Tetrakis(hydroxymethyl)phosphonium sulphate(2:1)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November- december 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study, performed according to standard method.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

: the grading scale was from 0 to 4 both for erythema and oedema formation, according to Draize (1959), instead of 0 to 3 for erythema formation as described in the OECD guideline 406.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPP 81-6 (Skin Sensitisation)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

EPA OTS 798.4100 (Skin Sensitisation)

Deviations:

no

Principles of method if other than guideline:

Not applicable.

GLP compliance:

yes (incl. QA statement)

Remarks:

1992-06-11

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study performed before the adoption of the OECD 429 guideline

Test material

Test material information

Constituent 1

Reference substance name:

Tetrakis(hydroxymethyl)phosphonium sulphate(2:1)

EC Number:

259-709-0

EC Name:

Tetrakis(hydroxymethyl)phosphonium sulphate(2:1)

Cas Number:

55566-30-8

Molecular formula:

C4H12O4P.1/2O4S

IUPAC Name:

tetrakis(hydroxymethyl)phosphonium sulphate(2:1)

Test material form:

other: liquid stored at ambient temperature.

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Ltd., UK
- Age at study initiation: 8-12 weeks old
- Weight at study initiation: 333-410 g
- Housing: in groups of up to three in solid-floor polypropylene cages furnished with woodflakes
- Diet/ water : Free access to mains tap water and food
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19-22°C
- Humidity: 50-66%
- Air changes (per hr): 15
- Photoperiod: 12 hr dark / 12 hr light

IN-LIFE DATES: From 16 November 1993 to 24 December 1993

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

water

Induction 2

Concentration / amount:

see below, details on study design

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

water

Challenge 2

Concentration / amount:

see below, details on study design

No. of animals per dose:

30 (20 in the test group; 10 in the control group)

Details on study design:

RANGE FINDING TESTS:
The selection of the concentrations used for the induction and challenge phases in the main study was based on the results of the pilot studies.
For the selection of concentration for topical challenge, the tested concentration range, 4 concentrations from 5 to 50 % v/v (as active substance; THPS 75%) for 24 hours, none of the two tested guinea pigs showed any skin reaction. According to this result, it was decided to use the highest tested concentration inducing no irritation effect (50 % v/v active substance) on one flank region and a higher concentration ensuring a positive skin reaction (75 % v/v) on the other flank side.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
1st application: Induction 0.1 % intracutaneous (day 0)
2nd application: Induction 25 % occlusive epicutaneous (day 7)
- Site: the shoulder region of each animal
- Duration: 48h
Concentrations for induction: (day 0 and 7)
Intradermal induction: 0.1% w/v in distilled water, that is 0.75 µg main ingredient/mL,
Topical induction: 25% v/v in distilled water, that is 34.8 µg active substance/mL or 26.1 µg main ingredient/mL.

B. CHALLENGE EXPOSURE
- No. of exposures: 1
3rd application: Challenge 75 % occlusive epicutaneous
- Day(s) of challenge: 21
- Exposure period: test substance was removed using water 24 hours following application
- Site: the shorn right flank of each animal
Two concentrations were used for challenge: (day 21)
- 50% v/v in distilled water (69.6 µg active substance/mL or 52.2 µg main ingredient/mL) applied on the left flank, which is the highest concentration producing no evidence of skin irritation 24 and 48 hours after dressing removal,
- and 75% v/v in distilled water (104.4 µg active substance/mL or 78.3 µg main ingredient/mL) applied on the right flank, to ensure that the maximum non-irritant concentration (50 % v/v) was really used at challenge.
- examination: skin response, bodyweight
- Evaluation: 24 and 48 h after challenge

Challenge controls:

10 animals

Positive control substance(s):

no

Results and discussion

Positive control results:

none.

