Dibutyl phthalate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline-Studie (GLP, QAU)

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Species:

guinea pig

Strain:

Pirbright-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Pirbright White, Dunkin Hartley HOE DHPK [SPF-LAC] BO from Lippische Versuchstierzucht, Hagemann GmbH & Co. KG, D-4923 Extertal 1, FRG
- Weight at study initiation: 252 – 313 g
- Housing: the animals, identified by ear tag numbering, were housed 5 per cage in Makrolon, type IV
- Diet (e.g. ad libitum): Kliba 341.4 mm (Kaninchen-Meerschweinchen-Haltungsdiät) from Firma Klingentalmühle AG, CH-4303 Kaiseraugst, Switzerland
- Water (e.g. ad libitum): tap water; about 2 g of ascorbic acid per 10 l water was added to the drinking water twice a week
- Acclimation period: at least 8 days before the beginning of the study in the laboratory for dermal toxicity

ENVIRONMENTAL CONDITIONS
The animals were housed in fully air-conditioned rooms in which a central air-conditioning system
- Temperature (°C): 20 - 24
- Humidity (%): 30 - 70
- Air changes (per hr): - Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal

Vehicle:

other: olive oil

Concentration / amount:

5% at intradermal induction, 75% at epicutaneous induction and 50% at challenge

Route:

epicutaneous, occlusive

Vehicle:

other: olive oil

Concentration / amount:

5% at intradermal induction, 75% at epicutaneous induction and 50% at challenge

No. of animals per dose:

10 in the control groups, 20 in the test group (see Table 1)

Details on study design:

RANGE FINDING TESTS:
The test substance was applied 2 times for 24 hours within a period of 96 hours in order to detect non-specific phenomena that are not caused by a sensitization reaction but could possibly be attributed to a shift in the irritation threshold. (1) Site of application: flank, respective on the same area; (2) number of test animals: 4 per test concentration; (3) readings: about 24 and 48 h after the beginning of application.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 6 intradermal injections in groups of two per animal
- Exposure period: at the beginning for intradermal injection and one week thereafter for epicutaneous treatment
- Test groups: a) front row: 2 injections each of 0.1 ml Freund's adjuvant without test substance emulsified with water in a ratio of 1:1; b) middle row: 2 injections each of 0.1 ml of the test substance formulation; c) back row: 2 injections each of 0.1 ml Freund's adjuvant/water (1:1) with test substance. A percutaneous induction was carried out about one week after intradermal induction, when 2x4 cm filter paper strips were applied to the skin of the shoulder under an occlusive dressing. In the case of liquids the filter paper strip was soaked in the test substance formulation; thus, the animals were exposed to about 0.3 g of the test substance formulation.
- Control group: the animals were given the same injections (a, b, c) as the test groups but without test substance, only with the formulating agent. At epicutaneous induction, the control groups were treated analogously to the test group but only with the solvent without the test substance.
- Site: shoulder at intradermal induction; shoulder at epicutaneous induction, same area as in the case of the previous intradermal application
- Duration: reading was done 24 h after the beginning of intradermal application. The epicutaneous patch was maintained for 48 hours
- Concentrations:

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: first challenge 14 days after percutaneous application, second challenge one week later
- Exposure period: 24 hours
- Test groups and control group: 1) first challenge; treatment of the test group and of control group 1 with the test substance formulation. Additionally, olive oil DAB 9 was applied as a vehicle. Control group 2 only received olive oil DAB 9. 2) 2nd challenge; treatment of the test group and of control groups 1 and 2 with the test substance formulation. Analogous to the first challenge olive oil DAB 9 was applied as a vehicle.
- Site: intact clipped flank
- Concentrations: non-irritant concentration; 2 x 2 cm filter paper strips were applied to the skin of the flank under an occlusive dressing. In the case of liquids the test filter paper strip was soaked in the test substance formulation; thus the animals were exposed to about 0 .15 g of the test substance formulation.
- Evaluation (hr after challenge): 24, 48 and 72 hours after the beginning of application

OTHER: erythema and the edema were scored according to the OECD guideline. The evaluation was based on the criteria of Annex VI/II D of the Council Directive of July 29, 1983 for the 5th Amendment of the Directive 67/548 EEC (= 83/467 EEC)

