate (DEGDA), tetraethyleneglycoldiacrylate (TEGDA), tripropyleneglycoldiacrylate (TPGDA), neopentylglycoldiacrylate (NPGDA).

Positive reaction was seen with BUDA (1/15), DEGDA (4/15) and TEGDA (4/15).

Interpretation of results:

sensitising

Reference 2

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The optimization test was used, according to the method by Maurer et al. (Agents and Actions, Vol 5 (2): 174-179, 1975). The method describes an intracutaneous sensitization procedure similar to the method recommended in the "Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics" (1959), the US Association of Food and Drug Officials (AFDO).

GLP compliance:

no

Remarks:

; GLP was not compulsory at the time the study was conducted

Type of study:

other: optimization test

Justification for non-LLNA method:

Older study available

Species:

guinea pig

Strain:

Pirbright-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Breeding at Ciba Geigy Ltd, Basel, Switzerland
- Weight at study initiation: 400-450 g
- Housing: individually in Macrolon cages, type 3
- Diet: standard guinea pig pellets, NAFAG, No. 830, Gossau SG, ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +- 1°C
- Humidity (%): 55 +- 5 %
- Photoperiod (hrs dark / hrs light): 14/10

Route:

intradermal

Vehicle:

propylene glycol

Concentration / amount:

Induction:
10 injections of each 0.1 ml every second day (except weekends) of a freshly prepared 0.1 % dilution of test material were made.
In the first week of induction only the test material dissolved in vehicle was injected. In the second and third week the test material was incorporated in a mixture of the normal vehicle with complete Freund Adjuvant (1:1). The control animals were dosed with the vehicle control, propylene glycol, only.
Challenge:
1st challenge: 14 days after the last induction 0.1 ml of a 0.1 % dilution of the test material in propylene glycol was administered intracutaneously into the left flank.
2nd challenge: 10 days after the first challenge, a subirritant dose of the test compound (0.1 % in vaseline) was applied epicutaneously under occlusive conditions for 24 hours.

Route:

intradermal and epicutaneous

Vehicle:

propylene glycol

Concentration / amount:

Induction:
10 injections of each 0.1 ml every second day (except weekends) of a freshly prepared 0.1 % dilution of test material were made.
In the first week of induction only the test material dissolved in vehicle was injected. In the second and third week the test material was incorporated in a mixture of the normal vehicle with complete Freund Adjuvant (1:1). The control animals were dosed with the vehicle control, propylene glycol, only.
Challenge:
1st challenge: 14 days after the last induction 0.1 ml of a 0.1 % dilution of the test material in propylene glycol was administered intracutaneously into the left flank.
2nd challenge: 10 days after the first challenge, a subirritant dose of the test compound (0.1 % in vaseline) was applied epicutaneously under occlusive conditions for 24 hours.

No. of animals per dose:

20 animals (10 males and 10 females) in the treated group
20 animals (10 males and 10 females) in the control group

Details on study design:

On the first day of induction, injections were administered into the shaven skin of the right flank and the back, in the following days a single intracutaneous injection was given into the back.
24 h after each injection during the first week of the induction period and 24 h after each challenge injection the reactions were recorded.

The two largest perpendicular diameters and the increase in the skin-fold thickness (both in mm) were measured and by multiplication of these values the "reaction volume" (in µl) was obtained for each reading from each animal. The mean volume plus one standard deviation of the induction reactions observed in the individual animal in the first week was taken as representing the skin irritation "threshold" for each animal. Any challenge reaction greater than this threshold value in the induction period was graded as an allergic reaction and the animal was termed "positive". The number of "positive" animals in the test group was compared with the number of animals in the control group (treated with vehicle alone) that showed a non-specific reaction of at least the same magnitude. The exact Fisher test of the basic probability of two binominal distributions was used. A probability of >0.01 was considered to indicate a significant difference.

The challenge reactions after occlusive, epicutaneous administration of the test material were evaluated using Erythema scores (according to the method of Draize) 24 h after removal of the dressing.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1 % in propylene glycol

No. with + reactions:

20

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.1 % in propylene glycol. No with. + reactions: 20.0. Total no. in groups: 20.0.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0.1 %

No. with + reactions:

2

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0.1 %. No with. + reactions: 2.0. Total no. in groups: 20.0.

Reading:

rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1 % in vaseline

No. with + reactions:

20

Total no. in group:

20

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 0.1 % in vaseline. No with. + reactions: 20.0. Total no. in groups: 20.0.

