Naphtha (Fischer-Tropsch), light, C4-10-branched and linear

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

, see "Principles of method if other than guideline"

Principles of method if other than guideline:

only 10 animals were used in the treatment group (instead of a minimum of 20 animals)

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

Reliable non-LLNA study / alternative method (Buehler test) was available. Conduction of LLNA study was considered to be scientifically not necessary.

Test material

Test material information

Constituent 1

Reference substance name:

Naphtha (petroleum), light alkylate

EC Number:

265-068-8

EC Name:

Naphtha (petroleum), light alkylate

Cas Number:

64741-66-8

IUPAC Name:

Naphtha (petroleum), light alkylate

Details on test material:

- Name of test material (as cited in study report): Naphtha (petroleum), light alkylate [CAS 64741-66-8]
- Test substance is closely related to Naphtha (Fischer-Tropsch), light, C4-10 - branched and linear; it is defined as : 'A complex combination of hydrocarbons produced by the distillation of the reaction products of isobutane with monoolefinic hydrocarbons usually ranging in carbon numbers from C3 through C5. It consists of predominantly branched chain saturated hydrocarbons having carbon numbers predominantly in the range of C7-C10 and boiling in the range 90-160°C (194-320°F).'

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: approx. 5 to 6 weeks
- Weight at study initiation: Average body weights at test initiation: 504 to 523 g
- Housing: Individual cages in temperature- and humidity-controlled rooms
- Diet (e.g. ad libitum): continuous access to Purina Certified Guinea Pig Chow f5026
- Water (e.g. ad libitum): ad-libitum
- Acclimation period: at least 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-24 °C
- Humidity (%): 37 to 58 % R.H.
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Induction 2

Concentration / amount:

Concentrations of test material and vehicle used at each stage of induction:
- Test material: 50% v/v in paraffin oil
- Vehicle control: paraffin oil undiluted
Concentrations of test material and vehicle used at each stage of challenge:
- Test material: 25% v/v in paraffin oil
- Vehicle control: paraffin oil undiluted
- Naive control: 25% v/v test material in paraffin oil

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Challenge 2

Concentration / amount:

Concentrations of test material and vehicle used at each stage of induction:
- Test material: 50% v/v in paraffin oil
- Vehicle control: paraffin oil undiluted
Concentrations of test material and vehicle used at each stage of challenge:
- Test material: 25% v/v in paraffin oil
- Vehicle control: paraffin oil undiluted
- Naive control: 25% v/v test material in paraffin oil

No. of animals per dose:

- test group: 10
- naive control group: 10
- vehicle control group: 10
- positive control group: 20
- naive positive control group: 20

Details on study design:

RANGE FINDING TESTS:
A range-finding study consisting of 4 guinea pigs was utilized.
The sample was administered undiluted and at concentrations of 25 %, 50 % and 75 % v/v in paraffin oil
to determine the irritation treshold of the test material.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures:
3 applications
- Exposure period:
1 application per week, 2 weeks plus two weeks period prior to challenge
- Test groups:
treated group of 10 animals
- Control group:
naive control group of 10 animals, vehicle control group of 10 animals, positive control group of 20 guinea pigs
- Site:
test site on the left anterior quadrant (right anterior quadrant for challenge dose) of each animal
- Frequency of applications:
1 application per week,
- Duration:
6 hours
- Concentrations:
0.4 mL of test material mixture


B. CHALLENGE EXPOSURE
- No. of exposures:
1 application
- Day(s) of challenge:
two weeks after administration of the third sensitising dose, challenge dose was applied.
- Exposure period:
48 hours
- Test groups:
treated group of 10 animals
- Control group:
naive control group of 10 animals, vehicle control group of 10 animals, positive control group of 20 guinea pigs
- Site:
test site on the left anterior quadrant (right anterior quadrant for challenge dose) of each animal
- Concentrations:
0.4 mL of a 25 % v/v mixture of the test material in paraffin oil
- Evaluation (hr after challenge):
24 and 48 hours

Challenge controls:

At this time, the animals in the naive (previously untreated) control group were also dosed with the test material mixture in the same manner as the test group.
The vehicle control group animals were dosed with 0.4 mL of undiluted paraffin oil. For the positive control group and the previously untreated positive control group the animals were dosed with 0.4 mL of a 0.1 % w/v suspension of 2,4-dinitrochlorobenzene in acetone.

Positive control substance(s):

yes

Remarks:

2,4-Dinitrochlorobenzene

Study design: in vivo (LLNA)

Positive control substance(s):

other: 2,4-Dinitrochlorobenzene

Results and discussion

Positive control results:

Very slight to severe irritation was exhibited by all 20 animals. The reactions of 18 animals exceeded the highest reaction observed in the naive positive control animals.

