Sodium phenoxyacetate hemihydrate

Endpoint summary

Description of key information

The substance is not classified as irritant to skin and eyes.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Remarks:

in vitro

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A study according to the EU and OECD methods, including GLP.

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Deviations:

yes

Remarks:

Only 2 tissues could be used for the test substance; without affecting the validity of the test.

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)

Version / remarks:

Only the draft of the guideline 431 was available in 2009.

Deviations:

yes

Remarks:

Only 2 tissues could be used for the test substance; without affecting the validity of the test.

Principles of method if other than guideline:

The test consists of topical exposure of the neat test substance to a human reconstituted epidermis model followed by a cell viability test. Cell viability is measured by dehydrogenase conversion of MTT, present in cell mitochondria, into a blue formazan salt that is quantitatively measured after extraction from tissues. The reduction of viability of tissue exposed to chemicals in comparison to negative controls is used to predict skin irritation potential.

GLP compliance:

yes

Species:

other: In vitro test using human reconstituted epidermis.

Type of coverage:

open

Preparation of test site:

other: none

Vehicle:

other: Phosphate buffered saline (PBS)

Amount / concentration applied:

The application spoon was filled with 25 mg finely grounded test substance. The "spoonful" was levelled by gently scratching the excess material away, avoiding compression. 25 µL PBS were added for wetting of the tissue.
30 µL of each reference substance.

Duration of treatment / exposure:

1 hour.

Observation period:

MTT-test after a post-exposure period of 42 hours.

Number of animals:

3 tissue replicates were used.

Details on study design:

MatTek's EpiDerm System consists of normal, human-derived epidermal keratinocytes which have been cultured form a multilayered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDerm™ tissues (surface 0.6 cm2) are cultured on specially prepared cell culture inserts (MILLICELLs®, 10 mm Ø) and shipped as kits, containing 24 tissues on shipping agarose.

Negative control: distilled water.
Positive control: 5 % sodium dodecylsulfate (SDS).

MTT-test:
After incubation with the test substance, post-incubation and washing with PBS, the tissues were incubated with MTT medium at 37 °C and 5 % CO2. After 3 hours, the MTT medium was aspirated from all wells and the tissues were gently rinsed with PBS (2 times). For extraction, the tissues were incubated with extractant solution (isopropanol) for 2 hours with shaking.
After the extraction period, the tissues were pierced with an injection needle and the extract (now a blue formazan solution) was allowed to run into the well from which the tissue was taken. The 24-well plates were placed on a shaker for 15 minutes until the solutions were homogeneous in colour.

Cell viability measurement:
Per each tissue 2 x 200 µL aliquots of the blue formazan solution were transferred into a 96- well flat bottom microliter plate and the optical density (OD) was measured using the extractant solution as blank in a plate spectrophotometer at 570 nm, without reference filter.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1

Value:

69

Vehicle controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

2

Value:

87.7

Vehicle controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The tissue viabilities of 69.0 and 87.7 % (mean: 78.4 %) for the test substance indicate "no irritation".

Assay acceptance criteria:

• The mean OD 570 of the negative control tissues is≥1.0 and≤2.5. Actually obtained for water: 1.569.

• The mean tissue viability of the positive control is≤20 %. Actually obtained for 5 %-SDS: 10.5 %.

• The standard deviation calculated from individual percentual tissue viabilities of the 3 identically treated replicates is <18. Actually obtained for the test substance treated tissues: 13.2.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: expert judgment

Conclusions:

Under the experimental conditions of this study, the test substance is considered to be 'non-irritant' to skin.

Executive summary:

The EpiDerm Skin Irritation Test (Model EPI-200) was performed to reveal possible irreversible tissue damages of the skin following the application of sodium phenoxyacetate. The test substance was topically applied for 60 minutes to the epidermal surfaces of three­ dimensional human epidermis models. After a post-incubation of 42 hours, a cell viability test was performed.