Positive control substance(s):

no

Remarks:

the maximization test is often conducted in the testing facility

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

15

Total no. in group:

20

Clinical observations:

8 animals with erythema score of 2 and 7 animals with erythema score of 1; maximum erythema score: 4

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50%. No with. + reactions: 15.0. Total no. in groups: 20.0. Clinical observations: 8 animals with erythema score of 2 and 7 animals with erythema score of 1; maximum erythema score: 4.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

2

Total no. in group:

20

Clinical observations:

both animals with erythema score of 1; all animals showed negative reactions at the 72 hours reading

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 2.0. Total no. in groups: 20.0. Clinical observations: both animals with erythema score of 1; all animals showed negative reactions at the 72 hours reading.

Reading:

other: 1st readingd after rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

18

Total no. in group:

20

Clinical observations:

7 animals with erythema score of 2 and 11 animals with erythema score of 1

Remarks on result:

other: see Remark

Remarks:

Reading: other: 1st readingd after rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 50%. No with. + reactions: 18.0. Total no. in groups: 20.0. Clinical observations: 7 animals with erythema score of 2 and 11 animals with erythema score of 1.

Reading:

other: 2nd readingd after rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no irritation was observed at this reading time point and 24 hours thereafter

Remarks on result:

other: see Remark

Remarks:

Reading: other: 2nd readingd after rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: no irritation was observed at this reading time point and 24 hours thereafter.

- The injection of test substance preparation in olive oil DAB 9 resp. in Freund's adjuvant/aqua dest. (1 : 1) caused distinct erythema and edema in the test animals. The control animals, injected with olive oil DAB 9 (vehicle) exhibited distinct erythema.

 

- After percutaneous induction incrustation, partially open (caused by the intradermal induction) was observed in the test animals in addition to distinct erythema and edema. Control group 1 and 2 which were applied with the vehicle (olive oil DAB 9) exhibited the same reactions as the test animals.

 

Table 1: Summary of number of animals with skin findings after the 1^stchallenge (20 days after intradermal induction) and after the 2nd challenge (27 days after intradermal induction)

	1^stchallenge		2nd challenge
	50% TS in olive oil DAB 9	Olive oil DAB 9	50% TS in olive oil DAB 9	Olive oil DAB 9
Control group 1	0/10	0/10	0/10	0/10
Control group 2	-	1/10	0/10	0/10
Test group	2/20	0/20	0/20	0/20
TS: Test substance; -: no application of test substance; x/y : number of positive reactions/number of animals tested; readings 48 h after the beginning of application

 

 

- After the first challenge (48 hours after the beginning of application) the 50% test substance preparation in olive oil DAB 9 caused slight erythema in 2 of 20 test animals. Control group 1 did not show any skin reactions.

 

- After the second challenge (48 hours after the beginning of application) with the 50 % test substance preparation in olive oil DAB 9 no skin reactions could be observed neither in the test group nor in the control groups.

 

- Olive oil DAB 9 which was applied as a vehicle caused slight erythema in 1 of 10 animals of control group 2 after the first challenge (48 hours after the beginning of application).

 

- Olive oil DAB 9 caused no skin reactions in all animals after the second challenge (48 hours after the beginning of application).

Interpretation of results:

not sensitising

Remarks:

Migrated information

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

taken from EU RAR Dibutyl Phthalate (2004):

Conclusion on sensitisation:

Dibutyl phthalate did not show skin sensitising properties in two maximization tests in guinea pigs (BASF, 1990c; Greenough et al., 1981). According to EC criteria the substance does not need to be classified on the basis of the available tests.

The results of the available case studies with respect to the possible induction of sensitisation in human by DBP (e.g. Husain, 1975; Vidovic and Kansky, 1985) are not appropriate for a definite conclusion due to the limited documentation of the studies and additionally sometimes conflicting results of the studies (based on EU RAR Dibutyl Phthalate (2004).

Migrated from Short description of key information:
result corresponding with BASF study (endpoint 7.4.1)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Justification for classification or non-classification

According to the EC criteria, dibutyl phthalate does not need to be classified on the basis of its sensitising effects.