In vivo (non-LLNA)

Results

Results 1

Reading:

other: mean of 1st and 2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

25% v/v

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

slight erythema

Remarks on result:

other: Reading: other: mean of 1st and 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 25% v/v. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: slight erythema .

Results 2

Reading:

other: mean of 1st and 2nd reading

Hours after challenge:

48

Group:

other: naive control group

Dose level:

25% v/v

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

slight erythema

Remarks on result:

other: Reading: other: mean of 1st and 2nd reading. . Hours after challenge: 48.0. Group: other: naive control group. Dose level: 25% v/v. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: slight erythema.

Results 3

Reading:

other: mean of 1st and 2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

paraffin only

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

-

Remarks on result:

other: Reading: other: mean of 1st and 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: paraffin only. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: -.

Results 4

Reading:

other: mean of 1st and 2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

0,1% w/v

No. with + reactions:

20

Total no. in group:

20

Clinical observations:

very slight erythema and edema

Remarks on result:

other: Reading: other: mean of 1st and 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0,1% w/v. No with. + reactions: 20.0. Total no. in groups: 20.0. Clinical observations: very slight erythema and edema.

Results 5

Reading:

other: mean of 1st and 2nd reading

Hours after challenge:

48

Group:

other: naive positive control group

Dose level:

0,1% w/v

No. with + reactions:

3

Total no. in group:

20

Clinical observations:

very slight erythema

Remarks on result:

other: Reading: other: mean of 1st and 2nd reading. . Hours after challenge: 48.0. Group: other: naive positive control group. Dose level: 0,1% w/v. No with. + reactions: 3.0. Total no. in groups: 20.0. Clinical observations: very slight erythema.

Any other information on results incl. tables

Observations

- Test group: A very slight erthyema reaction was exhibited by one animal. The reaction did not exceed the highest reaction of the naive control animals.The other nine animals exhibited no reaction.

- Naive control group: A very slight erthyema reaction was exhibited by one animal. The other nine animals exhibited no reaction.

- Negative control group: No reaction was exhibited by any animal.

- Positive control group: Very slight to severe irritation was exhibited by all 20 animals. The reactions of 18 animals exceeded the highest reaction observed in the naive positive control animals.

- Naive positive control group: Three of the 20 animals exhibited very slight erythema reactions. The other 17 animals exhibited no reaction.

Other observations:

- All animals appeared normal throughout the study period with the exception of two test animals, five positive control animals, and two naive control animals which exhibited soft stool/diarrhea sporadically throughout the study.

- A slight bodyweight loss of 5 g was recorded during the last week of the study for one test animal. This animal exhibited normal bodyweight gains at all other weighings. Normal body weight gains were recorded for all other animals during the study.

Test Animal: Albino guinea pigs - Hartley strain

Date Animals Received: 12/18/84 and 01/08/85

Date Test Started: 01/02/85

Date Test Completed: 02/28/85

Temperature and Humidity of Animal Room: 21°C to 24°C

37% to 58% relative humidity

 

Summary of Skin Reactions*

Test Material: Naphtha (petroleum), light alkylate

 

	Sensitizing Phase				Challenge Phase
Animal Number	Three Applications (50% v/v)				Single Application (25% v/v)
	Erythema		Edema		Erythema		Edema
	Average	(High)	Average	(High)	Average	(High)	Average	(High)
	Test Group
E03281	0.8	(1)	0.0	(0)	0.0	(0)	0.0	(0)
E03282	1.3	(2)	0.3	(1)	0.0	(0)	0.0	(0)
E03283	0.8	(1)	0.0	(0)	0.0	(0)	0.0	(0)
E03284	1.3	(2)	0.3	(1)	0.0	(0)	0.0	(0)
E03285	1.0	(1)	0.0	(0)	1.0	(1)	0.0	(0)
E03286	1.0	(1)	0.0	(0)	0.0	(0)	0.0	(0)
E03287	0.5	(1)	0.0	(0)	0.0	(0)	0.0	(0)
E03288	1.3	(2)	0.2	(1)	0.0	(0)	0.0	(0)
E03289	0.3	(1)	0.0	(0)	0.0	(0)	0.0	(0)
E03290	1.0	(1)	0.0	(0)	0.0	(0)	0.0	(0)

 

	Challenge Phase
Animal Number	Single Application (25% v/v)
	Erythema		Edema
	Average	(High)	Average	(High)
	Naive Control Group
E03291	0.0	(0)	0.0	(0)
E03292	0.0	(0)	0.0	(0)
E03293	0.5	(1)	0.0	(0)
E03294	0.0	(0)	0.0	(0)
E03295	0.0	(0)	0.0	(0)
E03296	0.0	(0)	0.0	(0)
E03297	0.0	(0)	0.0	(0)
E03298	0.0	(0)	0.0	(0)
E03299	0.0	(0)	0.0	(0)
E03300	0.0	(0)	0.0	(0)

 

*The average erythema and edema value is the mean of the Draize scores for the six observations (sensitizing treatment) or two observations (challenge treatment) of the application site for each animal. The high reading is the largest score recorded for the respective animal during that phase of the study.

