Decanoic acid

Endpoint summary

Description of key information

Skin irritation/corrosion (weight of evidence of available studies): irritating

Eye irritation (weight of evidence of available studies including RA CAS# 124-07-2, C8): irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Human skin tissue samples were exposed to the test item for 24 h. Afterwards, in vitro skin corrosivity potential was evaluated via transcutaneous electrical resistance (TER) measurements.

GLP compliance:

not specified

Species:

human

Strain:

other: human mammary full-thickness tissue without subcutaneous tissue

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Controls:

other: concurrent control tissues treated with distilled water (negative control)

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 150 µL
- Concentration: 100%

Duration of treatment / exposure:

24 h

Observation period:

Not applicable.

Number of animals:

Not applicable.
Skin samples were obtained from 1 donor.
The test was performed in at least triplicates.

Details on study design:

SKIN PREPARATION
Waste full-thickness human mammary tissue was obtained after cosmetic surgery. The tissue was stored at -70 °C and thawed when required by placing in a refrigerator for 24 h. Subcutaneous tissue was carefully removed, ensuring that no damage occured to the dermis. Tissue with epidermis uppermost was attached to polytetrafluorethylene tubes using a rubber "O" ring and sealed with soft paraffin wax. As supporting electrolyte, magnesium sulfate solution (154 mM MgSO4 in distilled water) was used. 150 µL of the test substance was added to the epidermis of each skin disc for 24 h.

REMOVAL OF TEST SUBSTANCE
- Washing: The test substance was washed away with a controlled jet of water.

TRANSCUTANEOUS ELECTRICAL RESISTANCE MEASUREMENTS: After washing, tissues were treated briefly with 20 µL 70% ethanol. Subsequently, 3 mL electrolyte solution was added to the tissue surface before resistance measurements occured using an AIM 6401 Databridge (H. Tinsley, Croydon, England). Corrosivity to human skin was considered when the TER is reduced to below 11.0 kΩ.

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Remarks:

mean of at least 3 skin discs

Run / experiment:

24 h

Value:

29.9

Remarks on result:

other: tissue stored frozen before use; standard deviation: ± 5.4 kΩ/disc

Other effects / acceptance of results:

No decrease below 11 kΩ in the transcutaneous electrical resistance was observed in the human tissue preparation after 24 h exposure to decanoic acid. Thus decanoic acid is considered to be non-corrosive.

Interpretation of results:

other: non-corrosive

Conclusions:

Decanoic acid showed no corrosive potential in the in vitro transcutaneous electrical resistance test in human tissue samples.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Guideline 430 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER)) adopted April 2004

Deviations:

yes

Remarks:

A positive control is missing. The O-ring was sealed with soft paraffin instead of petroleum jelly.

GLP compliance:

not specified

Species:

rat

Strain:

Wistar

Type of coverage:

open

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

other: concurrent control tissues treated with distilled water (negative control)

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 150 µL
- Concentration: 100%

Duration of treatment / exposure:

24 h

Observation period:

Not applicable.

Number of animals:

Not applicable.
The test was performed at least in triplicates.

Details on study design:

SKIN PREPARATION
Full-thickness dorsal and flank tissue was obtained from humanely killed Wistar rats. The rats were aged 27 - 29 days and had been shaved of dorsal and flank hair when ages 22 - 24 days.

SUBSTANCE APPLICATION
Tissue with epidermis uppermost was attached to polytetrafluorethylene tubes using a rubber "O" ring and sealed with soft paraffin wax. As supporting electrolyte, physiological magnesium sulfate solution (154 mM MgSO4 in distilled water) was used. 150 µL of the test substance was added to the epidermis of each skin disc for 24 h.

REMOVAL OF TEST SUBSTANCE
- Washing: The test substance was thoroughly washed away with a controlled jet of water.