In vivo (non-LLNA)

Results

Results 1

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

14

Total no. in group:

20

Clinical observations:

Erythem, Oedema, small scateered scab, large dried scab, bleeding caused by animal scratching intradermal induction site

Remarks on result:

positive indication of skin sensitisation

Results 2

Reading:

rechallenge

Hours after challenge:

48

Group:

negative control

Dose level:

75%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No clinical observation

Remarks on result:

no indication of skin sensitisation

Results 3

Group:

positive control

Remarks on result:

not measured/tested

Any other information on results incl. tables

After an injection of 0.1 % w/v of the test material, a topical induction at 25 % seven days after the injection, and a topical challenge at 50 % on day 21 post-injection, fourteen guinea pigs on the twenty treated animals showed irritation signs, against non from the control group. The test material produced a 70% sensitization rate and was classified as a strong sensitiser to guinea pig skin.

 

Considering a relative density of 1.392 and a THPS concentration of 75 %, exposure concentrations expressed as main ingredient are as follow:

(1) Intradermal induction: 0.075 % w/v = 0.75 g/L

(2) Topical induction: 26.1 g/L

(3) Topical challenge: 52.2 g/L

 

 Main skin reactions for each step were:

(1) Intradermal induction: Very slight to well defined erythema for all test group animals at hour 24 post-injection and in eighteen test group animals at the 48-hour observation.

Very slight erythema was noted at the vehicle intradermal injection sites of five control group animals at the 24-hour observation; all control animals recovered at hour 48 post-injection.

 

(2) Topical induction: Very slight to well-defined erythema with or without very slight oedema was noted at the induction sites of eleven test group animals one hour after dressing removal. Only erythema was noted for 4 animals at the 24-hour observation. No skin reactions were noted at the treatment sites of control group animals at the one and 24-hour observations.

 

(3) Topical challenge: Positive sensitisation responses, identified as very slight to well-defined erythema with or without very slight to slight oedema, were noted at the challenge sites of fourteen test four animals at the 24 and 48-hour observations. The skin reactions extended beyond challenge sites of five test animals on hour 24 post-application and four test animals on hour 48. Skin exposure to a test material concentration of 75 % showed skin reactions from very slight to moderate erythema and oedema for all test animals.

 

No skin reaction was observed at the challenge sites of control group animals at the 24 and 48-hour observations. Only a focal necrosis was noted for one control animal on hours 24 and 48 post-application.

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the test conditions of this study, the test material appears to be a strong sensitizer as it produced a 70% (14/20) sensitisation rate on guinea pig skin. Therefore, the active substance THPS 75% is considered as sensitizing to skin and classified into category 1A (H317) according to EU criteria. Based on these results, THPS100% is also considered as sensitizing to skin and classified into category 1A (H317) according to EU criteria.

Executive summary:

In a dermal sensitization study (GUEST, 1994), with THPS 75% in water, male albino guinea pigs (20 treated females + 10 controls) were tested using the US EPA Pesticide Assessment Guidelines, Subdivision F, § 81-6 in compliance with OECD 406, method B6 in Commission Directive 84/449/EEC and in compliance with GLP.

Based on the results of the pilot tests, the concentrations of test material were 0.1 % (w/v) and 25 % (v/v) for the intradermal and topical applications of the induction phase, respectively, and 50 % or 75 % (v/v) in the challenge phase. These concentrations expressed as main ingredient were as follows: considering a THPS concentration of 75 %:

- Intradermal induction:       0.1 %w/v of THPS 75 % = 0.75 mg/L,

- Topical induction:             25 % v/v of THPS 75 % = 26.1 mg/L,

- Topical challenge:              50 % v/v of THPS 75 % = 52.2 mg/L

Positive sensitisation responses, identified as very slight to well-defined erythema with or without very slight to slight oedema, were noted at the challenge sites of fourteen test animals at the 24 and 48-hour observations. The skin reactions extended beyond challenge sites of five test animals on hour 24 post-application and four test animals on hour 48. Skin exposure to a test material concentration of 75 % showed skin reactions from very slight to moderate erythema and oedema for all test animals.

No skin reaction was observed at the challenge sites of control group animals at the 24 and 48-hour observations.

Under the test conditions of this study, THPS appears to be a strong sensitizer as it produced a 70% (14/20) sensitisation rate on guinea pig skin. Therefore, the active substanceTHPS is considered as sensitizing to skin and classified into category 1A (H317) according to the criteria of the CLP Regulation (EC) N°1272/2008. Based on these results, THPS 75% (and also THPS 100%) are also considered as sensitizing to skin and classified into category 1A (H317) according to EU criteria.