Reading:

rechallenge

Hours after challenge:

24

Group:

negative control

Dose level:

0.1 %

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 24.0. Group: negative control. Dose level: 0.1 %. No with. + reactions: 0.0. Total no. in groups: 20.0.

Group:

positive control

Remarks on result:

not measured/tested

Table 1: Reaction volumes [µl] after first challenge of the test substance or vehicle intradermally and Erythema scores (according to Draize) after 2nd challenge of the test substance (epicutaneous administration)

	1st challenge: reaction volumes after intradermal injection of vehicle (propylene glycol) [µl]		1st challenge: reaction volumes after intradermal injection of 0.1 % test substance [µl]		2nd challenge: reaction after occlusive epicutaneous administration of the test material
animal number	reaction volume (mean value of 4 applications) [µl]	reaction volume after skin sensitization [µl]	reaction volume (mean value of 4 applications) [µl]	reaction volume after skin sensitization [µl]	Erythema score (according to Draize) 24 h after removal of the dressing
male, 1	63 ± 30	36	151 ± 26	292	2
2	105 ± 25	77	156 ± 31	570	2
3	114 ± 30	110	175 ± 34	600	2
4	109 ± 62	0	144 ± 9	336	1
5	102 ± 31	28	96 ± 47	374	2
6	108 ± 26	132	186 ± 46	459	3
7	118 ± 38	143	170 ± 61	337	2
8	186 ± 54	0.6	147 ± 22	405	2
9	126 ± 72	252	129 ± 47	180	1
10	176 ± 109	120	130 ± 22	441	2
female, 11	156 ± 31	143	155 ± 7	583	2
12	128 ± 39	63	167 ± 32	254	2
13	125 ± 40	143	139 ± 36	372	2
14	87 ± 36	44	128 ± 34	392	4
15	128 ± 34	143	119 ± 16	294	3
16	141 ± 33	0.1	154 ± 15	441	3
17	186 ± 38	29	168 ± 22	585	3
18	173 ± 21	247	122 ± 29	331	2
19	131 ± 21	99	153 ± 21	462	2
20	123 ± 24	90	128 ± 50	333	3

Interpretation of results:

sensitising

Reference 3

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

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 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

simultaneous challenge with several acrylates and one isocyanate, use of 10%SDS prior to epicutaneous induction despite irritant properties of the test substance

Principles of method if other than guideline:

The guinea pig maximization (GPMT) test was performed as described by Magnusson and Kligman (Allergic contact dermatitis in the guinea pig. Identification of contact allergens. Springfield III: CC Thomas Publisher, 1970).

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Older study available

Species:

guinea pig

Strain:

other: SSc:AL

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Statens Seruminstitut, Copenhagen, Denmark
- Age at study initiation: approximately 1 month
- Weight at study initiation: 300-350 g
- Housing: 4 animals per cage in a room reserved for guinea pigs used in sensitization tests
- Diet: Hvidesten Marsvinepiller 69, pelleted diet (C.J. Boserup AS, Faxe, Denmark), ad libitum
- Water: ad libitum; water was supplemented with 1 g/l ascorbic acid.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 °C +- 2
- Humidity (%): 60 % +-10
- Air changes: 8 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12 from 21:00-09:00 h

Route:

intradermal and epicutaneous

Vehicle:

other: soy bean oil or a mixture of soy bean oil and 2-butanone (1:2)

Concentration / amount:

1st induction 1 % intracutaneous
2nd induction 25 % occlusive epicutaneous
Challenge 0.3 % (1st experiment), 0.5 % (2nd experiment), epicutaneous

Route:

epicutaneous, occlusive

Vehicle:

other: soy bean oil or a mixture of soy bean oil and 2-butanone (1:2)

Concentration / amount:

1st induction 1 % intracutaneous
2nd induction 25 % occlusive epicutaneous
Challenge 0.3 % (1st experiment), 0.5 % (2nd experiment), epicutaneous

No. of animals per dose:

36 animals in the treated group: 20 animals in the first experiment, 16 animals in the second experiment
20 animals in the control group

Details on study design:

PRETEST:
To determine the irritation threshold, the animals were injected in the nape of the neck with 2 x 50 µl Freund´s Complete Adjuvant (FCA)-emulsion 14 days before determination of the minimally irritating and maximally non-irritating concentration. For the pretest, 25 µl aliquots were either injected into the flank skin or applied on the flank for 24 h in aluminium chambers. The test sites were examined 24 and 48 hours later. The concentrations giving a definite irritative reaction were selected for induction. Only concentrations giving no reactions were used for challenge.