 

	Sensitizing Phase				Challenge Phase
Animal Number	Three Applications (Undiluted)				Single Application (Undiluted)
	Erythema		Edema		Erythema		Edema
	Average	(High)	Average	(High)	Average	(High)	Average	(High)
	Vehicle Control Group (Paraffin Oil)
E03301	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03302	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03303	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03304	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03305	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03306	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03307	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03308	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03309	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)
E03310	0.0	(0)	0.0	(0)	0.0	(0)	0.0	(0)

 

	Sensitizing Phase				Challenge Phase
	Three Applications (0.3% w/v)				Single Application (0.1% w/v)
Animal	Erythema		Edema		Erythema		Edema
Number	Average	(High)	Average	(High)	Average	(High)	Average	(High)
	Positive Control Group (2,4-dinitrochlorobenzene)
E03371	2.0	(3)	1.3	(2)	2.0	(2)	0.0	(0)
E03372	1.8	(3)	1.7	(3)	2.0	(2)	0.0	(0)
E03373	2.5	(3)	2.0	(3)	1.5	(2)	0.0	(0)
E03374	2.3	(3)	1.7	(3)	1.5	(2)	0.0	(0)
E03375	3.0	(4)	2.7	(4)	1.5	(2)	0.5	(1)
E03376	2.3	(3)	1.3	(3)	2.0	(2)	0.5	(1)
E03377	2.8	(4)	1.2	(2)	1.0	(1)	0.0	(0)
E03378	2.8	(4)	1.8	(3)	2.0	(2)	0.0	(0)
E03379	2.2	(3)	1.3	(2)	2.0	(2)	1.0	(1)
E03380	2.2	(3)	1.8	(3)	2.0	(2)	0.5	(1)
E03381	2.2	(3)	2.0	(3)	2.0	(2)	0.0	(0)
E03382	2.3	(3)	1.8	(3)	1.5	(2)	0.0	(0)
E03383	1.7	(2)	0.8	(2)	2.5	(3)	0.5	(1)
E03384	2.2	(3)	1.5	(2)	1.0	(1)	0.5	(1)
E03385	2.3	(3)	1.5	(3)	1.5	(2)	0.5	(1)
E03386	2.2	(3)	1.3	(2)	1.5	(2)	0.0	(0)
E03387	2.5	(4)	2.0	(4)	2.0	(2)	1.0	(2)
E03388	2.5	(4)	2.0	(3)	1.5	(2)	0.0	(0)
E03389	2.2	(3)	1.2	(2)	1.5	(2)	0.5	(1)
E03390	2.3	(3)	1.8	(3)	1.5	(2)	0.0	(0)

 

*The average erythema and edema value is the mean of the Draize scores for the six observations (sensitizing treatment) or two observations (challenge treatment) of the application site for each animal. The high reading is the largest score recorded for the respective animal during that phase of the study.

 

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

- Skin reactions to the induction dose: Slight to moderate erythema and slight edema were observed in the animals dosed with test material.
- Skin reactions to the challenge dose: the test group did not show any skin reaction, like erythema and edema after challange, except 1 out of 10
animals.
Result: It was concluded that, under the conditions of this study, repeated administration of 'Naphtha (petroleum), light alkylate' had a weak potential to cause delayed contact hypersensitivity in guinea pigs. The incident of significant response was below the EEC trigger threshold for classification as a dermal sensitizer.

Executive summary:

Young adult guinea pigs (males) were tested for possible sensitisation effects of the test substance 'Naphtha (petroleum), light alkylate' (similar to OECD guideline 406). After 3 consecutive administrations (induction, once per week) a challenge dose was applied. At challenge, a very slight erythema was exhibited by one animal. The other 9 animals had no response. In contrast all 20 of the positive controls responded with reactions ranging from slight to severe irritation. Only one naive control exhibited a very slight erythema upon challenge.

It was concluded that, under the conditions of this study, repeated administration of 'Naphtha (petroleum), light alkylate' had a weak potential to cause delayed contact hypersensitivity in guinea pigs.

The incident of significant response was below the EEC trigger threshold for classification as a dermal sensitizer.