TRANSCUTANEOUS ELECTRICAL RESISTANCE MEASUREMENTS/ASSESSMENT
After washing, tissues were treated briefly with 20 µL 70% ethanol. Subsequently, 3 mL electrolyte solution was added to the tissue surface before resistance measurements occured using an AIM 6401 Databridge (H. Tinsley, Croydon, England). Corrosivity to rat skin was considered when the TER is reduced to below 5.0 kΩ.

Irritation / corrosion parameter:

transcutaneous electrical resistance (in kΩ)

Remarks:

mean of three tissue samples

Run / experiment:

24 h

Value:

14.2

Remarks on result:

other: Standard deviation: ± 5.6 (kΩ/disc

Other effects / acceptance of results:

The transcutaneous electrical resistance was not decreased below 5 kΩ after 24 h exposure to decanoic acid. Thus decanoic aicd is considered to be non-corrosive.

Interpretation of results:

other: non-corrosive

Conclusions:

Decanoic acid showed no corrosive potential in the in vitro transcutaneous electrical resistance test in rat tissue samples.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

17 Jul - 10 Sep 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

adopted 24 April 2002

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Commission Regulation (EC) No 440/2008, L142, Annex Part B

Version / remarks:

30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2400 (Acute Eye Irritation)

Version / remarks:

August 1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

BAYRISCHES LANDESAMT FÜR GESUNDHEIT UND LEBENSMITTELSICHERHEIT, LANDESINSTITUT FÜR ARBEITSSCHUTZ UND PRODUKTSICHERHEIT, München, Germany

Species:

rabbit

Strain:

other: New Zealand White Rabbits, Crl:KBL (NZW)

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: approx. 20 weeks
- Weight at study initiation: 3.5 - 4.6 kg
- Housing: Rabbits were housed individually in ABS - plastic rabbit cages with a floor of 4200cm²
- Diet: autoclaved hay and Altromin 2123 maintenance diet for rabbits, rich in crude fiber, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days
The animals were derived from a controlled full-barrier maintained bredding system (SPF).

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 ± 3
- Humidity (%): 55 ± 10
- Air changes (per hr):at least 10 x
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: 17 Jul 2011 To: 10 Sep 2011

Vehicle:

other: vaseline

Controls:

other: The untreated eye served as control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL
- Concentration: 70% (v/v)

VEHICLE
- Amount(s) applied (volume or weight with unit): 0.1 mL
- Concentration (if solution): 100%
- Lot/batch no. (if required): 1004025-01

Duration of treatment / exposure:

24 h

Observation period (in vivo):

up to 11 days
Reading time points: 24, 48 and 72 h and every 24 h for up to 11 days

Number of animals or in vitro replicates:

4 females (including 1 animal for the preliminary test)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The treated eye was rinsed with physiological saline 0.9% NaCl
- Time after start of exposure: 24 h

TOOL USED TO ASSESS SCORE: fluorescein

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 9 days

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

other: mean over 24,48 and 72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 6 days

Remarks on result:

other: evaluated after fluoresceine application

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible within: 11 days

Irritation parameter:

iris score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 6 days

Irritation parameter:

iris score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible within: 4 days

Irritation parameter:

iris score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 4 days

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 7 days

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 3 days

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1.67

Max. score:

3

Reversibility:

fully reversible within: 11 days

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

0.66

Max. score:

4

Reversibility:

fully reversible within: 3 days

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 6 days

Irritant / corrosive response data:

The test item produced irritant ocular effects after application in 3 animals.
Conjunctival rednesses, chemosis and discharge were observed in 3 animals.
Upon fluoresceine examinations, corneal lesions were determined in 2 animals after 72 h.

A 70% mixture of octanoic acid in vaseline induced lesions of the iris in 2 out of 3 tested animals with a score equal to 1. Therefore, the test item has to be considered as eye irritant at a concentration of 70%.

Other effects:

Neither mortalities nor significant clinical signs of toxicity were observed (table 2).