MAIN STUDY:
INDUCTION EXPOSURE
Intradermal application:
- Hair was removed from an area of 4 cm x 6 cm in the shoulder region
- No. of exposures: 3 pairs of injections are made simultaneously: 2x 50 µl FCA suspension in sterile water; 2x 50 µl of test substance in vehicle; 2x 50 µl of the test substance emulsified in FCA and water
- Test groups: 36 animals
- Control group: 20 animals
- Site: Shoulder region
- Frequency of applications: one time

Epicutaneous application: 1 week after intradermal application
- No. of exposures: 1
- The skin was clipped again at the same area and ca. 250 mg of 10 % Sodium Dodecylsulfate (SDS) in petrolatum was massaged into the test area and left uncovered for 24 hours. Thereafter, 400 µl of the liquid test material (or an equivalent amount of petrolatum for controls) was placed on a patch which was applied onto the skin of the animal under occusive conditions for 48 hours.
- Test groups: 36 animals
- Control group: 20 animals
- Site: Shoulder region
- Frequency of applications: one time

CHALLENGE EXPOSURE
- No. of exposures: one challenge was conducted
- Day(s) of challenge: On day 21, hair was removed from the left flank and up to 6 patches were applied 3 hours later; one patch contained 25 µl test preparation in an aluminium chamber
- Exposure period: 24 hours
- Test groups: 36 animals
- Control group: 20 animals
- Site: Left flank of the animal
- Evaluation (hr after challenge): 24 and 48 hours after removing the patch
- Control and test animals received identical treatment

OTHER:
Reactions were graded according to Magnusson and Kligman with slight modifications.
Only animals showing at least one clear reaction with confluent erythema (grade 1) at a concentration at which none of the controls were positive, were considered sensitized.

Positive control substance(s):

no

Reading:

other: 1st experiment

Hours after challenge:

48

Group:

test chemical

Dose level:

0.3 %

No. with + reactions:

9

Total no. in group:

20

Remarks on result:

other: Reading: other: 1st experiment. . Hours after challenge: 48.0. Group: test group. Dose level: 0.3 %. No with. + reactions: 9.0. Total no. in groups: 20.0.

Reading:

other: 1st experiment

Hours after challenge:

48

Group:

negative control

Dose level:

0.3 %

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: other: 1st experiment. . Hours after challenge: 48.0. Group: negative control. Dose level: 0.3 %. No with. + reactions: 0.0. Total no. in groups: 20.0.

Reading:

other: 2nd experiment

Hours after challenge:

48

Group:

test chemical

Dose level:

0.5 %

No. with + reactions:

14

Total no. in group:

16

Remarks on result:

other: Reading: other: 2nd experiment. . Hours after challenge: 48.0. Group: test group. Dose level: 0.5 %. No with. + reactions: 14.0. Total no. in groups: 16.0.

Group:

positive control

Remarks on result:

not measured/tested

Interpretation of results:

sensitising

Reference 4

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Sufficient documentation available for assessment. No negative control was used, but since very low induction concentrations only led to a single positive reaction, the skin reactions observed are believed to be test substance related. Parallel experiments with several other substances showed sensitivity of the test system.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

. Control animals were not used.

Principles of method if other than guideline:

The guinea pig maximization (GPMT) test was performed as described by Magnusson and Kligman (Allergic contact dermatitis in the guinea pig. Identification of contact allergens. Springfield III: CC Thomas Publisher, 1970), but with multiple intradermal induction concentrations administered to different groups.

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Older study available

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Connaught Laboratories, Toronto, Canada
- Weight at study initiation: 300-500 g
- Housing: in metal cages
- Diet: Purina Guinea-Pig Chow, ad libitum
- Water: ad libitum

Route:

intradermal and epicutaneous

Vehicle:

other: propylene glycol for intradermal induction, petrolatum for epicutaneous induction and for challenge

Concentration / amount:

Intradermal induction concentration: 0.83, 2.5, 5.0 and 7.5 % in propylene glycol
Epicutaneous induction: 0.83, 2.5, 5.0 and 7.5 % in petrolatum
Epicutaneous challenge: non-irritating concentration, determined in irritancy test; no further information given

Route:

epicutaneous, occlusive

Vehicle:

other: propylene glycol for intradermal induction, petrolatum for epicutaneous induction and for challenge