Investigations performed were in conformance with the EC-method B.46 "In vitro skin irritation: Reconstructed Human Epidermis Model Test" and the draft OECD Guideline "In vitro Skin irritation: Reconstructed Human Epidermis (RhE) Test Method".

The mean percentage viability of the treated skin discs was 78.4 % which is above the threshold of 50 % for classification. According to the results of this study and the Directive 2001/59/EC, sodium phenoxyacetate is considered to be non-irritant to skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A study according to the EU and OECD methods, including GLP.

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Charles River Germany
- Age at study initiation: ca. 9 weeks.
- Weight at study initiation: 2.2 - 2.8
- Housing: single caging
- Diet: SNIFF K-H ad libitum
- Water: Tap water ad libitum
- Acclimation period: >= 7 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): ca. 20
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

Equivalent to 0.1 mL: 49 to 50 mg.

Duration of treatment / exposure:

Once.

Observation period (in vivo):

1, 24, 48, 72 h and 7 d p.a.

Number of animals or in vitro replicates:

3.

Details on study design:

Prior to starting the eye irritation/corrosion study the pH-value of the test substance was determined. Substances with a pH < 2.0 and pH > 11.5 need not to be tested for acute eye irritation/corrosion.
Firstly, the test substance was administered to one animal. As no evidence for a serious damage to the eye of this animal was found during the initial 72 hour observation period (no corrosive effect), the test substance was administered to the other two animals subsequently.

The approximate equivalent of 0.1 mL of the test substance was administered per animal into the conjunctival sacs of the right eyes by gently pulling the lower lids away from the eyeballs for instillation. The eyes were held closed for about one second to prevent a loss of test substance. The weighed amounts of the individual doses were 49, 49 and 50 mg. The left eyes remained untreated and served as a control.
The whole eyes, especially the corneae, the irises and the conjunctivae were examined, using an otoscope lamp.

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 24, 48, 72 h, and 7 d

Score:

0

Max. score:

0

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 24, 48, 72 h, and 7 d

Score:

0

Max. score:

0

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: 24, 48, 72 h

Score:

1

Max. score:

1

Reversibility:

fully reversible within: 7 d

Remarks on result:

other: A discharge was observed at 1 h p.a. in animal 1.

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

other: 24, 48, 72 h

Score:

0.7

Max. score:

2

Reversibility:

fully reversible within: 48 h

Remarks on result:

other: Score 4 was observed at 1 h p.a.

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

other: 24, 48, 72 h

Score:

1

Max. score:

1

Reversibility:

fully reversible within: 7 d

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

other: 24, 48, 72 h

Score:

1

Max. score:

1

Reversibility:

fully reversible within: 7 d

Other effects:

No signs of systemic toxicity were observed in the animals during the test period and no mortality occurred.
The untreated eyes ("control eyes") were normal at each observation time.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Cornea and iris were not affected by the test substance. The conjunctiva showed slight redness and chemosis at 24, 48 and 72 h p.a. which was fully reversible at 7 d p.a.

Executive summary:

Eye irritation was investigated according to the EU- and ORCD-methods. The approximate equivalent of 0.1 mL of sodium phenoxyacetate was instilled into the conjunctival sac of one eye of each of 3 New Zealand White rabbits. Results:

Corneae and irises: Not affected at any observation point.

Conjunctivae, redness: In all animals some injected blood vessels (score 1) were observed from 1 or 24 h onwards until 72 h p.a.

Conjunctivae, chemosis: Swelling (scores 1, 2 or 4) was seen in all animals 1 h p.a., decreasing in severity with time and lasting until a maximum of 72 h p.a.

Additional findings: Ocular discharge was noted in 1/3 animals only 1 h p.a.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Justification for selection of eye irritation endpoint:
Only slight effects, not justifying a classification were observed.

Effects on eye irritation: slightly irritating

Justification for classification or non-classification

Skin: An in vitro skin irritation test does not indicate a skin irritation potential of the test substance.

Eye: Only slight effects, not justifying a classification were observed.