Sodium phenoxyacetate hemihydrate

Endpoint summary

Description of key information

The substance is not a skin sensitizer.

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

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study with GLP.

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

yes

Remarks:

. modification according to Maurer and Hess

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

. modification according to Maurer and Hess

Principles of method if other than guideline:

The "maximisation test" of B. Magnusson and A. M. Kligman modified according to Maurer & Hess was performed to reveal a possible sensitising potential of sodium phenoxyacetate. The use of this test is justified by the fact, that a Local Lymph Node Assay LLNA can not be performed, as the test substance is poorly soluble in the solvents, commonly used for the LLNA. The same cause is the reason for choosing the modified test (Maurer and Hess) instead of the original GPMT.

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The "maximisation test" of B. Magnusson and A. M. Kligman modified according to Maurer & Hess was performed to reveal a possible sensitising potential of sodium phenoxyacetate. The use of this test is justified by the fact, that a Local Lymph Node Assay LLNA can not be performed, as the test substance is poorly soluble in the solvents, commonly used for the LLNA. The same cause is the reason for choosing the modified test (Maurer and Hess) instead of the original GPMT.

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, 88353 Kisslegg, Germany
- Age: Approx. 5 - 7 weeks at the first application
- Weight at the first application: Step 1: 306 g - 329 g. Step 2: 311 g - 345 g.

- Housing: Group caging in plastic containers (48 cm x 105 cm x 36 cm), partly shaded, 6 (control group) or 11 (test substance group) animals per container.
- Diet (e.g. ad libitum): Ssniff Ms-H (Guinea Pig Maintenance Diet V2233), including ascorbic acid (2400 mg/kg), ad libitum, offered in stainless steel containers. Analysis of the feed for ingredients and contaminants are performed randomly by ssniff Spezialdiäten GmbH, Ferdinand-Gabriel-Weg 16, 59494 Soest, Germany.
- Water (e.g. ad libitum): Tap water offered in Makrolon bottles with stainless steel canules ad libitum. Random samples of the water are analysed by the "AGES", A-1226 Vienna, to assure that the water fulfils the requirements for drinking water for humans.
- Acclimation period: 6 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Mean of 20.7 for step1, mean of 21.3 for step 2.
- Humidity (%): Mean of 39.5 for step 1 and mean of 38.9 % relative humidity for step2.
- Air changes (per hr): Approx. 12/h
- Photoperiod (hrs dark / hrs light): Only artificial light from 6.00 a.m. to 6.00 p.m.

IN-LIFE DATES: From: 23 November 2009, To: 11 February 2010.

Route:

epicutaneous, occlusive

Vehicle:

petrolatum

Concentration / amount:

50 % in white petrolatum.

Route:

epicutaneous, occlusive

Vehicle:

petrolatum

Concentration / amount:

50 % in white petrolatum.

No. of animals per dose:

The study was performed in two consecutive steps: In the first step 5 control and 10 test substance animals were used and as after the challenge exposure negative results were obtained, additional 5 control animals and 10 test substance animals were exposed. This procedure is in accordance with the guidelines.

Details on study design:

First induction exposure, commenced on Day 0:
Four separate intradermal injections of FCA, emulsified with isotonic saline (to enhance a possible sensitisation) were given at an area of approx. 2 x 4 cm in the interscapular region.
The injections were followed immediately afterwards by an epicutaneous application of the test substance, incorporated in white petrolatum (test substance groups) or plain white petrolatum (negative control groups) to the sites of the intradermal injections. Test patches (filter papers), 2 cm x 4 cm, with the test substance preparation (test substance group) or with the vehicle (negative control group), were applied. They were fixed with a strip of "Fixomull* stretch" (self adhesive non woven fabric, hypoallergenic, made by Beiersdorf AG, 20245 Hamburg, Germany).
The treated sites were covered occlusively with a Teflon ® - foil and kept in place and fixed with Guinea-Pig Jackets (Hugo Sachs Elektronik- Harvard Apparatus GmbH, 79232, March-Hugstetten, Germany).
24 h afterwards (Day 1) the jackets and the patches were removed.
Effects of the first induction exposure were checked by a skin examination 24 h after the end of the exposure period (Day 2).
On day 6, 24 h prior to the second induction exposure, the exposed skin sites were covered in all animals with a preparation of Na-dodecylsulfate, (E. Merck, 64271 Darmstadt, Germany, item No. 13760; approx. 0.5 g, 10 %, w/w, in white petrolatum), to produce a local hyperaemia.