Concentration / amount:

Intradermal induction concentration: 0.83, 2.5, 5.0 and 7.5 % in propylene glycol
Epicutaneous induction: 0.83, 2.5, 5.0 and 7.5 % in petrolatum
Epicutaneous challenge: non-irritating concentration, determined in irritancy test; no further information given

No. of animals per dose:

40 animals (10 animals per intradermal induction concentration)

Details on study design:

Irritancy test:
The test substance was intradermally injected to a group of 10 control guinea pigs. The animals were examined 24 h after injection to determine the maximum concentration that did not cause severe injury or systemic toxicity. This concentration was used as the highest concentration in the subsequent sensitization induction procedure.
Another group of 10 control guinea pigs was topically exposed to 3 concentrations of the test substance in petrolatum. The test substance was applied to "A1 test strips" that were affixed to the animals´flanks by occlusive tape that was then covered by a elastic adhesive bandage, wrapped around the torso of each animal. After 24 h the bandages were removed and the sites were examined for evidence of reactions at 48 hours. The non-irritating concentration was used for the challenge reaction.

Sensitization procedure:
Induction:
4 intradermal induction concentrations were tested and 10 animals were used for each concentration. The induction was performed in 2 stages. First, the test substance was injected intradermally into the shoulder region. Three pairs of intradermal injections were made into each animal group:
- 0.1 ml of the test substance dissolved in vehicle,
- 0.05 ml of Freund´s Complete Adjuvant, mixed with 0.05 ml of the test substance dissolved in vehicle,
- 0.1 ml of Freund´s Complete Adjuvant.
One week after injection, the animals were epicutaneously exposed to the clipped shoulder region to their respective concentrations in petrolatum. The test substance was applied to 2 cm x 4 cm filter paper which was held in place by impervious plastic tape and covered with an elastic adhesive bandage wrapped around the animals. After 48 h the bandages were removed.
Challenge:
The animals were challenged 2 weeks after topical induction on a 5 cm x 5 cm area of the flank. The concentrations used were not irritating and had been determined in control animals previously. The patches were applied as described above to assess irritancy and were removed after 24 hours. The reaction was assessed at 48 hours.

Positive control substance(s):

not specified

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.83 % induction dose; non-irritating challenge dose

No. with + reactions:

1

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.83 % induction dose; non-irritating challenge dose. No with. + reactions: 1.0. Total no. in groups: 10.0.

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

2.5 % induction dose; non-irritating challenge dose

No. with + reactions:

3

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 2.5 % induction dose; non-irritating challenge dose. No with. + reactions: 3.0. Total no. in groups: 10.0.

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5.0 % induction dose; non-irritating challenge dose

No. with + reactions:

5

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5.0 % induction dose; non-irritating challenge dose. No with. + reactions: 5.0. Total no. in groups: 10.0.

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

7.5 % induction dose; non-irritating challenge dose

No. with + reactions:

6

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 7.5 % induction dose; non-irritating challenge dose. No with. + reactions: 6.0. Total no. in groups: 10.0.

Group:

positive control

Remarks on result:

not measured/tested

Reference 5

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Documentation sufficient for assessment, but only half the required number of animals used in the GPMT.

Principles of method if other than guideline:

The sensitisation potential of the test substance was tested in the guinea pig maximization test (GPMT) and Freund´s Complete Adjuvant Test (FCAT).

Deviations from GPMT guideline:
- only 10 animals were used in the test group, though a negative result was obtained

Details on the protocol can be found in the third literature reference: Van der WValle H B. Klecak G. Geleick H. Bensink T. Sensitizing potential of 14 mono (meth)acrvlates in the guinea pig. Contact Dermatitis 1982: 8: 223-235.

GLP compliance:

not specified

Type of study:

other: guinea pig maximization test (GPMT) and Freund´s Complete Adjuvant Test (FCAT) were applied.

Justification for non-LLNA method:

Older study available

Species:

guinea pig

Strain:

other: 2 different strains were used in the study: Dunkin-Hartley-, and Himalayan white spotted guinea pigs

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Himalayan White Spotted Strain: Institute for Biomedical Research, Füllingsdorf, Switzerland; Dunkin-Hartley Strain: Olac Ltd, Bicester, England
- Weight at study initiation: 550-750 g
- Housing: in large iron cages in groups of 4 animals
- Diet: Pellet diet, ad libitum
- Water (e.g. ad libitum): yes, supplemented with vitamin C

Route:

intradermal and epicutaneous

Vehicle:

other: methylethylketon/arachis oil (2:1) was used as vehicle for all challenges, for the closed patch induction at day 7 of the GPMT, petrolatum or 80 % ethanol was used.