Table 2: Clinical signs of toxicity

 

	Time after application	Systemic findings	Local findings
animal 1	1 – 72 h	no specific findings	mild discharge
	4 – 6 days	no specific findings	slight discharge
	7 – 9 days	no specific findings	no specific findings
animal 2	1 h	no specific findings	mild discharge
	24 h	no specific findings	slight discharge
	48 h – 6 days	no specific findings	no specific findings
animal 3	1 h – 24 h	no specific findings	mild discharge
	48 h	no specific findings	severe discharge
	72 h	no specific findings	slight discharge
	4 – 5 days	no specific findings	no specific findings
	6 and 8 days	no specific findings	slight discharge
	9 – 11 days	no specific findings	no specific findings

Table 3: Absolute body weight (kg)

 

	animal 1	animal 2	animal 3
start of study	4.4	4.6	3.5
72 h post application	4.6	4.7	3.4
end of observation period	4.5	4.6	3.5

Interpretation of results:

other: Eye Cat. 2, H319 at a concentration of 70% according to Regulation (EC) No 1272/2008

Conclusions:

CLP: Eye irritation, Cat. 2, H319 at a concentration of 70%

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to the category justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 9 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

other: mean over 24,48 and 72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 6 days

Remarks on result:

other: evaluated after fluoresceine application; Source CAS 124-07-2

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible within: 11 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

iris score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 6 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

iris score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible within: 4 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

iris score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 4 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 3 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1.67

Max. score:

3

Reversibility:

fully reversible within: 11 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

other: mean over 24, 48 and 72 h

Score:

0.66

Max. score:

4

Reversibility:

fully reversible within: 3 days

Remarks on result:

other: Source CAS 124-07-2

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

other: mean over 24, 48 and 72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 6 days

Remarks on result:

other: Source CAS 124-07-2

Interpretation of results:

other: Eye Cat. 2, H319 at a concentration of 70% according to Regulation (EC) No 1272/2008

Conclusions:

Based on available read-across studies, decanoic acid is considered as an eye irritant.

Reference 3

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Only short abstract available

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: Regulation for the Enforcement of the Federal Hazardous Substances Act (Revised, Federal Register, September 17, 1964)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Title 49, Department of Transportation Code of Federal Regulation, Section 173, 240 (Federal Register, February 12, 1973)

Deviations:

no

GLP compliance:

no

Species:

rabbit

Strain:

not specified

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Duration of treatment / exposure:

single application

Observation period (in vivo):

72 h
Reading time points: 24, 48 and 72 h

Number of animals or in vitro replicates:

6

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1

Max. score:

4

Reversibility:

not fully reversible within: 72 h

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

>= 2

Max. score:

3

Reversibility:

not fully reversible within: 72 h

Irritant / corrosive response data:

Corneal opacity and moderate conjunctivitis was reported, which did not subside in 72 h. Decanoic acid was considered as eye irritant.

Reference 4

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: method not validated; insufficient for assessment (scoring scale does not comply with current regulations)

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Eye irritation was evaluated from the degree of corneal necrosis after exposure to different volumes and concentrations of the test item.

GLP compliance:

no

Species:

rabbit

Strain:

not specified

Vehicle:

other: undiluted and diluted in water or propylene glycol (not further specified)

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied: Various volumes and concentrations were applied including 0.5 and 0.005 mL undiluted test item and 0.5 mL of a 1% concentrated solution.

Duration of treatment / exposure:

single exposure, not further specified

Observation period (in vivo):

not further specified

Number of animals or in vitro replicates:

not further specified

Details on study design:

SCORING SYSTEM:
A 10-grade scale was used to describe the irritant potential of the test item on the eye.
Grade 1 indicates the presence of a very small area of necrosis induced by 0.5 mL of the undiluted test item; grade 5 describes severe burn from 0.005 mL of the undiluted test item and grade 10 indicates severe burn from 0.5 mL of a 1% solution in water or propylene glycol.