Second induction exposure, commenced on Day 7:
At the site of the preceding injections of the first induction exposure, an epicutaneous application of the test substance, incorporated in white petrolatum (test substance groups) or plain white petrolatum (negative control groups) to the sites of the intradermal injections analogously to the first induction exposure.
48 h afterwards (Day 9) the jackets and the patches were removed.
Effects of the second induction exposure were checked by a skin examination 24 h after the end of the exposure period (Day 10).

Challenge exposure, commenced on Day 21:
The challenge exposure consisted of two separate epicutaneous applications, identically given to test substance and negative control group animals: One with a test substance preparation to the left flanks and one with the vehicle (white petrolatum) to the right flanks of all animals. Both exposed sites were apart from the exposure sites of the two induction exposures.
Test patches (now only 2 cm x 2 cm) and coverings were the same as in both induction exposures.
24 h afterwards (Day 22) the jackets and the patches were removed.
Effects of the challenge exposure were checked by a skin examination 24 h after the end of the exposure period (Day 23) and a second skin examination further 24 h later (Day 24).
Positive skin reactions of the test substance treated sites after the challenge exposure indicate a sensitising effect of the test substance, if the scores are higher than those of the vehicle treated sites and if the rate of those - positively reacting - animals is higher than the corresponding percentage of animals in the negative control group.

Challenge controls:

The challenge exposure consisted of two separate epicutaneous applications, identically given to test substance and negative control group animals.

Positive control substance(s):

yes

Positive control results:

The net rate of animals with a positive skin reaction, regarded as sensitised by hexyl cinnamic aldehyde was 70 %.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50 %. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: no.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no

Remarks on result:

other: Reading: 2nd reading. . 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.

All animals survived till the end of the study.

No effects of the test substance on body weights was derived from the data.

Immediately after the beginning of all epicutaneous exposures (inductions, challenge) the motor activities of all animals were decreased. This is due to the dressings which restrict the freedom of movement. Soon afterwards the behaviour was regular again. Except of the observations described above no abnormal behaviour or clinical signs were detected during the experiment in the animals.

Skin reactions after the intradermal FCA administration:

Cranial and caudal injection sites: Local irritations were observed in all animals beginning on the day after the injections. The irritations started with local erythema, which became more severe and led to ulcerations. Lesions did not heal until the end of the study. These local alterations are known effects of Freund's adjuvant.

Skin reactions after the first and the second induction exposure:

All animals of both groups had severe erythema and oedema in the interscapular region (score "3"), which were attributed to the effects of the adjuvant.

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Sodium phenoxyacetate is not a skin sensitizer according to the criteria in 67/548/EEC and 1272/2008.

Executive summary:

The "maximisation test" of B. Magnusson and A. M. Kligman modified according to Maurer & Hess was performed to reveal a possible sensitising potential of the test substance. Methods of the EC-directive 96/54, B.6. and the OECD-guideline 406 were applied. The study was performed in two consecutive steps. In each step a test substance group with 10 female guinea pigs and a negative control group with 5 female guinea pigs were used. The administered test substance concentrations were derived from the results of a preliminary test.

Two induction exposures were performed with a one week interval. First induction exposure: Intracutaneous injection of Freund´s complete adjuvant emulsified with isotonic saline (1:1) and epicutaneous administration of the test substance (50 % in white petrolatum). Second induction exposure: Preceded by a topical application of 10 % Na-dodecylsulfate in petrolatum for erythema induction 24 h before the epicutaneous administration of the test substance (50 % in white petrolatum). Control animals were given plain white petrolatum at both inductions.

Challenge exposure: Two weeks after the second induction exposure. Epicutaneous administration of the test substance (50 % in white petrolatum) and the vehicle (white petrolatum), was identical for the test substance group and the negative control group. For the epicutaneous exposures occlusive dressings were used.

Results of the challenge exposure: The control sites of all animals of both groups were normal at each reading time. After the challenge exposures, no animal of the test substance group had positive skin reactions at the test substance treated sites 24 hours and/or 48 hours after the end of the exposure. No adverse skin reactions were observed in the control animals. Therefore no animal of the test substance group was regarded as sensitised.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Migrated from Short description of key information:
Sodium phenoxyacetate was not sensitizing in an in vivo GPMT-test, modified according to Maurer & Hess.