Nitrapyrin

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 November 1985 to 07 March 1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted to sound scientific principles with a sufficient level of detail to assess the quality of the submitted data.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: modified Maguire method

GLP compliance:

no

Remarks:

The report states that it was conducted with the intent of GLP

Type of study:

Freund's complete adjuvant test

Justification for non-LLNA method:

Adequate existing in vivo data using the Freund's complete adjuvant test was available.

Test material

Test material information

Constituent 1

Reference substance name:

Nitrapyrin

EC Number:

217-682-2

EC Name:

Nitrapyrin

Cas Number:

1929-82-4

Molecular formula:

C6H3Cl4N

IUPAC Name:

2-chloro-6-(trichloromethyl)pyridine

Test material form:

other: solid (unspecified)

Details on test material:

- Appearance: white solid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 275 - 325 g
- Housing: animals were housed in wire-bottom cages
- Diet: ad libitum
- Water: tap water, ad libitum
- Acclimation period: one week (housed 5 animals per cage)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): approximately 22 °C
- Humidity (%): approximately 50 %
- Air changes (per hr): approximately 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours of darkness / 12 hours of light

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

other: topical, semi-occlusive

Vehicle:

other: dipropylene glycol monomethyl ether/Tween 80 (9:1)

Induction 2

Concentration / amount:

Test material, and positive control, was applied as a 10 % solution in vehicle

Challenge

Challenge 1

Route:

other: topical, open

Vehicle:

other: dipropylene glycol monomethyl ether/Tween 80 (9:1)

Challenge 2

Concentration / amount:

Test material, and positive control, was applied as a 10 % solution in vehicle

No. of animals per dose:

10 animals were treated with test material
10 animals were treated with the positive control

Details on study design:

Approximately 48 hours prior to the start of the study the back of each guinea pig was clipped free of hair. The following day, a cream hair remover was applied over the clipped area to remove any remaining hair. Twenty four hours following this procedure, ten guinea pigs received four applications of the test material within ten days during the insult phase of testing. The test material was applied as a 10 % (w/v) solution.
An additional group of ten guinea pigs received an epoxy resin as a 10 % (v/v) solution. Both solutions were prepared in diprolylene glycol monomethyl ether/Tween 80 (9:1). The epoxy resin is known to be a skin sensitiser and served as a positive control. Each insult application consisted of 0.1 mL of the test material or the positive control applied to an approximately 15 x 15 mm gauze square patch placed on the back of the guinea pig, covered first with MICROPORE and then secured with adhesive tape. At the time of the third application, a total of 0.2 mL of Freund’s Adjuvant was injected intradermally at multiple points adjacent to the insult site.
Each time the patches were removed, observations for erythema and/or oedema were made and recorded. At the time of the last reading, the toe nails and distal portion of both rear feet were wrapped with adhesive tape. After the minimum two-week rest period the flanks of each animal were clipped. The left flank was challenged with 0.1 mL of either the test material or epoxy resin, the right flank with 0.1 mL of diprolylene glycol monomethyl ether/Tween 80 (9:1). The challenge applications were not occluded. Skin response was recorded at 24 and 48 hours.
Guinea pigs were weighed weekly throughout the study. Routine monitoring was limited to animal husbandry procedures required to ensure the availability of food and water. At the termination of the study, all guinea pigs were euthanatised.

Positive control substance(s):

yes

Remarks:

DER 331 epoxy resin

Results and discussion

Positive control results:

Following the challenge exposure with DER 331, slight to marked erythema was observed on all guinea pigs.

In vivo (non-LLNA)

Results

Results 1

Group:

negative control

Remarks on result:

not measured/tested

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

10%

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

Slight to Marked erythema

Results 3

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10 % w/v solution

No. with + reactions:

3

Total no. in group:

10

Clinical observations:

Slight to moderate erythema

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10 % w/v solution

No. with + reactions:

3

Total no. in group:

10

Clinical observations:

Slight to moderate erythema

Any other information on results incl. tables

Three of the ten guinea pigs challenged with the test material as a 10 % solution revealed signs of s1ight to moderate erythema. The degree of erythema and/ or oedema observed, along with the number of animals affected are taken into consideration in the evaluation of sensitisation potential. Since initial application of the test material as a 10 % solution proved to be non-irritating with regards to skin irritation, any reaction at the challenge site is considered a sensitisation response.

 

Table 1: Dermal Observations of Erythema

Test Group	Animal No.	Insult Phase*				Challenge Phase		Result
		2	5	7	9	24 Hours	48 Hours
Test Material	85B-0020 85B-0021 85B-0022 85B-0023 85B-0024 85B-0025 85B-0026 85B-0027 85B-0028 85B-0029	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	1 2 1 1 1 2 3 1 1 1	1 2 1 1 1 2 3 1 1 1	- + - - - + + - - -
Positive Control	85B-0030 85B-0031 85B-0032 85B-0033 85B-0034 85B-0035 85B-0036 85B-0037 85B-0038 85B-0039	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	1 1 1 1 1 1 1 1 1 1	3 4 3 4 4 2 2 3 2 4	4 4 3 3 3 2 3 2 2 4	+ + + + + + + + + +

*Indicates days post-exposure

1 = None

2 = Slight

3 = Moderate

4 = Marked

Applicant's summary and conclusion

Interpretation of results:

sensitising

Conclusions:

Under the conditions of the study, the test material was concluded to possess sensitising properties to the skin of guinea pigs.

Executive summary:

The skin sensitisation potential of the test material was investigated in a study which was conducted under the spirit of GLP and following a modified Maguire methodology.

During the study, 10 male Hartley guinea pigs received 4 applications of the test material within 10 days. The test material was applied as a 10 % w/v solution. An additional group of 10 guinea pigs, used as a positive control, received an epoxy resin (positive control) as a 10 % v/v solution. Both solutions were prepared in dipropylene glycol monomethyl ether/Tween 80 (9:1). Each application consisted of 0.1 mL of the test material or the positive control resin applied to a gauze patch, placed on the back of the guinea pig, then secured and covered with adhesive tape.

Following a minimum 2-week rest period, the animals were challenged. Challenge with the positive control resulted in slight to marked erythema on all guinea pigs. Under identical conditions, three of the guinea pigs challenged with the test material revealed signs of slight to moderate erythema. The degree of erythema and/or oedema observed, along with the number of animals affected are taken into consideration in the evaluation of sensitisation potential. Therefore, based on these results, the test material should be considered as possessing some potential to induce skin sensitisation.