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: not specified

Score:

9

Max. score:

10

Reversibility:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin

Whittle et al. published results of two in vitro tests on rat and human skin using the transcutaneous electrical resistance test (1996).The experiments with rat skin were performed similar to OECD guideline 430 released in April 2004. 150 µL of decanoic acid was added to the epidermis of each freshly prepared rat skin disc for 24 hours. After washing, the resistance measurements were conducted and resulted in a TER of 14.2 kΩ. Since the TER did not decrease below 5 kΩ (threshold value for corrosion), decanoic acid is considered to be non-corrosive to rat skin.

In the experiments with human skin, human skin samples (waste material obtained from mammary cosmetic surgery, 1 donor) were also exposed to 150 µL of decanoic acid for 24 hours. Tissue treated with distilled water served as concurrent control. The test was performed in at least triplicates and resulted in a mean TER value of 29.9 kΩ. As no decrease below 11 kΩ (threshold value for corrosion using human skin) was observed, decanoic acid showed no corrosive potential in the in vitro transcutaneous electrical resistance test in human tissue samples.

In a study by Smyth et al. (1962) decanoic acid (mixed isomers) were applied to the rabbit skin for 24 hours.In the used 10-grade ordinal scale decanoic acid resulted in a score of 5 (grade 2 describes the least visible capillary injection from the undiluted chemical, grade 6 indicates necrosis from the undiluted test material and grade 10 from a 0.01% solution).

Taken together in a weight of evidence approach, decanoic acid is non-corrosive to skin, but should be considered as skin irritant.

 

Eye

No guideline-compliant study on eye irritation is available for decanoic acid. There are two non-GLP studies available using decanoic acid in rabbits.

In a published study performed according to national guidelines, decanoic acid was instilled into the eyes of six rabbits (Briggs et al., 1976). Corneal opacity and moderate conjunctivitis was noted, which did not subside in 72 h. Thus, decanoic acid was found to be irritating to eyes under conditions of this test.

Smyth et al. (1962) reported strong eye injury (score 9) after application of decanoic acid to rabbit eyes. In the 10-grade ordinal scale used, the grade 5 describes severe burn from 0.005 mL of the undiluted test item and grade 10 indicates severe burn from 0.5 mL of a 1% solution. Reversibility is not assessed.

Based on the limited data on decanoic acid, eye irritation effects are also predicted from adequate and reliable data for source substances by read-across to the target substance within the group applying the group concept in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006. In particular, the source substance structurally closest to the target substance is chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Thus a study with C8fatty acid (octanoic acid) is used for hazard assessment in regard to eye irritation.

The eye irritation potential by octanoic acid (CAS# 124-07-2) at a concentration of 70% was examined in a GLP study according to OECD guideline 405. 0.1 mL of 70% octanoic acid in vaseline was instilled into one eye each of 3 female New Zealand White rabbits (2011). The untreated left eye of each animal served as control. After 24 h the eyes were rinsed. The eye reactions were examined 24, 48 and 72 h after application and every 24 h thereafter for up to 11 days. Under the conditions of the test, a single ocular application produced irritant effects in the rabbits, which were fully reversible within 6-11 days. The mean scores for corneal opacity, iris, conjunctival redness and chemosis were 0.78, 0.66, 1.6 and 1 respectively. Since, in 2 out of 3 tested animals lesions of the iris with a score equal to 1 were induced, octanoic acid has to be considered as eye irritant at a concentration of 70%.

Taken together in a weight of evidence approach decanoic acid is considered as irritating to the eyes.

Justification for classification or non-classification

The available data on skin irritation/corrosion of decanoic acid meet the criteria for classfication as Skin Irrit. 2, H315 according to Regulation (EC) 1272/2008.

The availalbe data on eye irrition of decanoic acid meet the criteria for classification as Eye Irrit. 2, H319 according to Regulation (EC) 1272/2008.

 

Harmonised classification for decanoic acid (7th ATP; Index: 607-709-00-X): Skin Irrit. 2, H315; Eye Irrit. 2, H319