Concentration / amount:

GPMT: Substance "A":
Induction: 0.5M (app.11%) on day 0 and 1M (app. 23%) on day 7
Epicutaneous Challenge: 0.01 M (app. 0.2%)

FCAT: Substance "B"
Induction: 0.5M (app. 11%) daily from day 0 to 9
Epicutaneous Challenge: 0.03 M (app. 0.6%

The maximum non-irritant concentration was obtained under open conditions in a pre-test using Aramek as a vehicle

Route:

epicutaneous, open

Vehicle:

other: methylethylketon/arachis oil (2:1) was used as vehicle for all challenges, for the closed patch induction at day 7 of the GPMT, petrolatum or 80 % ethanol was used.

Concentration / amount:

GPMT: Substance "A":
Induction: 0.5M (app.11%) on day 0 and 1M (app. 23%) on day 7
Epicutaneous Challenge: 0.01 M (app. 0.2%)

FCAT: Substance "B"
Induction: 0.5M (app. 11%) daily from day 0 to 9
Epicutaneous Challenge: 0.03 M (app. 0.6%

The maximum non-irritant concentration was obtained under open conditions in a pre-test using Aramek as a vehicle

No. of animals per dose:

GPMT: 10 animals in the experimental group, 6 animals in the control group
FCAT: 8 animals in the experimental group, 4-6 animals in the control group

Details on study design:

The guinea pig maximization test (GPMT) and Freund´s Complete Adjuvant Test (FCAT) were used to test the sensitisation potential of the test substance.
The GPMT method was decribed in detail by: Magnusson B, Kligman AM; Allergenic contact dermatitis in the guinea pig. Springfield, Illinois; Charles A. Thomas, 1970.
The FCAT method was described in detail by: Klecak G; Identification of contact allergens: Predicitive tests in animals. Dermatology and Pharmacology. Marzulli FN, Maibach HI (eds.), New York: John Wiley and Sons, 1977.

The Himalayan White Spotted guinea pig Strain was used in the GPMT, the Dunkin Hartley guinea pig strain was used in the FCAT.
Control animals were used in both studies.

GPMT:
2 inductions were performed on day 0 and day 7 followed by 2 challenges on day 21 and day 35. The readings were made 24 and 48hours after the each challenge. The first challenge was applied occlusively, while the second one was left open.

FCAT:
Induction: intradermal injections on days 0, 2, 4, 7, 9 with app. 11% HDDA in complete Freund's adjuvance in the shoulder area. Control animals received only the adjuvance with an equal volume of distilled water.
The animals were challenged epicutaneously on days 21 and 35 on different flanks.
2 FCATs were performed, the second test used less decreasing challenge concentrations. (0.03M - 0.02M - 0.01M instead of 0.03M - 0.01M - 0.003M)

The results of the GPMT were graded according to Magnusson and Kligman (1970); the results of the day 35 challenge were considered.
For the FCAT, the results of the day 21 challenge were graded according to van der Walle et al. (Contact dermatitis 8: 223-235, 1982).

Reading:

rechallenge

Group:

other: GPMT

Dose level:

0.01M (0.2%)

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: rechallenge. Group: other: GPMT. Dose level: 0.01M (0.2%). No with. + reactions: 0.0. Total no. in groups: 10.0.

Reading:

1st reading

Group:

other: FCAT

Dose level:

0.03M (0.6%)

No. with + reactions:

4

Total no. in group:

8

Remarks on result:

other: Reading: 1st reading. Group: other: FCAT. Dose level: 0.03M (0.6%). No with. + reactions: 4.0. Total no. in groups: 8.0.

Reading:

rechallenge

Group:

other: FCAT

Dose level:

0.03M (0.6%)

No. with + reactions:

3

Total no. in group:

8

Remarks on result:

other: Reading: rechallenge. Group: other: FCAT. Dose level: 0.03M (0.6%). No with. + reactions: 3.0. Total no. in groups: 8.0.

Reading:

1st reading

Group:

other: 2nd FCAT

Dose level:

0.03M

No. with + reactions:

3

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. Group: other: 2nd FCAT. Dose level: 0.03M. No with. + reactions: 3.0. Total no. in groups: 10.0.

Reading:

rechallenge

Group:

other: 2nd FCAT

Dose level:

0.03M

No. with + reactions:

1

Total no. in group:

10

Remarks on result:

other: Reading: rechallenge. Group: other: 2nd FCAT. Dose level: 0.03M. No with. + reactions: 1.0. Total no. in groups: 10.0.

Group:

positive control

Remarks on result:

not measured/tested

Interpretation of results:

sensitising

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Skin sensitization

There are valid in vivo data available for the assessment of the skin sensitization potential of 1,6-hexanedioldiacrylate.

 

In an in vivo study according to the method described by Magnusson and Kligman, 30 female Dunkin-Hartley guinea pigs were used (15 animals as test group, and 15 animals as control group). Sensitization was induced intradermally (1 % in olive oil/acetone using FCA) as well as epicutaneously (25 % in petrolatum) one week later. The animals were challenged epicutaneously two weeks later with 0.2% of the test material in petrolatum and 5 further structurally similar substances to assess cross reactivity. After an intradermal booster reaction (1%), animals were challenged again with 0.2% of the test material in petrolatum and 5 other structurally related substances. The authors mentioned the possibility that the induction procedure was repeated (depending on the number of positive reaction after the first round), but did not specify, if this was the case for HDDA. Despite these deviations (booster induction, possible repetition) only 9 of 15 animals showed positive reaction to HDDA) (Björkner, 1984).

In a second study, sensitisation was intradermally induced with 1% HDDA in soy bean oil in guinea pigs following a protocol similar to the GPMT described in the OECD 406 guideline. 25% HDDA were used for the epicutaneous induction. The challenge concentration was determined in a pre-test, but was increased in a second experiment. Dependent on the concentration used, 9/20 (0.3%) or 14 of 16 (0.5%) of the animals showed positive reactions. No control animals reacted to HDDA (Clemmensen, 1985).

In another GPMT performed according to the Magnusson and Klingman method, several induction concentrations were evaluated. The same concentration were used per animal for intradermal and epicutaneous induction: 0.83 , 2.5, 5.0 and 7.5 %. The positive reactions after challenge with a non-irritant concentration were 1/10, 3/10, 5/10 and 6/10, respectively. A clear dose response was observed. No negative control was used, but because of only one positive reaction in the lowest dose group, all reactions are assumed to be test substance related (Nethercott, 1983).

Three different assays, one GPMT and 2 FCATs. Intradermal induction with app. 11% HDDA was compartively high in all assays, followed in the case of the GPMT by an epicutaneous induction with 22%. While a single intradermal induction was used for the GPMT, 5 injections were performed for the FCATs. Two challenges were performed with 0.2% (GPMT) and 0.6% (FCAT). No positive reactions were observed in the GPMT. In the first FCAT three of eight animals reacted to HDDA, while in the second test only one out of ten showed a positive reaction. The authors conclude that HDDA, though a strong irritant to guinea pigs, is only a moderate sensitizer (Van der Walle, 1982).

In an unpublished optimisation test, all 20 animals reacted to an epicutaneous challenge of 0.1% HDDA in vaseline.The high number of positive reaction can be explained by the harsh conditions of induction. 0.1% HDDA in propylene glycol was injected 10 times in the course of three weeks, mixed with complete Freund's adjuvance in the latter two weeks Ciba Geigy, 1978).

A further guinea pig study as well as several reports in humans (see IUCLID section 7.10.4) confirm the sensitizing potential of HDDA (Paker et al., 1983).

 

Respiratory sensitization

No information is available.

 

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

1,6-hexanedioldiacrylate was demonstrated to be a skin sensitizer. No conclusion regarding the potency can be drawn. Most studies showed a moderate rather than strong sensitisation potential. Despite additional intradermal inductions, the GPMT by Björkner et al. does only just miss the criteria for subcategory 1B (60% react at 1% induction). In the study by Clemmensen, subcategorisation would be dependent on the challenge concentration, but only limited information is provided, how and why the different concentrations were selected. Further assays (Nethercott, Van der Walle) support at most a moderate potential, but lack certain information on dose selection.

There are no data available to classify 1,6-hexanedioldiacrylate as a sensitizer of the respiratory tract.

Based on the results, the test item is subject to classification and labelling according to Regulation (EC) No 1272/2008 (CLP) as skin sensitizer cat 1. The available data ist considered insufficient to assign a subcategory.